Circus Charlie Graphic Glitch

WarLordAG

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I have these vertical white bars on a Circus Charlie PCB.

I have reseated every socketed chip, tried a different ribbon cable, and even tested the board in my Gyruss machine. The problem is the same. The game plays fine otherwise. Test screen on boot indicates Ram and Rom all Ok

I don't have a logic probe. Has anyone seen this before or have any ideas. I've not done much board repair.
 

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Guess you'll have to give it to me now. ;)

If you're RAM is socketed, try swapping them to see if it changes...
 
Well just because you reseated all the rom doesn't mean the rom is good. You need to read the rom chip and see if it is bad but you need an rom programmer to do this. Then you could compare the checksums in Romident. It could also be a bad socket on the board for your rom. And ram almost always fails over time.
 
Charlie repair

I fixed a Circus Charlie board last night that had a similar graphics issue. There is a bank of 8 video DRAM chips (4164). With a logic probe check pin 14 of each chip (these are 1-bit DRAM, so that's the only output pin). On my board I found 4 bad ones: one had no output, one was stuck low, one didn't seem to be pulsing at the same rate as the others, and the last one may have actually been working but it was all corroded from a spill and looked like crap so I replaced it anyway. :)
Just thought I'd share my repair story. This is the first board I've had time to fix in months. :( I picked up a new (to me) Pace desoldering rig about a week ago and had to give it a try. Kicks ass! :thumbs_up:
 
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