Polaroid SX70 manual Flash Timing Sequence Chart

Page 24

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. The ECM however, will now provide power to solenoid #2 when switch S5 (in the gear train) opens, and will maintain it in a power down condition when S3 opens.

m- Within the shutter assembly a cam follower is driven by a cam on the focus wheel and arranged so that it will mechanically stop the travel of the shutter blades relative to the focus distance. When solenoid #2 is not energized, a spring on the cam follower prevents engagement of the cam follower and the shutter mechanism functions in the ambient exposure mode. When the ECM is programmed for flash, solenoid #2 is energized and the shutter openeing is controlled by focusing distance.

n- When making a flash exposure and the shutter blades start to open, the interceptor will be set to a position determined by the focusing mechanism but out of the path of the interceptor pin. When solenoid #2 is energized, it pulls the interceptor into the pins path of the blades and stops them

at the aperture for flash exposure at the set distance (Figure 1-13). The interceptor latches in this position. At this time, the ECM removes the power from solenoid #2. The solenoid, like any inductive device, produces a flyback voltage when its magnetic field collapses. This flyback voltage is used to trigger the ECM which, in turn, applies power to the FFA to ignite the next unused flashbulb.

o- The shutter performs an additional function in the flash mode. One of its circuits examines the #1 flashbulb contacts and by virtue of the resistance determines whethever or not the bulb has been fired. If the #1 lamp is exhausted, the circuit scans the #2, etc. When an unused lamp is located, the firing circuit remains connected to the lamp until is used.

NOTE : It is important to be aware that in early cameras the timing (integration) circuits of the substrate continue to function even though the insertion of a flash array has placed the substrate in the flash mode. Thus, if the ambient light level is high, the picture may be made by ambient light without firing the flash. Also, if all the flash 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 flash. However, he may still get an acceptable picture. the aperture in this case will be determined by the flash to subject distance.

FLASH TIMING SEQUENCE CHART

 

 

 

 

End

 

 

 

Sol. #1

S3

 

Flash

 

 

 

 

Delay

 

 

 

Power

Opens

 

 

 

 

 

 

 

 

 

Down/

Sol. #2

Activated

Sol. #2

Down

 

Sol. #1

SA BC

Power

Flash delay

Power Off

S4 BC

S3

Power Up

Closes

Down

FD

FF

Closes

Close

S1

Closes

S4 CA Opens

S5

Opens

Sol. #2

Power Up

Y DELAY

Blades Open to Correct Aperture S4 AC Close to Power FFA

FLASH DELAY

Sol. #15

 

Power Up /

Film

FT

Ejected

 

FTO Flash

Flash Time

Fires Out

Cycle

Complete/

S5

Closes

At Hight Light

Stop

Blades

Levels Early

Ambient

Close

Cameras will

Exposure

 

take Ambient

 

 

Exposure

 

 

(does not apply to

 

 

"P" configuration (T1)

 

 

and

 

 

Image 24
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 Exposures using flash Completing the film packDeveloping the print 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 Front COVER/SPREAD Roll Assembly InstallationRemoval Repairs / Adjsutments Loose Front Covers Front cover hinge studsBending the stop latch Interference Between Front and Bottom Covers Top Spread Roll LoosenessReplacing the Light Shield Cam Mirror Cover / Boot Assembly Front cover light shield camBoot retaining screws