Strange Flashgun Behaviour, any advice?

[RobEavis]

I have a Vivitar 285 but it doesn't fire when it is fully charged. Instead it just makes a "tick" noise. If i trigger it just before it is fuly charged it works fine! :bang:

I have a service manual and have got the thing apart fully but everything inside looks in good nick. Maybe a high-voltage protection circuit that's running to low, or something like that? :shrug:

Any ideas?

 

[chuckles]

Sounds to me like the Thyristor is duff!

 

[RobEavis]

But it still operates in this strange way when i detach the thyristor unit from the front (ie working on full manual mode).

 

[chuckles]

I thought that was just a sensor. I was under the impression the thyrsistor is an internal component. It seems it's breaking down under high voltage....

 

[CT]

I thought that was just a sensor. I was under the impression the thyristor is an internal component. It seems it's breaking down under high voltage....

It is an internal component. The thryistor circuit is the thing that enabled power saving and faster recycling times in flashguns. Prior to that they always full dumped the charge each time whether it output a large or small flash. Could well be the problem I'd think.

 

[RobEavis]

Cheers for te helps guys. Just took it apart and found a variable resistor tht seems to link into the final chaarge voltage. Turned this right down but it's still too high to make it work properly.

Also managed to zap mysef so bad that even typing this is really hard! :nuts: