SID graphic problem

Talon2000

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Got a SID that crapped out on me. Not a yoke wiring problem, as this was working fine, and no monitor work has been done.
Using a Braze kit which is known good.

Text is Backwards

IMAG0183.jpg


Invaders appear semi correct, but are split on the ends, and in the wrong order. Shields are split as is the laser base. Plus the laser base is on top shooting down, and scores are on the bottom.

IMAG0184.jpg


IMAG0185.jpg
 
So did this happen without changing anything, or is this a board with an unknown past?

For the screen backwards/upside down, well not the backwards part but upside down there's the 3 cocktail dip switches you can try.
 
Nothing has changed. Went from working to non working.

Cocktail mode I don't think would cause the split graphics I'm seeing. I think Mark is leaning towards Bit shifters. Having never really worked on a SI, or SID I'm not very familiar with the hardware on it, yet.
 
I could swear I've seen a similar fault before that was down to a bad chip on the main (CPU) board. Wish I could remember which one it was ..............
 
I haven't had the need to mess with the graphics portion yet but I'd double-check the daughterboard/reseat it a couple times before doing any troubleshooting.
 
Do you have the sound board with the MB14241 on it?

Ok. Confirmed it does.

Since I don't have one off hand, and this one was tarnished. I went ahead and clean the legs, and replaced the socket. No Change, I've not found a set of schematics showing that particular chip.. Are they available?
 
ok.. i have done some recent work with the Midway SI & SID boards
found when i dropped the voltage i had the same graphics problem as in your photo's
after some tweaking of the voltages i found my pcb sets worked best at 4.95 volts
so check you voltages !!
 
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