Electronics > Repair
Fix vertical hold on a monochrome monitor
rea5245:
Hi,
I have a monochrome monitor with a beautiful amber display, but I can't get the vertical hold to stay put.
It's a Magnavox 7BM623 074T. I can carefully find a sweet spot for the V Hold to stop the screen from rolling, but if I turn the computer and monitor off then on, it loses the hold and starts rolling slowly.
I've replaced all the electrolytic caps and the V Hold potentiometer. The problem remains.
Anything else I can try?
Thank you,
Bob
bob91343:
You would get better results if you had a schematic. The synchronizing pulse for the vertical oscillator is apparently weak or nonexistent. You need to find that circuit and troubleshoot it.
PKTKS:
--- Quote from: bob91343 on June 11, 2021, 05:48:00 am ---You would get better results if you had a schematic. The synchronizing pulse for the vertical oscillator is apparently weak or nonexistent. You need to find that circuit and troubleshoot it.
--- End quote ---
That is true..
When you *CAN* pause the rolling even for a second...
it means the local oscillator is perfect
but you have problem w/the sync integrator..
Just try to find hard that part of the circuit...
The fault should be at the integrator.
Paul
rea5245:
--- Quote from: bob91343 on June 11, 2021, 05:48:00 am ---You would get better results if you had a schematic.
--- End quote ---
Yeah. Alas, I do not, and Google can't find one either.
themadhippy:
I thought the correct fix for a rolling crt display was a sharp thump on case,or does that only apply to televisions?
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