Thanks everyone. I think Nick here found the winner. R670 and 672 have both drifted over 5 ohms on both vertical amps I have. I'll try replacing those two first.
Sean
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On Tue, Jan 26, 2021 at 07:04 AM, Nick Shipman wrote:
Hi Sean,
On the vertical amplifier board, take a look at resistors R657/R659,
R662/R663, R670/R672 and make sure their values match and are approximately
to spec. I think these are carbon composition and can drift high. A
mismatch will push the main trace up or down, so that when you centre the
main trace the auxiliary amplifier runs out of control authority and the
readout can't reach one edge.
Regards,
Nick
