Tech Sheet Do not discard

8205288 / 4619-651-98861 FOR SERVICE TECHNICIAN’S USE ONLY

PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE

MICROWAVE ENERGYa. Do not operate or allow the oven to be operated with

the door open.b. Make the following safety checks on all ovens to be

serviced before activating the magnetron or other microwave source, and make repairs as necessary:1. Interlock Operation2. Proper Door Closing3. Seal and Sealing Surfaces (Arcing, Wear and Other

Damage)4. Damage to or Loosening of Hinges and Latches5. Evidence of Dropping or Abuse

c. Before turning on microwave power for any service test or inspection within the microwave generating compartments, check the magnetron, waveguide or transmission line, and cavity for proper alignment, integrity and connections.

d. Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and transmission systems shall be repaired, replaced, or adjusted by procedures described in service manual before the oven is released to the owner.

e. A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to the owner.

f. Do not attempt to operate the oven if the door glass is broken.

WARNING

Electrical Shock Hazard

Disconnect power before servicing.

Replace all parts and panels before operating.

Failure to do so can result in death or electrical shock.

2

WIRING DIAGRAMSSchematic Diagram

Sym

bol N

otes

BK

: Bla

ckB

U: B

lue

R: R

ed

W: W

hite

G: G

reen

Y:

Yello

w

1BR

Wire

Col

or -

Bro

wn

Wire

No.

- 1

Con

ditio

n: D

oor

Ope

n.

DW

G N

O.

MU

-056

Mag

netr

on

Fus

e

5 W

27 BU

26 B

U

Sec

onda

ryIn

terlo

ckS

witc

h

Rel

ay B

oard

Prim

ary

Inte

rlock

Sw

itch

CF

TT

Cav

ity L

amp

Coo

ling

Fan

Mot

or

Turn

tabl

e M

otor

Hoo

d E

xhau

stFa

n M

otor

P21

/P31

/P32

/P33

/P34

/P35

/P51

/P52

/P53

/P54

/P55

/P56

/P57

/P58

/P61

/P62

/P63

/P64

/P65

/P66

/P67

/P68

/P71

/P72

/P73

/P

74/C

N70

1/C

N70

2/C

N70

3: W

ire to

PC

B C

onne

ctor

s

Hoo

d La

mp

(Coo

ktop

Lam

p)H

LCL

CavityThermostat

46 R

47 R

BR

: Bro

wn

OR

: Ora

nge

TR

:Tra

nspa

rent

CN

702

1 B

R20

Am

p

P81

/P82

/P83

/P84

/P85

/P86

: Wire

to W

ire C

onne

ctor

s

45 Y/G

GY

: Gra

y

CN

703

E70

1

Inve

rter

Mon

itor

Inte

rlock

Sw

itch

L N

G W120V

/125

V,60

Hz

72 R

/ 3C

Rib

bon

Cab

le /

3 C

ore

24 G

MW

Rel

ay49

03

TT

TT Rel

ay49

061P

53

CF

Rel

ay49

01

P52

N

CF

55 W

5P81

50 W

6P81

GN

D

R

HF

BK

CF

FCFA

500m

AF

use

L

P74

1

2 B

R

39 BU

35 BR

56 W

36 R

33 BK

12

Mag

netr

on T

herm

isto

r

Y

TR

TR

1P81

Y

1

HL

HL

32 W

31 W2P

81

P58

51 W

52 W

W

1P84

2P84

1

49 B

K4P

81

4121

3P81

17 B

K

P51

P57 P56

P67

P66

Relay Control Board

P65

1

P61

1CN701

Inve

rter

1P

54

1 P55

65 W

CL

1

P63

The

rmos

tat

Bas

e

1

P62

Doo

rN

FS

Inve

rter

500m

A

Fus

e

4170

22 G

Y

53 BK

2P83

1P83

42 GY

34 BU3 BR

L1 N1

P34

P31

Coi

lR

Cy

Cy

Cx

P32

P33

AC

Lin

e F

ilter

Cx

VD

RV

DR

P35

BK

MW Relayfeedback

1 2

TT

P64

UIB

75G

Y/5

CP

2P

3LC

D

18 B

U

23 O

R

28 B

U

67 B

K

1

RW

P68

Hum

idity

Sen

sor

Wav

egui

deT

herm

osta

t

29 BU

54 BK

R

HFW

BK

Mot

or C

apac

itor

Hoo

d E

xhau

stFa

n M

otor

37 R

1P822P82

10uF

3P82

38 R

58 R

VDR

8P81

UIB Thermistor

BK

BK

BK

R R

FC

FAR

elay

4907

64 B

U62 B

K 63 Y

PR

2P

R 1

7P81

9P81

60 G

59 OR22 G

Y

72 R

/3C

PR

1/2

Pow

er R

esis

tor

61 B

R

4 B

R

Rel

ay49

32R

elay

4931

Rel

ay49

30

37 R

77 R

/8C

Touc

h P

anel

B

oard

76 C

olor

/5C

P86

3600

P6

BR

66 R

BK

BK

BK

BK

P73

1

1

P21

73 W

/2C

74 W

/2C

P85

Hoo

dLi

ght

Sw

itch

70 Y

/3C

71 B

K/R

/10

C

3

Parts Layout(not to scale)

(+) Continuity (-) No Continuity

A. Humidity sensor B. Cavity thermostat—opens at 329ºF

(165ºC), closes at -22ºF (-30ºC) C. Waveguide thermostat—opens at

257ºF (125ºC), closes at -95ºF (-35ºC)D. AC line filter E. Relay boardF. Magnetron thermistor G. Magnetron H. Secondary interlock switch I. Ferrite ring

J. Inverter K. Cooling fan motor L. Motor capacitor

M. Monitor interlock switch N. Primary interlock switch O. Relay control board P. Line fuse (20 amp) Q. Fuse holder R. Hood exhaust fan motorS. Hood (cooktop) lamps T. Power resistor-1 (20 ohm/25 W)

U. Power resistor-2 (41 ohm/50 W)V. Base thermostat—closes at 140ºF

(60ºC), opens at 104ºF (40ºC) W. Turntable motor X. Touch panel (back and front views)Y. Cavity lamp Z. Hood/light switch

AA. Door control assembly (back view) (includes touch panel only)

BB. UIB (user interface board)CC. LCD module

Primary, Secondary, and Monitor Interlock Switch Checkout Procedure

Switch Check By Door Open Door Closed

Primary Interlock

1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Primary Interlock Switch.3. Check from the common terminal (brown wires) to the normally

open terminal (brown/white wires).

- +

1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Primary Interlock Switch.3. Check from the common terminal (brown wires) to the normally

closed terminal (orange wire).

+ -

Secondary Interlock

1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Secondary Interlock Switch.3. Check from the common terminal (green/blue wires) to the

normally open terminal (gray/blue wires).

- +

Monitor Interlock

1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Monitor Interlock Switch.3. Check from the common terminal (blue wire) to the normally

closed terminal (white wire).

+ -

CD

EFGH

I

J

K

LMNOPQRSTUV

SWX

ABAA

BB CC

X

YZ

4

NOTE: These diagrams are not intended to show a complete circuit; they represent the position of switches during “DOOR OPEN” or “DOOR CLOSED” (continuity checks only).

Door Closed Door Open

TROUBLESHOOTINGDo not continue with the diagnostics of appliance if the household fuse is blown, a circuit breaker is tripped or if there is less than 120-volt power supply at the wall outlet.Complete the following steps before checking microwave oven circuitry:1. Unplug microwave oven or disconnect power.2. Check for loose wiring or incorrect wiring within

microwave oven.

3. Disconnect white wire from power transformer and discharge high-voltage capacitor.

4. All testing must be done with an ohmmeter having a sensitivity of 20,000 ohms per volt DC or greater, and powered by at least a 9-volt battery.

5. All operational checks using microwave energy must be done with the microwave oven loaded with a minimum of 8 oz (250 mL) of water in a microwave-safe container.

Inverter and Magnetron Circuit

Hood Exhaust Fan on Low Speed

MonitorInterlockSwitch

PrimaryInterlockSwitch

SecondaryInterlockSwitch

(NC) (NO)(NO) (NC) (NO)L N

MonitorInterlockSwitch

PrimaryInterlockSwitch

SecondaryInterlockSwitch

(NC) (NO)(NO) (NC) (NO)L N

Filter2

49031

BU

CavityThermostatPrimary

InterlockSwitch

MW Relay BUBR

P56

P66CN702

P65

CN

701

CN

703Inverter

Magnetron

12

3

32

1

R

R Relay Control Board

Relay Board

BR

10

SecondaryInterlockSwitch

BK BU

RibbonCable

L

BK BRN

WFilter

RibbonCable

Fuse20 Amp

WaveguideThermostat

BU

Fuse 500mA

4170Inverter

1 2

Fuse 500mA

4170

Inverter

HF

Motor Capacitor

L NFuse

20 AmpBR WBK BR BR

P51BU BUG

Relay Board

P52

R

Filter Filter

CavityThermostat

BU

WaveguideThermostat

R R R GY

W W BR

3P82

2P82 5P81

8P81

4P54

4P53

1P54PR2 PR1Power

Resistor-2Power

Resistor-13P811P82

Relay 4930BK BK BK BR BK

5

Hood Exhaust Fan on High Speed

Hood Exhaust Fan on Medium Speed

Hood Exhaust Fan on MAX Speed Manually

Hood Exhaust Fan on MAX Speed Automatically

Fuse 500mA

4170

Inverter

HF

Motor Capacitor

L NFuse

20 AmpBR WBK BR BR

P51BU BUG

Relay Board

P52

R

Filter Filter

CavityThermostat

BU

WaveguideThermostat

R R R GY

W W BR

3P82

2P82 5P81

8P81

4P54

4P53

1P54PR2 PR1Power

Resistor-2Power

Resistor-13P811P82

Relay 4930BK BK BK BR BK

YGY

7P812P54

Relay 4932

BUOR

3P549P81

Fuse 500mA

4170

Inverter

HF

Motor Capacitor

L NFuse

20 AmpBR WBK BR BR P51 BU BUG

Relay Board

P52

R

Filter Filter

CavityThermostat

BU

WaveguideThermostat

R R R GY

W W BR

3P82

2P82 5P81

8P81

4P54

4P53

1P54PR2 PR1Power

Resistor-2Power

Resistor-13P811P82

Relay4930BK BK BK BR BK

YGY

7P812P54

Relay4931

Fuse 500mA

4170

Inverter

HF

Motor Capacitor

L NFuse

20 AmpBR WBK BR BR P51 BU BUG

Relay Board

P52

R

Filter Filter

CavityThermostat

BU

WaveguideThermostat

R R R GY

W W BR

3P82

2P82 5P81

8P81

4P54

4P53

9P811P82

Relay 4930

BK BU OR 3P54Relay4931

Relay4932

BK

Fuse 500mA

4170

Inverter

HF

Motor Capacitor

L NFuse

20 AmpBR WBK BR BR P51 BU BUG

Relay Board

P52

BK

R

BK

Filter

BaseThermostat

Filter

CavityThermostat

BU

WaveguideThermostat

R R R GY

W W BR

BK4P811P82

3P82

2P82 5P81

8P81

4P54

4P53

BU

6

Cooling Fan Motor Circuit

Turntable Motor Circuit

Door Open—Oven Cavity Light is On

Cooktop Light on Variable Light

4P53CF

2P53

2P83

1P83

CF Relay4901

Relay Board

GY

BU

GBR BR P52P51 Cavity

Thermostat

BR BU BUN

WL

BKFilterFilter

Fuse20 Amp

WaveguideThermostat

BUFuse 500mA

4170

Inverter

4P54W

TT

1P53

Relay Board

BR

W

5P81

R

GBR BRP52P51

CavityThermostat

BR BU BUN

WL

BKFilterFilter

6P81

Fuse20 Amp

TT Relay4906

WaveguideThermostat

BUFuse 500mA

4170

Inverter

Filter

LN

Fuse20 Amp BR

WBK BR B RP51 P52

2P55

Fuse500mA

Inverter

4170

4121

Fuse500mA

3P55

P611 2 3

BU BUG

Relay ControlBoard

Relay Board

P63

OR

1P62

12

Filter

PrimaryInterlock

Switch

CavityThermostat

CavityLamp

1P55

BU

WaveguideThermostat

RR

L NFuse

20 AmpBR WBK BR BR

P51 P52BU BUG

Relay Board

Fuse500mA

Inverter

P582

1 W

W

W

TR

Y

W

TR

Y

HL HL

1P84

2P84

2P81

1P81

4170Filter Filter

CavityThermostat

BU

WaveguideThermostat

7

Touch Panel

Touch Panel and Relay Control Board Tests

To access the test mode:1. Unplug microwave oven or disconnect power.2. Open the microwave oven door.3. Press and hold OFF/CANCEL.

4. Plug in microwave oven or reconnect power.5. Release OFF/CANCEL and close microwave oven door.NOTE: If the OFF/CANCEL key is pressed during this diagnostic routine, you will exit the test mode.

Test Mode Table

Microwave Oven Power Output Test1. Place 8 oz (250 mL) of lukewarm water in the center of the

microwave oven.2. Operate on HIGH power level for 2 minutes. Water

should be hot.

NOTE: If the water takes longer than 2 minutes to heat, this may indicate either the operating voltage is lower than 110 volts or there is a problem with the microwave oven.

Screen Display Display Explanation

UIB SW ver Version number of UIB (user interface board) software

PB SW Ver Flash Version number of power board (relay control board) software

UIB thermistor (ºC) The temperature (ºC) measured by UIB thermistor—ranges about 5ºC above room temperature, if oven has not been used recently

Magnetron thermistor (ºC)

The temperature (ºC) measured by magnetron thermistor—maximum 125ºC

HUM PWM Humidity level inside unit—ranges between 8,000 and 9,500, depending on humidity level in oven cavity

Hood Key Hood key number

Screen Display Display Explanation

Touch panel Touch panel error

EEPROM Version number of PB (relay control board) EEPROM (Electrically Erasable Programmable Read-Only Memory)

MW reply error MW relay error

Smps FB error Inverter feedback error

Hum sensor error Humidity sensor error

Cavity thermistor error Cavity thermistor error

Magnetron thermistor error

Magnetron thermistor error

EEPROM error EEPROM (Electrically Erasable Programmable Read-Only Memory) error

8

Failure Codes IndicationsNOTE: Many of the problems listed in the chart below may be solved by power cycling: unplug microwave oven or disconnect power. After one minute, plug in microwave oven or reconnect power.

Display Likely Failure Condition Recommended Repair Procedure

F1.E1 Relay control board defective

1. Unplug microwave oven or disconnect power.2. Replace the relay control board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.

F2.H1 Hood keys stuck 1. Unplug microwave oven or disconnect power.2. Replace hood/light switch. 3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.

F2.H2 Hood/light switch defective

1. Unplug microwave oven or disconnect power.2. Replace hood/light switch.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.

F2.Q1 Not reading keypad inputs

1. Unplug microwave oven or disconnect power.2. Replace the user interface board (UIB).3. Replace the door control assembly.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.

F3.H1 Humidity sensor 1. Unplug microwave oven or disconnect power.2. Check connection to relay control board.3. Replace humidity sensor.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power.7. Replace relay control board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.

F3.T1 UIB (user interface board) thermistor

1. Unplug microwave oven or disconnect power.2. Check the connections from the UIB to the relay control board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.5. If problem persists, unplug microwave oven or disconnect power.6. Replace relay control board.7. Replace all parts and panels before operating.8. Plug in microwave oven or reconnect power.9. If problem persists, unplug microwave oven or disconnect power.10. Replace the UIB.11. Replace all parts and panels before operating.12. Plug in microwave oven or reconnect power.

F3.T3 Hood thermistor 1. Unplug microwave oven or disconnect power.2. Check hood thermistor connection.3. Replace the hood thermistor.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power.7. Replace the relay control board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.

9

F3.T4 Magnetron thermistor 1. Unplug microwave oven or disconnect power.2. Check magnetron thermistor connection.3. Replace the magnetron thermistor.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power. 7. Replace the relay control board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.

F6 MW relay 1. Unplug microwave oven or disconnect power.2. Check the cable from Relay 4903 to inverter.3. Check to see if the relay (4903 on relay control board) contact has welded

closed.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power.7. Replace relay board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.10. If problem persists, unplug microwave oven or disconnect power.11. Replace relay control board.12. Replace all parts and panels before operating.13. Plug in microwave oven or reconnect power.

F7 Power to magnetron interrupted

1. Unplug microwave oven or disconnect power.2. After 40 seconds, check to see whether this solves the problem. 3. Unplug microwave oven or disconnect power.4. Check cooling fan operation5. Check the magnetron.6. Check P65 connection on the relay control board.7. Check the P56/P66 connection between relay board and relay control

board.8. Check wiring to the 1200W inverter and control system. See “Checking

Inverters.”9. Check operation of all interlock switches. 10. Replace all parts and panels before operating.11. Plug in microwave oven or reconnect power.12. Check voltage at 4903-1 on relay board. If it is 120, unplug microwave

oven or disconnect power.13. Replace inverter. 14. Replace all parts and panels before operating.15. Plug in microwave oven or reconnect power.16. If problem persists, unplug microwave oven or disconnect power.17. Replace relay control board.18. Replace all parts and panels before operating.19. Plug in microwave oven or reconnect power.20. If problem persists, unplug microwave oven or disconnect power.21. Check for reversed plug connection on controls or loose wiring.22. Replace all parts and panels before operating.23. Plug in microwave oven or reconnect power.

F9 Relay control board communications error

1. Unplug microwave oven or disconnect power.2. Check the communications cable from P66 to P56 between relay control

board and relay board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.5. If problem persists, unplug microwave oven or disconnect power.6. Replace the relay board and relay control board.7. Replace all parts and panels before operating.8. Plug in microwave oven or reconnect power.

Display Likely Failure Condition Recommended Repair Procedure

10

Component Tests

F9.Q Touch communication 1. Unplug microwave oven or disconnect power.2. Check the communications cable from UIB to the touch panel board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.5. If problem persists, unplug microwave oven or disconnect power.6. Replace the door control assembly.7. Replace all parts and panels before operating.8. Plug in microwave oven or reconnect power.

IMPORTANT:

■ Unplug microwave oven or disconnect power.■ Remove the lead wires from the related component

before conducting any of the following tests.■ Discharge the high-voltage capacitor and remove the

lead wires from the primary winding of the high-voltage transformer before conducting any of the following tests.

■ All operational checks using microwave energy must be done with the microwave oven loaded with a minimum of 8 oz (250 mL) of water in a microwave safe container.

■ Conduct a microwave energy test after performing any tests or repairs to the microwave oven.

■ Check that all wire leads are in the correct position before operating the microwave oven.

■ Grasp wire connectors when removing the wire leads from microwave oven parts.

■ All testing must be done with an ohmmeter having a sensitivity of 20,000 ohms per volt DC or greater, and powered by at least a 9-volt battery.

Components Tests/Results

Magnetron 1. Unplug microwave oven or disconnect power.2. Remove wire leads. Check that the seal is in good condition.3. Measure resistance:

■ Filament terminals: Normal: Less than 1 ohm■ Filament to chassis: Normal: Infinite

Cooling Fan Motor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Normal: 41 +/- 5 ohms■ Abnormal: Infinite

Turntable Motor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Normal: 2.2k +/- 0.5k ohms (approximate)■ Abnormal: Infinite

Hood Exhaust Fan Motor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Pins 1 and 2: Normal: 17 +/- 5 ohms; Abnormal: Infinite■ Pins 1 and 3: Normal: 21 +/- 5 ohms; Abnormal: Infinite

AC Line Filter 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ P31 and P32, P33 and P34: Normal: Greater than or equal to 300k ohms; Abnormal: Less than or equal to 100k ohms

■ P31 and P34, P32 and P33: Normal: 0 ohms; Abnormal: Greater than or equal to 100k ohms

Display Likely Failure Condition Recommended Repair Procedure

1 2 3BK

W

R

P34

P31

P33

P32

11

Humidity Sensor 1. Unplug microwave oven or disconnect power.2. Remove the 3-pin connector from Relay Control Board.3. Measure resistance across pins 1 and 3, and across pins 2 and 3:

■ Normal: 2.8k ohms (approximate) at 77º +/- 10ºF (25º +/- 10ºC)■ Abnormal: Infinite

Thermostats NOTE: Refer to “Parts Layout” for opening and closing temperatures.1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure continuity:

■ Cavity and Waveguide Thermostats: Normal: Continuity; Abnormal: Infinite■ Base Thermostat: Normal: Infinite; Abnormal: Continuity

Magnetron Thermistor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Normal: 10k +/- 5% ohms at 77ºF (25ºC)■ Abnormal: Infinite

Motor Capacitor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Normal: Momentarily 0 ohms, then goes to infinite■ Abnormal: Infinite

Cavity / Hood Lamp 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Normal: 1.5 +/- 0.5 ohms■ Abnormal: Infinite

Relay Control Board NOTE: Do not try to repair or make adjustments to the relay control board.1. Unplug microwave oven or disconnect power.2. Check wiring to relay control board.3. Visually inspect P61, P62, P63, P64, P65, P66, P67, P68, P71, P73 and P74 to see

whether there are signs of overheating or any signs of failure due to loose wires, bad crimping, etc.

Hood / Light Switch NOTE: Do not try to repair or make adjustments to the hood/light switch.1. Unplug microwave oven or disconnect power.2. Check wiring to hood/light switch.3. Visually inspect P21 to see whether there are signs of overheating or any signs of

failure due to loose wires, bad crimping, etc.

Power Resistor-1(20 ohm/ 25 W)

1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Normal: 20 +/- 2 ohm at 77ºF (25ºC)■ Abnormal: Infinite

Power Resistor-2 (41 ohm/50 W)

1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:

■ Normal: 41 +/- 2 ohm at 77ºF (25ºC)■ Abnormal: Infinite

Relay Board NOTE: Do not try to repair or make adjustments to the relay board.1. Unplug microwave oven or disconnect power.2. Check wiring to relay board.3. Visually inspect P51, P52, P53, P54, P55, P56 and P57 to see whether there are

signs of overheating or any signs of failure due to loose wires, bad crimping, etc.

Components Tests/Results

123

Y/G

BKRW

Cavity / WaveguideThermostat

BaseThermostat

31

21

1P

62

1P

61

61

52

P6

31

P6

6

P6

41

P6

8

70

01

46

25

P6

51

P6

71

P7

11

P7

31

P7

41

P21

P224501

45024503

49

14

49

04

49

24

49

05

P52

P51

31

1049

06

49

01

49

07

1P53

3191

49314932

1P54

4903

4121

P54

1

P56

P57

1

4170

P581

5174

5170

Checking Inverters

Measure Oven Input Current

Connect an ammeter (Valhalla Scientific 2101 or equivalent recommended) to measure the input current of microwave oven when the power level is set to Level 10 at the touch panel.

If more than 0.5A:The 1200W inverter is probably OK. Check the magnetron. See Magnetron test in “Component Tests.”

If less than 0.5A:There is no input to the 1200W inverter. Check the following:1. Unplug microwave oven or disconnect power.2. No AC voltage supply. Check relay control board and

wiring.3. No control signal. Check relay control board and wiring.

Check the 1200W Inverter

NOTE: Do not try to repair the inverter board, nor try to make any adjustments to the board.

Check wiring to 1200W inverter:1. Unplug microwave oven or disconnect power.2. Visually inspect 4 connectors on the 1200W inverter

board, CN701, CN702, CN703, E701, to see whether there are signs of overheating or any signs of failure due to loose wires, bad crimping, etc.

15A

Amps

A. CN702B. Heat sinkC. E701D. High-voltage output

to magnetron

E. CN703F. Control signal in/outG. CN701H. 120V AC

B

G

A

C

D

EF

H

8205288 / 4619-651-988613/06

FOR SERVICE TECHNICIAN’S USE ONLY