Graphic problem in 2-slot MVS

[Amano Jacu]

Long time no see! (Amano wonders if somebody remembers him)

I built a consolized 2-slot MVS 7 years ago, so far it worked pretty well. Just a month ago I used it and it worked fine. However, todays it shows a graphic glitch with all my MVS carts and both slots, as you can see in the example pic:

Same kind of error in all the games I have tried.

It has a 2.1 unibios installed, but I've tried it with the original bios and the error is the same.

Any idea of what could be wrong and if it would be possible to repair it? Some way to test for something broken? The board has been well preserved all these years as far as I know, I can't see any physical damage, etc.

Thanks a lot!

 

[Xian Xi]

Looks like an A3 problem on the C-rom data. I think it's A46 on the CHA board side.

 

[Amano Jacu]

Looks like an A3 problem on the C-rom data. I think it's A46 on the CHA board side.

Thanks for your reply! However, I'm afraid I'm not too savvy on this matters, so I would need more detailed guidelines... Are you referring to "chips" in the MVS cart or the MVS board? As I said, all the MVS carts I've tried so far (around 5) have the same kind of graphical glitch, so I believe the problem is in my 2-slot MVS board.

 

[smkdan]

It's your board if all the games have that problem. There's a page here for these GFX glitches and Xian is right (click the pic in the "A3" row to see) but the cart connector pin for that glitch is B12 on the CHA slot. The A3 row on that page shows the pin of the LSPC chip (P19 in this case) which goes to B12 on the cart slot. If you had a 1 slot board you could just connect that 1 cart slot pin straight to the LSPC pin # posted on that page to fix it, but on 2 slot there's an extra chip that sits in between them and it's different for each board type. Is this a MV-2 or MV-2F?

 

[Amano Jacu]

Thanks for your reply too! The board is a MV2F, and I can see two NEO-257 chips, one on each side of the cart slots. There's also a LPSC2-A2. Is there some pin I could check or try to re-connect?

 

[smkdan]

I checked on mine and it goes through NEO-E0 @ F4 (left of LS157).

LSPC2(137) -> NEO-E0(48)
NEO-E0(43) -> slot #1 and #2 CHA B12, the connector closer to the white arrow

There is a break somewhere in this path. Both slots being bad means it's probably before it is split out to each slot.

 

[Amano Jacu]

I've checked with a multimeter continuity test both paths "LSPC2(137) -> NEO-E0(48)" and "NEO-E0(43) -> slot #1 and #2 CHA B12" and they both check negative (no connection). I can't see the "connection trace" between them in the board so I can't look for a "break".

Assuming the problem is in one of these connection, would it be solved just connecting a wire between the corresponding points? Those chip legs are extremely tiny for my soldering abilities...

 

[Xian Xi]

Check to see where the break is then patch it with a wire.

Make sure everything is connected. LSPC(137) > Neo-E0(48), Neo-E0(48) > Neo-E0(43), Neo-E0(43) > CHA B12. Whatever isn't connected in between just patch with wire.

 

[Amano Jacu]

I've checked the connection again with my multimeter continuity test, and I got:

LSPC(137) > Neo-E0(48) CONNECTED
Neo-E0(48) > Neo-E0(43) NOT CONNECTED
Neo-E0(43) > CHA B12 CONNECTED (to both slots)

So should I just run a wire between 48 and 43 pins of Neo-E0?

By the way, messing whit the board, I accidentally disconnected the 3 audio cables from the headphone slot. Can somebody tell me which ones are audio left and right? (I already know which one is ground). I remember I used a pic from this thread:

http://www.neo-geo.com/forums/showt...consolized-with-only-5V!-NEWER-PICS-(August-5)!

But it's gone...

 

[Xian Xi]

Yup, just run a jumper wire connecting those two pins on the Neo-E0.

As for the audio, the one closet to the tip of the headphone is left.

 

[Amano Jacu]

Well, I have tried to connect a wire between the 48 and 43 pins of that NEO-E0, but my soldering skills suck just too much on so tiny pins... After a hard time I though I had it done, but when I tried it on my TV, not only the replicated graphic problem was still there, but now there's some color problem too. On the color section of the hardware test, one red block appears as white, some othere are missing or flicker.

I have a friend that knows more electronic thatn me, I'll tell him to have a look. Otherwise I don't think I'll bother much more with it.

Thanks for all your help in any case.

 

[Xian Xi]

Can you take pictures of the wiring/soldering?

 

[Amano Jacu]

Well, believe it or not, but a while ago my friend came, removed the wire I soldered, and when we tried the board again to see if at least the color problem was solved, BAM both problems were gone... Apparently the bord works perfect now. I'm not srue what has exactly happened, or if the board will stay like this for a long time, but I'm happy now. Thanks Xian and smkdan for all the help!

By the way, my friend brought 2 other MV2F boards (board only) to try them with my supergun, and one of them only shows garbled graphics, and the other says

COLOR RAM BANK0 ERROR
ADDRESS WRITE  READ
00400000   0000   00E0

I have a picture as well. Any idea what could be? Looks like a more serious problem...

 

[Xian Xi]

I think the zeros in the write read mean it's missing the control signals like /OE /WE.