Hi Barry, Adam,
Thank you for the nice words. Your detailed data taking and coming up with good questions were key to fixing the issues and it was fun to spend time on these puzzles.
Ozan
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On Thu, Apr 4, 2024 at 06:43 AM, n4buq wrote:
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
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
