25k7193 vertical issue.

fixel

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Jan 19, 2012
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This is neogeo cabinet. Chassis is P538. After cleaning the board and replacing all caps (including c51), the monitor was running well for few days. Then, all of sudden, it faded out. Slowly, like filament lost voltage. The picture was perfect, just fading out. After confirming that flyback got filament winding open, i've replaced the flyback. After replacing flyback i was greeted with vertical issue -- there is a ghost double of the image vertically shifted -- see video http://www.youtube.com/watch?v=A6qovxY7jM0 vhold trim doesn't do anything, 50/60 trim just moves image slightly up and down. vsize creates crazy vertical linearity issue...
I've checked trims with multimeter and they have proper impedance. no cracks or anything. Replacing ic2 and ic3 didn't helped either. All diodes and transistors are fine. All voltages seems normal, except when i'm looking with scope at pin2 of ic3, i see that second ghost sync pulse...
Any ideas anyone?
Thanks.
 
Last edited:
looks like your synk is off or has ben solder bridged some where.

check all of your solder work around IC2 and your header pins. and only use pin ten in the video connector.
if you have to desolder everything and re-flow.

you have raster lines. turn down the fly back screen nob some.

and update you general location in your profile and maybe another member is close and can come help you if needed.

Peace
Buffett
 
fixed!

Apparently there was micro crack on VHOLD trim! When i was probing it with DMM, disconnected from the main board, it showed ~ 180K. Apparently i was making it work by applying slight pressure with probes..
 
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