Polaroid 636 Repair Manual page 27

17. After the flash is charged and the exposure button is pressed all the way in, three things
happen simultaneously which decide how the flash is going to be controlled:
1 - The solenoid releases the shutter blades and they start to open;
2 - The photocell starts to measure scene light;
3 - An internal clock in the camera logic is started.
18. From this point, there is a race between the internal clock and the photocell to decide which
is going to control the flash. Either the internal clock will time-out before the photocell
measures a pre-determined amount of light or vice versa. Whichever occurs first will fire the
flash.
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