CPS2 Conversion - 98% Successful

[NoAffinity]

Just completed my first conversion, for a fellow collector - Xmen:COTA to HSF2AE.

The game is working great, with one wrinkle. The board seems to not like voltage greater than around 4.7V, specifically the audio. As voltage is increased from 4.7V toward 5V, sound starts getting "scratchy". It gets worse in the 4.8V - 4.9V range, and above 4.9V, the problem progresses to outright incorrect samples playing. This is voltage, as measured at the eproms.

Jumpers are all correct and have been re-checked multiple times. The only jumpers I had to change for the conversion are 11 and 12. I also tried putting them back to their original state and sound samples are all screwy, so they definitely needed to be modified for the conversion.

I also added the wire from pin 9 of BGS-B3G to CN3 C13, and lifted pin 9 and that too is confirmed to be necessary. I thought possibly the routing of the jumper wire as you see in the picture below was causing interference as the wire routes past various components and pins. I tried re-routing it through one of the holes near BGS-B3G, and running it on the solder side of the board to CN3 C13 - no improvement.

I have tested on multiple known good power supplies - no change.

I have re-verified the eproms, and burnt new eproms for 11 and 12 - the issue persists with the new roms. I am using 27C322's for the mask rom replacements, and 27C010's for replacement roms 1 and 2.

I have tested with decrypted code and native code/encryption - the issue persists.

The owner of the board is not opposed to always running it at 4.7V, but I believe it has been confirmed that CPS2 may suffer from CPU cycle losses below 5V. Is that generally agreed to be true, or is it a non-issue and if the board works fine at 4.7V, then all is well?

What am I missing and/or doing wrong?

[Mantrox]

Check the volume on the board.
It could be set very high and the sound starts distorting.

[pulstar]

Are you sure you have a G pal? X-Men has an F pal normally and if you have that, it's Pin 7 you need to lift and have the wire running, isn't it?

[NoAffinity]

It is a G pal. I've got a spare off a parts board, in addition to the GAL I burned. Same result with both.

^^Good though, but it's not distortion when outright incorrect samples are playing as voltage gets above ~4.9V. I tried the "audio system reset" trick too - pressing and holding the down volume button on the A board for 10 seconds while powering the game. No change.

I'm speculating possibly the roms may be at the end of their life but still semi-functional. Is that a possibility? I didn't burn and test alternate 01 and 02 roms. I'm going to give that a try tonight.

Another thought: possibly that jumper from BGS-B3G to CN3 is not a thick enough gauge, resulting in voltage drop that is leading to the problem? I used a 30 gauge wire. Hmm, that seems like a potential correlation. I've got some solid 26 gauge, I can try that with a jumper that is more of a straight b-line.

[Spork]

I would try an F gal with it attached to pin 7 instead of 9. I can't see your jumpers either but you should have

1 S
2 O
3 O
4 S

5 S
6 O

8 O
9 S
10 O
11 S
12 O
13 S

[pulstar]

With a G PAL you shouldn't need a wire to CN3. The wire is required on an F PAL to make it act like a G, so if you already have a G PAL you don't need any jumper wire.

[Spork]

You can't use a G pal like that on a PCB revision that old. You need to use F with jumper wire.

[pulstar]

I see it now, didn't even check the pic. Try an F pal with the jumper wire soldered to pin 7 of the PAL as suggested. On the Progear conversion I have Kynar wire is used and works perfectly fine.

[NoAffinity]

Great, thanks guys. I will give this a try tonight and report back.

[NoAffinity]

You guys nailed it. PAL F fixed the problem right up. Thank you as always!

[idc]

You can't use a G pal like that on a PCB revision that old. You need to use F with jumper wire.

You can, but you have to lift pin 9 of the PAL3 out of the socket and jumper wire it to pin C13 on connector CN3. This works on revision 3 and 4 boards.

[NoAffinity]

You can't use a G pal like that on a PCB revision that old. You need to use F with jumper wire.

You can, but you have to lift pin 9 of the PAL3 out of the socket and jumper wire it to pin C13 on connector CN3. This works on revision 3 and 4 boards.

That's what I had in place originally (PAL G), and was producing the audio anomalies at voltage above 4.7V. You can see it in the picture in the OP.

Once replaced with pal F (pin 7 lifted and jumpered to CN3 C13), the problem was resolved. I tested with a GAL16V8A I burned and an original pal G, both with the same result.

[idc]

That's what I had in place originally (PAL G), and was producing the audio anomalies at voltage above 4.7V. You can see it in the picture in the OP.

Once replaced with pal F (pin 7 lifted and jumpered to CN3 C13), the problem was resolved. I tested with a GAL16V8A I burned and an original pal G, both with the same result.

Apologies, I see now. Never seen it not work, to my knowledge, so quite curious. Might have to look into it sometime. For now, using an F PAL does indeed seem to be the more reliable solution.

[Rossyra]

I would remove the battery too, ahead of it leaking and destroying the board.

[NoAffinity]

I would remove the battery too, ahead of it leaking and destroying the board.

It's a brand new battery and running encrypted code.

[Rossyra]

That does seem a bit self-defeating on a conversion, but to each their own.

[NoAffinity]

That does seem a bit self-defeating on a conversion, but to each their own.

I'm not sure I follow your logic. Is there a rule that all conversions have to be decrypted or phoenix code? It seems a more pure conversion would be running native code/battery. Just my $.02, and if it were mine, I would absolutely want it running on battery/native code/encryption.

But, like you said, to each their own.

[caius]

You claim to offer a CPS2 desuiciding service in US and then you didn't know these simple things?

[NoAffinity]

You claim to offer a CPS2 desuiciding service in US and then you didn't know these simple things?

Which simple things are you referring to? It's all simple once you know. But you don't know what you don't know.

And I dont claim anything...

[caius]

Before offering not for-free service to people you should have all the needed knowledge and no need to ask help.Anyway, not referring to anyone, nowadays the internet is full of people improvising experts/repairers taking advantage of the work that other shares.