Neo Geo 4 Slot Sync Issue

xodaraP

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Donor 2015
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Hi guys,

Got a Neo 4 slot I've had for a while, decided to have another crack at fixing it, it's had a battery leak on it but that's been removed along with the charging circuit resistor. Unfortunately I seem to be getting no sync (just a grey screen that changes to a lighter shade of grey occasionally) - if I put a game in I can see colour but only in the top inch or so of the screen.

After reading some of CM's repair logs where he talked about sync I checked continuity from the sync line through to the resistors but couldn't see where the lines went to from there. There is a bit of corrosion on some components surrounding where the battery was, but they seem to check out ok, will replace them if there's anything specific likely to be causing the sync issue.
 
Have you tried putting the sync line on the scope to see if its there and correct?

Logic probe won't show it correctly just shows a pulse there but you can't say yes its the correct signal with that
 
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Don't have a scope unfortunately - so I need to know which ICs the sync line runs through so hopefully I can find the dodgy one.

Hoping it's not a custom, there is some dodgy looking traces near where the battery was but the only ICs in the area are audio system related and continuity seems to be fine on everything I tested
 
Going to be hard to find the issue then because if your using a logic probe you will be just guessing the whole time

There is schematics floating around for those Neo Geo pcbs

If you got a logic probe does that sync pin do anything at all on edge connector?
 
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