Polaroid SX70 manual Shutter Description Flash Mode

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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.

When the mirror swings up, a mecchanically operated switch (S3) actuates a «Y» delay circuit (40 milliseconds) (Figure 1-12) so that the shutter will not function until the mirror bounce has subsided. At the end of the delay period the electronic circuitly removes the power from the soleniod and the opening spring sets the shutter blades in motion toward the full open position. At the same instant an electronic switch opens and starts the integration cycle. The integration cycle is that period during which the total amount of light (intensity and duration) reaching the photocell is transformed electronically to regulate the lenght of time the fiml is exposed. The shape of the opening in the shutter blades and the

motion of the blades is such that all of the factors involved are continously variable throughout the exposure period. this fact, however, is a design consideration and should not confuse the theory of the shutter operation from a maintenance point of view.

When the camera completes all off its automafed functions and the release button has been released, all voltage is removed from solenoid #1 and the shutter opens in preparation for the next exposure.

It should be noted that under extremeley low light conditions, the shutter will closed completing the exposure cycle in 14 to 30 seconds whether a suitable exposure has produced or not.

C. SHUTTER DESCRIPTION (FLASH MODE)

The special ten-shot flash bar is equiped with a shorting bar so that when the bar is inserted, two contacts within the camera is shorted. This switch is identified as S2. When S2 is closed, the shutter electronic circuit detects that a flash bar is in place and ready for firing. In general, the sequence of the functions remains the same as for ambient light operation with the following exceptions :

Figure 1-12 S3 Being opened by recock ram

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Contents Page Page General Description DescriptionOpening the Camera Camera OperationStarting the Automatic Mechanism Loading the Film packViewing and focusing Setting the exposure counterViewing and shooting Developing the print Exposures using flashCompleting the film pack Closing the camera Shutter Description Ambient Light Mode11 a Location & Arrangement of internal parts Shutter Description Flash Mode Page 14 S5 being opened by the recock ram Gear train Page Viewing and Exposing System Power SourceIntroduction LensViewfinder optics exposing Fresnel Figures 2-3 a and 2-3 BFresnel screen Camera Elctronics 1. General ViewfinderMirrors Flare baffleSX-70 Switch locations Switch functionsS3 Being opened by recock ram S4 Switch operating configurations Function Sequence Switch Function TablePage Flash Timing Sequence Chart Shutter, exploded view Shutter Mechanical Details FigureA Solenoid S2 operation Sequence of Operations Film Processing ComponentsPage Max Introduction Initial Tests III TroubleshootingSX-70 Cmaera Repair Inspection Procedure Test Equipment Operation Power supply and pack simulator FigureLocation of new collimator target Collimator FigureDisengaging the idler gear Comprehensive tester Comprehensive Testers -6Model B Camera tester Model B Camera Tester Light Leak Tester Figure Comparalumen Light Levels TableLight leak test system Flash Simulator Board Figure10 Manual camera tester Manual Function Tester FigureManual Function Test Sequence Exit Pupil Test Optical System13 Aligning the exit pupil gage Entrance Pupil TestCollimation USE of Analysis ChartsConcave Mirror Distortion Check Fresnel Quality Check16 Fresnel standards chart 18 Flex circuit terminal locations Camera/Shutter Isolation19 Test points on SX-70 shutters Camera Analysis ChartsPage Removal Front COVER/SPREAD Roll AssemblyInstallation Front cover hinge studs Repairs / Adjsutments Loose Front CoversBending the stop latch Replacing the Light Shield Cam Interference Between Front and Bottom CoversTop Spread Roll Looseness Front cover light shield cam Mirror Cover / Boot AssemblyBoot retaining screws