> I would initially test replacing the thyristor with a momentary switch
> from anode to cathode. Be careful! 
> 
> If you can trigger the tube by activating the switch the t1, r21 and
> c15 are ok.

Tried that. The SCR was replaced with a pushbutton between the anode
and cathode pads. I see a very very short pulse at the transformer primary.
Not easy to see on the scope, but I reckon about 20V for less than 1us

Won't attempt to measure the secondary output in case something goes
right and HV takes out the scope input. But it's not enough to trigger the
flash anyway

> If you can not, expect a problem with the capacitor. try a different one

Bumped up the 0u1 to 0u16, no change

Tested the SCR. a-k both directions is > 50M, g-a > 50M one way
and 40M the other. Tried 3 optos and 3 SCRs. My guess is at this stage
it's too little current rather than too much blowing components


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