CPS2 Marvel vs SF - White screen on bootup

[The_A_Drain]

(I realized this is in fix logs instead of tech help! My mistake, feel free to delete or move if it's a problem)

Hi guys,

bought a few boards on ebay (yup, probably a mistake, about half of them have serious faults that weren't advertised in the listing despite being sold as 'tested working'... anyway, working through them one by one)

I'm trying to diagnose the issue with this Marvel Super Heroes vs Street Fighter board. I believe it is Asia region, grey cartridge.

It boots up to a white screen, but occasionally I'll get garbled tiles on the screen in pink/green instead. Re-seating the board, cleaning the Jamma edge did nothing but I seem to get the white screen more often since doing that.

I re-seated the chips in the game board that I could remove, most of them are socketed by they are so firmly seated I felt like I was going to pull the sockets off the board if I tried any harder, or damage a chip, so I re-seated what would come out and left the rest.

Tested the batter, it's reading 3.6v so I assume that's working ok. 5v and 12v power from my cabinet are good, Super Street Fighter 2 Turbo and a bunch of regular jamma boards work just fine.

I'd really appreciate any ideas as to how to proceed from here, I'm reasonably confident soldering a pin here and there, a couple chips, etc, but I am extremely lacking in my ability to diagnose issues.

Thanks guys!

edit: The fan works just fine also.

edit2: After re-seating it a few times, it seems I'm now consistently getting some garbled green sprites in a grid pattern for a few seconds, followed by a white screen.

The_A_Drain2020-05-09 16:49:17

 

[r-type]

How many CPS2 A Boards have you got?

 

[The_A_Drain]

Just the 2, Europe region Super Street Fighter 2 Turbo and this Asia region MvSF, so unfortunately the two base boards aren't compatible.

 

[r-type]

Ah, that's a shame. I've only had a solid red screen before which was related to encryption keys. A little searching on google has hinted that the white screen might be related to A & B board connectivity.

Have you tried de-casing the B board and then connecting onto your A board (ensuring that good connection is made)?

 

[The_A_Drain]

Yeah A/B board connectivity was about all I could find on this issue as well. Re-seated it several times, checked no pins were bent, even took the B board out of its cartridge while I was testing the battery and seated it without the shell to see if the shell was damaged and, nothing. Sorry shoulda mentioned I did that!

Good to know it's probably not an encryption keys issue, though.

edit: tomorrow when I have time I'll try using a spudger or something thin to pry up the rest of the chips and re-seat them, see if that does the trick. The chip puller I risk scratching them up they are just too firmly held and there's not much room for the little hook to grab onto, I'll have to be slow and careful.

The_A_Drain2020-05-09 15:48:23

 

[The_A_Drain]

Took both boards out of the case and attached them without the shells, still nothing. Tried re-seating some of the roms but honestly, I don't think they've moved in 30 years they are stuck pretty solid they aren't coming out without a fight.

I was getting green tiles for a few seconds then a solid white screen. Now I'm getting green tiles for a few seconds, then a solid white screen for a few seconds, then an off-white yellow screen. It's not solid yellow so I'm not sure what is happening.

But the battery is still reading 3.6v.

is there any way to know for sure if it's dead without burning an eprom? I'm wondering if I'm looking at a dead board because of a botched battery replacement.