SX70 Repair Manuel Rebuilt

8/13/2019 SX70 Repair Manuel Rebuilt

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I - DESCRIPTION

The Polaroid Land SX-70 is a folding, pocket

sized, single-lens reex camera which takes

and immediately delivers full-color picturesapproximately 31/4 inches square (see gures1-1, 1-2 and 1-3). Operation is automatic; theuser merely inserts the lm, focuses and shoots.power is provided by a six-volt battery inside thelm pack; therefore, the batteries are alwaysfresh as the lm.

The four element lens has a maximum apertureof f/8, and a focusing rang from 10,4 inches to

innity. The shutter is automatically controlledby a photocell and electronic timing. Electrical tomechanical energy conversion is accomplishedby two solenoids and a motor. There are noseparate diaphragm adjustement. The shutteropening and closing time is controlled by theexposure measuring system.

A. GENERAL DESCRIPTION

Figure 1-1 SX-70 Camera folded

Figure 1-2 Holding and opening the SX-70


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The subject is viewed and focused throught thetaking lens, a mirror, a Fresnel viewing screen

(with spilt-image focusing aid) and a opticalsystem to focus the image at the viewing eye-piece. As in all single-lens reex cameras, theshutter must be open to provide an image atthe eye-piece. This requirement is fullled bythe automatic electro-mechanical componentswhich are described in detail in Section II of thismanual.

When the exposure is made, the image must be

transferred from the viewing system to the surfaceof the lm in accurate focus. To accomplish this,the shutter closes and the viewing screen swingsout of the optical path which is then diverted bya mirror to the lm surface. These two pathsare described in greater detail elsewhere in thissection.

The exposure is made following the viewingscreen / mirror swing. The screen then returnsto the viewing position and the automatic

mechanism ejects the exposed sheet of lm.development takes place outside the cameraand can be observed by the operator. As soon asthe print is ejected, the mechanism completes its

cycle to prepare for the next exposure. Followingthenth exposure, the ash circuit is inhibited until

a fresh lm is inserted. Normal operation willresume when the camera is reloaded.

The following paragraphs describe the electro-mechanical events that occur in normal operation.the purpose of this desciption is to acquaint thereader with the manner in which the various

functions are accomplished. Detailed analysisat component / sub assembly level appears inSection II.

When the SX-70 is folded, an interlock switch(S6) removes all battery power from the cameramechanism to prevent any drain from the lmpack encapsulaetd batteries. To prepare thecamera for picture taking, hold the camera in theleft hand, pull straight up on the serrated portion

of the viewnder housing (Figure 1-2). thisaction releases latches, which, in turn, allow themain body of the camera to raise into operatingposition.

B. CAMERA OPERATION

1. Opening the Camera

Figure 1-3 Opened for picture taking


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When the camera is fully opened, the interlockswitch (S6), located at the left rear corner ofthe mirror cover, is closed and the battery isconnected to the camera electrical circuit.(Figure 1-4).

The front coverlatchis located on the right sideof the camera just inside the rim of the bottomcover assembly. Pressing down on this yellowlatch releases the front cover which drops downto expose the lm chamber. With the cover open,a lm pack can be inserted or an exhausted packcan be removed.

A fresh lm pack is loaded into the lm chamberobserving color coding (Figure 1-5). Undercertain circunstances a partially used pack couldbe inserted, but this action will cause somedeviation in the normal counting sequence.

The battery is a part of each lm pack, and thetwo exposed terminals on the pack engage twocontacts within the lm chamber as the pack is

inserted.

With the lm pack in place, the front cover canbe closed. It must be fully closed and latched.

2. Loading the Film pack

3. Starting the Automatic Mechanism

Figure 1-5 Inserting lm pack

Figure 1-4 S6 with contacts closed


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Thus, the cover must be fulled closed, the gearsengaged, and the latch fully seated, in order toactuate the drive motor.

As S7 closes, power is applied to the drive motor(S8 is also involved and is discussed in a followingparagraph), the gear train is set in motion andactuates a device called the lm pick. The pickengages the dark slide, pushes it into the spreadrolls and the dark slide is ejected from the lower

(1) A projection on the front cover latch (Figure 1-6 A), and

(2) A post on the right rear edge of the frontcover (Figure 1-6 B).

front edge of the front cover. The camera is nowready to take the rst picture.

When a used lm pack is removed from the lmchamber, the action automatically resets the

exposure counter at the rear of the camera to thestart position, closing S8. With a new lm packinstalled and the front cover closed and latched (S7 closed), the motor is powered, and the darkslide is ejected. The exposure counter turnsto number 10 (Figure 1-7), indicating that 10pictures remain in the pack.

Viewing and focusing is accomplished througha reect system (Figure 1-8 A). In the viewingmode the image passes through the lens to axed mirror which reects it down to the Fresnelviewing screen. The viewing path from theviewnder eyepiece lens is from a parabolic

mirror and wafer lens, off the xed mirror to theFresnel screen. On most cameras the Fresnelscreen contains a circular split-image aera whichis used to focusing aid. A knurled knob (thefocusing wheel) on the shutter housing is rotatedto adjust the camera focus. The scene is in focuswhen a vertical line within the split-image aerais perfectly straight. On early cameras (withouta split-image feature), the scene is in focuswhen the image seen on the Fresnel screen issharpest.

The exposure is made by pressing the releasebutton. This completes the electrical circuit to the

Gears in the front cover must engage the maingear train of the camera before the gear trainis put into motion. A switch (S7) located in theforward section of the gear train compartmentinitiates the application of power to the geartrain drive motor. Switch (S7) is actuated by twocomponents

4. Setting the exposure counter

5. Viewing and focusing

6. Viewing and focusing

Figure 1-6 S7 contacts open and closed

Figure 1-7 Counter


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shutter to initiate a series of events. The shutterblades close to cut off the optical path. Thehinged Fresnel viewing screen is swung upwardand comes to rest in front of the xed viewingmirror (Figure 1-8 B).

The shutter opens and closes to perform theexposure function.

A rst-surfaced taking mirror is fastened tothe underside of the Fresnel carrier assembly.

Figure 1-8 Viewing and shooting


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slide. The counter will start at number 10. Sinceswitches S8 and S9 are physically attached tothe counter, the camera will cycle through 10exposures even though there be less than 10sheets of lm in the pack. This deviation must berecognized whenever a partially exposed packis used.

The image is reected by the mirror onto thelm surface. the electronic metering systemdeterminesthe required exposure, and programsthe shutter opening and duration accordingly.

The incorporation of a mirror in tghe lens-to-lmpath necessitated by the nature of the lm. Noseparate negative lm is employed. Instead,the image appears as a direct positive. Sincethe nal product is an opaque print, it is viewedby reection. As a result, the mirror is neededto reverse the image so that the nal print willbe properly oriented. This requirement, inturn, dictates the use of the reectance typeviewing screen rather than a ground-glass typetransmission system.

Note that the lm surface is deplaced from

the Fresnel viewing screen by the thicknessof the viewing screen assembly. The correctfocal distance for both viewing and exposure isproperly maintened, however, since the surface-coated exposure mirror is deplaced by the samedimension.

During exposure, the light from the viewingsystem must be prevented from striking thelm. This is accomplished by a rubber light stop

adhered to the hinged Fresnel carrier. Whenthe Fresnel carrier moves upward, the light stopblocks off light from the viewnder eyepiece.

As indicated by the foregoing description, theviewing system is blacked out during the actualexposure.

As soon as the exposure is complete themechanism returns the viewing screen to itsinitial position and the picks feeds the exposedlm to the spreader rolls. The rolls break the pod,spread the developer, and eject the lm from thecamera.

As in orther Polaroid pack cameras, the pictureis developed ouside the camera. Unlike previousPolaroid Land Cameras, however, there is nonegative to pell off and discard.

The SX-70 accepts a special 10-lamp ash barthat plugs into a receptacle directly over thecamera lens. There are ve lamps in a rowoneither side of the bar which must be removed,

rotated and reinserted after the fth lamp hasbeen red (Figure 1-9).

Insering a ash into the ash socket closesswitch S2 in the socket. This action sets up theshutter electronic circuit to permet ring of theash lamp. A follow-focus mechanism, coupledto the lens focusing system arrests the shutterblades at an opening related to camera-to-sujectdistance.

NOTE : On early camera models, the lightmeasuring circuit remains active even with the

ash bar inserted into the socket. If the circuit

determines that there sufcient ambient light, an

exposure will be made without the ash. Cameras

with P conguration or later shutters, do not

have this light measuring feature in the ash

mode. Regardless of the ambient light level, the

circuits will re the ash when a ash bar is in

the socket (unless of course, the lamps have all

been used).

If the array has been exhausted, the shutterwill complete the exposure cycle without ash.Maximum exposure duration is 30 seconds.

When the exposure counter reaches 0 (empty)the camera will not re a ash lamp even thoughunused lamps remain in the bar. The previouslydiscussed deviation associated with the exposure

counter is applicable to the ash functions. If anunusedlamp is in position and if a partially emptylm pack has been reinserted, the camera willcontinue to re lamps after the last sheet of lmhas been exposed, until the counter reaches 0.

As each exposure is completed, the exposurecounter substracts one digit until the 10 exposureshave be made. The counter then indicates 0...When this occurs, switch S9 is closed. Closingthis switch inhibits the ash and the exposure

timing. Since the counting cycle is initiated bythe insertion of a lm pack, the pack may notnecessary contain a full supply of lm. If, forsome reason, a partially used pack is removedand reinserted, the top lm will be the dark

8. Developing the print

9. Exposures using ash

7. Completing the lm pack


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When through using camera it be can folded andlatched in its closed conguration by pushingthe erecting link. When the camera is closed,the interlock switch (S6) is opened so that thebattery is completely disconnect from the cameracircuits. The trim wheel (the lighten / darken

adjustement associated with the photocell)automatically returns to its normal position eachtime the camera is closed.

The shutter employed in the SX-70 camera isunique. No direct comparisons should be drawnbetween the manner in which it functions and thefunction of other Polaroid electronic shutters. Nomanually adjustable or xed aperture is employed.

When a picture is taken, two shutter blades, with

specially shaped cutouts, open the lens from atotally closed position to a suitable aperture. Thetwo blades then reverse direction and again shutoff the optical path. These same two blades alsocontain a similar (although differently shaped)pair of cutouts that open and close the light pathto the photocell in like manner. In the following

description the functions of photocell cutouts isdeferred until the action of the shutter cutouts isexplained although in operation, the two functionsare interdependent.When the camera is open for viewing, but beforethe release button is pressed, solenoid #1 isdeenergized and the shutter blades are open. Aspring (openong spring) holds the shutter bladeswide open (Figure 1-10). The lens thus providesmaximum viewing / focusing brilliance. Solenoid/ spring action is discussed in detail in the next

section of this manual.

Figure 1-9 Inserting the ash bar

10. Closing the camera

C. SHUTTER DESCRIPTION

(AMBIENT LIGHT MODE)

Figure 1-10 Shutter blades held opened


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When the release button is pressed, a switchS1 closes (Figure 1-11 A and B) and appliesoperating power to the shutter. As soon as poweris applied to the shutter, solenoid #1 is energizedand rapidly moves the shutter blades to theclosed position.

When the solenoid has reached the end of its

stroke (shutter closed, it no longer requiresmaximum current to hold it at that postion.Switch S4 (located on solenoid #1) closes (CB)and activates an electronic circuit called thePOWER DOWN CIRCUIT. This reduces power

Figure 1-11 B Operation

Figure 1-11 A Location & Arrangement of internal parts


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to an adequate level to hold the solenoid after thehigh-current circuit has completed the solenoidoperating function and switches on the motordrive circuit. Thus, the shutter will remain closed,with minimum battery drain.

Light entering the lens is now cut off and thereex mirror is swung upward to picture-takingposition. The electronic latch (activated byopening S5) assures that the sequence will becompleted even if the operator removes hisnger from the exposure button, S1.

When the mirror swings up, a mecchanicallyoperated switch (S3) actuates a Y delaycircuit (40 milliseconds) (Figure 1-12) so that theshutter will not function until the mirror bouncehas subsided. At the end of the delay period the

electronic circuitly removes the power from thesoleniod and the opening spring sets the shutterblades in motion toward the full open position.At the same instant an electronic switch opensand starts the integration cycle. The integrationcycle is that period during which the total amountof light (intensity and duration) reaching thephotocell is transformed electronically to regulatethe lenght of time the ml is exposed. The shapeof the opening in the shutter blades and the

motion of the blades is such that all of the factorsinvolved are continously variable throughout theexposure period. this fact, however, is a designconsideration and should not confuse the theoryof the shutter operation from a maintenancepoint of view.When the camera completes all off its automafedfunctions and the release button has beenreleased, all voltage is removed from solenoid #1and the shutter opens in preparation for the nextexposure.

It should be noted that under extremeley low lightconditions, the shutter will closed completing theexposure cycle in 14 to 30 seconds whether asuitable exposure has produced or not.

Figure 1-12 S3 Being opened by recock ram

C. SHUTTER DESCRIPTION

(FLASH MODE)The special ten-shot ash bar is equiped witha shorting bar so that when the bar is inserted,two contacts within the camera is shorted. Thisswitch is identied as S2. When S2 is closed,the shutter electronic circuit detects that a ashbar is in place and ready for ring. In general,the sequence of the functions remains the sameas for ambient light operation with the followingexceptions :


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mechanical device identied as the interceptorconnected to the lens focusing mecchanism(Figure 1-13 A). the interceptor is moved asthe lens is focused regardless of whetherambient-light or ash pictures are being taken.When ash bar is in place (S2 closed) and thegear train opens switchs S5 (Fighure 1-14),solenoid #2 is energized and pulls the interceptorinto position to phycally restrict the shutter bladetravel (Figure 1-13 B). Since the interceptor iscontrolled by the focusing mechanism, theshutter opening is related to camera-to-subjectdistance thus compensating for the ashbulb-to-subject distance to give proper ash exposure.As a solenoid #1 de-energizes switch S4 movesfrom the CB position to the CA position. Thisswitch conects VCC to the FFA.

Figure 1-13 A Interceptor link, Solenoid 2, S2 operation - Solenoid de-energized

When the ash delay period reaches completion,the circuitry removes the holding current fromsolenoid #2. Since the solenoid is an electro-mechanical device, removing power from itcauses a collapsing magnetic eld which inducesa y back voltage. This voltage pulse is fed tothe ash circuitry which then applies the ringvoltage across the ash lamp.


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Figure 1-14 S5 being opened by the recock ram (Gear train)

Figure 1-13 B Interceptor link, Solenoid 2, S2 operation - Solenoid energized


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In cameras with P conguration or later shutterthere is no ambient light measurement made. Ifa ash bar is in the shutter socket a ash picturewill result regardless of the ambient light level.

On early cameras, an ambient light measurementis made during the ash delay period. Since thephotocell aperture is a part of the shutter blades,the amount of reected light reaching the cell willalso be a function of focusing distance. the shutterelectronics delays ring the ash lamp until theshutter has opened to the aperture establishedby the focus wheel. during this delay period, ifthe ambient light level is sufciently high to causetriggering of the integrating circuits, the exposurewill be completed and the shutter closed beforethe ring voltage reaches the lamp and the lampwill not be red.

At the ends of the ash timing interval, the circuitenergizes solenoid #1, the shutter closes, andthe sequence proceeds as in the ambient-lightmode.

If the bulbs in the ash bar are all used when theoperator attemps to make a ash exposure, all ofthe previously described circuitly will function upto the actual ring of the ash lamp. Since there

is no lamp to ignite, no ash ring current will bedrawn.

There will be no output signal from the ashsequencing circuit, and an ambient light exposurewill be made. On cameras with P or laterconguration shutters, the result will be a blackpicture unless the ambient light level is highenough to give an exposure. this is caused bythe fact that P and later conguration shuttershave no integrating function as long as a ashbar is inserted in the socket. Early cameras havea twenty second time-out period even with a ashbar inserted in the socket. Therefore, if the ashbar is exhausted, a properly exposed picturewill result if the ambient light is great enough toproduce one in twenty seconds.


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II - THEORY OF OPERATION

A general description of the camera and thesequence of its functions is contained in

Section I. In that section, detailed analysis ofindividual assemblies and electrical circuits wasminimized so that emphasis could be placed onthe intenelation-ship of various functions. In thefollowing paragraphs, the individual groups ofcomponents are described in greater detail. Thedescription are presented in the sequence in thecommponents were mentioned in Section I.

Power for the drive motor, the shutter electronics,and the ash array is supplied by a speciallydesigned 6 volts battery incorporated in each10 exposures lm pack. When the pack isinserted into the camera, two contacts padson the bottom surface of the pack engage twospring-loaded contacts on the inner bottomsurface of the camera bottom plate. From thesetwo points, it is distributed to its destinations bythe copper foil strips of a ex circuit on the outersurface of the bottom plate.

The lens employed is a four element, glass lensof f/8 aperture with a focal lenght of 115mm. It hasa focusing range of innity down to 10,4 inches.Focusing is accomplished by movement of thefront element only. Helical threads in the lensmount provide the linear lens elemet movement.

Operation is by means of a geared focus wheelat the top of the shutter housing. There is nomanualy adjustable diaphragm associated withthe SX-70 lens.

The battery has adequate capacity to exposeall 10 lm frames with at least six months of

expected shelf life.

When the camera is erected to picture takingconguration, the subject can be viewed throughthe collapsible viewnder. Figures 2-1 and 2-2show the two optical paths in the camera. Notethe direction of the arrows. Reected light from

A. INTRODUCTION

C. LENS

D. VIEWING AND EXPOSING SYSTEM

B. POWER SOURCE

Figure 2-1 Viewnder optics (viewing)


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the subject passes through the camera lens andis reected by the viewing mirror (on the insidesurface of the mirror cover) to the Fresnel viewingscreen.

The entire subject image is now reproducedon the viewing screen. At this point, viewnderoptics must be employed for focusing. The opticsmust transfer the image from the viewing screento the eye (done by the parabolic mirror and theviewing mirror) and must present the image ina fairly sharp contrast to permit proper focusing(done by the eye lens and parabolic miror).

Figure 2-2 Viewnder optics (exposing)

The special Fresnel (pronouced Freh-nell)screen is employed to enhance the viewingimage by increasing the brightness and dention.If a matte white surface were substituted for theFresnel screen, an image would still be visible.However, the light rays striking nearest thecorners of the screen meet the screen at a moreoblique angle than the rays striking near thecenter. At this greater angle, a larger percentageof the light is dispersed and less light is returnedto the viewer. Thus, on a matte-screen image thecorners would appear darken than the center.The Fresnel screen is designed to overcome thisproblem.

1. Fresnel (Figures 2-3 A and 2-3 B)


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The screen itself is a sheet of plastic upon whichare impressed series of concentric rings much likethe grooves pressed into a phonograph record(Figure 2-3) instead of having a vee shaping;however, the grooves in the Fresnel screen forma saw-tooth with a tooth angle increasing slightlywith each successive groove in such a manner asto complement the decreasing angle of the lightray. The saw-tooth attens out completely at theexact optical center of the screen. In the SX-70camera, the optical center is not the geometricalcenter of the screen.

The surface of the screen is silvered to provideoptimum reectance. The result is a brilliantviewing image evenly illuminated from corner tocorner.

For the reader who is familar with the use of aFresnel lens used in conjunction with a ground-glass focusing screen, or a Fresnel-groundfocusing magnier, it must be noted that theseare transmission devices while the Polaroidscreen is a reecting medium. Otherwise, thebrilliance enhancing properties are the same.A suitable analogy would be the comparison ofa lenticular projection screen compared with amatte surface. The ribbed surface of the lenticular

screen narrows the angle of reectance but

increases the brilliance of the image within tehviewing aera.

In summary, the Fresnel satises three conditons:1 - it enhances focusing by distributing light raysevenly across the entire viewing aera.2 - it guarantees proper focusing by nature of itsacting as a ground glass - thus insuring that thesubject is in focus when the eye sees the imagein focus on the screen.3- it acts as a reecting surface to permit the eyeto see the image through the viewnder optics.

As show in Figures 2-3 A and 2-3 B, two typesof fresnel screens are used. Current types(Figure 2-3 A) have a split-image circle cut intothe center of the screen which makes focusingeasier. Specially oriented prisms within the circle

split the image unless the camera is perfectedfocused. Therefore, a straight vertical line in theimage aera would appear to be broken unlessthe subject is in focus. To further ease focusing,the image within the split circle appears brighterthan the rest of the Fresnel image. This ispossible because the split circle is not coated inthe same manner as the rest of the Fresnel. Thislatter feature improves the ability of the viewer tofocus the camera in dimly lit aeras.

Figure 2-3 Fresnel screen


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mirror, the 6-edges viewing mirror is used in theoptical path twice. First, the light rays enteringthe camera from the taking lens are reectedonto the Fresnel screen by the viewing mirror.Secondly, the operator views the image on thescreen with light reecting off the viewing mirror(Figure 2-1). (The viewing mirror is located onthe underside of the mirror cover assembly.)

Figure 2-4 Wafer lens assembly

Figure 2-5 ECM - Electronic Control Module

The viewnder optics consist of an eye lens, aconcave mirror and a wafer lens (Figure 2-4). Asin all simple optical system, a certain amount ofdistortion is inherent in this design. A small waferlens is introduced into the viewnder optical pathto limit to angle of acceptance and, thus, reducedistortion. The size of the lens opening is largeenough to provide acceptable viewing brillianceand, at the same time, small enough to be easilyclosed when the camera is in the exposure mode.(On earlier models a rectangular mask called astigmatic pupil takes the place of the wafer lens.

The are bafe (Figure 2-2) is a spring-loadedplate which springs up when the Fresnel screenmoves into the picture-taking mode. In this state,light is prevented from passing through the lensdirectly onto the lm without rst being reectedoff the taking mirror. This prevents hotspotsfrom appearing on the nished picture. When

the Fresnel carrier is in the lowered position, theare bafe is held down, out of the optical path.

The SX-70 is unique, both in its principles ofoperation and its functional design. It can beconsidered as aan electronically controlledmechanical device. An electronic control module(substrate or ECM) contains all of the electroniccomponents with the exception of the motorcontrol (MCC) integrated circuit and the ash reassembly (FFA). Because the ECM is locatedinside the shutteur housing, it becomes identiedas part of the shutter (Figure 2-5). It shouldbe noted that all of the camera automation iscontrolled by the integrated circuits in the ECM.

Ignoring the shutter functions momentarily, whenthe operators presses the exposure button, theFresnel carrier swings away from the lm planeand comes to rest in front of the viewing mirror.During the moment of the Fresnel carrier (anduntil it returns to its initial viewing position), aexible light stop closes a path between theviewnder and the inner camera to prevent lighttrough the eye lens from reaching the lm. Themovement of the spring-driven Fresnel carrier is

accomplished by the motor-driven gear train. Thedetails of the automated action are describedin the discussion of the electro / mechanicalassemblies.

2. Viewnder

4. Flare bafe

1. General

Two rst surface mirrors are used in the SX-70optical system. When a picture is being taken,

the Fresnel carrier is raised. This places the4-edges taking mirror into the optical path andlight is reected onto the lm plane. (The takingmirror is mounted on the Fresnel carrier on theside opposite the Fresnel screen.) The second

3. Mirrors

E. CAMERA ELCTRONICS


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The entire ECM (rather tna its individualintegrated circuits) is used as a remplacementitem. For that reason, the theory of operation andanalysis techniques presented in this manualhave prepared in such a way that the repairmancan relate a specic camera failure mode to anECM function.

Figure 2-6 SX-70 Switch locations

a-Switch S1 is actuated by either the red shutterrelease button or remote control cable release.It is operated by the photographer and it causesthe camera to run through a complet exposure /lm delevery cycle.

b-Switch S2 places the circuitry into the ashmode. Switch S2 si closed when the ash baris inserted into the FFA on the top of the shutterhousing. It commands the integrated circuitin the FFA to select the rst unused ashbulband, to re the bulb. It also enables the ECM toenergize solenoid #2 which limits the openingof the shutter blades so that ash exposurewill be determined by ash-to-subject distance.When the solenoid #2 is energized it engages amechanical coupling between the shutter bladesand the focusing mechanism.

2. Switch functions


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Figure 2-7 S3 Being opened by recock ram

c- Switch S3, normally closed at the beginingof the exposure cycle is opened by the recockram located in the gear train assembly. SeeFigure 2-7. As the exposure sequence begins,S3 opens and actuates a delay circuit (Y delay)in the EMC which retards the start of the actualexposure approximately 40 milliseconds sothat mirror bounce will have subsided before apicture is taken. At the end of the delay time, theshutter starts to open and the electronic timingfunction (integration) takes place. If a ash circuitis inserted into the FFA (S2 closed) an additionalash delay circuit is avtivated to insure that theexposure gets full effect of the light derived fromthe ash. At the end of the exposure cycle whenthe Fresnel carrier moves down into viewingposition, S3 closes as the recock ram movesaway. It is now reset for the next camera cycle.

d- Switch S4 is tripped by an actuator on theplunger of solenoid #1, the shutter blade actuatingsolenoid (Figure 2-8).

NOTE : Whenever the SX-70 shutter is discussed,

it must be noted that, since the camera is a single

lens reex and focusing is accomplished through

the taking lens, the shutters normal state si open,

not closed as in other Polaroid cameras.

When the shutter release button is pressed andthe exposure cycle is initiated full battery poweris delivred to solenoid #1, closing the shutter.Once the solenoid plunger is seated it no longerrequires as much power as was originallyneeded to overcome its static inertia. Switch S4,therefore, closes the S4 CB contacts to the ECMand the electrical power to the solenoid coil isreduced to the power down value which issufcient to continue the exposure cycle yet lowenough to conserve battery drain.

When the switch S4 (CB contacts closed) transfersto the ECM it sends power to the drive motor andoperates the gear train. When S4 is actuated,(CB contacts closed) it also disconnects powerfrom the FFA ash circuitry. This action prevents


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Figure 2-8 S4 Switch operating congurations

damage to the circuit in the event that ashbulbbecomes short-circuited after it is red.

e-Switch S5 (normally closed at the beginning ofthe exposure cycle), like S3, is located in the geartrain and actuated by the recock ram (Figure 2-7).When the gear train rotates to appropriate point in

its cycle, S5 opens and removes power from thedrive motor, applying dynamic braking voltage tostop the gear train quickly. The ECM reacts tothis command in such a way that exposure cyclecontinues completion even through the operatorhas released the exposure button (S1). After theexposure and when the Fresnel carrier returns tothe viewing position, S5 is closed by the recockram and stops the camera cycle.

f-Switch S6 is closed by openong the camerato the picture taking position. Its disconnects thenegative side of the battery from the communreturn (ground) when the camera is folded toassure the removal of power from the circuit.

g-Switch S7 is closed when the front cover isclosed. It is wired in series with S6. Like S6, S7disconnects the negative side of the battery fromthe commun return so that the camera cannotfunction until the front cover is closed andlatched. It is an interlock during normal picturetaking. With S6 and S8 closed, it initiates thedark slide function.


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Figure 2-8 A S8 - S9 Exposure counter switches

h-Switch S8 (Figure 2-8 A) is part of the exposurecounter operated by the counter wheel. As S7closes, power is applied, ejecting the dark slide.After the dark slide ejection, the counter wheelturns, opening S8. S8 then remains open untilthe lm pack is removed. When the pack is takenout, S8 closes.

i-Switch S9 is near S8 on the exposure counterassembly. When the counter reaches the 0position, switch S9 closes and the ECM inhibitsthe falsh-ring function, so that if an unused bulbis still available it will not be wasted.

j-For an handy summary, see the Switch FunctionTable.

The following paragraphs describe the sequence

in which operate during normal operation of thecamera.

a- The operator opens the camera. Switch S6connects the battery to the camera circuitry.

c- The operators open a lm pack. (when thepreviously used lm pack was removed, a

b- The operator opens the front cover. SwitchS7 opens and removes battery power from thecamera.

3. Function Sequence

Switch Action Result

1 closesInitiates exposure cycle and causes circuitry to take anddeliver the pictures.

2 closes Connects circuitry to take ash pictures.

3 opensInitiates Y, 40 milliseconds delay. (Power downsolenoid #2 in the ash mode)

4CA closes

Controls power to solenoid #1 (drop current to holding

level).CB closes Signals the ECM to start the motor.

5 opens / closesStops motor both by closing and opening depeending uponsequence of action and internal circuitry.

6closes

Connects the battery to the electronic circuitry when thecamera is open to use.

opens When the camera closed, cuts power from battery.

7 closes

When S8 is also closed, it provides power to the camerawhen the front power is latched (for dark slide eject). Alsoacts as an interlock during normal picture taking.

8 closesEnables (with S7 closed) the circuitry to eject dark slide.Opens again after the dark slide is ejected.

9 closes Prevents ring ash if lm pack counter is on 0.

SWITCH FUNCTION TABLE


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mechanical coupling device set the exposurecounter to the position just before the rstexposure and closed S8, but since S7 hasremoved all battery power no action occurs).

h-At the end of the 40 millisecond delay period,the ECM removes power from solenoid #1 and theshutter opens. Simultaneously, the circuit startstiming the exposure (integration). The integrationcomponents of the ECm are controlled by theamount of light received by the photocell. At this

time, the ash delay section of the ECM is madeready but will not function unless a ashbar hasbeen plugged in, to close switch S2.

j-When, in the previous step, the solenoid closesthe shutter blades and drive motor is energized,

the gear train resumes its sequence with thefollowing results :

1. The lm pick feeds the exposed lm to thespread rolls.

2. At the end of its travel the pick uis held in itsforward position by the pick latch.

3. Film moves through the spread system.

4. The recock gear cam proceeds to retrun therecock ran which, through the bell crank, movesthe Fresnel carrier down.

5. The recock ram closes switch S3 to prepare foranother exposure.

6. The light stop opens the optical path to theviewnder.

7. The lm completes its passage through thespread rollers. The front cover idler gear meshingwith the gear train powers the top roller whichdrives the lm through the exit slot.

8. The Fresnel carrier when fully scated is held bythe recock ram.

9. The pick latch releases the pick and the pickreturns to its starting position.

10. The recock ram closes S5 to cause the ECM toshut off and dynamically brake the drive motor.

i-When power is removed from solenoid #1 (andthe shutter begins opening), the actuator on theplunger returns switch S4 to its original condition(CA closed); When the exposure timing cycleis complete, power is returned to solenoid #1and the shutter closes, opening CA, closing CB,placing solenoid #1 again in the power down

condition and starting the motor to eject theexposed lm.

NOTE : the lenght of, the timing cycle is

determined in amount of the light reaching the

photocell. If there is insufcient light to correctly

operate the integration circuits, the system will

automaticall terminate the exposure within 14 to

30 seconds.

taken until mirror bounce has subsided.

d- The operators closes and latches the front

cover. S7 closes, power is apllied and the cameraeject the dark slide.

NOTE : During this action (and in certain other

operations) other switches actuate and functions

occur but, unless they contribute to the paticular

camera function being described, they are

omitted from the discussion).

The counter indicates exposures #10 (and opensS8) thereby showing that the camera is ready totake rst picture.

e- The operators aims, focuses the lens, and

presses the red shutter release button (S1).The ECM actuates solenoid #1 which closesthe shutter blades. Solenoid #1 transfers the S4contacts from CA to CB, which in turn, switchesthe circuit from full solenoid power to holdingcurrent (power-down). Closing contacts CB ofswitch S4 also starts the drive motor. OpeningS4 (CA) removes power from the FFA.

f-As the gear train runs, it mechanically releasesthe spring-loaded Fresnel carrier so that it leaves

the lm plane and rises to its exposure position.This is accomplished by the mirror release camof the recock gear. the recock ram falls off therecock cam, allowing the ram to snap forward.This allows the drive spring to raise the Fresnelassembly to the exposure mode. The ram alsomoves away from S5 allowing S5 to open. Thisaction causes the ECM to dynamically brake themotor which will remain at the rest throughout theexposure segment of the cycle. The S5 switchaction also programs the ECM to complete thecycle even though the operator has released theexposure button after S5 is open.

NOTE : there would appear to be a contradiction

between this step and the step j-10 below wherein

closing of S5 performs the identical function, i.e,

stops the motor and applies braking. S5 is able

to perform in this manner, however, because

the circuit (gate) to which it is connected is in a

different condition during each of the steps.

g-While the Fresnel carrier was moving up priorto motor shutdown, the recock ram opens switchS3. When S3 opens, it signals the ECM to initiatea 40 millisecond delay in the sequence. Thisamount of time prevents a picture from being


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k- If the operator has removed pressure fromexposure button all power will be removed andthe shutter blades will open to permit viewing.If the button has not been released, the shutterblades will remain closed until the operatorremoves his nger from the button.

at the aperture for ash exposure at the setdistance (Figure 1-13). The interceptor latchesin this position. At this time, the ECM removesthe power from solenoid #2. The solenoid, likeany inductive device, produces a yback voltagewhen its magnetic eld collapses. This ybackvoltage is used to trigger the ECM which, inturn, applies power to the FFA to ignite the nextunused ashbulb.

l-When a ash bar is placed in its socket, it closes

switch S2. This switch connects the ECM in theash mode. All of the mechanical sequences willremain as just described. The ECM however, willnow provide power to solenoid #2 when switchS5 (in the gear train) opens, and will maintain itin a power down condition when S3 opens.

o- The shutter performs an additional functionin the ash mode. One of its circuits examinesthe #1 ashbulb contacts and by virtue of theresistance determines whethever or not the bulbhas been red. If the #1 lamp is exhausted, thecircuit scans the #2, etc. When an unused lampis located, the ring circuit remains connected tothe lamp until is used.

NOTE : It is important to be aware that in earlycameras the timing (integration) circuits of the

substrate continue to function even though the

insertion of a ash array has placed the substrate

in the ash mode. Thus, if the ambient light level

is high, the picture may be made by ambient light

without ring the ash. Also, if all the ash lamps

are expended and a picture is taken, an ambient

light exposure will result. The photographer will

recognize this situtation by the absence of a ash.

However, he may still get an acceptable picture.the aperture in this case will be determined by

the ash to subject distance.

m-Within the shutter assembly a cam followeris driven by a cam on the focus wheel andarranged so that it will mechanically stop thetravel of the shutter blades relative to the focus

distance. When solenoid #2 is not energized, aspring on the cam follower prevents engagementof the cam follower and the shutter mechanismfunctions in the ambient exposure mode. Whenthe ECM is programmed for ash, solenoid #2 isenergized and the shutter openeing is controlledby focusing distance.

n-When making a ash exposure and the shutterblades start to open, the interceptor will be set toa position determined by the focusing mechanism

but out of the path of the interceptor pin. Whensolenoid #2 is energized, it pulls the interceptorinto the pins path of the blades and stops them

S1

Closes

Y DELAY FLASH DELAY

Sol. #1

Power

Down/

SA BC

Closes

S3

Opens

Sol. #2

Power

Down

At Hight Light

Levels Early

Cameras willtake Ambient

Exposure

(does not apply to

"P" configuration (T1)

and

Stop

Ambient

Exposure

Blades

Close

S4 CA

Opens

Film

Ejected

Cycle

Complete/

S5

Closes

S5

Opens

Sol. #2

Power Up

Sol. #15

Power Up /

FT

Blades Open to Correct

Aperture S4 AC Close

to Power FFA

Sol. #1

Power Up

Activated

Flash delay

FD

Sol. #2

Power Off

FF

End

Flash

Delay

Down

S4 BC

Closes

S3

Close

Flash

Time

Out

FTO

Flash

Fires

FLASH TIMING SEQUENCE CHART


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The following paragraphs describe the manner inwhich the mechanical components of the shutterrespond to either manual or electrical direction.

1.When the operator prepares to take a picture,he rst must aim and focus the camera. As he

rotates the focus wheel to bring the split Fresnel

image into focus, a cam molded into the rearsurface of the focus wheel moves the componentidentied as the cam follower assembly. Thetrim link coupled to the trim assembly is pinnedto the cam follower in such a way that followermovement is also directly inuenced by thesetting of the trim wheel. (The trim wheel is thelighten / darken control on the photocell.)

F. SHUTTER MECHANICAL DETAILS

(Figure 2-9)

Figure 2-9 Shutter, exploded view


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Figure 2-9 A Solenoid S2 operation

2. When an ambeint light exposure is beingmade, all of the action just described takes placebut does not affect the shutter action. However,when a ash array is inserted switch S2 in theash socket programs the electronics to energizesolenoid #2. The impact of this action on themovement of the shutter blades is described inparagraph F.4. but rst the shutter blade actuationmust be described as follow :3. When the ECM circuit powers solenoid #1,the solenoid plunger is pulled into its seat,overcomming the opening spring force. Theplunger pulls the walking beam, rotating it about60 degrees.Each of the shutter blades has a pin whichengages a slot in the walking beam. As thewalking beam rotates, it transmits its rotary motionto the shutter pins and drives the rear blade to

the right (facing the front of the shutter) and thefront blade to the left thus closing the light pathof the picture taking lens and the light path of thephotocell lens. When the shutter is totally closedand the gear train has reached the point in the

sequence at which the Fresnel carrier snaps up,the exposure sequence starts. The blades willproceed toward the fully open position and retrunto a closed position in the time interval dictatedby the photocell and integrating circuit. The

blades may not reach the fully open condition ifthe illumination level is high, or they may fullyopen for a period of time if the light level is low.If a ash array is mounted, the blades may notbe permittedto open completely because of thefollow focus mechanism described in part in theforegoing paragraph. The following paragraphexplains the interaction of the follow focuscomponents and the shutter blades.4.Installing a ash bar in the camera ash socketswitches the ECM to the ash mode. As previouslyexplained, at a point in picture taking sequence(ash mode), solenoid #2 is energized. Fastenedto the plunger is pull down bar. when the plungerpulls this bar down, it moves the interceptor intothe position where it will intercept a pin (the stoppin) on the walking beam (Figure 2-9 A). Nowwhen the shutter blades move towards the openposition, they will be interrupted by the mechanismjust described which means the maximum sizeof the blade opening (aperture) is determined by

the focus setting of the camera. As the camera(and thus the ash lamp) is moved closer to thesubject, the maximum aperture is reduced sothat a correct exposure will result. The reverse(greater distance/greater aperture) is also true.

5.The shape of the pin on the walking beam sisuch that once contacted by the cam interceptor itremains latched in that position until solenoid #1actuated during the next phase of the shuttercycle. When the plunger on solenoid #1 pullsin, the follow focus pin disengages from theinterceptor and the solenoid #2 plunger returns

to it original position under the force of theinterceptor hinge spring.

6.Since the photocell components are containedwithin the shutter housing, they are included inthis discussion. A lens is employed to focus thereected light from the subject on the photocell.A second pair of openings in the shutter bladescontrol the amount of light received by the cellas previously described. A variable neutralitydensity wedge system is employed to provide

lighten / darken adjustements. (Trim assembly).The operation of this control differs slightly fromthose used on other Polaroid cameras. Whenthe camera is folded, a cam on the shield ofthe front cover strikes a release lever on thelighten / darken assembly and returns the trimadjusting wheel to its center (normal) position.The trim wheel is automatically centered whenthe camera is closed.

7.To compensate for any variations in individual

photocell characteristics, a neutral density lteris selected and installed in front of the photocell

lens during assembly. A calibration must beperformed and a lter of correct density installedany time the ECM requires replacement.


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Figure 2-10 Spread roller system

The basic theory of the lm processing methodremains unchanged from previous Polaroidsystem. That is , the developping chemistry isencapsuled in a pod on each sheet of lm and,as the sheet is passed between rollers, thepod is burst and the chemical spread evenly

between the negative and the mylar protectivecover. Except for this characteristics, no directsimilarities exist. The SX-70 camera employs aunique process which totally eliminates the throwarray negative. The print is drawn through thespread rolls by the motor drive system so thatno action need be taken by the operator. SeeFigure2-10. Development takes place outsideof the camera and unaffected by ambient lightconditions. Since the end result is determined

when the picture emerges from the camera, notime measurement si necessary. (Additional lminformation is available on page 60 and 61 ofThe world of SX-70)

The operator pushes S1, applying full power tosolenoid #1, which closes the shutter blades,and pushed solenoid #1 against S4, changing itfrom CA to CB. Closing CB cuts solenoid #1s

power from high to low; low is enough to hold theblades closed. Closing CB also signals the ECMto start the motor. The motor starts the gear trainmoving. The movement of a cam on cam on thegear train releases the recock ram and, through

G. FILM PROCESSING COMPONENTS

H. SEQUENCE OF OPERATIONS

spring action, raises the Fresnel carrier. Whenthe recock rammoves, it opens S5 and then S3at certain Fresnel carrier angles. Opening S5stops the motor after it has made only a brief jog.Opening S3 starts the Y delay : 40 millisecondsdelay which allows the Fresnel carrier to cometo rest after its travel. (This eliminates bouncingcaused by the sudden stop of the carrier on themirror cover.)

At the end of the Y delay, power is removedfrom solenoid #1, allowing the spring to open theshutter for exposure, and moving S4 from CB toCA position. When the proper exposure level isreached, the photocell trips the Schmitt Trigger(S/T) in the ECM which sends full power tosolenoid #1. This closes the blades and tranfersS4 from CA to CB. As before, closing CB cuts

solenoid #1s power from full to low, sufcient tohold the blades closed; closing CB also signalsthe electronics to start the motor.

The motor starts the gear train again, and thistime the cams cause a series of actions atdifferent position of gear train movement :

- it starts the pick which pulls the lm into therollers (one of which is attached to gear train itis this powered roller rotation that pulls the lm

through and out of the camera);- it stops the pick;- it pulls down the Fresnel carrier, which in turn,moves the counter to the next number;- it moves the recock ram, closing S3 (resetting itfor the next cycle);- it retruns the pick;- it seats the Fresnel carrier so it is ready for thenext cycle;- it moves the recock ram, closing S5, which

stops the motor;- and it stops the spred action.

When S5 closes, it cuts power to the solenoid #1;the spring opens the shutter blades, and S4 ispushed from CB to CA. (The blades open onlyif the operator releases the red button.) Thesystem is ready for a new exposure cycle.

Springs are used in three of the operationsdiscussed above : holds the shutter blades open,

lps the Fresnel carrier up, and holds the pick atthe rest position.

As indicated, inserting a lm pack causesautomatic action. This could, of course, be a


28/54

partial pack : the top of the sheet of lm wouldbe ejected as a dark slide and the counter wouldregistrer 10. After the last actual sheet isused, the camera would still function until 0is reached. If a ash bar were attached, and anunused bulb was available after the last lm sheetwas used, attempting to make another exposurewould re the ash.

The difference in the ash mode are :

inserting a ash bar closes S2, which activatessolenoid #2 to move the interceptor into position.This controls the shutter blades according tofocusing : the closer the subject the more lightfrom the ash will bounce back. Therefore, thesmaller the permitted aperture.

At the end of the Y delay, a ash delay circuitis activated, and when S4 switches from CB toCA, Ca sends power to the ash circuit. Duringthe xed ash delay, the photocell and S/T areoperative , so that if enough light energy iscollected before the end of the ash delay, theblades will be closed as in ambient picture.However, on newer cameras (P congurationshutters), the ash will re whether or notsufcient ambient light si available.

At the end of the ash delay (the blades atthis point are open to the aperture dictated byfocusing) power is removed from solenoid #2and the discharge (yback voltage) triggers theash circuit, ring the ash and starting the ashtime out interval (the xed exposure time). If, onearly cameras, an ambient exposure has beenmade, S/T-2 in the ECM receives the signal andno ash or ash time out occurs.

At the end of the ash time out, the circuitryenergizes solenoid #1 which closes the blades.if no ash has occured, caused by all the bulbshaving been used, no signal will be sent tosolenoid #1, and on early cameras an ambientexposure will be made. If the S/T has not collectedsufcient light energy at the end of a xed period(20 seconds), the blades will automatically close.

On newer cameras, the exposure time remainsshort and a black picture will result.


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CLOSED BY OPERTOR

S4 SWITCHES AC to BC

S4 SWITCHES AC to BC

CLOSES

CLOSES

S1

S4 BC

S4 BC

S4 AC

End "Y"

S5

S3

S3

S5

ST 2

S1 T - 0

S2 Closed if flash array inserted

Solenoid #2 power up (S2 closed)

S9 opens when previous pack removed

S6 closed during the erecting mode

S8 closed until film cover ejected

Gears between front cover and gear train

mesh as cover closes (3rd& 4thidler)

S7 closes during front cover closure

resulting in dark slide ejection after a

new pack inserted

S8 opens (counter set to 10)

S4 BC

S4 BC

S4 AC

End "Y"

S5

S3

S3

S5

FT

FF

S4 SWITCHES BC to AC

S4 AC/BC open

OPENS

POWER RELEASED FROM SOLENOID #1

EXPOSURE COMMAND SIGNAL COMPLETE

Shutter starts to close

Cam moves from 20 position

Solenoid #1 power down

Shutter close

Electronic Latch off

Motor stops

(if S1 closed, Solenoid #1 remaing in power down)

Shutter opened (provided S1 is open)

Counter set to next position

Mirror carrier starts to drive counter

Shutter close

Shutter starts to open

Starts integration ambient

Motor starts

Fresnel starts down

Integration

20 to 35 ms

Shutter at full open (f/8 16)

Mirror continue to rise

Mirror at rest

Y delay activated

Solenoid #1 power up

Solenoid #1 power up

Shutter starts to close

Motor braked

Cam stopped at 20

Electronic latch ON

(S1 may be opened)

Cam rotates

Mirror released

OPENS 26 34

AMBIENT

EXPOSURE / PROCESS

OPERATION SEQUENCE

FLASH

Solenoid #2 power down

Flash delay FD circuit actived

Switches power to falsh circuit (S2 closed)

Removes power from flash circuit

20 - pick starts

45 - spread starts

50 - pick stops and latches

130 - mirror starts to recock

260 - spread stops

325 - mirror is recocked, pick returns

345

Solenoid #2 back onf(power off) triggers FF circuit

at the end of flash delay (FD); ST 2 shorted out; time

out interval FT initiated.

Note 1. No flash fire signal if:

a- S9 closed (empty pack)

b- new pack inserted with array already

inserted (S8 function)

Note 2.

A 25 to 34 exposure results if the array

does not fire

200msmax.

60ms

12msmax

516.5m

s

Flashdelay

Y Delay

40 5ms

20 to 35 ms

FLASH

25 to 34 ms


30/54

III - TROUBLESHOOTING

The Sx-70 camera is an electronically controlleddevice, the electronics being in the integratedcircuits (IC) mounted in the Electronic ControlModul (ECM) and Flash Fire Assembly (FFA)in the shutter housing and in the Motor Control

Circuit (MCC) in the camera back. Becausethe ICs are non-reparaible items, there is norequirement to trace faults whithin the integratedcircuits. It is mandatory, however, to be able toidentify the command inputs (switches open orclosed, etc.) and the resulting output signals.The SX-70comprehensive Tester provides thereadouts necessary to conrm an exposuremalfunction; but thorough understanding of thetheory of operation is required if meaningful use

of the tester is expected. If a particular camerafunction fails, it is necessary to recognize howthe failure is related to the operating sequenceof events and thus reduce testing procedures tothose related to the aera malfunction.

Because of the cameras total automation, itis unlikely that much useful guidance can beobtained from customer complaints exceptin cases of visible mechanical damage. Forthis reason, a well dened series of checks,

observations, and tests must be followed. Thissection of the manual denes these procedures.

The primary purpose of any fault analysis programis to reduce the investigation time to a minimum.Thus, it is not only important to establish axed routine, but it is mandatory to acquire themaximum amount of information from each stepof the checkout procedure. Use the charts at theend of this section to guide through each stepof inspection, dynamic testing and post-repairs

tests.

Analysis of the SX-70 camera is a key part ofthe complete repair task. If the analysis is donecorrectly, it will eliminate excessive repair timeand high parts replacement cost. For instance,initial evaluation may show the entire shutterto be at fault; however, continuing analysisdetermines that the problem is in solenoid #2,which, when replaced reduces the materiel costconsiderably (from over 20 $ to under 2 $). Therepair person must always consider the labor vs.material trade-off when making a repair.

Do not make any arbitrary assumptions. Anassembly or component should be thoroughlytested to determine whether or not it is performingits function correctly. Complete the tests in thechart below.

A. INTRODUCTION B. INITIAL TESTS


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SX-70 CMAERA REPAIR INSPECTION PROCEDURE

A. FUNCTIONAL TEST1. Perform light leak test.

2. Check focus and trim wheel torque.3. Check trim wheel reset 2 teeth and frontcover to shutter gap.4. Cycle camera 3 times at 5.0 and 6.4 voltswith power pack.5. Focus camera at 8 - performe aperture test(see specication sheet).6. Ambient mode tracking at 3 lights levels(note current drain) (see specication sheet).7. Collimate at innity.

8. Flash mode tracking at 10.4 (seespecication sheet).9. Check ash system

a. Flash sequence (with camera tester)check counter rotationb. Flash on zero.

10. Inner frame bow ( +.004 to +.011)

B. OPERATIONAL SEQUENCE1. Check camera latching.2. Erecting link (grinding).

3. Positive lock.4. Check front movement and latch.

a. Check trim reset cam (correct cam andcondition).b. Light shield (condition and movement).c. Light piping seal.d. Idler gear stacking.e. Outpout gear slippage.

5. Check ash on dark slide power pack andash simulator.

6. Take ash pix at 10.4, check prematuredark slide.7. Check for dirty rollers and lm catcherspring.

C. FINAL VISUAL1. Check optical path.

2. Fresnel cosmetics (per standards chart).Split image.3. Wafer and 3 eye lens.4. Entrance and exit pupil position.

D. SHUTTER COSMETICS1. Chrome2. Lens conditions3. S1 button and photocell conditon - trimwheel decal.

4. S1 remote and ash socket condition.5. Shutter mounting screws (missing orloose).

E. CAMERA BACK1. Shade blade condition (scratched -distorted).2. Shade blade movement (gap betweenblades).3. Concave mirror condition (color coderefurbished only).

4. Repair techs scribe (data and repair centercode).5. Gear train cover.6. Bottom cover window and condition.7. Cable cover - cable camp - cable restrainer(conditon-position).8. Cable spring hook on.9. Boot retainer tabs in place.10. Cracked / broken hinges11. Shutter hinge bracket pivots and gap

(.0125 max).12. Leather and chrome cosmetics.13. Set lens at innity.

F. PICTURE EVALUATION1. Bafe in pix aera.2. Cracked / dirty taking mirror.3. Incomplete coverage (front cover related).4. Color code and FTC label (refurbishedcamera only).


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Figure 3-2 SX-70 Collimator

Figure 3-1 Film pack simulator and power suplly

Checkout the SX-70 camera requires the use ofseveral pieces of test equipment. The purpose ofthis section is to instruct you in the proper use ofthis equipment.

1. Power supply and pack simulator (Figure 3-1)

In use the system subsitutes for the lm pack,giving a steady, reliable source of power.

a. Plug the pack simulator into the power supplybeing careful to observe polarity (ground isnegative).b. Set the power supply switch to VOLTS andturn the supply ON.c. Adjust the output to the desired volatge (5.8vnormal).

NOTE : Except on Lafayette-made units, thepower supply mete is not adequate to set the

voltage. Use an external meter (VOM or VTVM)

to make this setting.

C. TEST EQUIPMENT OPERATION


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Figure 3-2 Typical collimation conditions

Figure 3-3 Location of new collimator target

a. Collimation of the Split Image ViewingSystem.

NOTE : If the collimator is not available, set the

focus wheel to innity and look at a scene at least

200 feet away. Observe that the focus is sharp

within a tolerance of -1 tooth to +2 teeth beyond

the innity setting of the focus wheel.

NOTE : If an early vintage collimator is being

used, a new adhesive backed label must be

added to the target in the position show in Figure

3-3.

(1) Remove the camera front cover and loadthe camera onto the horn of the collimator#321564 (Figure 3-2). (The collimator usesa rear illuminated target so no additionalequipment is needed).

(2) Turn on the collimator light(3) View the added target with the focu wheelset to innity.

(4) Compare the observed conditions with theexamples shown in Figure 3-4. As indicated(best case), the upper part of the vertical lineshould be aligned with the bottom part of theline or it may be displaced to the right. (Ifdisplaced to the right - acceptable -, it shouldstill be touching the lower part of the line.

(5) If the upper part of the line is displaced tothe right so far that it does not touch the lowerpart of the line or if it is displaced to the left (outof tolerance), the tolerance levels are exceededand the camera must be rejected. Correctiveprocedures are outlined in Section IV.

b. Collimation of Non-Split Image ViewingSystem

(1) Turn on the collimator light source.

d. Set the power supply to the AMPS position.b. Remove front cover from camera.c. Insert the pack simulator into the cameraas you would a lm pack (with the contactdown). Close the camera S7 switch using theactuator.

2. Collimator (Figure 3-2)

When performing several of the ComprehensiveTester checks, a requirement of the test is thatthe camera lens be correctly collimated. For thisreason and because the lens can be checkedsimply and rapidly, the collimation checks shouldbe done before Comprehensive Tester checks.Collimation for the SX-70 camera is done on thespecial collimator as indicated below.


34/54

Figure 3-5 Disengaging the idler gear

(2) Open the camera front cover slide thecamera onto the horn of the collimator. Makesure that the camera is all the way on the hornso that the camera is captured by the springlatches.

(3) Swing the collimator innity lens to itsvertical position. (Be sure the 8 lens is not in

the viewing path.)(4) Look into the camera viewnder whileturning the focus wheel counterclockwise untilthe image appears sharp. Look at the collimatorcenter target (top group of lines) and note thenumber .63. This number and the lines shouldhave maximum clarity as the focusing wheelreaches innity.

(5) if the wheel stops before the focus issharp, make the following adjustment before

continuing with the collimation procedure.

Spring Loaded Idler Gears

(a) With the camera still on the colimator, slipspecial tool #11939 over the lens and push itin, toward the back of the camera. This willdisengage the idler gear from the focus wheel,allowing the lens to be turned without affectingthe focus wheel.

(b) With the focus wheel still set it its innity

position, look through the camera while turingthe lens. (This is done by maintaining pressureon the tool.) While turning it, you will be ableto see the target through the opening in thetool.

(c) When the image is sharpest, release thespecial tool to reengage the refocused lens tothe focus wheel. (Continue setp 6.)

Non Spring Loaded Idler Gears

(a) Remove the camerar from the collimator

(b) Loosen the adjusting screw at the bottomof the shutter housing so the idler gear nolonger engages the focus wheel and lensbarrel (Figure 3-5).

(c) Return the camera to the collimator andadjust the innity focus by rotating the lensbarrel while maintaining the innity positionon the focus wheel.

(d) When the focus is sharpest, remove thecamera from the collimator and tighten theadjustement screw. Returns the camera to thecollimator and continue with step 6.

(6) Verify the innity setting. Do this byobserving the vertical line target through thecollimator innity lens and the camera optics.The line should be straight within the tolerance

in Figure 3-4.(7) Swing the collimator innity lens back downto its horizontal position, out of the viewing pathof the camera. Turn the camera focus wheel tothe 10.4 setting.


35/54

(8) Look through the camera and observe thevertical line target. Compare the observedimage with Figure 3-4 to determine if thecamera is within specications.

NOTE : There is no separate close-focus

adjustement on the camera. if the focus

wheel has reached its stop before maximumresolution is achieved, return to the innity

check. If there is any tolerance at that setting,

readjsut the innity setting as close as possilbe

to the focus wheel stopping point and recheck

the close focus. If it is still impossible to obtain

a sharp image, the lens is defective and the

shutter must be replaced.

NOTE : The foregoing tests assume that when

the camera is operated, the viewing mirror(Fresnel carrier) reaches the correct attitude

during the exposure cycle. If the lens has been

correctly collimated, the only check possible of

actual picture denition is to expose lm.

3. Comprehensive Testers (Figure 3-6 and 3-7)

There are two models of Comprehansive Testersavailable for semi-automatic testing of the SX-70 camera. The earlier model, Comprehensive

Tester Model A, consists of three interrelatedunits : the lightbox, the electronics module, andthe power supply (Figure 3-6). ComprehensiveTester Model B (Figure 3-7) also consists of three

interrelated units : the Comparalumen calibratedligh source, the electronics module, and themounting horn or holding xture. The purposeof both tester models is to check the dynamicoperating functions of the camera ( A detaileddescription of the later tester is available in atechnical manual titled Model B camea tester.This section will deal only with the operatinginstructions for the tester.)

MODEL A CAMERA TESTER

a. Set-up

Before testing the camera, perform the followingset-up procedure.

(1) Calibrate the tester daily. Record thecalibration reading in a log. (If the test equipmentis suspected of poor performance, calibrate

more frequently and repair if necessary.)(2) Remove the front cover from the camera

(3) Set the L/D control to the mid-range positionusiong the trim reset cam and focus the cameraat innity.

(4) using the S7 actuator, close teh s7 switch.

(5) Allow the tester to warm up for a period of30 minutes.

Figure 3-6 Comprehensive tester


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b. Ambient mode exposure test

(1) Place the S2 switch int he OPEN position.Set the voltage to 5.8 volts

(2) Set the light level selector to the desired 100light level

(3) Slide the camera over the horn on the tester.The camera should go through the dark slide(S8) cycle. If not, remove the camera from thehorn, determine the cause of failure, and correctthe dark slide operation. If the camera cyclescorrectly, push the simulator ash plug all theway down into the ash socket.

(4) Read the current meter - it should read 0after the dark slide cycle.

(5) Press the exposure button and hold itdown while observing the exposure meter. Thereadings must compare to the specicationsshown in the Standards paragraph at the endof this section. (When the exposure is released,the meters will automatically reset.)

(6) Observe teh BATTERY DRAIN meter. Thereading should be according to specications.

This test applies only to the rst exposure ofseries.

(7) Release the exposure button actuator. All ofthe meters will reset automatically.

(8) Repeat steps 5 through 7 twice ( a total of

three times). The exposure readings observetedmust be within specications.

(9) Move the light level selector to 6.25. Repeat

steps 5 through 7. The reading must agree withspecications.

(10) Move the light level selector to 800. Repeatsteps 5 through 7. All readings must agree withspecications.

(11) Recycle the camera by removing it from thehorn and then reinstalling it on the horn. This isnecessary for the next portion of the testing.

c. Flash Circuit and S9 Mode Test(1) Set 5.0 volts on the tester voltmeter. Setlight level at 6.25 and close S2.

(2) Press the exposure button. The numbereone READY lamp will go off and the number thenumber one FLASH indicator lamp will light.

(3) Press and release the exposure button fourmore times. The READY lamps should go offand the FLASH indicator lamps should light innumerical sequence each time hte exposure

button is pressed.(4) Press and release the RESET button on theash simulator assembly.

(5) Press and release the exposure button ve

Figure 3-7 Model B Camera tester


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more times. The READY and FLASH indicatorlamps should sequence as in step 3.

(6) On the ash simulator assembly, press andrelease the RESET button.

(7) Press the exposure button actuator. Thenumber one READY indicator lamp shouldremain lighted and the number one FLASH

indicator should not light. (Checks S9.)

NOTE : The toggle switches on the ash

simulator assembly can be used to simulate

normal or used ash lamps. By setting the

individual switches, partially exhausted or

deective ash bars can be simulated.

d. Follow-Focus Test

The follow-focus test is used to determinehow well the shutter blade opening follows thefocusing of the lens in ash mode operation.The APERTURE meter is used in this test.It is calibrated in stops and when the test isperformed, it will indicate stops deviation fromthe ideal design aperture. To perform the follow-focus test, proceed as follows :

(1) Set the camera focus to innity and the L/Dcontrol to mid-range. Set the power supply to5.8 volts.

(2) Remove the front cover from the cameraand install the S7 switch actuator.

(3) Install the camera on the horn of the tester.The camera should go through its dark slidecycle.

(4) Remove the camera from the tester and setit on the collimator.

(5) Swing the 8 and innity lenses into theirvertical positions on the collimator and look

through the camera.(6) Turn the focus wheel unti the vertical line inthe center target is straight (refer to Figure 3-4).The camera is now collimated for the 8 setting.Tape the focus wheel so it cant be accidentlymoved.

(7) Remove the camera from the collimator andplace it on the tester.

(8) Install the ash simulator plug into thesocket on the camera and close the S2 CLOSE

OPEN SWITCH(9) Set the light level selector to 800 cdls/ft.

(10) Set the ash mode aperture switch to 8.

(11) Block any light from the photocell on the

camera using a square of cardboard or othermaterial.

(12) Depress the exposure button and observethe APERTURE meter.

(13) Record the 8 APERTURE reading andcompare it to the STANDARDS Chart.

(14) Remove the tape form the focus wheel

and rotate the wheel to the 10.4 setting.(15) Set the ash mode aperture switch to10.4.

(16) With the photocell still blocked, press theexposure button and observe the APERTUREmeter.

(17) Record the 10.4 APERTURE reading andcompare it to the STANDARD Chart.

(18) If the reading is high at the 8 foot setting,

and the needle goes off scale at the 10.4 setting, the interceptor mechanism is defective.(See Section IV for repair/adjustment.)

(19) If on scale readings are obtained for 8but the 10.4 reading is either high or low, theinterceptor can be adjusted. The problem canbe either the interceptor link or the interceptorcam. (See Section IV for repair/adjustment.)

(20) When repairs/adjustements, interceptoron Wrong Side of Stop Pin.

MODEL B CAMERA TESTER

a. Set-up

(1) Be certain that the comparalumen lightsource and electronics module are on a at worksurface and plugged into separate 110 VACoutlets.

(2) Plug the cable assembly from the horn intothe socket located on the front of the electronics

module.

NOTE : There is no warm up time required for

the Model B Tester components.

b. Comparalumen Light Specications

The following table shows the luminance levelsof various setting used for camera testing.

c. Ambeint Exposure Measurements

(1) Remove the front cover from the camera.

(2) Close the S7 switch using the S7 actuator.

(3) Set the L/D control to the mid-range positionusing the trim reset cam and focus teh cameraat innity.


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(4) Slide the camera fully onto the horn.

(5) Select the light level desired on theComparalumen and slide the horn up againstthe appropriate window. (Position the horn sothat the locating pad on the front of the horn

touches the window.)

(6) Insert a remote shutter release cable into

the socket on the right side of the shutter.(7) Rotate the RANGE switch on the electronicsmodule to the SX-70 EXP position.

(8) Lift the EXPOSURE-APERTURE MODEswitch to the EXPOSURE position.

(9) Press the remote shutter trip button andread the exposure on the meter.

(10) Return the EXPOSURE-APERTUREMODE switch to the RESET position.

d. 10.4 Aperture Measurement

NOTE : This measurement must be preceded

by steps 1 throught of the Ambient Exposure

Measurement procedure, then complete the

following :

(1) Rotate the camera focus wheel to the 10.4setting.

(2) Insert a used ash bar into the camera ashsocket and position the spring clip (supplied with

the tester) over the ash bar so the photocell iscovered.

(3) Select the 800 cdls/ft on the Comparalumenand position the camera at the right-handscreen.

(4) Rotate the RANGE switch to the 10.4position.

(5) Place the EXPOSURE-APERTURE MODEswitch in APERTURE position.

(6) Press the remote shutter trip button and readthe aperture in the relative stops, on the meter.

(7) Return the EXPOSURE - APERTUREMODE switch to the center (RESET) position.

NOTE : If a meter reading goes off scale (greaterthan +1 stop), press the +1 stop pushbuttonon the electronics module and read the meter,adding +1 stops to whatever the meter isindicating.

4. Light Leak Tester (Figure 3-8)

Caution : When using the light leak tester, alwayshold the xture so the camera is in the uppermostposition witgh the lens pointing down. There isno latching device on the xture and the cameracould slide off it the xture were pointed down.

The light leak tester consists of two checks : the

static test (with the camera in the mirror down orviewing position) and the dynamic test (with the

COMPARALUMEN LIGHT LEVELS TABLE

800 cdls/ft - Move the center switch on the Comparalumen to the right toilluminate the right (high level) screen, No lters are used for the800 cdls/ft level.

100 cdls/ft - Proceed as for the 800 cdls/ft level, but insert both lters (onestop down and two stops down) into the slot above the right

(high level) screen.

50 cdls/ft - Move the center switch to the left to illuminate the left (low level)screen. No lters are used for the 50 cdls/ft level.

6.25 cdls/ft - Proceed as for the 50 cdls/ft level, but insert both lters (onestop down and two stops down) into the slot above the right (lowlevel) screen.

NOTE : On some Comparalumens it has been found necessary to reverse the lters when usedto reduce the 50 cdls/ft to 6.25 cdls/ft. In this case the lters are labeled so that the proper label(100 or 6.25) must facing the operator when the lters are used.

Caution : To avoid possible delamination of the lters, do not leave the Comparalumen on at100 cdls/ft any longer than necessary. It should not be on any longer than the minute or twoneeded to check the camera.


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camera in the mirror up picture taking position).(Both of these tests must be done in a darkenedaera.)

a. Static tests

(1) Erect the camera and remove the front coverassembly. Close S7.

(2) Turn on the power supply and insert the lightleak xture into the camera lm compartment.

The camera should run through the dark slideeject cycle.

(3) Darken room.

(4) Press and hold the xture trigger.

(5) Examine the camera from all angles, lookingfor light leaks. Note the location of any lightleaks and continue below with the dynamic test.(Leak are most likely at the hinge aera betweenthe inner frame and mirror cover and at the boottab aera).

b. Dynamic tests

(1) Cover the photocell lens and trip the shutter.With the photocell lens coveredn, the mirrorshould stay in the raised (picture taking) positionlong enough to perform the dynamic light leaktest, approximately 13 - 28 seconds.

(2) Press and hold the xture trigger.

(3) Examine the camera for light leaks. Gently

ex the boot while looking for leaks. Note thelocation of any light leaks. (You may see a smallamount of light in the aera where the boot joinsthe shutter housing. This is light emanating fromthe substrate and is normal.) Allow the camera

cycle completion and remove the xture.

(4) Turn off the power.

(5) Repair any light leaks noted in the previoustesting. If light leaks reparis are made, retestthe camera.

5. Flash Simulator Board (Figure 3-9)

The Flash Simulator Board provides a quick, easymethod for checking the ash ring capability ofthe SX-70 camera. Figure 3-9 shows the boardwhich contains ve light emitting diodes (LED),ve resistors, and ve toggle switches. Providingthe interface with the camera socket is a hotshoe assembly which reduces wear on theboard contacts. Use the simulator as follows :

a. Insure that all switchers are in the positionshown (down).

b. Insert a lm pack or lm pack simulator into

the camera. Operating voltage is 5.0V to 6.4V.

Figure 3-8 Light leak test system

Figure 3-9 Flash simulator board


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Figure 3-10 Manual camera tester

c. Install the ash simulator board into the cameraashbar socket in the same way as a ashbarwould be installed .

d. Press the red exposure button, S1.

e. Observe that LED #1 ashes.

f. Flip switch S1 up.

g. Press the red exposure button.

h. Observe that LED #2 ashes.

i. Flip switch S2 up.

j. In like manner, continue pressing the redexposure button and ipping the correspondingswitches up until all ve lights have ashed.

k. Repeat step d. though j. The lights should ashve more time.

l. Press S1.

m. Observe that no light ashes. This conrms

proper operation of S9.

6. Manual Function Tester (Figure 3-10).

NOTE : The Manual Fucntion Tester #11959 isupdated version of the Camera Back Simulator#11775. The basic difference between the twopieces of test equipment is that the simulatorrelies on an external power supply while the

function tester ahs a built-in power supply. Thesteps listed in paragraph b., Test, apply to bothunits. Remember, if the shutter tests satisfactorilyat 5 volts, the test must be repeated at 6.4 volts.

Set up.

(1) Using a VOM, check for shorts on the shutterbefore setting it on the tester. (Not necessary forplastic base shutter.) Check between + and -points on the substrate and the casting. Theremust be no shorts.

(2) Set power supply to 5.0 volts. (If simulatoris being used, connect to power supply, setsupply to 5.0 volts and switch supply fromVOLTS to AMPS.)

(3) CLOSE tester switches : S2, S3, S5, F1thru F5.

(4) OPEN tester switches : S1, S6/S7, S8, S9.(5) Clamp shutter cable in the connector andinsert ash bar connector into the shutter FFA.

(6) Set shutter lens to 10.4 and trim wheel tofull dark.

(7) Proceed with testing as indicated in tablebelow. If shutter tests ok at 5.0 volts, retest at6.40 volts.


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MANUAL FUNCTION TEST SEQUENCE

Test Mode Action Shutter Response

S6/S7 Close S6/S7

Press and release S1

button to check formechanical binding.Observe current drain.

No reaction (Blades open, motor off)

AMBIENT ExposureMode

Remove ash array fromshutter.

Close S1Open S5Open S1Open S3

Close S3Close S5

Blades close; motor runsBlades close; motor brakesBlades close; motor brakes (no reaction)Blades open then close; motor runs (exposure

time dependent on amount of light to seen byphotocell)

Blades close; motor runsBlades open; motor brakes

S8 Dark Slide eject mode

(Flash Array inserted)

Close S8Close S6/S7

Open S5Open S3Close S3Open S8Close S5

Blades open; motor brakes (no reaction)Blades close; motor runsBlades close; motor runsBlades close; motor runs; no ashBlades close; motor runsBlades close; motor runsBlades open; motor brakes

Flash Mode - ash arrayinserted into shutter

Close S1Open S5Open S1Open S3

Close S3Close S5

Open F1 thru F5

consecutively, repeatingabove test between each

switch opening.

Blades close; motor runsBlades close; motor brakesBlades close; motor brakes (no reaction)Blades open then close (small aperture)ashres; motor runsBlades close; motor runsBlades open; motor brakesBulbs re insequence

S9 - Empty lm packmode

Close switches F1 thru F5Close S9Close S1Open S5Open S1Open S3

Close S3Close S5

Blades open; motor brakes (no reaction)Blades close; motor runsBlades close; motor brakesBlades close; motor brakes (no reaction)Blades open then close (xed time)no ash;motor runs

Blades close; motor runsBlades open; motor brakes


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Figure 3-11 SX-70 Viewnder system

Figure 3-12 Installing the exit pupil gage

Viewnder quality refers to the general quality andalignment of the camera optics. For the user, itcan be precisely dened as the appearance and

clarity of the image as seen through the viewingsystem (Figure 3-11). When a camera has poorviewnder quality, it is difcult to obtain a sharpimage.Certain parts of the eld always seem outof focus and the image lacks crispness, havinga hazy appearance usually in the vertical plane.Since ash pictures are critically dependent onaccurate focusing, a poor viewnder system willmake the taking of good ash pictures difcult.

Failure Analysis Chart #5 will enable you to tracemost problems in the viewing system to theirsource. Corrective actions are shown and wherethey are complicated are presented in Section IV.Presented here are several checks with requiregreater detail than the charts provide.

1. Exit Pupil Test

a. Mount the exit pupil gage onto the camera eyelens (Figure 3-12).

(1) Engage the left side gage rail on the eyelens. (The right side is identied by a 3/4horizontal slot.)

(2) Slowly slide the right side in place. A distinct

clicking will be heard when the gage issecure.

D. OPTICAL SYSTEM


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Figure 3-14 Exit pupil images

Figure 3-13 Aligning the exit pupil gage

(3) The mounting rails for the gage must beush with the eyelens frame. Check by holdingthe bottom of the eyelens frame with the thumb

and apply slight pressure in the upper front ofthe gage with the right index nger. The gageshould be secure.

NOTE : A left handed person may nd it easier torerverse the mounting and securing process.

b. Point the camera lens at a light source whileholding the viewnder eyelens (with gage)about18 inches away from your eye.

c. Align the bottom of the viewnder cap with

the horizontal white line on the front of the gage.Center the eyelens supports with the vertical

lines (Figure 3-13).

d.Close one eye and view the exit pupil imagein the gage.

e. To be within acceptable limits, the pupil (abright circular image) must appear in the centerof the square opening in the face of the gage.If the pupil is not in the center, adjust the optics

system according to instructions in Section IVViewnder Sytem.

2. Entrance Pupil Test

a. Set the focus wheel to 10.4.

b. Hold the camera at arms lenght, with thetaking lens toward you and a bright light sourcebehind the camera.

c. Look through the taking lens, closing oneeye. Observe the entrance pupil in the lens.

d. Raise the front of the camera about 10and note two bright circles against a darkbackground. Both circles should be verticalypositoned .050 from the center as shown inFigure 3-14 B.

e. If the circles are not centered vertically (Figure3-14 A), perform the erecting link adjustment inSection IV.

f. If the circles are displaced horizontally (Figure

3-14 D), make the side to side adjustment of theFresnel carrier which is included in Section IV.


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Figure 3-15 Identifying distorted mirrors

3. Concave Mirror Distortion Check

a. Focus on a target which presents a clearvertical line (for example a door frame).

b. Scan the camera horizontally.

c. If the mirror is not distorted, the vertical lineseen in the eyepiece will vary at the camera isscanned. At either side of the eld, the line will

be bent while in the center of the eld, the linewill be straight (see Figure 3-15 A).

SX70 Repair Manuel Rebuilt

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