Re: Tektronix 2245a Flickering Trace

KB6NAX
 

Yup, I have to agree with Siggi. The "OSD," meaning the vertical
sensitivity callout in the lower left hand corner and the sweep time in the
lower right hand corner also are jumping sideways along with the
sine wave. So the jitter is occurring in the horizontal amplifier chain, not
the triggering circuit. With power off, carefully reseat anything that plugs in.
Don't slip up and plug anything back in wrong that you pulled out - no bent
pins, etc.

Arden


I think it's safe to say that you have more than just a triggering issue,
as your OSD (on-screen display) is jumping around as well as the traces
(see e.g. around here https://youtu.be/j6Dqke1CIRE?t=74). This could be as
simple as a marginally plugged-in connector somewhere, but you should be
looking at points common to the OSD and sweeps. This includes power
supplies and e.g. the horizontal amplifier. Your vertical appears
unaffected, however.
If you haven't read this:
https://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf already,
you may want to take a gander. Do you have a second scope you could turn on
your 2245A?

Siggi <

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