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Contrast/color issues on universal replacement chassis
snappleman:
There it went, flyback just died after about 5 hours of actual operation. RIP. :applaud:
Now to try and find a suitable replacement for it. Thankfully I need a project right now so this is gonna get a recap and I'll change out those absolutely awful trim pots to something serviceable. I don't suppose there's any chance I could put a better quality flyback in this than a direct replacement?
snappleman:
Waiiit, might have been premature. The flyback did the usual sizzle pop deal, but after coming back to this a few days later it seems like a really awful cheap 68uf cap was what popped right behind the flyback, along with the HOT right behind that.
I looked more carefully through everything, found 14 caps with bad ESR readings, which is the most bad caps I've ever seen on any kind of equipment. I messaged the seller on ebay and got partial (most of the cost) refund. Went ahead and recapped the entire board and was lucky to have a replacement HOT on hand, and now it "works"! I still want to find a replacement flyback, though, since this one is periodically making those awful sounds that make me nervous.
In the end it's been fun checking this chassis out, I figured since it's seemingly such a simple design that it would be somewhat more robust...
lilshawn:
typically if there is a color shift that changes due to brightness (usually tell cause bright white turn tinted but grays and black look okay)the HV is way too high and heating up the shadow mask/aperture grille and distorting it...
turn down screen voltage on the flyback and turn up color drives to compensate the brightness.
snappleman:
It was happening at very low screen voltage, at all settings. I ran it for a few more days and the flyback ended up fully dying (arcing and has a nice little hole in it now).
I have a couple much older boards that might work and found one that seems compatible (at least in yoke resistance which I know isn't the most accurate), which is a Pentranic 1019 CH-201.
The issue with this one is what it won't sync, as can be seen here (just imagine it jumping around):
This one has a damaged horizontal width coil, but it still seems to work:
The third leg is disconnected from the coil but it still turns and changes the horizontal size. This chassis is pretty beat up and probably should be trashed but if I can get it working then I'll use it on this monitor.
All the adjustments work, but there is no vertical hold adjustment. I also changed out most of the caps for good measure, but the sync issue persists.
grantspain:
if that chassis has two transistors driving the vertical then its high impedance, although you would get folderover and compression if that was the case