8 Dec
2009
8 Dec
'09
7:35 p.m.
Picked up an old terminal in very nice cosmetic condition; it works fine
Make/model? Just in case one of us has heard of it and knows any stock
faults.
barring a bit of visual "jitter" on the
display -- not sure how best to
describe it. The picture is clear and sharp but occasionally a few
scanlines will spike off to the right a bit. Coinciding with this
spiking are tiny crackling noises from inside the monitor. (Or at least
it seems like they coincide, obviously I can't verify this.)
I thought it might be HV leakage based on discussions I've seen on this
THis does intiially sound like HV leakage. The spike produced when
something breaks down could well upset the horizontal scan cirucitry too.
Where have you been looking for signs of this? I'd certainly look at the
flyback transfortmer, the CRT anode capp, the CRT earthing contacts (to
the outside aquadag coating on the flare), on the CRT base PCB (the EHT
is not he only voltage that can flash over, there could well be a few
hundred volts on a CRT base pin) and so on.
Have you examined the solder side of the monitor PCB with the power on? A
cracked solder joint can produce some intereting sparks.
Could it be internal breakdown of a capactior (e.g. the 3rd harmonic
tuninc capacitor on the flyback)?
-tony