SNK Neo Chip Question

[toymachine78]

Anybody know what a SNK PCM chip handles? Its on board 1.

I'm asking 'cause I bought Real Bout FF Special from eBay. When I first put the game in, it would play the NG splash screen but then threw an exception/Abend.

I opened the game to compare the boards to MVS scans and board one looks abused. The chips are scratched, a couple of traces are gouged, and the PCM chip on board 1 has 3 legs that are crushed and almost look like they may be touching. On top of that the boards do not match the scans. It looks like the boards are from 2 diff sets of scans, or they are mismatched.

Anyhoo, I plugged the game back in to get a shot of the error dump screen, but it booted this time. However the sound is scratchy and distorted. It seems the BG music plays fine, but scratches and cuts out with the sound effects.

Any ideas? I'm gonna contact the seller either way for refund, but he states no returns accepted, so wanted some more info before contacting him.

[cjameslv]

Well if you have an xacto knife you could fix the pins and then use a multimeter to see if the traces that are scratched are good. I had an issue like that before but i just fixed it instead of dealing with the hassle of returning it.

[thesteve]

PCM normally stands for a sound format

[toymachine78]

Well if you have an xacto knife you could fix the pins and then use a multimeter to see if the traces that are scratched are good. I had an issue like that before but i just fixed it instead of dealing with the hassle of returning it.

You're the one that sold me this POS aren't you? Lol

[bust3dstr8]

The Neo-PCM is the memory controller for the sound data. Pin 3 is NC by the looks of the board drill. You could cut it out to give yourself some room to work on pins 1 and 2.

[ccovell]

Yeah, as above.  The PCM chip multiplexes ADPCM sample buses A and B (though voices and music could use either/both buses).

The Neo-Geo CPU has no(?) way of knowing if its graphics or sample chips/lines had any malfunction, so the game would normally keep on running with graphics or sound errors.

[toymachine78]

Yeah it is def a sound chip. I tested the continuity and pins 2 and 3 are shorted.  I tried the exacto knife method, but really couldn't get any separation. I was afraid to apply too much pressure as I didn't want the leg to snap.

The buyer did accept a return, so that's good.

[BigusSchmuck]

I had a similar experience with my mvs mf-1f and found out it was the board as the sound would pop in certain places (like the vs screen in Fatal Fury 1 and the intro of Samurai Showdown). The seller claimed it worked fine with Puzzle Bubble Bobble, but that game didn't use the channel so I sent it back to him and he is going to fix it for free. People don't kid around when they say you really need shock boxes or some way to store Neo Geo MVS carts as those contacts can get dirty pretty easily and cause undesirable effects.

[toymachine78]

I had a similar experience with my mvs mf-1f and found out it was the board as the sound would pop in certain places (like the vs screen in Fatal Fury 1 and the intro of Samurai Showdown). The seller claimed it worked fine with Puzzle Bubble Bobble, but that game didn't use the channel so I sent it back to him and he is going to fix it for free. People don't kid around when they say you really need shock boxes or some way to store Neo Geo MVS carts as those contacts can get dirty pretty easily and cause undesirable effects.

Yeah the board on this cart just looks abused. I'm not sure how it even got like that considering these things are cased. And usually when someone removes them from the case they are very meticulous handling them.

But according to the seller... "Great condition! 100% tested and working!". Oh well. Maybe the seller is deaf, and couldn't tell the game sounds like its playing through a walkie-talkie. Who knows.

[toymachine78]

OK... So not sure how this return is gonna work out.  Tried to separate the pins again and leg 2 snapped off at the pad. Now sound is really snowy. I know some of you guys can repair this. Anyone interested? Shoot me a quote.

[thesteve]

i can fix it
if thats all it needs $20 plus shipping

[BigusSchmuck]

Toy, did you try Keith or Chop?

[toymachine78]

I'm gonna send it out to Steve.

[thesteve]

its here
pin1 was broken from chip
pin3 shorted to pin4
pin2 lifted from board

[EvilEvoIX]

I hope this cart gets repaired.  I just got a copy of the same game.  Is that AES/MVS?