Just a quick update. I had a look inside as I was putting together a
Digikey order to see if I could tack on some parts. At the power end
of the board, there are two BTA24-800B triacs on heatsinks. Nearby are
two MOC3041 zero crossing optoisolators. Around them are a few 470 Ohm
resistors, I would guess 0.5 Watt (2010 smt). Then there's the pulse
transformer. Only one of them, and it definitely looks like someone
let some magic smoke out. Naturally, no markings.

Does this make sense? It looks to me like two separate channels of
control, but there's two of everything except the transformer.

Second, what might be the best course of action here? I can easily
replace everything listed above to rule out failures there. Do I take
the transformer and unwind it so I can figure out the turns ratio?

I'm starting to wonder if this really is a thyristor drive pulse
transformer, or if it's at that end of the board for spacing. I will
have to remove it and start doing a bit of detective work to backtrack
the PCB.

Josh
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