Donkey Kong machine help--garbled screen

stevenrobday

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I'm getting a garbled screen with a vertical line going across. What causes this?
dkGarbled.jpg
 
If it were me, I'd be checking all socketed chips for leg corrosion. Specifically the Z80.

Carefully remove chips with a chip prybar. Blast away the corrosion with a dremmel and a brass wire wheel. Then swab legs with deoxit.

Wouldn't hurt to make sure you are getting 5vdc at the board too.
 
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That looks like a CPU board problem. Check your power first. You should have a stable 5, 12, and -5V. Check your ROMs and CPU. You can start by just reseating them. In some cases it can be one or more of the 2114s. Also, it looks like you are due for a recap on the monitor with those waves.
 
if the UV erase windows on the roms haven't been covered, and the back door has mysteriously been missing or something for the last 30 years, I would trend towards the rom data being corrupted. the accurate way to troubleshoot this issue would be to dump the roms and compare them to the appropriate MAME set (may be difficult) or upload them to Romident. Z80s are prone to just failing too, but I think it's crashing on bad roms. next course of action will be determined by what you find.
 
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