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Hacking the Vivitar Zoom Thyristor 3500 flash

Manual power hack

Control module connection pinout

Ok, I've dug out my multimeter today and worked out the rough pinout for the flash unit. I've also measured the voltages between the trigger, ground and the power control pins. This means that we can now hack-away and control the output of the flash without having to get anywhere near the 350V 380 mF capacitor. (drop me a line if you see an error: ilya at ilyatitov dot com)
Vivitar 3500 unit pinout

Polarity Function Voltage
1 - Ground? (this one is linked to ground via a ceramic capacitor ~10k picofarades?)  --
2 + Trigger 9.8 V
3 + Capacitor charge indicator 0 V when charging, 5.6 V when ready to fire.
4 - Flash power control (Highest when open, lowest when connected to pin 5) --
5 + Power 5.6 V
6 - Ground --

So here's what you can do:
To fire the flash, connect pin 2 to pin 6.
To change power, add resistance between pins 4 and 5.
To determine when the flash is ready to fire — read voltage on pin 3.

Some photos:

Vivitar 3500 power control voltage Vivitar 3500 charge indication Vivitar 3500 trigger voltage Vivitar 3500 both are ground