I - DESCRIPTION A. GENERAL DESCRIPTION The Polaroid Land SX-70 is a folding, pocket sized, single-lens reflex camera which takes and immediately delivers full-color pictures approximately 31/4 inches square (see figures 1-1, 1-2 and 1-3). Operation is automatic; the user merely inserts the film, focuses and shoots. power is provided by a six-volt battery inside the film pack; therefore, the batteries are always fresh as the film.
Figure 1-3 Opened for picture taking The subject is viewed and focused throught the taking lens, a mirror, a Fresnel viewing screen (with spilt-image focusing aid) and a optical system to focus the image at the viewing eyepiece. As in all single-lens reflex cameras, the shutter must be open to provide an image at the eye-piece. This requirement is fulfilled by the automatic electro-mechanical components which are described in detail in Section II of this manual.
When the camera is fully opened, the interlock switch (S6), located at the left rear corner of the mirror cover, is closed and the battery is connected to the camera electrical circuit. (Figure 1-4). 2. Loading the Film pack The front coverlatchis located on the right side of the camera just inside the rim of the bottom cover assembly. Pressing down on this yellow latch releases the front cover which drops down to expose the film chamber.
Gears in the front cover must engage the main gear train of the camera before the gear train is put into motion. A switch (S7) located in the forward section of the gear train compartment initiates the application of power to the gear train drive motor. Switch (S7) is actuated by two components (1) A projection on the front cover latch (Figure 1-6 A), and (2) A post on the right rear edge of the front cover (Figure 1-6 B). front edge of the front cover.
Figure 1-8 Viewing and shooting shutter to initiate a series of events. The shutter blades close to cut off the optical path. The hinged Fresnel viewing screen is swung upward and comes to rest in front of the fixed viewing mirror (Figure 1-8 B). The shutter opens and closes to perform the exposure function. A first-surfaced taking mirror is fastened to the underside of the Fresnel carrier assembly.
The image is reflected by the mirror onto the film surface. the electronic metering system determinesthe required exposure, and programs the shutter opening and duration accordingly. The incorporation of a mirror in tghe lens-to-film path necessitated by the nature of the film. No separate negative film is employed. Instead, the image appears as a direct positive. Since the final product is an opaque print, it is viewed by reflection.
Figure 1-9 Inserting the flash bar 10. Closing the camera When through using camera it be can folded and latched in its closed configuration by pushing the erecting link. When the camera is closed, the interlock switch (S6) is opened so that the battery is completely disconnect from the camera circuits. The trim wheel (the lighten / darken adjustement associated with the photocell) automatically returns to its normal position each time the camera is closed. C.
When the release button is pressed, a switch S1 closes (Figure 1-11 A and B) and applies operating power to the shutter. As soon as power is applied to the shutter, solenoid #1 is energized and rapidly moves the shutter blades to the closed position. Figure 1-11 A Location & Arrangement of internal parts Figure 1-11 B Operation When the solenoid has reached the end of its stroke (shutter closed, it no longer requires maximum current to hold it at that postion.
to an adequate level to hold the solenoid after the high-current circuit has completed the solenoid operating function and switches on the motor drive circuit. Thus, the shutter will remain closed, with minimum battery drain. Light entering the lens is now cut off and the reflex mirror is swung upward to picture-taking position. The electronic latch (activated by opening S5) assures that the sequence will be completed even if the operator removes his finger from the exposure button, S1.
mechanical device identified as the interceptor connected to the lens focusing mecchanism (Figure 1-13 A). the interceptor is moved as the lens is focused regardless of whether ambient-light or flash pictures are being taken. When flash bar is in place (S2 closed) and the gear train opens switchs S5 (Fighure 1-14), solenoid #2 is energized and pulls the interceptor into position to phycally restrict the shutter blade travel (Figure 1-13 B).
Figure 1-13 B Figure 1-14 Interceptor link, Solenoid 2, S2 operation - Solenoid energized S5 being opened by the recock ram (Gear train)
In cameras with «P» configuration or later shutter there is no ambient light measurement made. If a flash bar is in the shutter socket a flash picture will result regardless of the ambient light level. On early cameras, an ambient light measurement is made during the flash delay period. Since the photocell aperture is a part of the shutter blades, the amount of reflected light reaching the cell will also be a function of focusing distance.
II - THEORY OF OPERATION A. INTRODUCTION A general description of the camera and the sequence of its functions is contained in Section I. In that section, detailed analysis of individual assemblies and electrical circuits was minimized so that emphasis could be placed on the intenelation-ship of various functions. In the following paragraphs, the individual groups of components are described in greater detail. The description are presented in the sequence in the commponents were mentioned in Section I. B.
Figure 2-2 Viewfinder optics (exposing) the subject passes through the camera lens and is reflected by the viewing mirror (on the inside surface of the mirror cover) to the Fresnel viewing screen. The entire subject image is now reproduced on the viewing screen. At this point, viewfinder optics must be employed for focusing.
The screen itself is a sheet of plastic upon which are impressed series of concentric rings much like the grooves pressed into a phonograph record (Figure 2-3) instead of having a vee shaping; however, the grooves in the Fresnel screen form a saw-tooth with a tooth angle increasing slightly with each successive groove in such a manner as to complement the decreasing angle of the light ray. The saw-tooth flattens out completely at the exact optical center of the screen.
2. Viewfinder The viewfinder optics consist of an eye lens, a concave mirror and a wafer lens (Figure 2-4). As in all simple optical system, a certain amount of distortion is inherent in this design. A small wafer lens is introduced into the viewfinder optical path to limit to angle of acceptance and, thus, reduce distortion. The size of the lens opening is large enough to provide acceptable viewing brilliance and, at the same time, small enough to be easily closed when the camera is in the exposure mode.
The entire ECM (rather tna its individual integrated circuits) is used as a remplacement item. For that reason, the theory of operation and analysis techniques presented in this manual have prepared in such a way that the repairman can relate a specific camera failure mode to an ECM function. 2. Switch functions a- Switch S1 is actuated by either the red shutter release button or remote control cable release.
c- Switch S3, normally closed at the begining of the exposure cycle is opened by the recock ram located in the gear train assembly. See Figure 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 actual exposure approximately 40 milliseconds so that mirror bounce will have subsided before a picture is taken. At the end of the delay time, the shutter starts to open and the electronic timing function (integration) takes place.
Figure 2-8 S4 Switch operating configurations damage to the circuit in the event that flashbulb becomes short-circuited after it is fired. e- Switch S5 (normally closed at the beginning of the exposure cycle), like S3, is located in the gear train 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 the drive motor, applying dynamic braking voltage to stop the gear train quickly.
h- Switch S8 (Figure 2-8 A) is part of the exposure counter operated by the counter wheel. As S7 closes, power is applied, ejecting the dark slide. After the dark slide ejection, the counter wheel turns, opening S8. S8 then remains open until the film pack is removed. When the pack is taken out, S8 closes. i- Switch S9 is near S8 on the exposure counter assembly.
mechanical coupling device set the exposure counter to the position just before the first exposure and closed S8, but since S7 has removed all battery power no action occurs). d- The operators closes and latches the front cover. S7 closes, power is apllied and the camera eject the dark slide.
k- If the operator has removed pressure from exposure button all power will be removed and the shutter blades will open to permit viewing. If the button has not been released, the shutter blades will remain closed until the operator removes his finger from the button. l- When a flash bar is placed in its socket, it closes switch S2. This switch connects the ECM in the flash mode. All of the mechanical sequences will remain as just described.
F. SHUTTER MECHANICAL DETAILS (Figure 2-9) The following paragraphs describe the manner in which the mechanical components of the shutter respond to either manual or electrical direction. 1. When the operator prepares to take a picture, he first must aim and focus the camera. As he rotates the focus wheel to bring the split Fresnel Figure 2-9 Shutter, exploded view image into focus, a cam molded into the rear surface of the focus wheel moves the component identified as the cam follower assembly.
2. When an ambeint light exposure is being made, all of the action just described takes place but does not affect the shutter action. However, when a flash array is inserted switch S2 in the flash socket programs the electronics to energize solenoid #2. The impact of this action on the movement of the shutter blades is described in paragraph F.4. but first the shutter blade actuation must be described as follow : 3.
G. FILM PROCESSING COMPONENTS The basic theory of the film processing method remains unchanged from previous Polaroid system. That is , the developping chemistry is encapsuled in a pod on each sheet of film and, as the sheet is passed between rollers, the pod is burst and the chemical spread evenly between the negative and the mylar protective cover. Except for this characteristics, no direct similarities exist. The SX-70 camera employs a unique process which totally eliminates the «throw array» negative.
partial pack : the top of the sheet of film would be ejected as a dark slide and the counter would registrer «10». After the last actual sheet is used, the camera would still function until «0» is reached. If a flash bar were attached, and an unused bulb was available after the last film sheet was used, attempting to make another exposure would fire the flash. The difference in the flash mode are : inserting a flash bar closes S2, which activates solenoid #2 to move the interceptor into position.
EXPOSURE / PROCESS OPERATION SEQUENCE ● S9 opens when previous pack removed closed during the erecting mode ● S8 closed until film cover ejected ● Gears between front cover and gear train mesh as cover closes (3rd & 4th idler) ● S7 closes during front cover closure resulting in dark slide ejection after a new pack inserted ● S6 ● S8 S1 opens (counter set to 10) CLOSED BY OPERTOR Solenoid #1 power up Shutter starts to close FLASH S2 → Closed if flash array inserted S1 T-0 200 ms max.
A. INTRODUCTION III - TROUBLESHOOTING The Sx-70 camera is an electronically controlled device, the electronics being in the integrated circuits (IC) mounted in the Electronic Control Modul (ECM) and Flash Fire Assembly (FFA) in the shutter housing and in the Motor Control Circuit (MCC) in the camera back. Because the IC’s are non-reparaible items, there is no requirement to trace faults whithin the integrated circuits.
SX-70 CMAERA REPAIR INSPECTION PROCEDURE A. FUNCTIONAL TEST C. FINAL VISUAL 1. Perform light leak test. 1. Check optical path. 2. Check focus and trim wheel torque. 2. Fresnel cosmetics (per standards chart). 3. Check trim wheel reset ±2 teeth and front Split image. cover to shutter gap. 3. Wafer and 3° eye lens. 4. Cycle camera 3 times at 5.0 and 6.4 volts 4. Entrance and exit pupil position. with power pack. 5. Focus camera at 8’ - performe aperture test D. SHUTTER COSMETICS (see specification sheet). 1.
C. TEST EQUIPMENT OPERATION Checkout the SX-70 camera requires the use of several pieces of test equipment. The purpose of this section is to instruct you in the proper use of this equipment. 1. Power supply and pack simulator (Figure 3-1) In use the system subsitutes for the film pack, giving a steady, reliable source of power. a. Plug the pack simulator into the power supply being careful to observe polarity (ground is negative). b. Set the power supply switch to VOLTS and turn the supply ON. c.
a. Collimation of the Split Image Viewing System. NOTE : If the collimator is not available, set the focus wheel to infinity 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 infinity setting of the focus wheel. Figure 3-3 Location of new collimator target d. Set the power supply to the AMPS position. b. Remove front cover from camera. c.
(2) Open the camera front cover slide the camera onto the horn of the collimator. Make sure that the camera is all the way on the horn so that the camera is captured by the spring latches. (3) Swing the collimator infinity lens to its vertical position. (Be sure the 8’ lens is not in the viewing path.) (4) Look into the camera viewfinder while turning the focus wheel counterclockwise until the image appears sharp. Look at the collimator center target (top group of lines) and note the number .63.
(8) Look through the camera and observe the vertical line target. Compare the observed image with Figure 3-4 to determine if the camera is within specifications. NOTE : There is no separate close-focus adjustement on the camera. if the focus wheel has reached its stop before maximum resolution is achieved, return to the infinity check. If there is any tolerance at that setting, readjsut the infinity setting as close as possilbe to the focus wheel stopping point and recheck the close focus.
Figure 3-7 Model B Camera tester 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 100 light 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 the horn, determine the cause of failure, and correct the dark slide operation.
more times. The READY and FLASH indicator lamps should sequence as in step 3. (6) On the flash simulator assembly, press and release the RESET button. (7) Press the exposure button actuator. The number one READY indicator lamp should remain lighted and the number one FLASH indicator should not light. (Checks S9.) NOTE : The toggle switches on the flash simulator assembly can be used to simulate normal or used flash lamps.
(4) Slide the camera fully onto the horn. (5) Select the light level desired on the Comparalumen and slide the horn up against the appropriate window. (Position the horn so that 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 electronics module to the SX-70 EXP position. (8) Lift the EXPOSURE-APERTURE MODE switch to the EXPOSURE position.
Figure 3-8 Light leak test system camera in the mirror up picture taking position). (Both of these tests must be done in a darkened aera.) a. Static tests (1) Erect the camera and remove the front cover assembly. Close S7. (2) Turn on the power supply and insert the light leak fixture into the camera film compartment. The camera should run through the dark slide eject cycle. (3) Darken room. (4) Press and hold the fixture trigger. (5) Examine the camera from all angles, looking for light leaks.
c. Install the flash simulator board into the camera flashbar socket in the same way as a flashbar would be installed . d. Press the red exposure button, S1. e. Observe that LED #1 flashes. f. Flip switch S1 up. g. Press the red exposure button. h. Observe that LED #2 flashes. i. Flip switch S2 up. j. In like manner, continue pressing the red exposure button and flipping the corresponding switches up until all five lights have flashed. k. Repeat step d. though j. The lights should flash five more time. l.
MANUAL FUNCTION TEST SEQUENCE Test Mode S6/S7 Action Close S6/S7 Shutter Response No reaction (Blades open, motor off) Press and release S1 button to check for mechanical binding. Observe current drain. AMBIENT Exposure Mode Remove flash array from shutter.
Figure 3-11 SX-70 Viewfinder system D. OPTICAL SYSTEM Viewfinder quality refers to the general quality and alignment of the camera optics. For the user, it can be precisely defined as the appearance and clarity of the image as seen through the viewing system (Figure 3-11). When a camera has poor viewfinder quality, it is difficult to obtain a sharp image.Certain parts of the field always seem out of focus and the image lacks crispness, having a hazy appearance usually in the vertical plane.
lines (Figure 3-13). d.Close one eye and view the exit pupil image in the gage. e. To be within acceptable limits, the pupil (a bright circular image) must appear in the center of 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 IV «Viewfinder Sytem». Figure 3-13 Aligning the exit pupil gage (3) The mounting rails for the gage must be flush with the eyelens frame.
3. Concave Mirror Distortion Check a. Focus on a target which presents a clear vertical line (for example a door frame). b. Scan the camera horizontally. c. If the mirror is not distorted, the vertical line seen in the eyepiece will vary at the camera is scanned. At either side of the field, the line will be bent while in the center of the field, the line will be straight (see Figure 3-15 A). d.
you to a chart. In all cases, the fault analysis charts present the logical sequence of checks and remedial procedures. These charts are divided into three parts : - one, (CAMERAANALYSIS) for problem analysis when the camera is completely assembled - two, (OPTICAL ANALYSIS) for analysis of the viewfinder parts - three, (SHUTTER ANALYSIS) for detailed shutter analysis. The SHUTTER ANALYSIS charts should be Figure 3-16 Fresnel standards chart used only after the shutter has been unsoldered from the camera.
Figure 3-18 Flex circuit terminal locations 1. Camera/Shutter Isolation To expedite the repair procedure, it is essential that the malfunction be isolated to either the camera back or the shutter as early as possible in the troubleshooting procedure. The sequence should not be considered inflexible, however. a. Disassemble the camera to the point where the terminals on the flex circuit are accessible (Figure 3-17). b. Tack solder a 1000 ohm, 1/2 watt resistor across the VCC and NPN terminals as shown.
d. With the 1000 ohm resistor still in place, connect a jumper wire between the motor (minus TP9 contact) and the battery (minus TP1 contact) for a moment : (1) If the motor runs, the MMC is defective. (2) If the motor does not run, the motor is defective e. Remove the jumper immediatly after determining the fault aera. 2. Camera Analysis Charts Once familiarity with the system is gained, repair people can rely on the failure analysis charts to troubleshoot camera problems.
IV - REPAIR AND ADJUSTMENTS INTRODUCTION This section of the manual is primarily devoted to disassembly/reassembly procedures. These procedures provide step by step instructions aimed at guiding the technician through the intricacies of SX-70 camera repair. The procedures cover such things as replacement of improper linkages or connections, repair of electrical malfunctions, and adjustments needed to return the camera to proper operation.
Figure 4-1 Front cover hinge studs Repairs / Adjsutments 1. Loose Front Covers Some cameras have been detected with loose front covers due to improper latching. This problem occurs when the «knife edge» of the front cover latch is not firmly, and/or correctly seated in the latch retainer, thereby causing excess «play» between the latch and retainer. To resolve this problem, perform the following procedures : a.
Figure 4-3 Bending the stop latch Figure 4-4 Comparison of decal before and after front cover closure
1. Interference Between Front and Bottom Covers A few cameras may have an interference fit between the S7 actuator post and the edge of the bottom cover when the front cover is opened. The problem has been traced to slightly oversize bottom covers. Problem bottom covers have a mark «PP 2½». One method of correction is to bias the bottom cover and front cover away from each other to the limit of the screw holes.
B. MIRROR COVER / BOOT ASSEMBLY Figure 4-6 Front cover light shield cam When a new type shutter is installed, the cam in the light shield must be inspected and changed if necessary. The new cam should be installed in the same place and manner as the old cam (Figure 4-7). Remove the old cam uising an x-acto knife to cut the plastic rivets. Place the new cam in the same position, making sure the cam lip goes over the edge of the light-shield as shown, and the pins through the four holes.
5. In the following step, the bottom cover will be removed. To prevent damage to the flex circuit, insert a thin strip (a small, metal, six-inch pocket scale, for example) between flex circuit and the inside cover surface. Move the tool from one locating stud to the other as the cover is being removed to prevent sticking to the flex circuit. 6. Lift the cover a small distance away from the camera, then slide the cover from the assembly. 7. remove the inner-frame-to-boot-retainer screws (Figure 4-8).
