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Pretty much, 5.02V in the far corner. LS series chips are specced down to 4.75V VCC with a high logic level above 2V so one would actually expect the board to continue working at 4.8, 4.9 no problem. My other Simpsons board for example runs perfectly with 4.8 on the far chips. This was a new...

Yeah, for sure. It was just dumb of me because I saw it glitching in the arcade, brought it home and saw the exact same glitching and went right to chips. In fact the board I switched in at the arcade had been repaired semi-recently ( View: https://youtube.com/live/neQ6uf4uzY4 around 44 minutes...

Thanks, can you explain what you mean by "mess around with different chips" in MAME? I've heard of people injecting bad ROMs to see effects or poking around in memory, but if I'm expecting the customs to be bad, how can I affect that in MAME to test?

Hmm, well while testing I found that if I bumped the voltage up to about 5.15 at the JAMMA edge everything comes back fine. Probably not a great sign for the future, but for now this board is 100% working!

Tried replacing the 053251 custom since there was some evidence this had to do with layer priority, but no go. I did find that by shorting some address pins on the SRAM at 1J just below the sprite customs I could conjure the missing bits back to the screen (although causing other errors in the...

This game was on location, and after about 6 months I was in and noticed some flickering graphics. It seems that some portions of the sprite layer is not working. During the intro the "sons" is missing from The Simpsons but at the last few frames before it changes to the next screen, you can...

Just to wrap this up, I found some PRO-B0 chips on eBay, received one today and it has fixed my problem!

Cool, thanks for that info. My 4 slot actually has LSPC-A0 and PRO-B0. So I went through with those two figures and checked all the connections - they are all there, nothing missing that I can find. What could I try next?

Hi all, Wondering if anyone has seen this before. This 4 slot board is showing black dots on the right quadrant of the screen on all slots, and different cartridges. Thanks!

Yep. Even swapped the bad EEPROM into the X Men to check.

Yes, it seems to be, and I can confirm it's working on my board. There's a list here, and those are the only two 64x16/4-wire entries: http://www.cnc-lab.com/eeprome.htm

I had the EEPROM failure on a Simpsons machine that was on-location just a few weeks ago. Stole one from an X-Men board and that fixed it right up. Bought a new one (actually a 5-pack of OKI M16911 on eBay for $10) and that worked in the X-Men as well.