Models1492 and 2092

SERVICE MANUAL

2 YEAR LIMITED WARRANTY

This product is warranted by CERONIX to be free of defects in materialand workmanship for a period of two years from the date of purchase.

In case of a fault, developed during this time, it is the customer's responsibility to transport the defective unit to CERONIX orone of the authorized service centers for repair. Please attach a note describing the problem. All parts and labor are free of charge during the warranty period.

CERONIX 12265 Locksley Lane Auburn, CA. 95602-2055 (530) 888-1044

This warranty does not cover mechanical breakage due to physical abuse.

CERONIX shall not be liable for any consequential damages, includingwithout limitation damages resulting from loss of use. Some states do not allow limitation of incidental or consequential damages, so the limitation or exclusion may not apply to you.

This warranty gives you specific rights and you may also haveother rights which vary from state to state.

The information contained in this manualis subject to change without prior notice.

COPYRIGHT 1988, 1990, 1998

CERONIX

All rights reserved.

Recognized under the Component Programof Underwriters Laboratories Inc. andthe Canadian Standards Association.

©

®

®

This manual is specifically written to aid the service technician, repairingCERONIX Models 1492 and 2092 color monitors.

There are three main sections: 1. General Description. 2. Circuit Description. 3. Solutions to Problems.

To understand how the Monitor works, it is best to know what eachcircuit does and how each circuit relates to the other circuits.The Block Diagram is presented in a simplified view and a comprehensiveview to accomplish the goal of understanding the whole unit.Once the general picture is clear, the complexity of each circuit will be easierto understand.

The Circuit Description is also written in two views, a simplified view and a detailed view to help give the reader a clear understanding of what each component does. This understanding is most helpful for the morecomplex problems or multiple problems that sometimes occur.

The Trouble Finder section is made up of an index, which listssymptoms of problems, and a list of possible solutions. Part of this sectionalso deals with setting up conditions which make it easier to trouble shootspecific circuits such as the power supply.

ABOUT THIS MANUAL

INTRO-DUCTION

BlockDiagram

BLOCKDiagram

Schematic CircuitDescription

ProblemSolving Tools &

Examples

AppendixA

VideoInterfaceprograms

1

Description

TABLE OF CONTENTS

About This Manual. 1CERONIX Models 1492 and 2092 Electrical Specification. 3 & 4Drive Signals to the Monitor Input voltage and waveforms, work sheet. 5

2

Equipment setup for repairing the Model 1492 Monitor. 47Problem Solving Tools. 48

Block Diagram Review. 31Auto Bias and Auto Bright Circuit, Function, Description. 32Auto Bias and Auto Bright Circuit Description. 33Auto Bias and Auto Bright Schematic. 34Vertical and Horizontal Sync Circuit Description. 35Vertical Deflection Circuit, Function, Description. 36Vertical Deflection Circuit Description. 37 & 38Horizontal Deflection Circuit Description. 39 & 40Horizontal Raster Width Control Circuit Description. 41Horizontal Raster Width and Position Control Schematic. 42Simplified Power Supply Circuit, Function, Description. 43Simplified Power Supply Circuit Description. 44Switch Mode Power Supply Circuit Description. 45Switch Mode Power Supply Schematic. 46

Replacement PARTS LIST. 25 & 281492 and 2092 Main Board ASSEMBLY DRAWING. 29 & 30

Video Interface Circuit Description. 16 & 17Video Interface Schematic. 18Video Amplifier Circuit, Function, Description. 19Video Amplifier Circuit Description. 19 & 20Socket Board, Degaussing Circuit, and Legend Description. 21Blanking and Master Gain Circuit, Function, Description. 22Blanking and Master Gain Circuit Description. 23Blanking and Master Gain Schematic. 24

1492 and 2092 Monitor SCHEMATIC 14 & 15

1492 and 2092 Simplified Block Diagram. 6

Description

Block Diagram

Blocks A-D 7Blocks E-G 8Blocks H-L 9Blocks M-Q 10Blocks R-U 11Blocks V-Y 12

Video Section Description. Auto Bias and Socket Board. Blanking, Sync, & Vertical.Horizontal Deflection & Remote. Horizontal Size & Power Supply.Power Supply Continued.

- - - - - - - - - - - - -

- - - - - - -- - -- - -

- - - - - - - -

1492 and 2092 Monitor BLOCK DIAGRAM. 13

VideoSocket Board

Blanking

Circuit &Function

Description

Master Gain

Circuit &Function

Description

Auto Bias

Auto Bright

Sync

Vertical

Horizontal

Power Supply

Appendix A --- Setup and Convergence Procedure. 49Appendix B --- Video Interface Programs. 50 to 55Appendix C --- Resistor Array Layout for; B, C, G, H, I, & J. 57 & 58

1.8K

C. 4 Line TTL

CERONIX MODELS 1492 and 2092 Electrical Specification

INPUTSStandard Video Configurations, available, are:A. Positive Analog

Black levelSaturated colorSource

only

SourceandMonitor

Black levelSaturated color

To Amp.Video

Gnd

.6mA

Monitor

1492 & 2092Min. Typ. Max

3.1V 3.2V 3.3V

.06V .09V

0V 0V .05V

.15V

1.61V 1.69V 1.75V

B. Negative Analog

D-A

VideoSource

Video

Gnd

VideoSourceD-A

Black levelRed & GreenBlue Black levelSaturated color

5.4V 5.6V 5.8V4.85V 5.05V 5.25V.7V .9V 1.1V

+12VTo Amp.

BIAS

VB

R,G,BVideo

Intensity

Black levelColor on

Low intensityFull intensity

0V .2V .5V2.7V 3.5V 6.0V

0V .2V .4V4.5V 4.6V 4.8V

VideoSource

No pullup resistor on intensity line.*

*

Note: RS170 and other voltage combinations optional for analog video.

1.

The Sync signals may be of either polarity and separate or composite.2.

SyncSource .15V

1.8K

220 2 PL

High input voltageLow input voltage

Horizontal sync pulseVertical sync pulse

Horizontal frequency

Vertical frequency

2.2V 3.5V 20V-2.7V .30V .80V1.5uS 4.5uS 31uS

15.3KHz 15.6KHz 15.9KHz

120uS .5mS 1.5mS

60Hz 65Hz45Hz 50Hz

For composite sync, vertical and horizontalsync lines are connected together.

Hs

Vs

3.Model 1492 Model 2092

Min. Typ. Max. Min. Typ. Max.85VAC

170VAC 230VAC290VAC230VAC 290VAC180VAC

90VAC 115VAC 145VAC115VAC 145VAC

32W 44W 60W 30W 50W 67W

115VAC 50Hz or 60Hz230VAC 50HZ or 60Hz

Power

The Power to the monitor is to be supplied by a secondary windingof an isolation transformer.

To Amp.

905

INRVBlk.+.7 V

Gnd

Gnd

3

301Ω

Ω

Ω,

301Ω

Monitor

Monitor

Monitor

4. The remote Controls are located ona separate PCB for easy access.

H SIZE--------------Horizontal raster sizeV SIZE---------------Vertical raster sizeV RAS. POS.-----Vertical raster positionH POS-------Horizontal picture position*M GAIN---------------------Master gain

Model 1492 Model 2092

9.9" 11.4" 14.8" 16.3"6.3" 10.3" 10.0" 14.0"0" .44" 0" .60"

.9" Right 2" Left 1.2 right 2.8" left

Min. Max. Min. Max.

LightScreen

DarkScreen

DarkScreen

LightScreen

* For start of horizontal sync 1.7uS after end of picture.Focus on the flyback transformer and an optional Horizontal hold control.The board Controls are located on the main PCB, and are:

5. Picture

Min. Typ.

Max.Min. Typ.

Max.Model 1492 Model 2092

Rise timeFall time

OvershootBand width

Horizontal blank timeVertical blank timeHorizontal linearity

Vertical linearityPincushion

Video response is measured at thetube socket, using low capacitancecoupling. The input signal shouldbe fully damped and faster than the expected response.

35nS 44nS 49nS 37nS 46nS 52nS32nS 42nS 47nS 35nS 44nS 50nS0% 0%0% 0%2% 2%

DCDC to to 8MHz8MHz12.9uS 13.4uS12.4uS

20H20H20H20H 1.28mS1.28mS

1%1%

1%

1%1%1%

2%2%

2%2%

2%

2%

6. Picture tube Model 1492 Model 2092InchInch mmmm

13 328 20 50810.83 275 16 406.68.13 206.5 12 304.8

.015 .39 .029 .74Useful area

Useful horizontalUseful vertical

Useful diagonal

Spacing between dot/line trios

PixelsPixelsPixels

PixelsPixelsPixels680 550

240240480480

90°90°46% 46%

Horizontal resolutionVertical resolution

InterlacedDeflection angle

Light transmission at center of glass Approximately Approximately

CRT also features: Enhanced contrast, Internal magnetic shield, andX-Ray output Less than .3mR/hour.

7. Environmental Operating temperatureStorage temperature

Operating humidityStorage humidity

0° C 0° C 70° C70° C85° C85° C -20° C-20° C

20%20% 80%80%10%10% 95%95%

4

12.9uS 13.4uS12.4uS

86 558 192 1,239

DRIVE SIGNALS to the MONITOR INPUTvoltage and waveforms, work sheet.

CERONIX 12265 Locksley Lane Auburn, CA, USA 95602-2055

Company name: Date:Drive signal source Model number:

VIDEO: For the following measurements use an oscilloscope.

the black level voltage is:the saturated color voltage is:

RED GREEN BLUE

If available, sketch the video drive circuit on the back of a copy of this form.

Horizontal or composite sync:Horizontal frequency: Hz "High" voltage: VHorizontal sync pulse time: uS "Low" voltage: V

Compare your sync tothis table and checkthe best fit.

For composite sync.

Sketch if different.

Vertical sync:Vertical frequency: Hz "High" voltage: VVertical sync pulse time: uS "Low" voltage: V

Check correct polarity.

Complete form and send to: CERONIX, 12265 Locksley Lane If there are any questions, call (530) 888-1044.

The "Drive Signals To The Monitor Input" form is included here for those people who haveproblems interfacing their drive electronics with the Ceronix Monitor.

With no load the black level voltage is:With no load the saturated color voltage is:

With 301Ω loador otherTo GND, or tovoltage V.

load.Ω

5Auburn, CA. 95602-2055

1492 and 2092 Simplified Block Diagram

This block diagram gives a broad view of the circuit organization ofthe 1492 and 2092 monitors. The blocks with the bold outline representcircuits that are quite different than most other monitors.

The auto bias circuit is designed to actively compensate for picturetube and circuit drift which normally cause the color balance to becomeunbalanced and also brightness variation. This circuit eliminates the needfor the color setup procedure.

The horizontal size control circuit permits the horizontal size to beadjusted from a remote control board instead of a coil on the main board.It is also used to compensate for pincushion distortion and acts as ananti-blooming circuit by correcting for horizontal size variations whichare caused by the additional load on the flyback transformer under high beam current conditions.

The 1492 and 2092 power supplies differ from most other monitorsbecause of their high efficiency switching mode power supply. It is not difficult to troubleshoot if the techniques presented in this manual areclearly understood. Careful reading of all the information presented in this manual will make trouble shooting of the CERONIX monitor no more difficultthan any other monitor and maybe even easier.

6

VIDEOOutput

GAME

SYNCOutput

InterfaceVIDEO

Blanking

VIDEO Amps.

AUTO BIAS

Vertical Deflection

Horizontal Deflection

CRT

FBT

Horizontal Size Control

POWER SUPPLY

RemoteControls

IsolatedPower

The Beam Current Buffer converts the, high impedance low current, beamcurrent signal into a low impedance voltage. This voltage is applied to theauto bias IC through a 200 ohm resistor. After the three lines of beamcurrent are measured, the program pulse from the auto bias IC, produces avoltage drop across this 200 ohm resistor that equals the amplitude of thebeam current voltage.

A

B

C

D

Refer to the block diagram on page 13 (foldout) when reading this description.

7

The Video Interface is designed around a custom IC and will accept positive or negative analog video signals and also 4 line TTL. This IC also has a built in multiplier circuit for the master gain control and blanking.Resistors are used to protect the IC and to set the gain. The programmed gain is dependent on the input signal amplitude except on TTL. Solder jumpers are used to program the Video Interface for the type of input signal to be received. The output of the IC drives the video amplifiers. This drive is a current where 0 mA is black and 4.5 mA is a satur`ted color.

The Video Amplifiers are of the push pull type. They are built partly onthick films and partly on the PCB. Spreading out the amplifier reduces thecomponent heat and improves the life of the unit. The bandwidth is 8 MHzwith 60Vp-p output. The rise and fall times are .04uS.

The Beam Current Feedback circuit directs most of the beam current of eachamplifier to the beam current buffer. The only time this current is measured by the auto bias circuit is during the time of the three faint lines at the top of the screen and three lines thereafter. The auto bias circuit is designed to adjust thevideo amplifier bias voltage such that the beam current of each of the three guns isset (programmed), at this time.

The aging of the picture tube (CRT) not only affects the balance of the cathode cutoff voltage, which is corrected by the auto bias circuit, but it also affects the gain of the CRT. The Auto Bright circuit actively corrects for CRT gain changes by sensing any common bias change from the auto bias circuit and adjusts the screen voltage to hold the average bias voltage constant. The lower adjustment on the flyback transformer is used to set the auto bright voltage to the center of its range. This sets up a second control feedback loop to eliminate picture variation due to the aging of the picture tube.

8

E

F

G

The Auto Bias IC is a combination of digital and analog circuitry. The digital part is a counter and control logic which steps the analog circuits through a sequence of sample and hold conditions. The analog part uses a transconductance amplifier to control the voltage ona 10uF capacitor (one per gun). This voltage is buffered and sent to thevideo amplifhers as the bias voltage. In monitors without auto bias, thisvoltage has to be set manually using a setup procedure to set the colorbalance. With the auto bias, the color balance is set during the end of eachvertical blanking time.

The control sequence is:

The CRT is a 90° deflection type color picture tube with a 25KV EHT and has integral implosion protection.

After the grid pulse is over, the program pulse matches the voltage from the beam current buffer. If the voltage from the beam current buffer, during the grid pulse, is the same as thevoltage from the program pulse, the bias is correct and no biasadjustment is made for that vertical cycle.

Auto bias IC outputs a reference voltage at its input pin which sets the voltage across the coupling capacitor. This coupling capacitor voltage is directly dependent on beam current.

1.

2.

3.

Grid pulse on G1 causes cathode current (3 lines top of screen)which is transmitted by the beam current feedback to thebeam current buffer where it is converted to a voltage andapplied to the auto bias input pin.

The aging of the picture tube (CRT) not only affects the balance of the cathodecutoff voltage, which is corrected by the auto bias circuit, but it also affectsthe gain of the CRT. The Auto Bright circuit actively corrects for CRT gain changesby sensing any common bias change from the auto bias circuit and adjusts the screen voltage to hold the

H

I

J

9

The Vertical Auto Bias circuit greatly increases the range of the bias circuit built into the LA7851. It is made up of a negative peak detector and an amplifier which outputs current to the normal bias circuit, but with a much lower frequency response.This then eliminates the need for adjustments during production and permits the useof 50Hz and 60Hz vertical sync with only a size adjustment on the remote control board.

Blanking is accomplished by setting the gain of the interface IC to zero duringblank time. The Horizontal Blanking pulse is generated by amplifying the flybackpulse. The Vertical Blanking pulse is started by the vertical oscillator and ended by the counter in the auto bias IC via the "bias out" pulse. The Master Gain control,located on the remote PCB, sets the gain of the video signal when blanking is notactive. The Beam Current Limiter circuit, which is designed to keep the FBT fromoverloading, will reduce the video gain if the average beam current exceeds .75mA.

The Sync Interface can be made to accept separate or composite sync. Twocomparators are used to receive sync, one for vertical sync and the other forhorizontal sync. Resistor dividers are used to protect the comparator IC fromover voltage damage.

1. Vertical sync circuit.2. Vertical oscillator.3. Linear ramp generator.4. Output control and bias circuits for controlling the power driver.

The Vertical Control circuit consists of:

The active components that make up these circuits, except for part of the bias circuit,are located in the deflection control IC (LA7851). The vertical sync circuit is capableof accepting either positive or negative going sync pulses without adjustment. The vertical oscillator in the LA7851 is set at 45 Hz and will sync up to 65 Hz without adjustment. The deflection yoke is driven with a linear current ramp whichproduces evenly spaced horizontal lines on the raster. This linear ramp is generatedby supplying a 1uF capacitor with a constant current. The vertical output voltage isheld within range (biased) by a timer which partly discharges the 1uF ramp capacitorat the start of vertical retrace. The duration of the timer is controlled by the verticaloutput voltage and the vertical auto bias circuit.

K

K

The Horizontal Control incorporates a variable sync delay and a phase locked loop to generate the horizontal timing. The H POS. adjustment on theremote control board sets the sync delay time which controls the picture position.The phase locked loop uses the flyback pulse to generate a sawtooth wavewhich is gated with the delayed sync pulse to control the horizontal oscillator.

M

N

O

10

P

Q

1. H SIZE ----------- Horizontal raster size --------- Diode modulator 2. V SIZE ----------- Vertical raster size ------------- Vertical drive3. V RAS. POS. --- Vertical raster position ------- DC current to V. yoke4. H POS ------------ Horizontal picture position -- H. sync delay5. M GAIN ---------- Master gain ---------------------- Video interface

The Remote Control PCB houses the:

CONTROL DESCRIPTION CIRCUIT

The main function of the Flyback Transformer (FBT) is to generate a 25,000 volt (EHT) potential for the anode of the picture tube. This voltagetimes the beam current is the power that lights up the phosphor on the faceof the picture tube. At .75mA beam current the FBT is producing almost 19watts of high voltage power. The FBT also sources the focus voltage and thefilament power. The FBT has a built in high voltage load resistor whichstabilizes the EHT, for the low beam current condition. This resistor alsodischarges the EHT, when the monitor is turned off, which improves thesafety of handling the monitor.

The Horizontal Output transistor is mounted to the rear frame which acts as a heat sink. The collector conducts 1,000 volt flyback pulses which shouldnot be measured unless the equipment is specifically designed to withstandthis type of stress. A linear ramp current is produced in the horizontalyoke by the conduction of the horizontal output transistor (trace time). A fast current reversal (retrace time) is achieved by the high voltage pulsethat follows the turn off of the horizontal output transistor. This pulse is due to the inductive action of the yoke and flyback transformer.

The Horizontal Driver supplies the high base current necessary to drive thehorizontal output transistor which has a beta as low as three.It also protects the horizontal output transistor since it is a transformer andcannot keep the base turned on for longer than its inductive time constant.

The Horizontal Size Control circuit has four inputs:

11

R

S

T

U

The Switching Regulator is synchronized to the horizontal pulse and drives a power MOSFET. Unlike most regulators that have a common GND, thispower supply has a common V+ and current is supplied from V- to GND.The MOSFET is connected to V- and signal ground (GND) through atransformer which is used as an inductor for series switchmode regulation.An operational amplifier, voltage reference, comparator, and oscillatorin the power supply controller IC are used to accomplished regulation bymeans of pulse width modulation.

1. To improve the efficiency of the power supply.2. To permit 120 volt and 220 volt operation. For the 220 volt operation the voltage doubler is replaced with a bridge rectifier.

A Voltage Doubler is used in the power supply for two reasons:

The Diode Modulator is a series element of the horizontal tuned circuit.It forms a node between GND and the normal yoke return circuit. If this node is shorted to GND, maximum horizontal size is present. A diode is used to control the starting time of the retrace pulse at this node. The reverse conduction time is dependent on the forward current because thecurrent waveform at this node has to exceed the forward current in the diode. A diode, placed in series with the yoke, is then used to control the retrace pulse amplitude across the yoke. The horizontal size, therefore, is controlled bycontrolling the current to this diode via the horizontal size control circuit.

The horizontal size control circuit sums the four signals at one node toproduce the diode modulator control voltage.

# SIGNAL FUNCTION1. Horizontal size ---------------------- Horizontal size control2. Beam current ----------------------- Blooming control3. Vertical linear ramp ---------------- (#4)-(#3)=Vertical parabolic4. Vertical parabolic + V. linear ramp (Pincushion)

The transformer has two taps on the main winding which are used togenerate the +16 volt and +24 volt supplies. It also has a secondary which is referenced to V- and supplies the power supply. Since the power supply is generating its own power, a special start up circuit is built into the powersupply controller IC that delays start up until its supply capacitor ischarged up enough to furnish the current to start the power supply. This capacitor is charged with current through a high value resistor from the raw dc supply. This is why the power supply chirps whenan overload or underload occurs.

The Load consists of the video amplifiers and the horizontal flyback circuit.The power supply will not operate without the load since the voltage thatsustains the power supply comes from a secondary in the power transformer and depends on some primary current to generate secondary current.

12

V

W X&

Y

The Over Voltage Protect circuit is built into the power supply and monitors theflyback transformer peak pulse voltage. This circuit will turn off the powersupply and hold it off if the EHT exceeds its rated value. This circuit not onlyprovides assurance that the X-ray specifications are met but also protects themonitor from catastrophic failure due to a minor component failure.

A separate +12V regulator for the video and the deflection circuits are used in thismonitor to minimize raster and video interactions. This also simplifies PCB layout,since the video GND loops are separate from the deflection GND loops.

13

1492 & 2092 Monitor Block Diagram

SYNC

VIDEO

GAME

CRT

H

V

VERTICAL

CONTROL

CONTROLVERTICAL

OUTPUT

HORIZONTAL H.H.

REMOTECONTROLS

HORIZONTALSize Control

DIODEModulator

FBT

LOADISOLATIONTransformer DOUBLER

VOLTAGE

SWITCHINGREGULATOR

Raw DC320V

+127V

-200V

Driver Output

3

Interface

DY

DY

G

sV

I. V. Feedback High Efficiency

EHT

J

Hs

H. Pos.

V. Size &V. Ras. Pos.

PINCUSHION

Sync delayM

N O

(PCB)

P

Q R

(IN GAME)

S

Beam Current

(VIDEO & DEFLECTION)

U

+16V

+27VRegulator+12V Video

SupplyT

Sync

OVERVOLTAGEPROTECT

DeflectionSupply

V

W

X

+12VZener

2

V-

VIDEOVIDEOAMPS.

BrightAuto

AUTO BIASSYNC IC

Bias

BLANKING

Interface

F.B.P.V retrace

Beam limitM. gain

H. blankV. blank

Program pulseGrid pulse

Beam currentbuffer

3 3

33

3

2

3

A BC

E

F

H

I

D

3

VERTICALAUTO BIAS

L

Y

BeamCurrentFeedback

K

Optional

12

4.67K

7

7

GND

10

GND

10

+12V

1 6 9 107 84 52 3

6800pF

13

13

8

10

1K 1/2W

425

150Ω 1/2W

390Ω, 2W

311

431

++

+

414412403

422

405413

418

432

416

420402

415

424

209

433195

180

237

182

236

I11

304

234

157

293314

309

312

203 178

172

184

G4 G5

167

162

G17

G1

G2

171161

164

G16

G15 168

G14

G11

278

315 307

305 310

308

306

297

CERONIX 12265 Locksley LaneAuburn, California 95602-2055

SCALE:

DRAWN BY:

DATE & REV.NONE

CERONIX MODEL 1492 MONITOR CIRCUIT

2.7uF

1N4937

630V.022uF

0ΩG13

44.2K

2.2K

470Ω,1/2W

.01uF16K

LM3241/4

LM3241/4

750uH316

38.3K

*

6.8K

LM3241/4

10K

10K6.8K

.1uF

50KG10

100K163

.01uF.047uF

2

31

1214

4

11

LM3241/4

1.82K

G12

28K

16612K 8.87K

.33uF

10K 5K

10K

300

3,300pF

1N4005

1N4005

.01uF1.5KV

G310K

1K36K

CPT1500

FR205FR205

2,200pF

100Ω2SD1651

Horizontal Drive

VERTICAL

YOKE

.01uF

+1,000uF 35V

100K2SC3675

200K

47Ω47Ω

.015uF 250V

407

408

410

406

404

411

FDH400 1K 1/2W

1K 1/2W

100K 1/2W

10K 1/2W

.68Ω1/2W470Ω

1K 1/2W

330pF 4,700pF

EHT

GND

FIL.

*

GRID PULSE

RED

GREEN

BLUE

8

6

11

10 9 5 7 1

Socket BoardPCB 428

10

968

73

2

45

1

FLYBACKTRANSFORMER

2SC3467

2SC4159E

201

10uF+

5

6

423 421417

TC1

TC2

TC4

TC3

TC10

TC6

8

H11DEFLECTION

1K

YC1

YC2

433HORIZONTAL YOKE

GND

RAS. POS.0 TO 7 VDC

V

2

134

12.7VDC33V 63uS

NO DVM1KV 63uS

GND

19

20

18

19

GND

+127V

V-

270Ω, 2W

D

+6V

071

064 066

070

063065

PN2222MPSA64270Ω

750Ω 10uF

62K

Beam current limiter circuit.

GND

303

EHT

FOCUS

SCREEN

FIL.

FIL.

BeamCurrent

+12V

127VDC150V 300V

MAX. MIN. H. Size

250V.47uF

6VDC17mS4V 6VDC

3V 17mS

Blooming correction.

Pincushion correction.

7.15K

YC3

YC4

89

5G6

G7

10K

220K

6

4

3

1 13

18 1715 16

20

19

8VDC 22V

MAX. MIN. H. Size4V 12Vp-p

2SC4159E

FDH400

FDH400

+

165 298

2.2K1/2W

HEATSINK185

186

1/8/88

1/16/88

2ED0114-EDRAWINGNUMBER

HSIZE

GND

+6V

183

7

8

4

19

2, 12

G9

14

VERTICAL LINEARITY

No.

LTR.No.

X-Y VDCX-Y V

X-Y VDCTIMEVp-p

WAVEFORM

X X

LEGEND

BOARD PART No.PART No. ON PRA.PRA PIN No.

DC VOLTAGERANGE, USING

A DMM.

AC VOLTSPeak to Peak

CYCLETIME

Measured with scope

3/11/88

5/21/88

3.4-4.2VDC

5.7-6.3VDC

16.3-17.8VDC

OUTPUT

1

2

4

3

1516

14

5

6

7

8

12

11

10

9V-+7.5V REF.

XRC5184

Osc.

Rx

Cx

CurrentSENSE

DRIVE

CONTROL &FAULT SENSE

+15V+17V

INPUT

INPUT

INPUT

ERRORAMP.

COMP.

Output

OverVoltageProtectINPUT

+COMP.4uS

DELAY

280

282

SMXFR

D11

13

9

10

8

12

14

15

7

6

5

4

16

17

18

19

1

2

3 20

21

22GND Vcc

Red Red

GND

CA3224E

AUTO BIAS IC

+4.2V

+10V

200Ω

68.1K

200Ω

68.1K

200Ω

68.1K

.047uF

.047uF

.047uF

.1uF

.1uF

.1uF

153

77

176

080

078

C1

C16

152

33K

116

117

118

120

121

122

C2

C13

C3

C8

144.1uF

126

141

127

123

142

125

143

147251

215 262 131 261

263

260

258248 266

285

287

291J9

290

271J10

J11 J12

275

273

J3

274

J4

275

252

253

256 247

276

255

254

J6

286

277288

240

241

245

292

J8

270

283

284

265

2642,200pF

MPSA641N4005

18Ω

510Ω

14.7K 15.8K

1.2Ω 150Ω

200pF

2SK1446LS

1.00M

38.3K1,000

pF

191K

.1uF

FR205FR205

1N4148

11K

56K

6,800pF 56pF

10.6K

23.2K

1.8K

56pF

100K2SA1371E

++ 1,000uF1,000uF

FR205

FR205

.1uF

FR205

150uF

250V

250V90K

100K

100uF

330pF

6,800pF

J7

33.2K

1.00M

268

33K

10uF

10uF

10uF

33K

33K

CurrentLimit

Inrush

25-.5Ω

22K

1/4LM324

146

1.8K

12K

PN2222

2 1PCPC

10

9

8.1uF

1K

295

317 294TZ160B-T3160V Zener

+27V

+16V

+127V

150uF250V

.1uF250V

GNDGND

14.8-16.3VDC

3

1

594

2

+127V

6-7VDC

3.6-4.4VDC6V 63uS

5.3-5.7VDC

63uS.10-.17VDC

1V

63uS2.4-3.6VDC14V

3.5-4.1VDC3-4V 63uS

.1-.5VDC

.5-.8VDC

6.5-7.5VDC

6.5-7.5VDC

POWER SUPPLY VOLTAGES REFERENCED FROM V-

V- V-

NOTES:

SCOPE GND MUST NOT BE CONNECTED TO GND AND V- AT THE SAME TIME.

0VDC48V 63uS

244

BF5ROM125

CC1

CC2

1312

17 18

16

J PRA PINS:

220Vo

220Vo

1/2WCUTFOR220Vo

150uF

8,14

246

C-200

115VACINPUT

6

GND

+127V

V-296

.022uF

148150

.1uF 22K

2.5-6.7V

2.5-6.7V

2.5-6.7V

4.6-5.2VDC

1.9-2.3VDC4V 17mS

8.0-9.0VDC8.4V 17mS

6.3-7.7V

.1-

.3V

1.2-2.5V

5.8-6.4V

.5-.8VDC .7V 17mS

1.2-2.5V

1.2-2.5V

5.8-6.4V

5.8-6.4V

7

5

4

6.8K

HEATSINK

GND267

238

20KC5

comp.

inputholdcap.

comp.

holdcap.

comp.

holdcap.

sw.

sw. in grid pls. pos.

sw.

sw.

normal

6V Ref.

V. RETRACE

StartCounter

FF

CL

Q

EN21 H. LineCounterCLDecoder

5V Ref.

BIAS

AutoBias

Active

PROGRAM

PULSE

GRIDPULSE

sw. controlHB

20

9

2

4

5

72,9

8

1

3,10,15, & 19

Green input

Blue input

Green

Blue

GND

7

5

TTL

909Ω

301Ω 301Ω301Ω

RVC4 5

VCG

1N4005

4

16

1.65K

1.8K

B16

B15B14

B13

B11

B10B9

B8B6

B5

93B

92B

91B

90B

88B

87B86B

Red Video Amplifier

Green Video Amplifier

392Ω

539Ω

1.27K

40.2K

606Ω NE592

3.78K

790Ω 836Ω

.1uF

1.2K

270Ω

1N41482SA

1370

66

510

510B22

81B

82B

83B

84B

89B

.015uF

1000pF

FDH400

2SA137027

32

180

68K

2SC3467

1.8K

1.8K

B1

B2

B3

B4 B7

B17

B19

B20

096

13

1214

10

7

8

5

SOT

3.32K

.1uF

19

18

15

3

2

5 14

20

Blue Video Amplifier

81R

81G

1N4148

604Ω

75Ω

301Ω

12.1K 340Ω

6

BVC

1N4148

464Ω

75Ω

301Ω

12.1K 340Ω

1N4148

604Ω

75Ω

301Ω

12.1K 340Ω

.1uF095

1.21K

1.62K097

100MPS A64

098D

4K

6,800pF

4K

6,800pF

4K

6,800pF

2 1 14 15 7 8

BoRo Go GAINMTTL+ ENABLB

GNDControls XRC5346A

INBGINRIN RR RG RB

Y

3.92K 3.92K6.8K 15.8K 62K

GND+12V

VERTICAL BLANKING

1N4005 1N4005

REDINPUT

GREENINPUT

BLUEINPUT

HORIZONTALSYNC

+10V

GND

VC2

VC1

Hs VsVERTICALSYNC

VC0

4 LINETH

GND

GND

270Ω

270

1K

4.42K

1.8K

1.8K

2.7K

270Ω050047

046

045

048

67

1/2LM393

1/2LM393

061

154

051

005 027 002

004 026 001

021 043 011

010041022

020 042 012025

052

023 024 034 037 008

038 035 031

030 033 017016 013 003

015

055

054 056 057040

C6

1/2

B00

3.3pF

B12

5.62K

1uF+

2.7K

+12V

I101

1113

18

1415

16

Vo

3

20 19 18 17 16 14 13 12 11

15

16

14,6

4

7

GND

1 4

15

13

12

GND

OUT IN7812

130

128

+16V

.1uF

X-RAYPROTECT

DISCHARGEHORIZONTALOSCILLATOR

H. V+Horizontal

SYNC INPUT

PICTUREPOSITION

O/S

DELAYEDSYNC O/S SAW TOOTH

GENERATORTR .

V+GND

± SYNC INPUTVERTICAL VERTICAL

OSCILLATOR V Ref.RETRACE &BIAS O/S

9.31K

1K33K10K

1uF+

.01uF6,800pF

45K8.8K22K

12K

0Ω

100uF

225

173

I2

I3 I12

I7 I8 I9

232231233

230

228I6

I1

224

216

175068

485

484

483

206 200

H17

VERTICAL

H6

210

H7223

H9 H8

218

LA7851

481

482

486

0Ω

193

3.3Ω

10K

500Ω

750Ω

20K

1K208

330pF

.047uF

4.75K4.99K1N4742

330Ω76.8K

127K

22K

.1uF

0Ω

1K

10uF

100uF

198

56pF 1.8K

VERTICAL DRIVE

INPUT

GND

POWERAMPLIFIER

LA7830VERTICAL 192

+12V

1K

MasterGain

HorizontalPosition

VerticalRaster

Position

VerticalSize

HorizontalSize

Remote ControlPCB 490

2

VERTICAL OUTPUT

Vo

22-25VDC25V 17mS

5 6 7

205196

191204

56pF

1,000pF200Ω, 2W

470uF,50V

RETRACEBOOSTER

COMP.

+

1N4005190

1.2VDC25V 17mS

22-25VDC1V 16mS

+27V

0Ω160

+127V GND

V-

+27V

.36-.4VDC

.6V 63uS.16-.23VDC

5V 17mS5.8-6.5VDC

4V 17mS

5.7-6.6VDC4V 17mS

VERT.OSC.

187

.047uF

7.2-8.1VDC5V 63uS Reverse

Hs

+12V

GND

3.6-4.1VDC 3.2VDC 5.9VDC 6.3VDC1.6V 63uS63uS 63uS 63uS 63uS

2.9-3.4VDC 5.7-6.3VDC 5.9-6.4VDC4V

5.3-6VDC7.5V.2V0V

.1-.3VDC1.4V4.4V

6,10

9

25K 330pF1,000

pFI5 227226

7.9-8.5VDC4.4V 63uS 63uS

8.2-9VDC

6-6.4VDC

11.5-12.5V

.7-1.2VDC

.9V 17mS3.0-3.8VDC 3V 17mS

or

.7-1.0VDC

.9V 17mS

RetraceBooster

RC8

RC6

RC5

RC3

RC2

058

+12V

GND

+12V

GND

RC1RC4

HEATSINK

188

RC7

Vs

Hp5,2

2

7

3Hs H.Fo ADJ.

20

17

comp.+-

VIDEO GAIN LINE

18Ω

13

13

13

3

3

20

20

11

11

8

8

7

7

6

6

156

1.8K

1N4148

HORIZONTALBLANKING

1N4148

107

105

112 197

106

6.8K 1K .01uF

104

PN2222

200Ω 412Ω1.62K

S T U

J K N L OM

G H I.1uF

A B

P

D E F

INPUT

053

PN2907

LM3241/4

111C15

C12

C14

C11

110

LM3241/4

C9108

C10

C4

C7

1.82K

2.74K

103 145101

GND

FBP

B18

270

+

+10V

133

137

134

136

124

138

LM393

155

6.8K 6.8K

1.8K

132

1351.8K

.047uF1.8K

22K

+12V

20

8.0-9.2VDC

WITH GRID

4uS1-2V

1.8-2.3VDC

124-126VDC

Dark screen80-112VDC

85Bacross

1.5-2.4V

8

8

8.9-9.8VDC

WITH GRID

4uS 1V

7.4-8.4VDCGND

GND

1N414813

2

4

8 6

+12V

3.0-3.8VDC 3V 17mS

1.82K

6.4-7.5VDC8V 63uS

0VDC47V 63uS

1.62K

15

18

14

5

6

3

2

1

12

13

14

13

12

17

16

19

20

062

1

3

2

7

6

5

8

4

1N4148102

129

1.8K

PN2907

139

2.7K

.1uF060

11.5-12.5V

GND

+12V

.14-.16V

036

A- BL

16 13 5 123X Q R

9 6 11

*

2.7K

094.1uF

032

9

1.9-2.3V

Hs

Bias Control Line

11

+127V

5K

5K

5K

11

10

146

340Ω 340Ω340Ω

0Ω

17

1

4

11/12/90

FR205

C

9

8

7

6

5

4

3

2

1

0

9

8

7

6

5

4

3

2

1

0

BBAA CC DD EE FF GG HH II JJ KK LL MM NN PP RR

BBAA CC DD EE FF GG HH II JJ KK LL MM NN PP RR

044018 014

007

+

+12V

LM393

+

1/2

LM3241/4

8

17mS

Ω

ΩΩ

Ω

Ω

Ω

Ω

8

275281.01uF

J1193K

250

1

20

DC

2.33K

J13 J14

-1.5V -3V

J2

J5

J16

J15

260Ω

130Ω

+3V

+1.5V

B

A

235

+200Hz

+400Hz+800Hz

FG

340Ω680Ω170Ω

2.05K

6.8K

I13D

E

I16

I14

I15

HL ZHR

HORIZONTAL RASTER ADJ.

.1uF069

62K

65A

H2H1174

0Ω 330Ω330Ω1

8

H18

H3

200K

84K

500KH19

C

B

-9Hz

+9Hz

118K

.068uF

34K

9

17

18

.01uF

11

202

1uF

H5

301Ω10

207

H4

220

H10

+12V

GND

10uF

1K

H25

H12

1N4148H2088K

200K

H13

H16H1522K 22K

22KH24 H14

H23

H22

39063904

18

181

12.4 TO 14V17mS42V

11

15

Ω

FRAMEGND

FG

+

+

+

+

+ +

18Ω

248A

+ 100uF

+6V LINE

302

68uHH. Lin.

220uH301

WidthH.

209268uH301

2092.33uF305

209222K167

209236K166

H. Pincushion

Parabolic Linear

9

20920Ω405

F. H.

4.2-8.2VDC5-10 17mS

257

Transformer

8VDC 23V

MAX. MIN. H. Size70V 250V 63uS

20928.2nF306

1K 1/2W

1K1/2W

249

*

0 VDC17mS2-4V

0Ω289

166A

159

1.8K

169

179

3.3K

CRT

1/2W 1/2W

62K

H. Width Adj.

BIASMULTIPLIER

I4

VC3

GND

2.2nF

254A

2.2nF

254A

279

239FUSE3A

209228K203

1514

2/12/98

246Dual Posistor Optional.

In the positive analog mode, a bias current flows to the input which is set by resistorat the +Analog Enable input. This current produces a voltage, across the parallel resistance of the (game and ) plus resistor , at the IC pin 2. Without this bias current the black level input voltage to the C5346 would be 0V and resistor would not be needed. With a bias resistor of 15.8K, the bias current is .6mA. If the external source resistance is 300 ohms, the black level voltage at pin 2 is .27V. A black level voltage of .3V is set by resistor divider , to compensate for the bias current voltage drop. The input termination resistor reduces video line ringing and sets a dark screen when the video input connector is disconnected. The saturated color is the highest input voltage. There are two standard, saturated color, voltages available: 1.6V connected and 3.2V connected.

VIDEO INTERFACE CIRCUIT DESCRIPTION (+ & - Analog)

The video interface circuit is a general purpose RGB type input circuit. This circuitconnects the external video signal to the video amplifiers. It can accept positive goinganalog, negative going analog, and 4 line TTL. The particular mode of operation isselected by placing solder bridges on the foil side of the PCB. The solder bridge patternsare given in appendix A. Simplified video interface circuit:

In the negative analog mode, the video signal has a black level which is the -A BL voltage.This voltage is normally 5.6V and may be set to 5.1V by adding solder connection .The saturated color is the lowest input voltage (.9V-1.1V). To prevent input line ringingfrom exceeding the saturated color voltage limit, a clamp diode has been added.The current amplitude to the video amplifiers is defined by resistors & and the master gain voltage.

21 18

7.5V BIAS LINE

MASTER GAIN&BLANKING

+12V

200 3.6K

2

3

16

12R,G,&BVIDEO INPUTS

1. NEGATIVE GOING ANALOG MODE.

MG

1821

2.2V

20

C534636

RED channel shown

-Analog Black Level (-A BL)

J

232104

21

7.5V BIAS LINE

MASTER GAIN &BLANKING

+12V

200Ω 3.6K

2

16

12

+ANALOG ENABLE

R,G,&BVIDEO INPUTS

2. POSITIVE GOING ANALOG MODE.

MG

11

+12V

3

33

15.8K

23

24

12.1K

340Ω04

301Ω

C534636

RED channel shown

301Ω

J

38

23 2404

Connections Installed

ALWAYS NORMALLY

Q & Y S & X

20

Connection InstalledALWAYS NORMALLY

Y D,E,F,G,H,I,J,K,L,P, & T

M

340Ω

33

16M

301Ω 604Ω

Ω

R

Saturated Color (1V)

Black Level (5.6V)

16 R

62K

6.3V

Saturated Color (1.6V or 3.2V)

Black Level (.27V)

VIDEOAMPS

VIDEOAMPS

0575Ω

AD

Refer to the video interface schematic to the right for the following component description.Both the blanking and the gain control is accomplished by the Master Gain line to the video interface IC (C5346 pin 12). Resistors , , , , & 94 provide fiveprogrammable voltages for setting the max. MG voltage. The video gain is also affected by each of the input modes. Resistors , , , , , and set the video gain for the -Analog mode and provide protection to the video interface IC inputs in the+Analog and TTL modes. Resistors and modify the blue video response in theAnalog mode. The video gain, for the +Analog mode is set by resistors , , , , , , , , and . The TTL video gain is set by resistors , ,and . In the +Analog mode, G , H , AND I are bridged to reduce the offset voltagecaused by the bias current. Also, input termination resistors , , and are used to improve input line matching. In the TTL mode resistors , , and may be 1K &programmed in. A clamp circuit is used in the -Analog mode to reduce the effect of line ringing. Resistors and provide a reference voltage which is buffered by PNP transistor ,load resistor , capacitor , and applied to diodes , , and to perform this clamping function. P is bridged to reference the clamp to GND for the +Analog and TTLmodes. Resistor is used to set the -Analog black level lower than 5.6 volts. If the -Analog black level is set below 4.9 volts, both resistors & are used tooverride the chip resistor tolerance. The black level for the blue channel may be increasedfor all modes by connecting resistor . The C5346 has, built in, separate circuitsfor each of the three input modes. These modes are selected by bridge points Q & Y .

In the 4 line TTL mode the red, green, and blue video lines will pass color when high.The intensity of the color is set by the fourth TTL line. Saturated color is displayed whenthe intensity line is high or open, and when it is low, the displayed color is half intensity.Although the R, G, and B lines are logic lines, the intensity line is an analog line.To insure full saturated color, the TTL driver to the intensity line should have no other loads. The, 1K to GND, input resistor on the color lines may be installed to keep the screen dark whenno video input cable is connected. The logic 0 voltage at the input is 0 to .4V @ .6mA. The logic 1 voltage at the input is 2.7V to 5.5V @ -2.1mA with the 1K pulldown and .6mA without.

Connections Installed

+12V

7.5V BIAS LINE VIDEO

MASTER GAIN &BLANKING

+12V

200 3.6K

2

16

12

+ANALOG EN. &TTL

R,G,&BVIDEO INPUTS

3. 4 LINE TTL MODE.

MG

11

5

33

15.8K

18 21

04

905

C534636

03

15

133.92K 3.92K

1.87K

GND

+12V

2.7V

RED channel shown

1K (Optional)ALWAYS NORMALLY

None

INTENSITYINPUT

VIDEO INTERFACE CIRCUIT DESCRIPTION (TTL)

ΩΩ

P, & TA, B, C,

AMPS

17

021 018 043 044 011 014

023 024

034 037

038

035 007 031 003

015

055054 056 057

030014

004 026 001

005 027 002

050 051 053

052 025 020 042 012

016

016

017

030 036

094

008 013

Master Gain line (MG)ToVideo Amps.

P.S.

18

VIDEO INTERFACE SCHEMATIC

10

TTL

909

301 301301

RVC4 5

VCG

4

1.87K

1N4148

604

75

301

12.1K 340

6

BVC

1N4148

464

75

301

12.1K 340

1N4148

604

75

301

12.1K 340

2 1 14 15 7 8

BoRo Go GAINMTTL+ ENABLB

GND

Controls C5346

INBGINRIN RR RG RB

Y

3.92K 3.92K6.8K 15.8K 62K

GND+12V

REDINPUT

GREENINPUT

BLUEINPUT

HORIZONTALSYNC

VC0

4 LINETH

GND

1.00K

4.42K

050

051

005 027 002

004 026 001

021 043 011

010041022

020 042 012025

052

023 024 034 037 008

038 035 031

030 033 017016 013 003

015

055

054 056 057

040200 412

1.5KS T U

J K N L OM

G H I.1uF

A B

P

D E F

INPUT

053

PN2907

1.62K

2.7K

.1uF060

GND

+12V

036

A- BL

16 13 5 123X Q R

9 6 11

*

2.7K

094.1uF

032

340 340340

C

044018 014

007

+12V

Ω Ω Ω

Ω Ω Ω

Ω Ω Ω

Ω Ω Ω

Ω Ω

ΩΩ

Ω

Ω

FRAMEGND

FG

Ω Ω Ω

4.2-8.2VDC5-10 17mS

The control circuit for the video amplifier is located on the B PRA (B precision resistor array).The B PRA includes all the resistors and the NE592. All of the parts labeled Rxx , xxG , and xxB , are components located on the circuit board, which are part of the red,green, and blue video amplifiers.

The video amplifier's stability and precise response to the input signal comes from a combination of the geometric layout of the B PRA and the high frequency response of the NE592.The NE592 stabilization capacitor B00 is an integral part of the B PRA conductor layout.Resistor B 4 is used to boost the NE592 drive current to the PNP transistor 87B .The NE592 bias circuit, at the input side, consists of B 5 , B6 , and B 9 .The negative feedback bias resistors are, B11 , B10 , and B 12 with B 17 as theoutput feedback resistor. Resistors B19 and B20 are connected to solder pads which, when bridged, permit the 1492 B PRA to be used on the models 1490 and 1491 monitors.

The NE592 gain is set by resistor B8 . The drive signal from the NE592, B22 pin 7,is coupled to the base of the NPN transistor 83B through an impedance matching resistor B2 .This drive is also coupled to the base of the PNP transistor 87B via a coupling capacitor 82B .The NE592 output voltage range is 6V to 10V, which is the reason for the 7.9 volt NPN bias line.The 7.9 volt bias line is generated by buffering a voltage divider, formed by resistors 97 and 100 , with a PNP darlington transistor 98 . A capacitor 9 5 is connected to shunt the high current spikes to GND. This line is common to all three video amplifiers.

The AC current gain is set by resistor B3 for the NPN output transistor and by B13 for the PNP output transistor which is AC coupled via a capacitor 84B . On a positive output transition of the video amplifier, the current of the PNP transistor can go as high as 32mA and on a negative transition the current drops to 0mA

VIDEO AMPLIFIER CIRCUIT, FUNCTION, DESCRIPTION

The video amplifier, is a high speed push pull amplifier, which can swing as much as 92 volts.The maximum dynamic output swing is limited to 60 volts. The rest of the output voltage range is reserved for bias adjustment.

SIMPLIFIED VIDEO AMPLIFIER CIRCUIT:

+

+7.9V lineFrom Auto Biascontrol output

C5346

+12V

B5

B6

B9

B11

B10

NE592

B17

B12

B14

B182B

B15

87B

83B

B3

+127V

270Ω 66Ω

27Ω

68K.015uF

40.2K1.65K

836Ω

392Ω

606Ω

790Ω 5.62K

VIDEOINTERFACE

2SA1370

2SC3467

The voltage swing at the output is 60 volts for a 4.3 mA current signal from the C5346.For this same 4.3 mA current signal the voltage swing at the video amp. input is 1.32 volts and the -input voltage swing at the NE592 is .75 volts. The reason for using the voltage matching resistor B6 is that the C5346 minimum output voltage is 7.7 volts, and the bias voltage at the NE592 input is 5.3 volts.

VIDEO AMPLIFIER CIRCUIT DESCRIPTION

19

1

14

7

The video amplifier's output voltage, With no input signal, is the black level which is the picture tube cut off voltage. This voltage is set for each of the three videoamplifiers by the auto bias circuit. This black level voltage has a range of 80V to 112V.

xxG xxBxxRBxx

B0087B

B5 B6 B9B11 B10 B12 B17

B19 B20

B4

B8 B2283B

87B 82B

097095098

B1384B

B3

100

B6

B2

R G BGND

16

1.65K

B16

B15B14

B13

B11

B10B9

B8B6

B5

93B

92B

91B

90B

88B

87B86B

392

539

1.27K

40.2K

606 NE592

3.78K

790 836

.1uF

1.2K

270

1N41482SA

1370

66

510

510B22

81B

82B

83B

84B

85B

.015uF

1000pF

FDH400

2SA1370

27

32

180

68K

2SC3467

2.2K

2.2K

B1

B2

B3

B4 B7

B17

B19

B20

096

13

1214

10

7

8

5

SOT

3.32K

.1uF

19

18

15

3

2

5 14

20

Blue Video Amplifier

.1uF095

1.21K

1.62K097

100MPS A64

098D

B00

3.3pF

B12

5.62K

13376

B18

270+12V

20

8.0-9.2VDC

WITH GRID

4uS1-2V

1.8-2.3VDC

124-126VDC

Dark screen80-112VDC

85Bacross

1.5-2.4V

8

8

8.9-9.8VDC

WITH GRID

4uS 1V

7.4-8.4VDCGND

+12V

BIAS CONTROL LINE

11

+127V

17

1

4

Ω

Ω

Ω

ΩΩ

Ω

Ω

Ω Ω

Ω

Ω

Ω

Ω

VIDEO INTERFACE VERTICAL andHORIZONTAL

BLANKING,Master Gain, &Beam limiter

MG

VIDEO SOURCE (external)

For low output distortion, the PNP transistor is biased with a 6 mA current. The NPN transistor and resistor B 17 conduct the PNP bias current to GND. Diode 86B balances the PNP base to emitter voltage. Resistors B1 and B14 set the voltage across B 15 which define the video amplifier output stage bias current. A quick way to check this current, is to measure the voltage drop across the 510 ohm 85B . The permissible voltage range is listed on the schematic as 1.5-2.4V. The PNP and NPN collector resistors B16 and 85B help stabilize the amplifier and provide some arc protection. Resistor B 18 is used to decouple the video amplifiers from the +127V line. Capacitor 96 is used to decouple the +12 volt lineclose to the video amplifiers. If this capacitor or the 7.9V line capacitor 095 is open, the video may be unstable and distorted. Resistor B7 is the auto bias output load resistor.

If there is a problem with the video, first check the output waveform of the video amplifier, with the oscilloscope, if ok the problem is not in the video section. If not ok, check the input waveform at B PRA pin 8, if not ok there, check the video interface, If ok at the video amplifier input, refer to this section to help with analyzing the video amplifier problems.

20

VIDEO AMPLIFIER SCHEMATIC

+12V

PART OFAUTO BIAS

GND

+12V

86BB1 B14 B15

85BB16 85B

B18

B7095

096

B17

The primary function of the socket board is to connect the main board to the CRT and toprotect the main board against arc related voltage spikes which originate in the CRT. The tube socket has built in spark gaps which direct part of the arc energy to thetube ground (aquadag) through a dissipation resistor 403 . The remaining high voltage from an arc is dropped across current limit resistors: Resistors 404 , 406 , and 411 anddiodes 407 , 408 , & 410 protect the video amplifiers by directing the arc energy tocapacitor 414 . Since arcing does not normally occur in rapid succession, capacitor 414is left to discharge by the leakage current of diodes 407 , 408 , & 410 and zener diode 412 is not normally used. The grid pulse transistor is protected by a low pass filter made up of resistors 422 & 425 and capacitor 423 . The auto bright transistor 417 is protected by resistors 416 & 420 and by a low pass filter comprised of resistors 413 , 418 , & 415 and capacitor 421 . Resistors 402 & 424 reduce the arc energy from the tube ground to signal GND. The current gain of the auto bright control loop is set by resistor 420 . The filament current is fine tuned by resistor 405 . The degaussing coil 432 is energized when power is turned on. It then rapidly turns off due to the heating of posistor 244 .

432

SOCKET BOARD , DEGAUSSING CIRCUIT, AND LEGEND DESCRIPTION

241

245

3A FUSE

2 1PCPC 115VAC

INPUT 238

244

CC1

CC2

No. Represents the 1492 board part number. The parts list gives the CERONIX PART NUMBER which is indexed to the board part number.

LTR.No. Part numbers of the resistors on the PRA indicated by LTR.

X X PRA pin number. To determine which PRA the pin numberbelongs to, look for the nearest PRA part number on that line.

X-Y VDC

X-Y V

DC voltages are measured to GND except in the power supplywhere V- is the reference. Use a DVM for DC measurements.

CAUTION: When making measurements on the power supply be sure that the other scope probe is not connected to GND.

TIME is the cycle time of the waveform.The waveform is normally checked with a oscilloscope.

Vp-pIt has a P-P voltage amplitude ofX-Y VDC

TIMEVp-p

WAVEFORM .

Legend Description

21

12

GND

1K 1/2W

425

431

414412403

422

405413

418

416

420402

415

424

100K2SC3675

200K

47Ω 47Ω

.1uF 250V

407

408

410

406

404

411

FDH400 1K 1/2W

1K 1/2W

100K 1/2W

10K 1/2W

.68Ω1/2W470Ω

1K 1/2W

330pF 2,200pF

EHT

FIL.

*

GRID PULSE

RED

GREEN

BLUE

8

6

11

10

9 5 7 1

Socket BoardPCB 428

423 421417

TC1

TC2

TC4

TC3

TC10

TC6

8

FDH400

FDH400

20920Ω405

1K 1/2W

1K1/2W

EHTFOCUSSCREEN

FIL.FIL.

FBT

BF5ROM125

No.

LTR.No.

X-Y VDCX-Y V

X-Y VDCTIMEVp-p

WAVEFORM

X X

LEGEND

BOARD PART No.PART No. ON PRA.PRA PIN No.

DC VOLTAGERANGE, USING

A DMM.

AC VOLTSPeak to Peak

CYCLETIME

Measured with scope

414

406 411 404403

407 408 410

407 408 410

414

412422 425 423

413 418 415416 420

402421 424

420405

244432

417

BLANKING AND MASTER GAIN CIRCUIT, FUNCTION, DESCRIPTION

Blanking in this monitor is accomplished by reducing the video gain to zero during thevertical and horizontal blank time. During video time, the gain is set by the mastergain control which is located on the remote control PCB. If the overall beam currentexceeds .75mA for more then ten frames, the beam current limiter circuit will reduce thevideo gain to protect the FBT.

SIMPLIFIED GAIN CONTROL CIRCUIT:

The video P-P voltage amplitude at the cathodes, is the video input signal amplitude times the master gain control setting times the video amplifier gain. The gain select resistors set the maximum video gain via the master gain line. For a greater range of brightness,(highlighting) the video system is allowed to supply high peak video currents which coulddamage the FBT if sustained. The beam current limiter circuit insures that the long term maximum beam current is not exceeded.

Horizontal blanking is achieved by amplifying the flyback pulse (FBP) with transistor 104 . Vertical blanking starts as soon as the LA7851 starts the vertical retrace sequence and is terminated by the auto bias, bias active signal. A comparator is used to sense the vertical bias O/S, at pin 16 of the LA7851, which goes low when vertical retrace starts. Capacitor 132 holds the vertical blanking active, between the vertical bias O/S pulse, and the bias active pulse. When the bias active line goes high, the capacitor 132 is reset and vertical blanking ends, after the bias active line returns to it's high impedance state.

+2V

+VideoAmp.

+7.5V

+12V

One of three input circuits.

C5346

+12V

0VDC47V 63uS

FLYBACK PULSE SIGNAL CONDITIONING CIRCUIT 104

PN2222

MASTER GAIN

HORIZONTAL BLANKING

132

.047uF

134

1N4148

+3LM3931/2 1

2

+

LM3931/2 7

VERTICAL BLANKING

6+2V

D

+6VBEAM CURRENT LIMITER

beam currentFrom FBT

Total

ToCRT

VIDEO INTERFACE

200Ω3.6K

1K

485 58

1K

10uF

66

MPSA64

6365

PN2222

155

36

GAIN SELECT RESISTORS

VIDEO GAIN LINE

132

132

104

BIAS ACTIVE

Vertical Bias O/S5

22

HIGH Z

The master gain control 485 is connected to the video gain line through a 1K resistor 58 . The voltage range of the video gain line is programmable via resistor 094

and solder bridges at S , T , & U which may connect resistors 54 , 55 , 56 , and 57 to the video gain line. This arrangement permits a variety of input signals andpicture tubes to be used with the same monitor PCB.

Horizontal blanking ( ) is added to the gain line by transistors 104 . This transistorpulls down on the gain line through diode 102 when the flyback pulse is high. Capacitor 197 is charged by diodes 105 , 106 and resistor 112 such that, as soon asthe flyback pulse starts going positive the NPN transistor 104 turns on and horizontalblanking starts. The time constant of capacitor 197 and resistors 112 and 107 ischosen such that the capacitor will lead the FBP on the downward slope and turn thehorizontal blanking transistor off just at the end of the FBP.

Vertical blank time is started when a low going pulse from the LA7851 pin 16 causesthe output, pin 7, of the dual comparator 155 to go low. Capacitor 132 is dischargedthrough resistor 135 at this time. After the end of the LA7851 pulse, the capacitor 132

holds the output, pin 1 of the comparator, low until the bias active pulse recharges thecapacitor 132 through diode 134 . During the high time of the bias active pulse, thesecond comparator output is still low, because of the voltage drop across the diode 134 .The end of vertical blank time occurs when the bias active line returns to it's highimpedance state. The capacitor 132 holds the charge from the bias active pulse until thenext vertical blank time. The video gain line will source up to 32mA during blank time, which is the reason forbuffering the vertical blank comparator with a PNP transistor 139 and E-B resistor 129 .Resistors 137 and 138 supply a voltage that is midrange relative to the LA7851 pulsefor maximum noise immunity. Resistors 133 and 136 also supply another midrangevoltage for the bias active pulse and the, vertical blanking, hold capacitor to work against. Resistors 124 and 156 are used as jumpers.

The beam current limiter circuit uses the base to emitter voltage of a darlingtontransistor 65 to set the maximum beam current. The beam current is converted to avoltage across resistor G17 . This voltage is applied to a long time constant RC circuit,resistor 70 and capacitor 66 , before it is sensed by the darlington transistor. Resistor 65 A has been added to protect the darlington transistor from arc energy. The sharpness of the limiting response is set by resistors 64 and 71 . Transistor 63 then, reduces the video gain by pulling down on the master gain lineupon excessive beam current.

BLANKING AND MASTER GAIN CIRCUIT DESCRIPTION

23

HB

66

485

54 55 56

57

58

104

102

105 106 112

104

197

197 112 107

155 132

132

132 134

135

134

132

129139

133 136

70

63

7164

137 138

124 156

65

G17

094

S UT

65A

BLANKING AND MASTER GAIN SCHEMATIC

0VDC47V 63uS

5

VERTICAL BLANKING

GND

1/2

156

1.8K

1N4148

HORIZONTALBLANKING

1N4148

107

105

112 197

106

6.8K 1K .01uF

104

PN2222

LM393+

+10V

+

133

137

134

136

124

138

LM3931/2

155

6.8K 6.8K

1.8K

132

1351.8K

.047uF1.8K

GND

1N41481

3

2

4

8

76

6.4-7.5VDC8V 63uS

1N4148102

129

1.8K

MPS2907

139

1.9-2.3V

From FBT pin 8

VIDEO GAIN LINE

TO AUTO BIAS IC

FROM AUTO BIAS SUPPLY

3.0-3.8VDC 3V 17mS

909

055

054 056 057040

200 4121.62K

S T U

1.62K

094

1.9-2.3VDC4V 17mS

D

+6V

071

064 066

070

063065

PN2222MPSA64270

750 10uF

62K

BEAM CURRENT LIMITER CIRCUIT.

GND

+

Remote control PCB+12V

GND

MASTERGAIN 1K1K

058 485RC2

+12V

GAIN SELECT RESISTORS

+6V

1.8KGI7

GND

FBT

EHT Return

VIDEO INTERFACE IC

C5346M GAIN

From auto bias IC pin 130Ω

From LA7851 pin 16

(BIAS ACTIVE)

HB

036

(VERTICAL BIAS O/S)

(FLYBACK PULSE)

24

10K

Ω

Ω

Ω Ω Ω

4.2-8.2VDC5-10 17mS

065A

62K

BO

AR

D N

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CERONIXPART No. DESCRIPTION

PR

ICE

Ref

eren

ceS

chem

atic

Boa

rd R

ef.

BO

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D N

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CERONIXPART No. DESCRIPTION

PR

ICE

Ref

eren

ceS

chem

atic

Boa

rd R

ef.

.01001002003004005006007008009010011012013014015016017018019020021022023024025026027028029030031032033034035036037038039040041042043044045046047048049050

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.05

.01

.22

CPR0128CPR0124CPR0140CPR0128CPR0124

CPR0129CPR0144

CPD1251CPR0140CPR0131CPR0011CPR0018

CPR0132

CPD1251CPR0128

CPR0144CPR0129CPC1039CPR0128CPR0124CPR0050

CPR0013CPR0129CPC1039CPR0145CPR0144CPR0129CPI1409CPR0129CPR0129

CPR0136

CPD1251CPR0128CPR0132CPR0004CPR0011CPR0011CPR0004

CPR0009

CPS1754

CPR0128

.01

.01

.05

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

25

051052053054055056057058059060061062063064065

06606706806907007107207307407507607707807908081B82B83B84B85B86B87B88B89B90B91B92B93B094095096097098099100

065A

Board No.s 001 to 100 REPLACEMENT PARTS LIST Models 1492 and 2092

CC8CC8CC8AA5AA5AA5BB5EE3

CC8DD9DD8PP5PP5PP5

RR5DD8GG2PP5RR5PP5

EE9EE8

DD8CC1CC1CC2DD1

CC2

CC1CC1DD2

DD2DD2DD2DD2

DD3BB2CC3DD3

CC3

RR5

BB5

301 ohm ±1%, .25W75 ohm ±1%, .25W3.92K ohm ±1%, .25W301 ohm ±1%, .25W75 ohm ±1%, .25W6 Conductor Header.340 ohm ±1%, .25W12.1K ohm ±1%, .25W

301 ohm ±1%, .25W1N4148 10mA, 75V Diode3.92K ohm ±1%, .25W464 ohm ±1%, .25W1.8K ohm ±5%, .25W62K ohm ±5%, .25W

604 ohm ±1%, .25W

1N4148 10mA, 75V Diode301 ohm ±1%, .25W

12.1K ohm ±1%, .25W340 ohm ±1%, .25W.1uF ±5% @ 50V301 ohm ±1%, .25W75 ohm ±1%, .25W0 ohm Jumper

6.8K ohm ±5%, .25W340 ohm ±1%, .25W.1uF ±5% @ 50V15.8K ohm ±1%, .25W12.1K ohm ±1%, .25W340 ohm ±1%, .25WXRC5346A Custom Video IC340 ohm ±1%, .25W340 ohm ± 1%, .25W

1.62K ohm ±1%, .25W

1N4148 10mA, 75V Diode301 ohm ± 1%, .25W604 ohm ±1%, .25W270 ohm ±5%, .25W1.8K ohm ±5%, .25W1.8K ohm ±5%, .25W270 ohm ±5%, .25W

1K ohm ±5%, .25W

Optional input filter capacitor.

Optional input filter capacitor.

Optional input filter capacitor.

Optional -BL adjust resistor.

BB9BB9CC6AA9AA9

BB7BB7

BB8BB8BB6BB7BB6BB6

AA7

AA8AA8

AA7AA7CC8BB9BB9

AA6BB7AA5AA6AA7BB7AA6BB7AA7

BB5

AA8AA8AA7DD8CC8CC9DD8

CC9

BB8

BB8

AA8

BB6

.01

.01

CPR0141CPR0012CPQ1301CPR0126CPR0136CPR0127CPR0130CPR0009

CPC1039CPR0004

CPQ1303CPR0007CPQ1302

CPC1101CPI1410CPC1101CPC1039CPR0018CPR0004

CPR0011CPR0009

CPR0013CPR0500CPC1040CPQ1308CPC1037CPR0050CPD1251CPQ1309CPC1005

CPQ1309CPR0011

CPR0012CPC1039CPC1039CPR0136CPQ1302

CPR0134

CPR0015

CPD1250

CPR0011

CPR0018

CPR0006

750 ohm ±5%, .25W

4.42K ohm ±1%, .25W2.7K ohm ±5%, .25WPN2907 .6A, 40V, .6W, PNP909 ohm ±1%, .25W1.62K ohm ±1%, .25W205 ohm ±1%, .25W412 ohm ±1%, .25W1K ohm ±5%, .25W

.1uF ±5% @ 50V270 ohm ±5%, .25W22K ohm ±5%, .25WPN2222A .6A, 30V, .5W, NPN

MPSA64 .3A, 30V, D-PNP

10uF ±20% @ 50VLM393 Dual Comparator10uF ±20% @ 50V.1uF ±5%, @ 50V62K ohm ±5%, .25W270 ohm ±5%, .25W

1.8K ohm ±5%, .25W1K ohm ±5%, .25W

6.8K ohm ±5%, .25WBlue Video Amplifier.015uF ±10% @ 250V2SC3467AE .1A, 200V, 1W, NPN..1uF ±10% @ 250V

510 ohm ±5%, .25W

1N4148 10mA, 75V Diode2SA1370E .1A, 200V, 1W, PNP1000pF ±20% @ 500V

FDH400 .1A, 200V, Diode2SA1370E .1A, 200V, 1W, PNP1.8K ohm ±5%, .25W CF1.8K ohm ±5%, .25W CF2.7K ohm ±5%, .25W.1uF ±5% @ 50V.1uF ±5% @ 50V1.62K ohm ±1%, .25WMPSA64 .3A, 30V, D-PNP

1.21K ohm ±1%, .25W

62K ohm ±5%, .25W

0Ω Jumper

.01

.05

.01

.01

.06

.01

.01

.01

.01

.05

.01

.01

.05

.01

.08

.04

.31

.04

.01

.01

.01

.01

.011.12.07.16.07.01.01.19.03

.03

.19

.01 .01 .01

.05.05.01.08

.01

.01

.01

.01

1.51

A1A1B1B1B1C1A2A2

A2A2A2B1B2B1B1B1B2

B1B2B2B2C2C2C2C2A2

A2A2A2A2B3B2B2B2B2

B2C2C2C2C2D1D1D1D1

D1B4

A4A4B3A3B3C4C3C3C3C3C3C3C3B3C3A3A3C3E1

E2E1E1E1E1E1E1E2E2D1E2E1D2D2D2D2D1D1D1D1

C2D2D2D2D2C2C1D1

BO

AR

D N

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CERONIXPART No. DESCRIPTION

PR

ICE

Ref

eren

ceS

chem

atic

Boa

rd R

ef.

BO

AR

D N

o.

CERONIXPART No. DESCRIPTION

PR

ICE

Ref

eren

ceS

chem

atic

Boa

rd R

ef.

101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152

CPQ1303CPR0012CPI1410CPR0011

CPS1755

CPR0050CPC1039CPC1036CPC1032

CPI1405CPR0144

CPC1032CPC1102CPR0504CPR0013CPR0142CPR0050CPR0050CPR0050CPR0144CPR0050CPR0009

CPQ1308CPR0050CPR0351CPC1041

CPR0143CPQ1307CPM2037CPC1036CPM2036

CPD1252CPC1109CPI1401CPR0377CPR0050CPC1104CPR0391CPC1032CPC1000

6800pF ±10% @ 100V

6800pF ±10% @ 100V

1N4005 1A, 600V, R-Diode1N4148 10mA, 75V, Diode .01

.02

1N4005 1A, 600V, R-Diode .02PN2222A .8A, 40V, .5W, NPN .051N4148 10mA, 75V, Diode .011N4148 10mA, 75V, Diode .016.8K ohm ±5%, .25W .01

.03

.036800pF ±10% @ 100V .031K ohm ±5%, .25W .01

"TC" 10 Conductor Header .29"C" PRA (Auto Bias) .68.047 uF ±5% @ 50V .04.1 uF ±5% @ 50V .05.047uF ±5% @ 50V .04

.1uF ±5% @ 50V .05

CPD1252

CPR0050

CPD1251

CPR0016

CPD1252

CPD1251CPD1251CPR0013CPC1028

CPC1028CPR0009

CPS1756CPR0506CPC1036CPC1039CPC1036

CPC1039

CPC1039CPI1402CPR0050CPC1101CPC1101CPC1101CPC1039CPR0011CPI1407CPC1104CPC1036CPR0011CPD1251CPR0011CPR0013CPR0011CPR0013CPQ1301CPR0050CPR0016CPR0016CPR0016CPC1039CPD1252CPI1405CPR0015CPR0015

CPC1039

CPQ1303

CPC1028

CPC1036 .047uF ±5% @ 50V .04.1uF ±5% @ 50V .05

1.950 ohm Jumper. .0110uF ±20% @ 50V .0410uF ±20% @ 50V .0410uF ±20% @ 50V .04.1uF ±5% @ 50V .051.8K ohm ±5%, .25W .01NJM7812FA 12V, 1A, Regulator. .301000uF ±20% @ 35V .22.047uF ±5% @ 50V .041.8K ohm ±5%, .25W .011N4148 10mA, 75V, Diode .011.8K ohm ±5%, .25W .016.8K ohm ±5%, .25W .011.8K ohm ±5%, .25W .01 6.8K ohm ±5%, .25W .01MPS2907 .6A, 40V, .6W, PNP .060 ohm Jumper .0133K ohm ±5%, .25W .0133K ohm ±5%, .25W .0133K ohm ±5%, .25W .01.1uF ±5% @ 50V .051N4005 1A, 600V, R-Diode .02LM324 Quad Op. Amp. .3122K ohm ±5%, .25W .0122K ohm ±5%, .25W .01

.1uF ±5% @ 50V .050 ohm Jumper .01

DD5AA4DD5AA4BB4BB4BB4DD6

DD7DD7BB4

EE7EE7EE7

EE6EE6EE6FF7CC3FF7FF6FF6EE3AA3EE3JJ6BB4BB4BB3BB4BB3CC4CC3AA3

GG6GG7GG7EE5DD5GG6GG6GG6

GG5

EE8 33K ohm ±5%, .25W .01

PN2222A .6A, 30V, .5W, NPN .052.7K ohm ±5%, .25W .01LM393 Dual Comparators .311.8K ohm ±5%, .25W .01

CPR0393 390 ohm ±5%, 2W .04"RC" 8 Conductor Header .26

0 ohm Jumper .01.1uF ±5% @ 50V .05.047uF ±5% @ 50V.01uF ±5% @ 50V .04

.04

LM324 Quad Op. Amp. .31.0112.1KΩ ±1%.25W (Pin. Adj) 1492

CPR0168 8.06KΩ ±1%.25W (Pin. Adj) 1492 .01

.01uF ±5% @ 50V .04100uF ±20% @ 25V .05"G" PRA (H. Width Control) .926.8K ohm ±5%, .25W .017.15K ohm ±1%, .25W .010 ohm Jumper .010 ohm Jumper .010 ohm Jumper .0112.1K ohm ±1%, .25W .010 ohm Jumper .011K ohm ±5%, .25W .01

2SC3467F .1A, 200V, 1W, NPN .160 ohm Jumper .01150 ohm ±10%, .5W, CC .05.33uF ±5% @ 50V .08

10.0K ohm ±1%, .25W .012SC4159E 1.5A, 180V, 15W, NPN .36Heat Sink, H. Width output .11.047uF ±5% @ 50V .04Heat Sink, V. Deflection out .13

1N4005 1A, 600V, R-Diode .02470uF ±20% @ 50V .19LA7830 Vert. Def. Output .673.3 ohm ±5%, 1W .030 ohm Jumper .011000uF ±20% @ 35V .22200 ohm ±5%, 2W .04.01uF ±5% @ 50V .0456pF ±5% @ 100V .03

CA3224E Auto Bias IC

26

Board No.s 101 to 200 REPLACEMENT PARTS LIST Models 1492 and 2092

CPR0157 127K ohm ±1%, .25W

CPR0018 .0162KΩ ±5%, .25W (H. Ras. Adj.)

CPR0011 .011.8K ohm ±5% (Blooming adjust)

CPR0024 .013.3KΩ ±5% .25W (Max. iBeam adj.)

CPR0050 0 ohm Jumper .01

62K ±5%, .25W (2092 Option)

CPR0017 .0136KΩ ±5%, .25W (Pin. Adj) 2092

CPR0015 22KΩ ±5%, .25W (Pin. Adj) 2092 .01

CPR0018 .01

.01

153154155156157158159160161162163164165166

167

168169170171172173174175176177178

180181182183

184185186187188

189190191192193194195196197198200

166A

179

183A

166

167

188A CPM2037

EE9DD9BB3CC4MM4

LL0NN8MM7NN7

NN7NN7

NN7

PP8MM7

MM8NN5GG4GG1GG2EE8

NN5

MM2GG1NN3MM5

NN6PP8PP8GG3GG1

KK1KK1

GG2

MM2JJ2BB4

HH1

EE4HH2

NN7

MM7

MM7

NN8

NN7

NN7

GG1 Heat Sink (2092 Option) .11

.01

A5A5B5B5B5B5B4C5

C5C5D5

D4C5A5B5B5

B5B5B5A6A6B6B6B6A7A6A7B7B7C7C7C7C7C7C6A6C6C6C6C6B6C5C5C6C6

C6D6C6 E5

D5D5D5G4F4F4E4E4E4F4

E4D4G3F3E3E3E4E3E3E4F3E3E3D3D3D3D3E3F3F3E2E3E3E3E3E3E3E2E2E2E2E2D2F3C2D7D7C7C6C6

BO

AR

D N

o.

CERONIXPART No. DESCRIPTION

PR

ICE

Ref

eren

ceS

chem

atic

Boa

rd R

ef.

BO

AR

D N

o.

CERONIXPART No. DESCRIPTION

PR

ICE

Ref

eren

ceS

chem

atic

Boa

rd R

ef.

.04.17

.01

.03

.03

.05

.04 .03 .04 .04

.011.26

.22

.05

1.48

.04

.68

.05 .01 .05.06.06.03

.04

.04

.06 .04.03.01.36.60.21

.28

.02

.02

.96

.25

.01

.04

.22

.01

.04

.04.04

.04

.88

.88 2.10

.04.05.05

.07.04.04.08.94

.01 .01.68.01.03.03.03.06.01

1.91.04.03.04.08.05.05.01.03

.01

.06

.03

.04 .07.18.08

.07

.06

27

Board No.s 201 to 300 REPLACEMENT PARTS LIST Models 1492 and 2092

.01

.03

.01

.01

201202

203204205206207208209210211212213214215216217218219220222223224225226227228229230231232233234235236237238239240241242243244245246247248

248A

250251

249

203 .01

.03

.01

.04

10.64

252

253254

255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298

300

252A

254A254B

298

CPD1264

CPD1264CPD1264

CPD1264CPC1105

CPT1503

CPD1264CPC1039CPC1039

CPR0351CPC1006CPD1264CPM2027CPQ1304

CPR0002CPR0147CPR0501CPR0011CPC1028CPC1000CPC1000CPC1027CPR0050

CPI1403CPC1032CPC1003CPD1252CPQ1302CPC1039CPC1102CPR0169CPC1002

CPD1251CPC1026CPR0376CPD1264CPC1037CPD1256CPC1034CPT1500CPR0356

CPC1035

CPC1105

CPC1003

CPR0050

CPR0050

CPC1003CPR0050

CPD1264

CPR0353 .07

MM5GG2

MM5JJ1JJ2

HH2HH2II1

NN2JJ2

JJ6GG3

KK3

II1KK4JJ2GG3GG3HH4HH4II4

II4JJ4JJ4JJ4

MM3KK4MM3NN3GG9

GG9

LL9GG9

HH8KK6

HH6HH6

HH6JJ6

GG9

GG9

MM5

LL9

GG8

GG8GG9

KK9KK8KK6LL8KK8

KK8KK7

HH7HH7II7

HH7HH8PP8

II6-8HH6JJ9KK8KK9JJ7

HH9KK7II8

LL7KK7KK9MM4II5II5JJ6PP3PP6

PP6

GG7

HH8

GG9HH8HH8KK6

KK5KK6JJ6JJ5

GG7

PP6

RR4

FR205 2A, 600V, F-Diode

FR205 (220V Option)FR205 2A, 600V, F-Diode

FR205 (220V Option)150uF ±20% @ 250V150uF ±20% @ 250VSwitch Mode Transformer

FR205 2A, 600V, F-Diode.1uF ±5% @ 50V.1uF ±5% @ 50V

150 ohm ±10%, .5W, CC200pF ±10% @ 1KV, NPOFR205 2A, 600V, F-DiodeHEAT SINK , Power Supply2SK1446LS 450V, 7A, MOS FET

18 ohm ±5%, .25W1.0 Meg ohm ±1%, .25W"J" Power Supply PRA1.8K ±5%, 127V line adjust.6800pF ±10% @ 100V56pF ±5% @ 100V56pF ±5% @ 100V6800pF ±5% @ 100V0 ohm Jumper

XRC5184 Custom P. S. IC.01uF ±5% @ 50V2200pF ±20% @ 1KV1N4005 1A, 600V, R-DiodeMPSA64 .3A, 30V, D-PNP.1uF ±5% @ 50V100uF ±20% @ 25V191K ohm ±1%, .25W330pF ±10% @ 100V

1N4148 10mA, 75V, Diode1000pF ±5% @ 100V1.2 ohm ±5%, 1WFR205 2A, 600V, F-Diode.1uF ±10% @ 250VTZ160B-T3 160V ±5%, 1W, Z-Diode.022uF ±5% @ 630VFlyback Transformer2.2KΩ ±10%, .5W, CC 1492

3,300pF ±5% @ 200V

2,200pF ±20% @ 1KV

0 ohm Jumper

Power Supply Fo Adjustment.

0 ohm Jumper

2,200pF ±20% @ 1KV0 ohm Jumper

FR205 2A, 600V, F-Diode

1KΩ ±10%, .5W, CC 2092

10uF ±20% @ 50V1.0uF ±5% @ 50V

28.0KΩ ±1%, .25W 209256pF ±5% @ 100V1000pF ±20% @ 500V.1uF ±5% @ 50V.01uF ±5% @ 50V330pF ±10% @ 100V.01uF ±5% @ 50V.047uF ±5% @ 50V

4X .062 Dia. Bead Pins (YC)"H" PRA Vertical Control1000uF ±20% @ 35V100uF ±20% @ 25V

LA7851 V. & H. Control IC

.047uF ±5% @ 50V"I" PRA Horizontal Control1N4742 12V ±5%, 1W, Z. DIODE18 ohm ±5%, .25W100uF ±20% @ 25V1000pF ±5% @ 100V330pF ±5% @ 100V6800pF ±10% @ 100V

1uF ±20% @ 50V.01uF ±5% @ 50V6800pF ±5% @ 100V1uF ±20% @ 50V2,200pF ±20% @ 1KV2.05K ohm ±1%, Hfo adjust.2SC4159E 1.5A, 180V, 15W, NPNHorizontal Drive Transformer "PC" 2 Conductor Header

C-200-7, 25-.5Ω Inrush Current Limiter

"CC" .093 Dia. Bead Pins"CC" .093 Dia. Bead PinsBF5ROM125 Posistor (Optional)SS1-3A 3 AMP FUSE

100K ohm ±5%, .5W, CFFR205 2A, 600V, F-Diode18 ohm ± 5%, .25W

2SA1371E .1A, 300V, 1W, PNP100K ohm ±5%, .25W

Optional 127V line control.

Optional AC noise capacitor.

Optional AC line capacitor.

36K ohm ±5%, .25W 1492

Dual Posistor (Optional)

CPC1101CPC1043

CPR0163CPC1000CPC1005CPC1058CPC1032CPC1002CPC1032CPC1036

CPS1759CPR0503CPC1104CPC1102

CPI1400

CPC1036CPR0502CPD1257CPR0002CPC1102CPC1026CPC1025CPC1028

CPC1100CPC1032CPC1027CPC1100CPC1003CPR0138CPQ1307CPT1505CPS1753

CPR0426

CPS1758CPS1758CPRO427CPR0425

CPR0366CPD1264CPR0002

CPQ1310CPR0019

CPR0017

CPRO430

E5E5E5E5F5F5F5F5F5F5F5F5F5G5F5D6D6

E6

F5F6D6D6D6E6E6E6

E6F6F6F6F6F7F7E7F1F1F1F2F2F2F3F3G1G2G2G2G2G3H3 G5

G5G5I5I4J3J3J3I3I3I4G3I4I3H3I3H3H3H3H3H4G3G4G4G3G3G3G3I3I3I2

J3J3I2I2I2J2J2J2J1I1J1H2H1H2H2G2H2H1H1H1

Vertical Deflection Bias Adj.Vertical Deflection Bias Adj.

HH2

.01CPR0050 0Ω Jumper, to ground PS H. S. 267J3

BO

AR

D N

o.

CERONIXPART No. DESCRIPTION

PR

ICERef

eren

ceS

chem

atic

Boa

rd R

ef.

BO

AR

D N

o.

CERONIXPART No. DESCRIPTION

PR

ICERef

eren

ceS

chem

atic

Boa

rd R

ef.

301

302303304305

306

307308309310

CPT1523

311312313314315316317

401402403404405

406407408409410411

CPT1506CPR0392CPQ1305CPC1050

CPC1030

CPC1034CPD1252CPR0365CPD1252CPD1253CPD1264CPR0050

CPC1044CPT1504CPC1105

CPS1750CPR0350CPR0352CPR0353CPR0375

CPR0353CPD1250CPD1250

CPD1250CPR0353

CPR0353CPC1040CPR0355CPR0019CPQ1306CPR0353

CPR0029CPC1003CPR0353CPC1002CPR0350CPR0354

CPS1758

CPS1769CPS1768

CPR0402481

482 CPR0405

CPR0401

CPR0403

CPR0400

CPR0007CPS1767

CPA4102REMOTE CONTROL BOARD

PCB ASSEMBLIES

TUBE SOCKET BOARD

PP7 220uH Horz. Width Coil. 1492

PP6 Horz. Linearity Coil .60NN4 270 ohm ±5%, 2W .04NN3 2SD1651 5A, 1.5KV, NPN 1.48RR7 .47uF ±5% @ 250V 1492 .36

RR6 .01uF ±3% @ 1.6KV 1492 .26

RR8 .022uF ±5% @ 630V .08RR6 1N4005 1A, 600V, R-Diode .02NN4 470 ohm ±5%, .5W, CF .01RR7 1N4005 1A, 600V, R-Diode .02RR8 1N4937 1A, 600V, F-Diode .03NN4 FR205 2A, 600V, F-Diode .04

0 ohm Jumper .01

PP8 2.7uF ±10% @ 100V .32PP7 Horizontal Width Coil .63II5 150uF ±20% @ 250V .88

CRT SOCKETNN1 47 ohm ±10%, .5W, CC

1.54

NN1 470 ohm ±10%, .5W, CC.07.07

NN0 1K ohm ±10%, .5W, CC .07PP1 .68 ohm ±5%, 1W 1492 .03

NN1 1K ohm ±10%, .5W, CC .07MM0 FDH400 .1A, 200V, Diode .03MM0 FDH400 .1A, 200V, Diode .03

MM0 FDH400 .1A, 200V, Diode .03NN0 1K ohm ±10%, .5W, CC .07

413 PP1 1K ohm ±10%, .5W, CC .07414 MM1 .015uF ±10% @ 250V415 NN1 100K ohm ±10%, .5W, CC .07416 MM1 100K ohm ±5%, .25W, CF .01417 MM1 2SC3675 .1A, 1.5KV, NPN .67418 PP1 1K ohm ±10%, .5W, CC .07

420 MM1 200K ohm ±10%, .25W, CF .01421 PP1 2200pF ±20% @ 1KV .03422 PP1 1K ohm ±10%, .5W, CC .07423424425

PP1 330pF ±10% @ 100V .03NN1 47 ohm ±10%, .5W, CC .07NN1 10K ohm ±10%, .5W, CC .07

426

427 .093 Dia. Bead Pin .02

10 Conductor Cable .8310 Conductor Cable, Double length. .99

FF1 10K ohm Yellow Pot

FF1 500 ohm Black Pot

483

484

485

486487

FF2 1K ohm Blue Pot

FF2 20K ohm Orange Pot

FF2 1K ohm White Pot .17

FF1 750 ohm ±5%, .25W .01"RC" 8 Conductor Cable .87

Remote PCB Assembly. 4.75

CPA4100 1492 Main PCB Assembly 105.00

CPA4101 CRT P.C. Board Assembly 7.50

28

Board No.s 301 to 490 REPLACEMENT PARTS LIST Models 1492 and 2092

419

412

.60

306 CPC1055 RR6 8,200pF ±3% @ 1.6KV 2092 .37

301 CPT1506 PP7 .60

305 CPC1059 RR7 .33uF ±5% @ 250V 2092 .38

405 PP1CPR0050 0Ω Jumper 2092 .01

.07

.17

.17

.17

.17

CPA4103 2092 Main PCB Assembly 115.00

Horz. Linearity Coil 2092G5G5G6F7G7H6H6H6H6H7I6H7I6I6J6J6

I6I7J7

A B C D E F G H I J

1

2

3

4

5

6

7

A B C D E F G H I J

1

2

3

4

5

6

7

A B C D E F G H I J

E

C

B

RC

LM324146

C5346 036

VIDEO INPUT CONN.

006

3.92K, 003

.1uF

, 025

15.8K, 03312.1K, 034

340R, 035

.1uF

, 032

340R,038

604R, 044

1.8K, 047

2.7K, 052

158

1K, 058

81B

.015uF, 82R

346783B

346783R

346783G

137087B

137087R

137087G A64

0981.62K, 097

1.21K, 100

.1uF, 095 .1uF, 096

137091B

137091G

137091R

.015uF, 82G

.015uF, 82B .1uF, 84B

.1uF, 84R

.1uF, 84G

4148, 86G

4148, 86B

H400, 90R

H400, 90B

1nF, 88R

1nF, 88G

1nF, 88B

H400,90G

1.8K, 92B

1.8K, 92G

1.8K, 92R

1.8K

, 93R

1.8K

, 93G

1.8K

, 93B

4148, 86R

2.7K, 094

6,80

0pF

108

6,80

0pF

6,80

0pF

110

111

6.8K, 107

4148, 106

4005, 101

22221044148, 102

4005,103

4148, 105

115

123

CA3224

47nF

, 116

.1uF

, 117

47nF

, 118

.1uF

, 120

47nF

, 121

.1uF

, 122

10uF125

+10uF126

+10uF127

+

1,000uF

131

+12

V

+16V

GNDGND

GND +24V

4005

, 145

.1uF

, 144

22K, 147

22K, 148

33K, 143

33K, 142

33K, 141

0Ω, 140

0Ω, 160

7812, 130

.1uF

, 128

2907139

1.8K, 133

4148, 134

1.8K, 135

1.8K, 137

6.8K, 136

6.8K, 138

47nF

, 132

2.7K, 154

33K, 152

.1uF,150

0Ω, 1

24

1.8K

, 129

340R, 031

"C" PRA

REMOTE C.

LM393155

1,000uF

VC

215

200R

390R

1K, 050

4.42K, 051

301R

, 001

75Ω

, 00

2

301R

, 004

75Ω

, 00

5

340R

, 007

12.1

K, 0

08

301R

, 011

4148

, 012

3.92

K, 0

13

464R

,014 62

K, 0

16 017

604R

, 018

1.8K

, 015

4148

, 020

301R

, 021

022

12.1

K, 0

23

340R

, 024

301R

, 026

75Ω

, 02

7

6.8K

, 030

340R

, 037

1.62

K, 0

40

041

4148

, 042

301R

, 043

0Ω,

028

010

GND

+24V

GND

FR205,248

100K, 251

56pF, 275

56pF, 276

279

6.8nF, 277

0Ω, 2

78

2.2K298

3.3nF300

305

.01uF for 1492

306

6.8nF,274

270R, 045

1.8K, 046

270R, 048

909R, 054

1.8K, 156

0Ω,151

TC

LA7851 218

074

073

076

1.8K, 077

1K, 078

6.8K, 080

.1uF

,060

270R

, 061

22K

, 06

2

2222063

750R, 064

+10uF068

+10uF066

A64065

62K, 070

270R, 071

.1uF, 161.01uF, 163

47nF

, 162

none, 62K, 164

C-200,240

AC POWER

238

241

12K, 36K, 166

8.1K, 22K, 167 10nF, 168244

5ROM

7.15K, 172 6.8K, 171

0Ω, 1

73

0Ω, 1

74

0Ω, 1

75

0Ω,

177

12K

, 176

1K,

178

3467180

0 oh

m,1

94

0Ω, 1

81

.33u

F, 1

83

150R

, 182

185

2SC4159

186

1371250

470uF

191

3.3R

, 193

10.0

K, 1

84

1,000uF

195

192LA7830

196

56pF, 198

10nF

, 197

+

+

10uF201

100uF216

56pF, 204 330pF, 208 10nF, 209

1nF, 205

.1uF, 206

10nF, 2071.0uF, 202

47nF, 210

211

212

Vo Vr Hr Ho

214

222

301

302

LINEARITYCOIL

H. WIDTHCOIL, 1492

+100uF

2254742

, 223

18R

, 224

1nF

, 226

330p

F, 2

27

6.8n

F, 2

28

10nF

, 231+

1uF230

+1uF233

6.8n

F, 2

32

2.2n

F, 2

34

2SC4159, 236

2.05K, 235

H. HOLDSEL. RES.

157 303

HORIZONTALDRIVE XFR.

237

270R

100K, 247

242

243

PC

CC

YC

47nF,187

4005

, 190

188

3 AMPFUSE

245

213

246

LM324165

1.62K, 055

205R, 056

412R, 057

LM393067

+

+

+

FR

205,

254

FR

205,

252

25

5

150uF250V

150uF250V

256

257

SWITCH MODETRANSFORMER

258

150R, 264.1uF, 262

.1uF

, 261

FR

205,

260

FR205,266 FR205,263

200pF, 265

18R, 270

1.00M, 271

10nF, 281 2.2nF, 282.1uF,285

1nF

, 291

280

C5184

1.2Ω

292

4005

,283

A64284

+100uF286

4148

, 290

191K

, 287

330pF,288 296

22nF

267

268

FR205,293

.1uF, 294

TZ160B, 295160V

ZENER

+127V GND

FLYBACKTRANSFORMER

297

.022uF

307

4005, 308

4005, 310

4937, 311

2.7uF

315

FR205, 312

0 ohm, 313

470R, 309

H. Width Coil

316

150uF @ 250V

3172SD1651, 304

1.8K

, 273

2907053

0Ω, 85R

0Ω, 85G

0Ω, 85B

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

12345678

1614129

181311

81G181311

81R"B" PRA 181311

12345678

161412

9

18 20 22

1234567

8 14129

1532222

1 2 3 4

5678

1K, 112

2

3

4

5

6

7

8

9

10114

2 3 4 5 6 7 8

.1uF, 69

075

1 2 3 4 5 6 7 8

11

1 2 3 4 5 6R G BVHS S

1234567

8 14129

9 1614 20

"H" PRA1 2 3 4 5 6 7 8 9 1614 20

"I" PRA1 2 3 6 7 8 9 1614

1 2 3 4 5 6 7 8 9

20 18 16 14 12

1234567

127K

, 200

170"G" PRA1 2 3 4 5 6 7 8 9 1614 20

272"J" PRA1 2 3 4 5 6 7 8 9 1614 20

1

2

3

4

5

6

78 9

16

15

14

13

12

11

10

13

4

5

6

7

89

10

2

18Ω, 248A

100uF169+

0Ω,

259

2.2n

F, 2

54A

2.2n

F, 2

52A

0Ω,

254B

220 VACInput

1234

5 6 7 8

20

1 2

34

8.2nF for 2092

LINEARITYCOIL, 2092

0Ω,1

83A

3029

072

62K, 166A 3.3K

, 17

9

1.8K

, 15

9

189

*

36K

, 203

0Ω, 2

89

*

249*

510R, 89G

510R, 89R

510R, 89B

"B" PRA

"B" PRA

253

G

D

S

62K

, 065

A

2

39

G

H

I47

nF, 2

20.47uF for 1492.33uF for 2092

Optional DualPosistor.

CPT1504

CPT1523

CPT1506

CPT1505

CPT1506

0Ω, 269

2SK1446

31

Block Diagram Review

SYNC

VIDEO

GAME

CRT

H

V

VERTICAL

CONTROL

CONTROLVERTICAL

OUTPUT

HORIZONTAL H.H.

REMOTECONTROLS

HORIZONTALSize Control

DIODEModulator

FBT

LOADISOLATIONTransformer DOUBLER

VOLTAGE

SWITCHINGREGULATOR

Raw DC320V

+127V

-200V

Driver Output

3

Interface

DY

DY

G

sV

I. V. Feedback High Efficiency

EHT

J

Hs

H. Pos.

V. Size &V. Ras. Pos.

PINCUSHION

Sync delayM

N O

(PCB)

P

Q R

(IN GAME)

S

Beam Current

(VIDEO & DEFLECTION)

U

+16V

+27VRegulator+12V Video

SupplyT

Sync

OVERVOLTAGEPROTECT

DeflectionSupply

V

W

X

+12VZener

2

V-

BrightAuto

AUTO BIASSYNC IC

BLANKINGF.B.P.

V retraceBeam limit

M. gain

H. blankV. blank

Program pulseGrid pulse

Beam currentbuffer

3 3

33

3

2

3

A BC

E

F

H

I

D

3

VERTICALAUTO BIAS

L

Y

BeamCurrentFeedback

VIDEOInterface

VIDEOAMPS.

Bias

K

The auto bias circuit performs all of its sensing and bias corrections during the sixteenth tothe twenty first horizontal cycle, after the vertical blanking has started. Before the sixteenthcycle, the SW in the auto bias IC is open ( SW in "C" position).

If the CRT cathode is too far into cutoff, less beam current flows, the beam current bufferputs out a smaller negative pulse, less voltage is stored in the coupling capacitor, theprogram pulse amplitude (which is constant) is now larger than the stored (beam current)voltage and the channel amplifier will add current to the bias voltage, storage capacitor 127 , correcting the low bias voltage which caused the cathode to be too far into cutoff.After the program pulse is over, the SW is switched to the open position again and the next time the bias voltage can be adjusted is during the next vertical blank time.

During the next three horizontal cycles (19, 20, and 21), the SW is switched to passcurrent to capacitor 127 which is the bias voltage storage capacitor. At the same time aprogram pulse is applied to resistor C8 which, if the bias was correct during the previouscycle, exactly balances the voltage stored in the coupling capacitor and no difference issensed at the channel input. The channel amplifier, in this case, does not output currentand the voltage of capacitor 127 stays unchanged.

During the 16,17, and 18 horizontal cycle, the CRT is brought out of cutoff by the gridpulse. The resulting beam current produces a voltage at the beam current buffer output.This voltage is applied to the coupling capacitor 122 . At the other side of the couplingcapacitor is the channel input, which is clamped to V ref. (SW in "A" position). The voltageamplitude of the amplifier output with the cathode current information is then stored in thecoupling capacitor 122 during this time.

The auto bias circuit is a control system that forms a closed loop for controlling the CRT biasvoltage. It generates a set of conditions where the current near the cutoff voltage of each gunis measured, and then adjusts the bias voltage of the video amplifiers, to set the correct blacklevel voltage for each gun. This color balance adjustment is necessary, since each gun in thecolor picture tube can have a different cutoff voltage, which also, will change as the CRT ages.

AUTO BIAS AND AUTO BRIGHT CIRCUIT, FUNCTION, DESCRIPTION

SIMPLIFIED PICTURE TUBE VIDEO BIAS CONTROL CIRCUIT: (One channel shown)

32

Red Red

CA3224E

127

123

+10uF

inputholdcap.

SWnormal

GREEN CHANNEL

BLUE CHANNEL

Counter, DecoderControl Logic

V sync

Hsync

Grid pulse

Program

V ref.

4.2V

G1 G2

CRTVIDEO

INTERFACEVideoAmp.

comp.4.2V

LM324LM32433K

33K

33K

22K

ABC

Auto BrightAmplifier

BeamCurrentBuffer 5K

200

68.1K

.047uF

.1uF

122

C8 100K

2.7K +10V

8

GB

R

G

B

R

*

*Adjust, FBT bottom pot, for 4.6V at pin 8.

FBTScreen

adj.

+

+

+

Ω

If the picture tube gain changes, the auto bias circuit would adjust all three guns in the samedirection to maintain constant black level. This effect reduces the auto bias voltage range whichis needed for the cathode differential voltage adjustment. To prevent this occurrence a secondcontrol loop is added to the system. This second control loop is called the auto bright circuit andcorrects for CRT gain changes. The auto bright circuit senses any common bias voltage changeand controls the screen grid (G2) to hold the common bias voltage constant.

Note; All XX92 boards have a solder connection on;C thick films, with a solder connection in the middle.

Pulse

122

122

127

C8

127

127

Resistor 141 , 142 , and 143 are part of the auto bright circuit. They are used tosum the bias voltage of each of the three channels via a voltage node at the autobright amplifier, 146 pin 9. The resulting output voltage then controls the screengrid via transistor 417 . Resistors 413 and 418 protect the CRT from excessivecurrent during arcing. Capacitor 423 supplies a low AC impedance to GND toinsure that the CRT gain is constant during each horizontal line. Resistor 420 defines the current gain of, and stabilizes, the auto bright control loop.Resistor 148 and capacitor 150 act as a low pass filter to reduce the chance ofdamaging the amplifier 146 due to CRT arcing. Resistors 415 , and 416 protectthe auto bright control transistor 417 . The grid pulse is generated by a discretetransistor 153 to protect the auto bias IC from possible arc energy. Pullup resistor 154 supplies the grid pulse voltage during the grid pulse time. The auto bias IC (CA3224E) is designed for a supply voltage of +10V and since thevideo amplifier requires +12V, three diodes 101 , 103 , and 145 are used to supplythis IC. Resistors C4 and C7 form a voltage divider which supplies the biasvoltage to the LM324 146 . The green and blue channel circuits are identical to thered channel and are controlled by the timing logic in the same way. Refer to thewaveforms at the bottom left of page 34 for the timing relationship. The verticalretrace pulse, from the LA7851, starts the 21 count auto bias state counter. Thegrid pulse becomes active between the 15 and 18 horizontal cycle and the programpulse is active between the 18 and 21 horizontal cycle. These two pulses inconjunction with the internal control of the transconductance amplifier output switchare what measure and set the video bias.

The beam current feedback circuit uses a PNP video transistor 91R to direct most ofthe beam current to the auto bias circuit while passing the voltage waveform, from thevideo amplifiers to the CRT cathodes. Diode 90R and capacitor 88R insure that novideo waveform distortion occurs. An additional benefit of this circuit is that it protectsthe video amplifiers from the destructive arc energy. Resistors 92R and 93R divideenergy due to CRT arcing, between the video amplifier transistors and the beam currentfeedback transistor 91R . The beam current is filtered by capacitor 108 and resistor C10 and is buffered by an operational amplifier, which translates the beam current into a low impedance voltage. This voltage is applied to a coupling capacitor 122 through a200 ohm resistor C8 . The 200 ohm and the 68.1K resistor C3 forms the programvalue which sets the black level voltage via the action of the program pulse. Capacitor 121 is used to stabilize the transconductance amplifier which is used at thechannel input of the auto bias IC 123 . The auto bias IC stores the bias voltage of thischannel in capacitor 127 at pin 21. This voltage is buffered by an internal amplifier,with output at pin 20, which is connected to the Red video amplifier bias input.

AUTO BIAS AND AUTO BRIGHT CIRCUIT DESCRIPTION

91R

90R 88R

92R 93R

91R 108

C10

122

C8 C3

121

123

127

143

417

141 142

146

413

423

146

148

101 103

C7C4

146

417

416415

145

154

150

420

418

33

153

8

+

AUTO BIAS CIRCUIT1N400110

11

13

9

10

12

14

15

7

6

5

4

16

17

18

19

1

2

3 20

21

22GND Vcc

Red Red

GND

CA3224E

AUTO BIAS IC

+10V

68.1K

68.1K

68.1K

.047uF

.047uF

.047uF

.1uF

.1uF

.1uF

C1

C16

152

33K

116

117

118

120

121

122

C2

C13

C3

C8

144.1uF

126

141

127

123

142

125

143

33K

+

+10uF

10uF

10uF

33K

33K

153

PN2222

2.5-6.7V

2.5-6.7V

2.5-6.7V

4.6-5.2VDC

1.9-2.3VDC4V 17mS

8.0-9.0VDC8.4V 17mS

6.3-7.7V

.1-

.3V

1.2-2.5V

5.8-6.4V

.5-.8VDC .7V 17mS

1.2-2.5V

1.2-2.5V

5.8-6.4V

5.8-6.4V

7

5

4

20KC5

comp.

inputholdcap.

comp.

holdcap.

comp.

holdcap.

sw.

sw. in grid pls. pos.

sw.

sw.

normal

V. RETRACE

STARTCOUNTER

FF

CL

Q

EN21 H. LINECOUNTERCLDECODER

5V REF

BIAS

AUTOBIAS

ACTIVE

PROGRAM

PULSE

GRIDPULSE

sw. control

HB 2,9

8

1

Green input

Blue input

Green

Blue

To vertical blanking

7

4K

6,800pF

4K

6,800pF

4K

6,800pF

LM3241/4

111C15

C12

C14

C11

110

LM3241/4

LM3241/4

C9108

C10

C4

C7

1.82K

2.74K

1N4001 1N4001

103 145101

15

18

14

5

6

3

2

1

12

1314

13

12

17

16

19

20

5K

5K

5K

11

+12V Video Supply

90R

88R

1000pF

FDH400

93R

91R

2SA1370

2.2K

92R2.2K

VIDEOINTERFACE Video

Amp.

GND

To CRT Grid #1

2.7K154

+10V

Green &Blue BEAM CURRENT

Red BEAM CURRENTRed video BIAS control line.

.1uF

+4.2V

147

22K

1/4LM324

146

10

9

8148

22K

Green, BlueVideo BIAS

LINES

AUTO BRIGHT CIRCUIT

G1

1K1K100K

100K

RGB

100K

416415 413418

423420150

4,700pF

G2

CRT

GND

V. Retrace

V. Blanking

H. Blanking

Bias active

Grid pulse

Program pulse

Grid pulse

2SC3675

417

1 18

AUTO BIAS AND AUTO BRIGHT SCHEMATIC

34

10K 1K

330pF425 422

421

200Ω

200Ω

200Ω

+

+

+

+

+

146

6V REF.

This sync interface incorporates a dual voltage comparator 67 and a resistive input circuit for high reliability. For TTL level sync signals, the resistive inputs are seven to oneattenuators comprised of resistors 45 , 46 , 47 , and 48 . The comparators are biased to .15 volts by resistors 61 , 62 which permit direct connection to an RS170sync source by removing resistors 45 and 48 .

The vertical sync signal from the second comparator is coupled to the LA7851, vertical syncinput, via a coupling capacitor 68 . Resistor 77 and capacitor 187 form a low passfilter to eliminate false triggering by horizontal sync pulses in the case of composite sync.Resistor 78 and capacitor 77 compliments the comparator open collector output byacting as a pullup. These resistors also form a voltage divider which insures that thecapacitor 68 is not reverse biased and provide the proper vertical sync drive amplitude.The LA7851 vertical sync input circuit is designed to accept either positive or negative syncpulses, but will not work with a sync signal that is close to a square wave.

The horizontal sync signal from the comparator output is pulled up by resistor 80 andattenuated by resistor 176 and I1 , for correct drive amplitude. It is differentiated by capacitor 198 and applied to the horizontal sync input, pin 1, of the LA7851. Bias resistors I2 and I3 set up the correct voltage for positive edge triggering. By adding resistor I12 , the LA7851 is programmed for negative edge triggering. This is used when the horizontal sync pulses are negative going. Resistor I12 is connectedby adding a solder bridge to the I PRA solder pads above pin 6.

VERTICAL AND HORIZONTAL SYNC CIRCUIT DESCRIPTION

The 1492 Monitor has a separate input for horizontal and vertical sync. The horizontalsync pulse is normally positive going. The horizontal deflection control circuit will syncon the rising edge of this pulse. If horizontal sync is negative going, the picture is shiftedto the left, and may be out of range of the horizontal picture position adjustment circuit.To sync on the falling edge of horizontal sync, a solder bridge is installed on the I PRA.

HORIZONTALSYNC

GND

VC2

VC1

Hs V s

VERTICALSYNC

GND

270

270

1.8K

1.8K

270

47

46

45

48

67

1/2LM393

1/2LM393

61

22K62

13

2

7

6

5

8

4

6.8K

.14-.16V

VERTICAL AND HORIZONTAL SYNC CIRCUIT

1.8K

12K

1KVIDEO +12V

80

176

78

77

LA7851DeflectionControl IC

HorizontalSync input

VerticalSync input

1.8K12K

8.8K 22K

.047uF

10uF

56pF

+

1

19

198 I1

I2

I3I12

187

68

DEFLECTION +12V

Ω

Ω

+

+

Ω

The vertical deflection circuit will sync on either a negative or positive sync pulse,provided that the pulse width is between two and twenty horizontal cycles long. Both thevertical and horizontal sync lines are joined for composite sync operation.

35

78 77

68 77 187

68

198176

45 48

6145 46 47 48

62

67

I2I12

I3

I180

I12

VERTICAL DEFLECTION CIRCUIT, FUNCTION, DESCRIPTION

The LA7851 IC and the H PRA have all the active components to control the vertical deflection. LA7830 is a high efficiency vertical yolk driver IC. Together they form a compact and efficient vertical deflection system. SIMPLIFIED VERTICAL DEFLECTION CIRCUIT

The vertical oscillator supplies the start time for the vertical cycle and when vertical syncis present, sync supplies the start time to the vertical oscillator. The linear vertical ramp current which is necessary for linear vertical deflection is generated by supplying a capacitor 202 with a constant current from resistor H6 , at a voltage node (pin 16). The voltage at this node is held constant by a system of amplifiers which drive the deflection yoke. The yoke current sensing resistor 193 is connected to the other side of this capacitor 202 and supplies the ramp voltage which balances the current from H6 during trace time.

2

CONTROL

OUTPUT

RETRACEBOOSTER

LA7830

+24V LINE

+220uF

192

73

4

6

SYNCV

+12V

.1uFOSC

+ or -VERT.SYNC

V. S QFF

R Q 5V

3.4V

COMP.

AMP.

17 16

15

18

19LA7851

218

+12V

H6

202 193

SIZEV118K

500

330

330301 1uF

.047uF

.01uF

3.3

VERT. YOLK

+ 1000uF76.8K

34K

Ω Ω

Ω

Ω Ω

V. Auto Bias on H PRA22K 22K

22K

200K

10uF+

To better understand the LA7851 bias control loop, imagine the vertical output voltagegoes up, the time out shortens which causes the capacitor 202 to be less discharged. Thisraises the voltage on capacitor 202 and lowers the vertical output voltage. This type ofvertical bias control system has the advantage of only correcting the bias during retracewhich means that it will not cause current ramp distortion during vertical trace time.

The vertical yoke driver LA7830 is the power output stage for the vertical amplifier.It has a built-in voltage booster circuit to reduce vertical retrace time without the power losses associated with a high vertical supply voltage.

To generate the other half of the deflection yoke sawtooth current (vertical retrace),a flip flop is set by the vertical oscillator which partly discharges the capacitor 202 and causes the drive voltage across the yoke to reverse. The amount of discharge ofcapacitor 202 determines the vertical output voltage for the next cycle and is controlled by atimer at pin 17. The time out of the timer is controlled by the vertical output voltage from twodifferent paths. One path is through the 34K and 118K resistors which supplies the higherfrequency component for the timer and stabilize the vertical amplifier. The other path isthrough the vertical auto bias circuit which detects the minimum vertical output voltage overmany vertical cycles and supplies a second current source to the timer. This second currentsource has a wide dynamic range and will hold the vertical output voltage well within operatinglimits for both 50Hz and 60Hz with no need for manual adjustment.

H6

H6

193

202

202

202

202

36

202

202

The vertical sync, input circuit (LA7851 pin 19),is coupled to the sync interface circuit with a 10uFcapacitor 6 8 . The oscillator cycle is terminated ifthe voltage at pin 19 goes up or down more thanone volt from its DC bias voltage, which enablessynchronizing on positive or negative sync pulses.For composite sync, capacitor 187 limits the P-Phorizontal component to less than .4 volts.

The V. Auto Bias senses the lowest point of thevertical output waveform with resistors H12 , H13 And diode H25 . This voltage Storedby H24 is converted to a current by transistor H23 and resistors H14 & H20 . This current isreflected from the +12V line via resistors H15 , H16 and transistor H22 . This current then adds to the charging current ofthe bias O/S capacitor 207 . The retrace and biasO/S outputs a low pulse, which is conducted by adiode to pin 16 and discharges capacitor 202through resistor H5 which causes the system toretrace. The pulse duration determines the extentof the 2 02 discharge which has to be made up byresistor H6 during trace time. This balancebetween the 2 02 charge during trace time anddischarge during retrace is what keeps thevertical output waveform at the proper DC level.

rTottt

37

During the discharge time of 206 the retraceand bias one shot (O/S) is triggered. This O/Sconsists of the flip flop and comparator mentionedin the function description. The time duration ofthe O/S is set by capacitor 207 and two low passfilters which are connected to the vertical output.The higher frequency filter is made up of resistors H10 , H4 and capacitor 2 20 . The lowerfrequency filter is the Vertical Auto Bias circuit.

The charge current to (the vertical oscillatorcapacitor) 206 comes from +12V through acombination of five resistors. This resistor networkis made up of 200 , H17 , H3 , H18 , and H19 .[Solder connection B decreases Vfo by 6Hz and connection Cincreases Vfo by 5Hz. See page 56 for the location of the solderconnections on the H PRA. This adjustment is only used if Vfo isoutside the range of 39Hz to 48Hz. The normal vertical sync,frequency range, of the LA7851 is 44Hz (Vfo) to 70Hz.] Uponvertical sync, or when the oscillator waveformreaches 6 volts, the capacitor 2 06 is rapidlydischarged by a transistor and a resistor, inside the LA7851, to 2 volts at which time the cycle starts over. Note the voltage and waveform blockabove pin 18.

Pin 16 is the minus input of the verticalamplifier that extends to the LA7830 for itsoutput stage. The other input of the verticalamplifier is tied to V ref. (3.5V).

187

68

206

H3200

206

206

207

220H10 H4

H12

202

H17 H18 H19

H14H23

H25H13

H3

H5

H22H16

H15H20

202

202

207

H24

22K

GND

V. RTN.+12V

20 19 18

4

7

GND

1

V+ ± SYNC INPUTVERTICAL VERTICAL

OSCILLATOR

216

175068

206 200

H17

VERTICAL

0Ω

193

3.3Ω

127K

22K

.1uF

0Ω10uF

100uF

GND

POWERAMPLIFIER

LA7830VERTICAL 192

+12V

VERTICAL

5.8-6.5VDC 4V 17mS

5.7-6.6VDC4V 17mS

VERT.OSC.

187

.047uF

or

HEATSINK

188

Vs

Hp5,2

20

H2H1174

0Ω 330Ω330Ω1

8

H384K C

+5Hz

.01uF

11

202

1uF

H5

301Ω10

207

+12V

GND

10uF

1K

H25

H12

1N4148H2088K

200K

H13

H15

22K

22KH24 H14

H23

H22

39063904

18

181

15

VIDEO +12V SUPPLY

483

482

486

500Ω

750Ω

1K

VERTICALRASTER

POSITION

VERTICALSIZE

RC8

RC6

RC3

Remote Control PCB

VERTICAL SYNC

DEFLECTION +12V SUPPLY

0 VDC17mS2-4V

H16

GND

VERTICAL DEFLECTION CIRCUIT DESCRIPTION

e

fs

t

Retrace is started by partly discharging the ramp capacitor 202 through resistor H5 .The vertical amplifier responds to the dischargeof cap. 202 by outputting a high voltage across the yoke which reverses the yoke current. Whenthe yoke current reaches the new value dictated bythe voltage on 202 , the vertical cycle starts over.

Vertical size is dependent on H6 , 202 , 193 , H1 , H2 , and 482 . The vertical yokecurrent is converted to a voltage across resistor 193 and applied to the ramp generatingcapacitor 202 through resistor H1 and H2 .The ramp waveform on the H1 side of thecapacitor 202 is constant for any vertical sizebecause of the constant current from resistors H6 . For minimum vertical size, the feedbackvoltage is present on both resistors H1 and H2 . For maximum vertical size H1 isgrounded and twice the amplitude across thecurrent feedback resistor 1 93 is required togenerate the ramp waveform.

The vertical amplifier consists of adifferential amplifier in the LA7851 with the + input at pin 16 and the - input is connected to an internal reference voltage (3.5V). The output of this amplifier is connected to the power driver stage which is located in theLA7830. Resistors H7 , H11 and capacitors 208 , 209 , & 2 10 stabilize the LA7830 duringtrace time and capacitors 2 04 and 2 05 providestabilization during retrace. The retracebooster doubles the 27 volt line voltage duringretrace by connecting pin 7 of the LA7830 to the27 volt line. This raises capacitor 1 91 27 voltswhich then applies 54 volts to pin 3 of theLA7830. Pin 3 is the retrace booster input andis connected to the vertical output stage. Afterthe retrace cycle is over, capacitor 191 isrecharged through diode 190 .

38

The yoke return blocking capacitor 195 provides a voltage such that the verticalamplifier can drive the yoke with a + and a - current.

The vertical raster position control 483 setsthe NPN transistor 1 80 base voltage. Theemitter resistor 1 82 supplies current to theyoke through transistor 180 . The magnitude ofthis DC current directly effects the verticalraster position.

H6 202193

H1

H2 482

193

202

H1

H2H1

202

H6H1

H2 H1

193

202 H5

202

H7 H11208 209 210

204 205

191

191

483180

182

180

195

190

202

Vo

3

17 16 14

14,6

4

15

13

12

GNDV Ref.

RETRACE &BIAS O/S

H6

210

H7 223

LA7851

208

330pF

.047uF

1N4742330Ω76.8K

VERTICAL DRIVE

INPUT

2

OUTPUT

Vo

22-25VDC25V 17mS

5 6 7

205196

191204

56pF

1,000pF220Ω, 2W

220uF,35V

RETRACEBOOSTER

COMP.

+

1N4005190

1.2VDC25V 17mS

22-25VDC1V 16mS

+27V

.16-.23VDC5V 17mS

11.5-12.5V

.7-1.2VDC.9V 17mS

3.0-3.8VDC 3V 17mS

.7-1.0VDC.9V 17mS

RetraceBooster

H18200K

500KH19

B

-6Hz

+

.068uF

34K

9

17

18

H4

220

H10

12.4 TO 14V17mS42V

11

218

150Ω, 1/2W

209

433

180

182

.01uFH111K

YC1

YC2

18

19

195

+1,000uF,35V

2SC3467RAS. POS.

0 TO 7 VDCV

GND

+27 V LINE

V. BOOSTV. OUTPUT

VERTICAL DEFLECTION SCHEMATIC

VERTICALYOKE

GND

V. RTN.+12V

10K1uF+

18

1 64 5

1uF+6800pF8.8K22K

12K

0Ω 2.7K

+100uF

225

173

I2

I4

I3 I12

I7

233

230

228

224H8

4.75K

7.2-8.1VDC5V 63uS

ReverseHs

+12V

GND

3.6-4.1VDC 3.2VDC1.6V 63uS63uS

2.9-3.4VDC0V

.1-.3VDC1.4V4.4V

6,10

9

2 3

25K 330pF1,000

I5 227226

7.9-8.5VDC4.4V 63uS 63uS

8.2-9VDC

HORIZONTALPOSITION

484

20K RC7 2

7

I1

1.8K

8

198

56pFHs

FROM SYNCINTERFACE

GND

+12V

100uF216

18Ω

1N4742223

+REMOTE CONTROL

PCB

160Ω, 2WHORIZONTAL DEFLECTION CIRCUIT DESCRIPTION

196

D

LA7851

HorizontalSYNC INPUT

PICTUREPOSITION

O/S

DELAYEDSYNC O/S SAW TOOTH

GENERATORTR.MULTIPLIER

BIAS

218

pF

1

11

45KI6

6.8K

I13

All of these functions except for the picture position adjustment are accomplished by the phase locked loop (PLL). Delaying the horizontal sync with an adjustable timer produces the picture position adjustment.

If the delayed sync pulse occurs when the sawtooth is at a low voltage part of its cycle, capacitor 231 discharges and the oscillator frequency lowers. If the delayed sync pulse occurs at the top part of the sawtooth wave no current flows to capacitor 231 . This action, phase locks the horizontal oscillatorto the incoming sync pulses.

position control 484 and resistor I 4 . When the voltage, at pin 2, drops below 4 volts thedelayed sync O/S is triggered and capacitor 226is reset to its clamped voltage. The delayed syncO/S functions the same as the picture position O/S with the exception that it is not adjustable.

The picture position O/S clamps timing capacitor 226 to 8.2 volts until horizontal sync triggers this O/S. The voltage on the timing capacitor drops at a rate set by the horizontal 39

The horizontal control circuit's functions are: 1. To provide the horizontal output circuit with a stable frequency with or without incoming horizontal sync.

2. To be able to adjust the picture position, horizontally, with respect to the raster.

3. To operate stability through periods of missing horizontal sync pulses.

4. To keep the picture from drifting within the operating temperature range.

During the active part of the delayed sync pulse, the multiplier gates current to capacitor 231 which is dependent on the sawtooth voltage at the delayed sync pulse time.capacitor 230 sets the "0" voltage for the multiplier which is the average value of thesawtooth waveform.

The flyback pulse, connected to pin 4 throughresistor I6 , starts the negative slope of the saw tooth generator. When the sawtooth wave,which is produced by a current to capacitor 228 ,drops to 3 volts, the sawtooth generator switchesback to the positive slope part of the wave till thenext FBP.

The horizontal sync input circuit (pin 1) will trigger the picture position O/S on either the rising edge, or the falling edge, of the horizontal sync pulse. To accomplish the edge triggering, the sync pulse is differentiated by capacitor 198 into two short pulses, one for the rising edge and one for the falling edge of the sync pulse.Which edge is the trigger depends on the bias voltage at pin 1. For positive edge triggering ,the bias voltage is set to 7.8 volts by resistors I2and I3 . For negative edge triggering, the biasvoltage is set to 4.1V by connecting I 12 via a solder bridge on the I PRA

I12

198

I2I3

231

230

I6

228

484 I4

226

231

231

226

1314

12 11

7

33K

.01uFI8

231

H9

4.99K

.36-.4VDC

.6V 63uS

5.9VDC63uS

5.7-6.3VDC.2V

6-6.4VDCGND

CURRENT

297

10

968

73

2

45

1

FLYBACKTRANSFORMER

EHT

FOCUS

SCREEN

FIL.

FIL.

BEAM

237

236

I11

304

234

157

270Ω .01uF

100Ω

2SD1651

HORIZONTALDRIVE

TRANSFORMER2SC2344

2

134

33V 63uS

GND

19

20

GND

+127V

2W

+24V

HORIZONTAL DEFLECTION CONTROL SCHEMATIC

2435322

12.7VDC

9 108

6800pFI10

15

16

9.31K

1K

I9

232

6.3VDC63uS 63uS

5.9-6.4VDC4V

5.3-6VDC7.5V

HFo ADJ.

17

235

+200Hz

+400Hz+800Hz

FG

340Ω680Ω170Ω

1.87K

E

I16

I14

I15

comp.+-

X-RAYPROTECT

DISCHARGEHORIZONTALOSCILLATOR H.

V+

The horizontal oscillator capacitor 232 charges to its upper voltage limit through resistors I10 , I16 , I15 , I 14 and 235 . Thiscapacitor is then discharged to the lower voltagelimit through the action of discharge pin 9 andresistor I 9 . The free running frequency (Hfo)may be adjusted by making solder connections onthe I PRA. (see page 56 for the I PRA layout)In some cases where there are many missinghorizontal sync pulses, it is necessary to adjustthe Hfo closer than ±200 Hz. For fine tuning theHfo, resistor 2 35 is replaced with a pot.

The horizontal output transistor 304 conducts about three amps of horizontal flyback transformer primary current and deflection yoke current. This transistor has a beta as lowas three. To supply the high base current a horizontal output transistor drive transformer is used. The drive transformer 237 builds up energy during the on time of the drive transistor, 236 which is the off time of the horizontal output transistor 304 . Capacitor 2 34 and resistor I 11 damps the drivetransformer primary waveform.

The duty cycle of the horizontal drivetransistor is generated by comparing theoscillator waveform against a fixed voltage.This fixed voltage is set by resistors H8 and H 9 .

40

The voltage on capacitor 231 controls the horizontal oscillator frequency via I8 . in the case of missing horizontal sync pulses,the multiplier does not sink current and flywheelcapacitor 233 holds the horizontal frequency constant. Resistor I7 permits small rapid changes of the control voltage at pin 7 for locking of the oscillator to horizontal sync.

The horizontal phase locked loop then consistsof an oscillator which sets the flyback timing.The flyback pulse is then compared to the incoming sync pulse and the difference voltage holds the oscillator at the sync frequency.

The flyback transformer's main function is to supply EHT to the CRT. It also supplies thefocus and screen grid voltages which are tapson the EHT supply. There are three lowvoltage secondaries. One supplies the filamentcurrent. Another supplies sync and EHTinformation to the power supply. The thirdsecondary supplies sync for the horizontal PLLand drives the horizontal blanking circuit.

231

I8

233

232

235

235

I7

I9

304

237

236

234 I11

H9H8

I14I15I10 I16

304

The purpose of the horizontal width control circuit is to: 1. Provide a convenient means for adjusting the horizontal raster size. 2. Correct pincushion distortion in the vertical axis. 3. Correct horizontal raster distortion caused by periods of high beam current. The horizontal width control circuit is comprised of two main parts; The control circuit andthe diode modulator (DM). The control circuit combines four signals in the monitor to producethe width control circuit. These signals are: 1. Horizontal size From the H. Size Pot. 2. Vertical current (Iv) From the 3.3 ohm vertical current feedback resistor. 3. Vertical parabolic + Iv From the vertical yoke return. 4. Beam current From the EHT return on the FBT.

HORIZONTAL RASTER WIDTH CONTROL CIRCUIT DESCRIPTION

The diode modulator (DM) incorporates diode 311 to control the voltage on the DM main node(cathode of 311 ) during the flyback pulse time. If the diode 311 has low forward current, the DMnode voltage will be high during flyback time and the horizontal size will be small. The forwardcurrent in the diode 311 comes from the current buildup in inductor 316 during flyback time and thevoltage across the capacitor 315 during trace time. If the voltage is large across the capacitor 315 during trace time, most of the inductor current is discharged before the next retrace cycle and thehorizontal size is small. This condition can be checked by connecting a DVM to the vertical heat sink(GND) and to the heat sink 186 (collector 185 ). The voltage for minimum horizontal size is about 22V.Capacitor 315 supplies a voltage for the inductor 316 to work against similar to the 1,000uFcapacitor 195 in the vertical yoke circuit. For max. horizontal size, the voltage across 3 15 is about 8V,and the diode 311 , current before retrace is high. Diodes 3 08 and 3 10 clamp the DM node to GNDto keep the yoke current stable during trace time. Inductor 3 01 is an additional width coil and 3 02 is a horizontal linearity coil. Capacitor 300 and resistors 298 keep the coils from ringing afterretrace. Capacitors 306 and 307 form the normal Cp. The raster may be shifted by making solderconnections: left HL or right HR with increased effect Z . These solder connections introduces a DC current in the horizontal yoke via diode 193 or diode 312 . Resistor 303 limitsthe maximum current and resistor 309 permits fine adjustment.

The beam current from the FBT is converted to a voltage by resistors G17 , adj. 159 & adj. 179 andis filtered by capacitor 162 . Resistor G12 then connects the signal to the width control amplifiernode which accomplishes the blooming control function. The control amplifier converts the current atthe summing node (LM324 Pin 12) to a voltage across capacitor 315 , via feedback resistor G13 . A power transistor 185 is necessary since up to 2 watts may be dissipated by the control amplifier. Resistor G15 and capacitor 163 & 168 set the AC gain of the control Op Amp for stable operation.Resistor G14 stabilizes the complete control amplifier by reducing the overall gain. Resistors G 9 , G 10 , 1 64 and 166A provide adjustment for setting the horizontal size range. The fourth Op Amp ofthe LM324 and resistors G 1 and G 2 are used to generate a +6 volt ref. voltage for the controlcircuit. Resistor 1 71 stabilizes this +6V line with a load to GND. Capacitor 161 decouples thedeflection +12 volt supply by the LM324 165 . Components G4 , G5 , 178 , 201 , and 203 areused to correct a slight nonlinearity in the vertical deflection yoke via the vertical control circuit.

The horizontal size voltage from the remote control PCB 490 is applied directly to the controlamplifier summing node (LM324 Pin 12) by resistor G11 . For pincushion correction, the verticalparabolic voltage is needed, but it is not directly available since the vertical current,voltage (Iv) is partof the vertical parabolic voltage with respect to GND. The + Iv from the current sensing resistor 193 , is inverted by an Op Amp and resistors 148 and 1 72 . Resistor G 3 level shifts theinverted Iv to + 6V. The (vertical parabolic + Iv) is AC coupled by capacitor 1 83 and resistor G6 . It is then amplified by an Op Amp connected as a voltage follower. Resistor G7 protects the Op Ampagainst arc related voltage spikes. The inverted Iv (-Iv) and (parabolic voltage +Iv) are added to theamplifier node by resistors 1 67 and 166 which then makes up the pincushion correction signal.

41

The diode modulator controls the horizontal yoke current which affects the horizontal size. This isaccomplished by controlling the start time of the flyback pulse in the diode modulator node at thecathode of 311 . The start time of this pulse is then a function of the forward current of the diode 311 . This is because the current in the pulse across capacitor 306 must exceed the current inthe diode 311 before the pulse in the diode modulator node can start. The current used to control thestart time of the pulse comes from the voltage across inductor 316 from the previous horizontal pulseand is controlled by the control circuit.

315

311

311311

311 316315

183

G7

193

167 166

G12

490G11

184 172 G3

162

315

G13185

G15G14

G10G1 G2

163

164G9

165 201178 203G4 G5171

311

186 185

195

315

310301

293

308302

306 307

309312

315

300

303

161

168

316

G6

G17

ZHL HR

298

166A

159 179

311311

311306

316

7

10

+12V

13

8

10

311

++

+

203 178

172

184

G4 G5

167

G1

G2

171161

164

G16

G15 168

G14

G11

278

315 307

305 310

308

306

2.7uF

1N4937

630V.022uF

0ΩG13

44.2K

2.2K

.01uF16K

LM3241/4

LM3241/4

750uH316

38.3K

*

6.8K

LM3241/4

10K

10K6.8K

.1uF

2

3

1

12144

11

LM3241/4

16612K 8.87K

.33uF

10K 5K

10K

300

3,300pF

1N4005

1N4005

.01uF1.5KV

G310K

1K36K

201

10uF+

5

6

HORIZONTAL YOKE

250V.47uF

6VDC17mS4V 6VDC

3V 17mS

Blooming correction.

Pincushion correction.

7.15K

YC3

YC4

89

5G6

G7

10K

220K

6

4

3

1 13

18 17

15 16

8VDC 22V

MAX. MIN. H. Size4V 12Vp-p

2SC2344

165

302

68uH

298

2.2K1/2W

HEATSINK185

186

HSIZE

GND

+6V

183

7

8

4

19

2, 12

14

+

17mS

H. LIN.

220uH

WIDTH

301

H.

209268uH301

20928.2nF306

2092.33uF305

209222K167

209236K166

PincushionParabolic Linear

9

8VDC 23V

MAX. MIN. H. Size70V 250V 63uS

127VDC50V 170V

MAX. MIN. H. Size

127VDC150V 300V

MAX. MIN.

FBT Pin 10

FBT Pin 4

BEAMCURRENT

HORIZONTALOUTPUT

433

293314

309

312

470Ω,1/2W

FR205

270Ω, 2W

303

HORIZONTAL RASTER ADJ.+127V

481

10KHORIZONTAL

SIZERC5

+12V

GND

Remote ControlPCB 490

VERTICALLINEARITY

3.3Ω

1,000uF

VERTICALOUTPUT

+

-

CONTROLVERTICAL

195

193GND

HORIZONTAL RASTER WIDTH and POSITION CONTROL SCHEMATIC

H. RAS POS. CONTROL

VERTICAL

Horizontal+6V LINE

+12V

FBT Pin 9

127VDC

42

GND

YOKE

HL ZHR

28K

162

G17

50KG10

100K163

.01uF.047uF

1.82K

G12

20

19

+6V

G9

+ 100uF166A

Width Adj.

159

2.2K

169

179

3.3K

12K, 2W

289

FR205

ACline

User suppliedIsolationTransformer

V-

GND

+127V

+

+

LOADH Dy & EHT

VIDEO266

SECONDARIES

268

258

292

VREF.

Error Amp.Comp.

OSC. ENABLE

DRIVER

280

C5184

(-200V)

FET

V-

FLYBACKDIODE

GND

Res.

+

SIMPLIFIED POWER SUPPLY CIRCUIT FUNCTION DESCRIPTION

The switching regulator includes the power FET 268 which passes current from V- to GND through the inductor 258 . During the time the FET is on, the current in the inductor is increasing and the inductor is storing energy. When the FET is turned off, the stored energy in the inductor continues supplying current to GND.But in this case, the current path is from V+ to GND, instead of V-to GND. During this part of the cycle, the current in the inductor is decreasing.Under normal conditions, the current will decrease to zero and the voltage will ring.

As can be seen from the waveforms, the largest number of changes occur whenthe FET is turned off. Also, the FET drain voltage switches fast due to the high inductor current. To minimize video interference from the power supply, thepower supply is synchronized to the horizontal oscillator such that horizontalblanking is coincident with the FET turn off time. The C5184 280 is the series regulator IC. All of the control circuits that are builtinto this IC work together to produce one output signal, which is the FET drive signal. This signal can take on many shapes depending on the load conditions of the power supply. The waveforms for normal operation are shown above. For the shorted +127V to GND condition, which also occur right on power up,

FET Gate Drive

FET Drain Voltage

Inductor Current

The first FET pulse is a full on pulse which causes current to flow in the inductor.After the FET is turned off the current in the inductor drops much more slowly thannormal since the inductor is discharging into a much lower than normal voltage.If the FET were turned on for full power in the next cycle with current still flowingin the flyback diode, a current spike of 6A would occur, which is a power spike of 2,000W. The reason for this is that the diode stores charge when current flowswhich turns into reverse current for a short time when the voltage is reversed across the diode. 43

The waveforms are:

FET drain voltage

Flyback pulse

Current in diode

Voltage across 292

Current in inductor Current supplying GND

Current from V-

Current added to the +127V line266

268258

280

The regulator IC has a built in reference voltage which is used by the error amplifier set and hold the +127V line constant. Solder connections on the J PRA are used to adjust the +127V line in steps of ±1.5V. The over voltage protect circuit, when activated, turns off the regulator IC untilpower is disconnected. This circuit is connected to the rectified flyback pulse, which outputs a voltage that is proportional to the EHT. The circuit's main purposeis to protect the user against excessive x-ray which is caused by excessive EHT.

The FET drive waveform avoids this problem by sensing flyback diode conduction.If the flyback diode conduction is sensed, the low current start mode is selected.this mode turns the FET on, to a current of .1A, for not more than 4uS. If before or during the low current FET on time, the flyback diode breaks free, and the FET drain voltage goes down, the flyback diode voltage comparator will signal the regulator to permit the FET to be turned on for a full power cycle.The cycle after the last low power cycle in the waveform above is an example of thiscondition. The flyback diode voltage comparator inputs are located at pins 12 & 13 of the C5184. The two resistor dividers J10 J11 and J12 271 connect thecomparator across the flyback diode. The comparator enables the FET drive only after a 10% voltage drop is measured across this diode.

Most of the power supply fault conditions cause the power supply to chirpbecause the source of +17V for the regulator IC is generated by the power supply.A special circuit is built into the regulator IC, which permits charging the +17V linefilter capacitor with only a very low load from the IC. This circuit turns the restof the IC on only after the voltage at pin 15 reaches 17V. If the transformer does notsupply at least 12V to this line before the filter capacitor discharges to 12V, the regulator IC turns off. The reason for the audible chirp, is that, the power supplyis not full on for each cycle which produces a frequency low enough to hear. A 19V to 20V @ 1A, DC, isolated power supply is a tool necessary for trouble shooting CERONIX monitors. When trouble shooting the power supply, it can be connected toV- and the +17V line to keep the power supply running while checking the voltagesand waveforms to find the fault. It can also be used to supply the GND to +24V linefor checking the horizontal circuit. If the horizontal circuit does not work, thepower supply will chirp. Without the horizontal circuit working, there is not enough load on the power supply for transformer action to keep the regulator IC +17V line up to the minimum of +12V. A quick check for this condition is to clip a 2-4K@10W power resistor from GND to +127V line. If the chirping stops, the horizontal is probably not working.

44

SIMPLIFIED POWER SUPPLY CIRCUIT DESCRIPTION

Another fault condition exists when the FET exceeds 1.6A drain current.This condition can occur if the oscillator frequency is too low, the FET drain is shorted to GND or V+, the transformer has a shorted secondary, or the core is broken.In these cases the voltage across the FET source resistor 292 exceeds 1.6V whichis sensed by the over current comparator at pin 11. If pin 11 exceeds 1.6V, the FETdrive is set to 0V for the rest of the cycle. In some cases, this condition canproduce an output waveform which looks normal, but the voltage across the load (+127V to GND) would be low or unstable. A quick check for this condition is to check the peak voltage across the FET source resistor. CAUTION; Wheneverconnecting a scope ground to V-, be sure that the other scope probe or common grounded devices are not connected to the monitor GND.

The heart of the power supply is the oscillator which supplies the basic timing.The FET drive is always low during the negative slope of the oscillator or, when synchronized, after the start of the sync pulse. The low to high transition of theFET drive, pin 10, is determined by the voltage at the output of the error amplifier.If the 127V line goes up in voltage, the error amplifier voltage goes up, which thenintersects the oscillator waveform at a higher voltage and causes the FET on time to start later and be shorter. This negative feedback accomplishes the control loop of the power supply.

J12 271,J10 J11,

292

The FET drive is always off during the negative slope of the oscillator, or just after the sync pulse. Since the FET drive pulse is started by the error amplifier voltage and terminated by the end of the oscillator cycle, a control system via pulse width modulation has been established. The oscillator waveform is produced by charging capacitor 277 with a constant current set by resistor J7 to a voltage of 5V and then discharging the capacitor with double the charging current to 2.5V.Adding the flyback pulse, via capacitor 288 to this waveform synchronizes the oscillator, since theoscillator frequency is set below the horizontal frequency.Resistors J2 , J4 and capacitor 274 limit the error amplifier's AC gain, to hold the control loop stable. Capacitor 275 holds the error amplifier stable. Capacitor 281 reduces power supply noise, but, if too large, will cause the power supply to be unstable. The 127V line is adjusted by making solder connections on the J PRA(refer to page 56 for the layout). Solder connections A and B are used to raise the 127V line up to 4.5 volts in steps of 1.5 volts. Connections C and D lower the 127V line as much as 4.5V. The 127V line should be adjusted if below 125.8V or higher than 128.2V. Resistors 273 and 249 are used for monitors with special 127V line voltages.

The series regulator IC 280 , controls current to the monitor GND by pulse width modulation.A PNP transistor 250 , has an emitter current, that is directly proportional to the 127V line voltagedue to resistor J1 and adjustment resistors J13 & J14 . This current is transmitted to the power supply V- line, and is applied to a resistor J5 , J15 , & J16 . The voltage across these resistors is compared to a reference voltage by the error amplifier. If the +127V line goes up the output ofthe error amplifier voltage goes up. The pulse width modulation, which controls the + 127V linevoltage, is accomplished by turning the FET drive on at some particular voltage along the risingslope of the oscillator waveform. This particular voltage is the error amplifier output voltage.

Oscillator waveform with sync:

FET drive, C5184 pin 10:

Error Amp. V.

Fet DriveWith Sync

SWITCH MODE POWER SUPPLY CIRCUIT DESCRIPTION

Oscillator waveform without sync:

The FET 268 works together with the transformer 258 to provide a low resistance current path from V- to GND.This low resistance coupled with no large voltage times current products is what makes the power supply efficient. Resistor 292 provides a means for sensing the FET current.In the low current mode, it is used to set the 100mA currentand in the full on mode it is used to sense the max. current.Resistors 264 , 270 and capacitor 265 reduce power supplyelectrical noise. Transistor 284 and diode 283 short the FET drive to V- when the monitor is turned off to protect the FET from conducting current with a still large drain voltage. Resistors J10 , J11 , J12 and 271 provide a means forchecking flyback diode 266 conduction via a comparator.If the comparator measures low flyback diode voltage the FET is turned on to the .1A low current mode. This mode is necessary during power up, since initially the +127V line is 0V and no reverse diode voltage exists. The over voltage protect circuit has a trip voltage of 8Vand when it is activated, it shuts down the power supply. The EHT is measured by rectifying theflyback pulse, with diode 290 , from a secondary winding of the FBT. Capacitors 291 , 285 andresistors 287 , J9 are connected as a low pass filter to smooth out the simulated EHT voltage whichis then applied to the C5184 at pin 14. Resistor J8 protects the IC current sense input from voltagespikes and resistor 251 protects the PNP transistor from momentary overvoltage damage due to line spikes. Zener diode 295 protects the horizontal and video circuits from overvoltage due to power supply failure. If the +127V line exceeds 160V, the zener diode 295 shorts to GND the +127V line. 45

250

280

J1

277 J7

288

J2 J4 274

J5

275 281

273

268 258

292

264 270 265284 283

J10 J11 J12 271266

290 291 285287

295

251J8

J9

295

J13 J14J15 J16

249

A B

C D

256 247

257J6

286

150uF

250V

250V

90K

100K

100uF

1/2W

+

8,147

252

253

255

254

240

241

245

FR205

3A FUSE

CURRENTLIMIT

INRUSH

25-.5Ω

2 1PCPC

220Vo

220Vo

CUTFOR220Vo

+

+246

GL200

115VACINPUT 238

To deguassing coiland posistor.

V-

127V

FR205

2,200pF

252A

150uF

2,200pF

254A

At the input to the power supply is a voltage doubler which outputs between 240 to 425VDCdepending on the AC line voltage. It has a three amp fuse 245 to protect the PCB traces, an inrushcurrent limiter 240 to protect the rectifier diodes 252 , 254 , and optional capacitor 241 andinductor 246 which can be used to reduce conducted noise from the monitor AC input. For 220VACoperation the voltage doubler is replaced by a full wave rectifier by adding diodes 253 , 255 andcutting the 220Vo trace. 256 & 257 are the raw DC filter capacitors. Resistor J6 supplies thepower supply start current and resistor 247 balances the series connected filter capacitors for 220VAC operation. 46

248260263

1,000uF1,000uF

NONE.1uF.1uF

286131215

261262

POWER SUPPLY CONTROLVOLTAGE CURRENT CIRCUIT SUPPLIED DIODE FILTER CAP. NOISE CAP.

17VDC16VDC27VDC

7mA250mA250mA

VIDEO AND INPUTV. &H. DEFLECTION

100uF

255253J6

247

257256

254240245

252 241246

POWERSUPPLY

LOW VOLTAGESECONDARIES

4.67K

13

3.4-4.2VDC

5.7-6.3VDC

16.3-17.8VDC

OUTPUT

1

2

4

3

1516

14

5

6

7

8

12

11

10

9V-+7.5V REF.

XRC5184

Osc.

Rx

Cx

CurrentSENSE

DRIVE

CONTROL &FAULT SENSE

+15V+17V

INPUT

INPUT

INPUT

ERRORAMP.

COMP.

Output

OverVoltageProtectINPUT

+COMP.4uS

DELAY

280

282

SMXFR

D

251

215 262 131 261

263

260

258248 266

285

287

291J9

290

271J10

J11 J12

275

273

J3

274

J4

275

276

J7

277288

292

J8

270

283

284

265

2642,200pF

MPSA641N4005

18Ω

510Ω

14.7K 15.8K

1.2Ω 150Ω

200pF

2SK1446

1.00M

38.3K1,000

pF

191K

.1uF

FR205FR205

11K

56K

6,800pF 56pF

10.6K

23.2K

1.87K

56pF

100K2SA1371E

++ 1,000uF1,000uF

FR205

FR205

.1uF

330pF

6,800pF

33.2K

1.00M

268

.1uF295

317 294TZ160B-T3

160V

+27V

+16V

+127V

150uF250V

.1uF250V

14.8-16.3VDC

3

1

594

2

6-7VDC

3.6-4.4VDC6V 63uS

5.3-5.7VDC

63uS.10-.17VDC

1V

63uS2.4-3.6VDC14V

3.5-4.1VDC3-4V 63uS

.1-.5VDC

.5-.8VDC

6.5-7.5VDC

6.5-7.5VDC

V- V-

1312

17 18

16

J PRA PINS:

6

GND

+127V

V-296

.022uF

HeatSink267

20

9

2

4

5

3,10,15, & 19

275281.01uF

J1193K

250

1

20

DC

2.33K

J13 J14

-1.5V -3V

J2

J5

J16

J15

260Ω

130Ω

+3V

+1.5V

B

A

18Ω

248A

249

*

SWITCH MODE POWER SUPPLY SCHEMATIC+24V

FROMFBT

+16V +127V

17V

0VDC48V 63uSFROM

FBT

GND

127V

1N4148

20 Volt

IN OUTADJ.

LM337MT

115 VAC 60 Hz

1,000uF20V @ 1A

TransformerTriad #F-254 X

1N4005

35V

301R,1%

1N4005

1N4005

1N4005 -7V

+20V

HEAT SINK

4.75K,1%

47K 10K 1uF

1A Std. Fuse

24V Zener1N4749A

1A Std. Fuse

@.5 APower SW

ISOLATED +20V POWER SUPPLY CIRCUIT.

0V

Equipment setup for repairing the Model 1492 Monitor

47

+127.0

DVM

OSCILLOSCOPE

TRANSFORMER

VARIABLE

ISOLATION

TRANSFORMER

ISOLATED +20V @.5A DC

POWERSUPPLY

115VAC

CERONIX Model 1492

SAFETY FIRST; Use only one hand when working on a powered up monitor to avoid electricalshock.

Problem Solving Tools

48 There is a line voltage range of about 60% to 70% AC line voltage where a correctly operating monitor will chirp.

The power supply may chirp if:

If the +127V crowbar zener 295 is shorted, a fault exists in the power supply whichpermitted the +127V line to exceed +160V. First replace the zener. Never operate the monitorwithout the crowbar zener installed. Then with the external supply, the DVM, and the scope connected to the power supply (as in 2) slowly increase the AC line and observe the power supply response. Do not exceed +145V on the +127 V line. If the monitor runs normally, a fault maystill exist in the power supply power down circuit. Check parts 283 and 284 . If the crowbarzener is shorted and the FET is internally shorted, the C5184 IC 280 should also be replaced. If there is no FET drive waveform, check the voltages and waveforms on the C5184 pinsand compare them to the voltages and waveforms on the schematic. Shorts on the +127V, 24V, and 16V lines other than the crowbar zener are not likely to beconnected to the power supply even though the power supply chirps. By operating the powersupply with the +20V external power supply many of these problems can be found using the sameprocedure as are used in trouble shooting monitors with linear power supplies.

For the overloaded supply line problems, which often occur only when the +127V line is fullypowered up, the +20 volt external power supply is used to keep the monitor power supply running.To use the external supply, connect the 0V line to V- (anode of diode 254 ) and the +20V line tothe monitor power supply +17V line (cathode of diode 248 ). Connect the oscilloscope GND to V- and the probe to the FET drive (anode of diode 283 ).TAKE CARE NOT TO TOUCH THE OSCILLOSCOPE AND MONITOR CHASSIS DURING THISTEST, SINCETHE VOLTAGE DIFFERENCE CAN BE AS HIGH AS 400 VOLTS.Increase the AC supply, slowly, to the normal operating voltage while monitoring the +127V lineto GND voltage with the DVM. The power supply overload condition can be seen on the scopeas an almost square wave which can break up into short and long pulses as the AC line voltageis increased. The short pulses are the flyback diode current sense pulses. Sometimes the monitorwill operate normally in this mode, in which case, watch for smoke and after a few minutes ofoperation disconnect the power connections and carefully feel around the conductor side of theboard for hot spots. Overload conditions will not harm the power supply unless there is a problemin the power supply.

A quick check for the insufficient +127V load is to connect a 2K to 4K ohm 10 watt powerresistor to GND and the +127V line. If the chirping stops, proceed to check the horizontaldeflection circuit. First disconnect the board from the AC supply. Then connect the +20V supply,0V line to GND, and the +20V line to +127V and +24V lines on the monitor. Now the completehorizontal and vertical circuits can be checked with the oscilloscope and DVM. The flyback waveform will be about 140Vp–p instead of 1,000Vp–p which permits checking eventhe horizontal output transistor, collector, waveform.

Many of the failures that cause burnt components and boards are eliminated by the load sensitiveswitching mode power supply in the CERONIX monitor. This feature can cause problems withservicing the monitor if the proper trouble shooting approach is not used. The equipment setup, shown here, is necessary for efficient trouble shooting of the CERONIX monitors. Problems that cause the power supply to chirp are: 1. Insufficient +127V line load. 2. Overloaded +127V, +24V, or +16V lines. 3. Shorted +127V, +24V, or +16V lines. 4. Power supply component failure. 5. Raw DC (+127V to V-) voltage too low.

Always wear safety glasses.

The +17V line is open. (goes away when ext. PS is used)The 1.2 ohm current sensing resistor value is too high.The transformer core is broken or a winding is shorted.

1.

2.

3.

4.

5.

283 284

280

295

248283

254

1. Use a knife to brake free the magnetic rings on the yoke which are locked with red varnish. Bring the adjustment tabs on each pair of magnetic rings in line for the starting point.

2. Loosen the yoke clamp. Remove the yoke wedges and the tape from the CRT.

3. Connect a test generator to the video input and clip the red lead to the +12V line (anode of diode 101 ).

4. Turn the monitor on. Switch the test generator to red field. Adjust the horizontal and vertical raster size, on the remote control board, for under scan. Let the monitor run for at least half an hour.

5. Check the auto bright control voltage with a DVM connected to GND and pin 8 of the LM324 146 . The voltage range is 4.3V to 4.9V. If out of range, adjust this voltage to 4.6V by using pliers to rotate the bottom knob on the FBT.

6. Degauss the picture tube and front part of the frame.

CAUTION: To avoid electrical shock , take care not to touch the yoke conductors or push against the anode cap. Always keep one hand away from unit.

7. Adjust the yoke position, on the CRT neck, to the center of purity. One way to locate this yoke position is to make a felt pen mark on the CRT neck at the rear extreme of purity and another mark at the front extreme of purity. Make a third mark between the two marks and set the yoke to this position. Rotate the yoke to line up, the raster top line, with the top of the picture tube. Tighten the yoke clamp. Tilt the yoke side to side and up and down while watching the red field to verify that purity is good.

8. On the 13 inch CRT, use the purity magnets (closest to the yoke coils) to center the raster horizontally. To accomplish this, find the rotational position where spreading the tabs has the most effect on the horizontal position and spread the tabs a minimum to center the raster horizontally. On the 20 inch CRT, the purity magnets are often needed to optimize purity. The horizontal raster position solder connections are used to adjust the raster position. These solder connections are located on the foil side of the PCB next to the FBT. Connection HR shifts the raster right, HL shifts the raster left and the range of this shift can be increased by making solder connection Z under resistor 309 .

9. Check the purity with red field and with blue field while tilting the yoke side to side and up and down.

10. Switch the generator to red/blue grid. Adjust the 4 pole magnets (center pair) for convergence of the red and blue guns in the center of the screen.

11. Tilt the yoke up and down for the best convergence around the edge of the grid. Insert the top yoke wedge. Tilt the yoke side to side for the best convergence around the edge of the grid and insert the rest of the yoke wedges. Secure the wedges with tape.

12. Switch the generator to white grid. Adjust the 6 pole magnets (Pair closest to the socket board) for convergence of the green gun. Step #10 and this step may have to be repeated for optimum convergence.

SETUP AND CONVERGENCE PROCEDURE

49

146

309

101

Z

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

1492 & 2092 VIDEO INTERFACE PROGRAMS

50

NOTE: Solder connections S, T, & U, and resistor 094 set the video gain and may change due to component variations.

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

Altec; (1492)

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.

Advanced Touch Systems;

Change 007 , 024 , & 037 from 340Ω to 205Ω ±1%Change 008 , 023 , & 034 from 12.1K to 7.15K ±1%,

12 Solder Connections: A, B, C, G, H, I, J, K, L, P, T, & Y.

(1492)

AC Coin & Slot Service; (1492)

4 Solder Connections: Q, X, Y, & S.Standard Board.

Aeries International; (1492)

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.Standard Board.

Standard Board.HFo = 15,370 ±200Hz.

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

1492 & 2092 VIDEO INTERFACE PROGRAMS

51

NOTE: Solder connections S, T, & U, and resistor 094 set the video gain and may change due to component variations.

Bally;

12 Solder Connections: D, E, F, G, H, I, J, K, L, P, T, & Y.

Add a solder connection on the "I" PRA above pin 5.

(1492)

Brunswick;

11 Solder Connections: A, B, C, G, H, I, J, K, L, P, & Y.

(1492)Change 007 , 024 , & 037 from 340Ω to 301Ω ±1%Change 235 , from Hfo set resistor to 3K pot.Remove the 2.7K resistor at 094 .Add a solder connection on the I PRA above pin 5.

Before final test, add the AA solder connection and cut out the 270Ω resistor at 045 .

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

Automation; (1492)

Change 002 From 75Ω to 130Ω..

Change 027 From 75Ω to 47Ω.

Change 094 from 2.7K to 10K.

Install posistor 244 .

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y

Before final test add solder connections B & C.

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

Aristocrat;

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.

(1492)Install three 100pF disc capacitors at 010 , 022 , & 041 .

Invert horizontal sync by adding a solder connection on the "I" PRA above pin 5.

Before final test, clip out 045 , 270 ohm resistor, and add one solder connection AA by component no. 060 .

Install posistor at 244 .

High resolution board.

High resolution board.

Install posistor at 244 .

High resolution board.

Standard board.

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

1492 & 2092 VIDEO INTERFACE PROGRAMS

52

NOTE: Solder connections S, T, & U, and resistor 094 set the video gain and may change due to component variations.

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.

CEI; (1492)

For the 13" CRT monitor, Add solder connectionS, and omit T . do not change resistor 203

By Video;

12 Solder Connections: A, B, C, G, H, I, M, N, O, P, T, & Y.

(2092)Change 008 , 023 , & 034 from 12.1K to 2.67K,1%Change 002 , 005 , & 027 from 75Ω to 2.7K, 5%, 1/4WChange 203 from 36K, 5% to 24.3K, 1%.

Before final test, clip out 045 , 270 ohm resistor,and add one solder connection AA by 060 .

Add a solder connection on the I PRA above pin 5.

Change 094 from 2.7K to 10K.

CAS Ltd.; (1492)

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.

Install posistor at 244 .

Carson Valley Inn; (1492)

4 Solder Connections: Q, X, Y, & S.

Change 200 from 127K to a 200K pot.

High resolution board.

Standard board.

Change 094 from 2.7K to 10K.Install the posistor at 244 .

12 Solder Connections: Q, X, Y, & S.

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

1492 & 2092 VIDEO INTERFACE PROGRAMS

53

NOTE: Solder connections S, T, & U, and resistor 094 set the video gain and may change due to component variations.

Games of Nevada; (1492)

12 Solder connections: D, E, F, G, H, I, J, K, L, P, T, & Y.

High resolution board.

IGT;

4 Solder Connections: Q, S, X, & Y.

(1492)

Delete degaussing circuit.

High resolution board.

Keevex;

4 Solder Connections: Q, S, X, & Y.

(1492)

High resolution board.

Install posistor at 244 .

Horizontal frequency is 17,182Hz

Mast Keystone;

5 Solder Connections: A, B, C, P, & S.

(1492)

Change 002 , 005 , & 027 from 75Ω to 1K ±5%.

Standard Board.

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

1492 & 2092 VIDEO INTERFACE PROGRAMS

54

NOTE: Solder connections S, T, & U, and resistor 094 set the video gain and may change due to component variations.

Change 002 , 005 , & 027 from 75Ω to 1K ±5%.Change 008 , 023 , & 034 from 12.1K to 4.42K ±1%.

United Tote;

12 Solder Connections: A, B, C, G, H, I, M, N, O, P, U, & Y.

(1492)

Syntec;

5 Solder Connections: Q, U, R, X, & Y.

(2092)

Change 203 from a 36K ±5% to a 24.3K ±1% resistor.Change 094 from 2.7K to 10K ±5%.Delete degaussing circuit.

Change 002 , 005 , & 027 from 75Ω to 27Ω ±1%.Change 007 , 024 , & 037 from 340Ω to 140Ω ±1%.Change 008 , 023 , & 034 from 12.1K to 3.32K ±1%.Change 064 from 2.7K to 10K ±5%.

Semi-Conductor;

11 Solder Connections: A, B, C, G, H, I, J, K, L, P, & Y.

(1492)

Install posistor at 244 .

High resolution board.

Change 007 , 024 , & 037 from 340 ohm to 140 ohm ±1%.Change 008 , 023 , & 034 from 12.1K to 3.32K ±1%.Remove 045 , 046 , 047 , & 048 .Add a 2.2K resistor to hole by video connector 006 pin 5 and hole between resistors 050 & 051 .

RS 170; (1492)

12 Solder Connections: A, AA, B, C, G, H, I, J, K, L, P, & Y.

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

X

A

B

C D

E

F

G

H

I

J

K

L

N

P

Q

R ST U

Y

MO

AA

1492 & 2092 VIDEO INTERFACE PROGRAMS

55

NOTE: Solder connections S, T, & U, and resistor 094 set the video gain and may change due to component variations.

Change 002 , 005 , & 027 from 75Ω to 1K ±5%.Change, the video input connector, 006 from a 6 conductor to a 7 conductor header.

5 Solder Connections: A, B, C, P, & S

4 Line TTL; (1492)

Solder Connections:

Solder Connections:

Change 094 from 2.7K to 10K, ±5%.

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.

Western Amusement (1492)

Install posistor 244 .

Standard board.

NOTES:

56

2 3 5 6 7 8 9 10 13 14 15 16 17 18 19 201 114 12

P/N CPR0504

HORIZONTAL WIDTH CONTROL RESISTOR ARRAY "G"

G1 G2G7

G6

G5

G4

G3

G8 G10

G9

G11

G12

G13 G14 G15 G16 G1710K

10K

10K

10K

10K10K 5K

220K

50K

100K

44.2K

28K

38.3K

2.2K

16K 6.8K

1.82KA

Solder connection A reduces the horizontal raster size.

G

H. SIZEPOT GND

+6VSource

+12VLINE

Pincush.CoupleCap.

to Pin.Buffer

V. LIN.Correct.

LIN.buffernode

NC GND DMBuffer

DMcontrolV FB

DM ampOutput

NPNB

StabilityCap. Neg FB

+6VLINE

i BeamFB

DM amp

3 7 5 8 9 12 14 13 1LM324 Pin No.

AUTO BIAS RESISTOR ARRAY "C"

2 3 5 6 7 8 9 10 13 14 15 16 17 18 19 201 114 12

C15

C14

C12

C11C10

C9C4C7C6

C5

C8

C3C2C1

C16 C13

P/N CPR0503

68.1K

200ΩΩΩΩ 200ΩΩΩΩ

200ΩΩΩΩ

68.1K68.1K 20K 1.82K

2.74K 1.82K

5.00K

4K

5.00K

4K

5.00K

4K

C

ProgramPULSE

H.Blank

BLUEi Beam

GREEN REDGND NC

10.7VLINE

4.2VLINE

REDAmp out

REDAmp FB

ProgramPULSE

ProgramPULSEi Beam i Beam

REDi sense

GREENAmp FBGREEN

i sense Amp outGREEN BLUE

Amp FBi sense Amp outBLUE BLUE

4 5 7 6 LM324 Pin No. 2 1 13 14

2 3 5 6 7 8 9 10 13 14 15 16 17 18 19 201 114 12

P/N CPR0500

VIDEO AMPLIFIER RESISTOR ARRAY "B"

1234567

10 11 12 13 148 9

B4

B1

B3B2

B5

B20

B7

B18

B13

B6

B14B15

B16

B17

B9 B19

B11 B10

B12

B8

1.2K

68K

180ΩΩΩΩ

27ΩΩΩΩ

392ΩΩΩΩ

606ΩΩΩΩ3.32

K

1.27K

790ΩΩΩΩ 3.78K

1.65K836ΩΩΩΩ

5.62K

40.2K

510ΩΩΩΩ66ΩΩΩΩ270ΩΩΩΩ

32ΩΩΩΩ

270ΩΩΩΩ539ΩΩΩΩ

1490-91

1490-91

B

NE592

PNPdrivecap.

NPNE

NE592OutputB

NPN7.9VLINE GND +12V

LINEVIDEOINPUT

AUTOBIAS

127VLINE

7.9V PNP ECAP.

PNP BDIODE

PNPB

PNPE

PNPC

AMPOutputGND GND

57

2 3 4 5 6 7 8 9 10 12 13 14 15 16 17 18 19 201

R2

R8

2.33K

POWER SUPPLY. RESISTOR ARRAY "J"

P/N CPR0501

193KJ1

J13 4.67

J14 130

J15

11KJ2

56KJ4

10.6K

J5

260ΩΩΩΩJ16

33.2kJ7 J8

510ΩΩΩΩ

J1114.7K

J1215.8K

J101M

J6B

45KJ6A

45K

23.2KJ3

A

B

C D

A - Increases +127Vline by 1.5V

B - Increases +127Vline by 3V

C - Decreases +127Vline by 1.5V

D - Decreases +127Vline by 3V

V-1/2 Raw

DC 17V V- i SenseFET

Source +17V V- O.V.P.LOAD

D 266+ Comp.

D 266- Comp. V- 127V

V+

V-, 100V to 300V below GND. Normally GND -200V.

J9

38.3K

JP/N CPR0501Power Supply Resistor Array "J"

K

ΩΩΩΩ

+127VSENSE

Old+127V

SET

E. Amp.-FB cap.

E. AmpOutput

E. Amp+Input

Osc.Rx

FET

2 1 C5184 Pin No. 11 15 14 13 12

2 3 5 6 7 8 9 10 13 14 15 16 17 18 19 201 11

1/2I11

200ΩΩΩΩ

1/2I11

200ΩΩΩΩ

I14170ΩΩΩΩ

I15340ΩΩΩΩ

I16680ΩΩΩΩ

I91K

I10

9.31K

I833K

I710K

I136.8K

I4

2.7K

I322K

I5

25K

1.8KI1

I2

12K

I12

8.8K

I6

45K

I Horizontal Control Resistor Array "I" P/N CPR0502

FBPH. Pos.POT

H. SyncCap.

H.

+12V GND GNDH. SyncOutput

H. Pos.O/S

PLLO/S

PLLSYNC

PLLoutputCap.

OSC. Osc. Dis-charge

HfoSET

H. +12VLine

Fly-

Cap.wheel H. Drive

DamperDamper

Cap.

9874321 LA7851 Pin No.

D

E F G

D - Inverts Horizontal Sync. E, F, & G Adjust the Horizontal Oscillator Frequency. E=Hfo +200 Hz, F=Hfo +400Hz, & G=Hfo +800Hz.

Vertical Control Resistor Array "H"

2 5 6 7 8 9 10 13 14 15 16 17 18 19 201 114 12

H1

330ΩΩΩΩH2

330ΩΩΩΩ

H19

.5M

H18

.2M

H1722K

H3

84K

H1422K

H1522K

H5301ΩΩΩΩ

H1622K

H6

76.8K

H7

330

H13

.2M

H2088K

H94.99K

H84.75K H10

34K

H4118K

H12

1K

H11

1K

ΩΩΩΩ

P/N CPR0503D

Solder jumpers B and C are used to keep the vertical oscillator (with no sync) within the range of 43 to 47Hz.B - Decreases Vfo. C - Increases Vfo.

B

C

H21

H22C

B

E

3906

H26

1N4148H25+ 10uF

16VH24H23

3904

C

B

E

H

VERT.SIZE

SYNCINPUT

V. OSC.RES.

VERT.SYNC

+12VLINE

V. OSC.CAP.

RAMPCAP.

BIASO/S

V. OUTLA7851

LA7830INPUT

Outputbias

ControlRAMPCAP.

+12VLINE GND

H. DutyCycle

BIASH.F. FB

TOYOKE

YOKEReturn

YOKEi sense

19 20 18 17 16 15 1413 11 LA7851 Pin No.

58

Precision Resisitor Arrays (PRAs).