Polaroid SX70 manual S3 Being opened by recock ram

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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. If a flash circuit is inserted into the FFA (S2 closed) an additional flash delay circuit is avtivated to insure that the exposure gets full effect of the light derived from the flash. At the end of the exposure cycle when the Fresnel carrier moves down into viewing position, S3 closes as the recock ram moves away. It is now reset for the next camera cycle.

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

NOTE : Whenever the SX-70 shutter is discussed, it must be noted that, since the camera is a single lens reflex and focusing is accomplished through the taking lens, the shutter’s normal state si open, not closed as in other Polaroid cameras.

When the shutter release button is pressed and the exposure cycle is initiated full battery power is delivred to solenoid #1, closing the shutter. Once the solenoid plunger is seated it no longer requires as much power as was originally needed to overcome its static inertia. Switch S4, therefore, closes the S4 CB contacts to the ECM and the electrical power to the solenoid coil is reduced to the «power down» value which is sufficient to continue the exposure cycle yet low enough to conserve battery drain.

WhentheswitchS4(CBcontactsclosed)transfers to the ECM it sends power to the drive motor and operates the gear train. When S4 is actuated, (CB contacts closed) it also disconnects power from the FFA flash circuitry. This action prevents

Figure 2-7 S3 Being opened by recock ram

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Contents Page Page Description General DescriptionCamera Operation Opening the CameraLoading the Film pack Starting the Automatic MechanismSetting the exposure counter Viewing and focusingViewing and shooting Developing the print Exposures using flashCompleting the film pack Shutter Description Ambient Light Mode Closing the camera11 a Location & Arrangement of internal parts Shutter Description Flash Mode Page 14 S5 being opened by the recock ram Gear train Page Power Source IntroductionLens Viewing and Exposing SystemFresnel Figures 2-3 a and 2-3 B Viewfinder optics exposingFresnel screen Viewfinder MirrorsFlare baffle Camera Elctronics 1. GeneralSwitch functions SX-70 Switch locationsS3 Being opened by recock ram S4 Switch operating configurations Switch Function Table Function SequencePage Flash Timing Sequence Chart Shutter Mechanical Details Figure Shutter, exploded viewA Solenoid S2 operation Film Processing Components Sequence of OperationsPage Max III Troubleshooting Introduction Initial TestsSX-70 Cmaera Repair Inspection Procedure Power supply and pack simulator Figure Test Equipment OperationCollimator Figure Location of new collimator targetDisengaging the idler gear Comprehensive Testers -6 Comprehensive testerModel B Camera tester Model B Camera Tester Comparalumen Light Levels Table Light Leak Tester FigureFlash Simulator Board Figure Light leak test systemManual Function Tester Figure 10 Manual camera testerManual Function Test Sequence Optical System Exit Pupil TestEntrance Pupil Test 13 Aligning the exit pupil gageUSE of Analysis Charts Concave Mirror Distortion CheckFresnel Quality Check Collimation16 Fresnel standards chart Camera/Shutter Isolation 18 Flex circuit terminal locationsCamera Analysis Charts 19 Test points on SX-70 shuttersPage Removal Front COVER/SPREAD Roll AssemblyInstallation Repairs / Adjsutments Loose Front Covers Front cover hinge studsBending the stop latch Replacing the Light Shield Cam Interference Between Front and Bottom CoversTop Spread Roll Looseness Mirror Cover / Boot Assembly Front cover light shield camBoot retaining screws