Polaroid SX70 manual A Solenoid S2 operation

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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.When the ECM circuit powers solenoid #1, the solenoid plunger is pulled into its seat, overcomming the opening spring force. The plunger pulls the walking beam, rotating it about

60degrees.

Each of the shutter blades has a pin which engages a slot in the walking beam. As the walking beam rotates, it transmits its rotary motion to the shutter pins and drives the rear blade to the right (facing the front of the shutter) and the front blade to the left thus closing the light path of the picture taking lens and the light path of the photocell lens. When the shutter is totally closed and the gear train has reached the point in the sequence at which the Fresnel carrier snaps up, the exposure sequence starts. The blades will proceed toward the fully open position and retrun to a closed position in the time interval dictated by the photocell and integrating circuit. The blades may not reach the fully open condition if the illumination level is high, or they may fully open for a period of time if the light level is low. If a flash array is mounted, the blades may not be permittedto open completely because of the follow focus mechanism described in part in the foregoing paragraph. The following paragraph explains the interaction of the follow focus components and the shutter blades.

4.Installing a flash bar in the camera flash socket switches the ECM to the flash mode.As previously explained, at a point in picture taking sequence (flash mode), solenoid #2 is energized. Fastened to the plunger is pull down bar. when the plunger pulls this bar down, it moves the interceptor into the position where it will intercept a pin (the stop pin) on the walking beam (Figure 2-9 A). Now when the shutter blades move towards the open position, they will be interrupted by the mechanism just described which means the maximum size of the blade opening (aperture) is determined by the focus setting of the camera. As the camera (and thus the flash lamp) is moved closer to the subject, the maximum aperture is reduced so that a correct exposure will result. The reverse (greater distance/greater aperture) is also true.

Figure 2-9 A Solenoid S2 operation

5.The shape of the pin on the walking beam si such that once contacted by the cam interceptor it remains latched in that position until solenoid #1 actuated during the next phase of the shutter cycle. When the plunger on solenoid #1 pulls in, the follow focus pin disengages from the interceptor and the solenoid #2 plunger returns to it original position under the force of the interceptor hinge spring.

6.Since the photocell components are contained within the shutter housing, they are included in this discussion. A lens is employed to focus the reflected light from the subject on the photocell. A second pair of openings in the shutter blades control the amount of light received by the cell as previously described. A variable neutrality density wedge system is employed to provide lighten / darken adjustements. (Trim assembly). The operation of this control differs slightly from those used on other Polaroid cameras. When the camera is folded, a cam on the shield of the front cover strikes a release lever on the lighten / darken assembly and returns the trim adjusting wheel to its center (normal) position. The trim wheel is automatically centered when the camera is closed.

7.To compensate for any variations in individual photocell characteristics, a neutral density filter is selected and installed in front of the photocell lens during assembly. A calibration must be performed and a filter of correct density installed any time the ECM requires replacement.

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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 Lens Power SourceIntroduction Viewing and Exposing SystemFresnel Figures 2-3 a and 2-3 B Viewfinder optics exposingFresnel screen Flare baffle ViewfinderMirrors 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 gageFresnel Quality Check USE of Analysis ChartsConcave Mirror Distortion 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