I'll second Ozan's helpfulness with this sort of thing. He has helped me a few times isolate a problem like that whcih I'm pretty sure I would not have found on my own. Glad you have something going and hope the correct transistors will fix the rest of the issues with this.
Barry - N4BUQ
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Thanks to Ozan for helping off-list with some additional measurement advice and
insight on expected values. I continue to be amazed at what some of you can
understand from a schematic.
He suggested replacing Q309/Q317 in the trigger pulse generator with the pair
from my working 7B70, and that did the trick: stable waveform with
sine/triangle/square, and controls work as expected.
I had previously tried replacing them individually with a 2N3906 (one of the few
PNP transistors I have on hand), with no luck. Replacing both Q309 and Q317
with 2N3906s actually shows a waveform instead of a blank screen, but it
stutters so I've ordered some 151-0220-00 replacements.
Adam
