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buffi

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My PGM mobo used to be able to play cave Conversions just fine, but suddenly stopped being able to do that, despite playing normal games fine.

Sortof wondering if there's some of the RAM chips that the Cave stuff uses that my non-cave stuff does not use or something?

Now I get really weird graphics glitches. Some examples below:

Ketsui:
Main screen graphics glitching (the green stuff)
tuFH7JN.jpg

Color test (well... thats not great)
Gkabqiw.jpg


DDP:
Cave logo covering just half screen
4iki1d8.jpg

Colors:
JCuWthN.jpg

Crosshatch
YoQte9o.jpg


Original games play fine though?!? Example:
DSZ2ksR.jpg


Any ideas on what to troubleshoot?
Doesn't seem to be cart connectivity.
 

Fluffy

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At first glance it doesn't look like a problem with A or B roms. The title screen one could be some kind of palette/DAC problem, the scaled logo could be a problem with sprite attributes. The SRAMs/latch should be patched out of the code, so shouldn't be actually used.
Sorry, no idea what to test right away...
 

buffi

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Demon Front also had weird glitches (in the middle. The stuff at top is just the tv being shit)

Simpler mahjong games seems fine though?!?

Lnlj3Xkr.jpg
 

Invader

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I don't know if this helps, but I had a similar issue. I had glitches on the Cave conversions of Dodonpachi DaiOuJou, but all original PGM games did work well.

For me decreasing the voltage did the trick, I went even a little bit below 5V. Big thanks to @mastercello for his tip and helping me :)

With to high voltage (my super gun was drawing around 5.5V, measured on the pcb):
20200514_195843_1.jpg

With a little bit less than 5v it runs flawless:

20200523_214735_2.jpg

Some times the glitches appeared after playing for a couple of minutes, so I'm guessing the memory chips (which are in the conversion brought down to 3.3V) are overheating and glitching, but absolutely not sure...
 
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