Irritating Maze Cart Bad Sound

[Neo Alec]

I bought this cart on ebay in 2005 and right away I noticed even though it's all original, all the roms have been desoldered (presumably to dump the game). The condition is quite poor, and I probably should have gotten rid of it, but it was a good deal so I kept it.

Back when I first got it it was flaky. It needed to be cleaned and seated just right or I got glitchy graphics and bad sound.

Fast forward to today, and now the sound is permanently bad (tested on MV-1C and MV-4F), but the cart's working otherwise. I think the issue is bad ADPCM. I cleaned the cart with Deoxit D5, reflowed the V roms, checked the jumpers, but no change.

On a closer inspection, the V roms look badly corroded. This cartridge is really in abysmal condition. I decoded and listened to both V roms that I downloaded online to to try to narrow it down to one V rom or the other, but I can't really tell if one or both is affected.

Suggestions?

Video of the issue:

 

[Misos]

I don't think it's a bad PCM because you still have some music going on.
Generally with a bad a PCM the entire game would sound like it was possessed by demons.
Do you have a programmer to dump the v-roms? I would just replace them.

 

[Neo Alec]

I don't think it's a bad PCM because you still have some music going on.
Generally with a bad a PCM the entire game would sound like it was possessed by demons.
Do you have a programmer to dump the v-roms? I would just replace them.

Yeah, I was thinking next steps were desoldering the v roms, cleaning, and crc checking them in my programmer.

I was kinda hoping someone would see the video and point me in the direction of something easier to check first I guess.

 

[pierpa86]

Check your v rom, and be alert for the crc, around there are two version and one have bad v2 dump.
V1 = CRC: 5f89c3b4
V2 = CRC: 72e3add7

V2= 1e843567 <- "This is the bad dump rom"

If you get pin error on programmer, you find the bad rom.

 

[Neo Alec]

Yeah, thanks. If I don't find a bad trace first, the plan is to desolder, crc check and clean.

 

[maki]

You can run the CRC check from the Unibios, but I've found out it won't help much for the problematic sound have on the MS3 module.

Furrtek has the PCM replacements every now and then on Tindie

PCM chip replacement by furrtek on Tindie

Small board meant to replace faulty PCM custom chips in SNK game cartridges.

www.tindie.com

 

[ack]

CRC check in unibios is only checking the program rom(s). The CPU doesn't have direct access to V/C/S1/M1 roms to be able to crc check them.

 

[Neo Alec]

Check your v rom, and be alert for the crc, around there are two version and one have bad v2 dump.
V1 = CRC: 5f89c3b4
V2 = CRC: 72e3add7

V2= 1e843567 <- "This is the bad dump rom"

If you get pin error on programmer, you find the bad rom.

I think the notorious bad dump that's been around forever is from my cart. lol

 

[Neo Alec]

By isolating the ADPCM-B in NeoJuke, I was able to determine that only the ADPCPM-A is bad. The ADPCM-B is playing fine in the video I posted.
This would seem to point to a problem with PCM chip. Maybe the roms are working okay.

Edit: It really seems like the PCM chip is. Bad I've checked all the traces to it, and the cart edge connections. I've cleaned everything in that area well with Deoxit. I can't isolate it to one or the other rom.

 

[wyo]

@BIG BEAR can you help with this?

 

[Neo Alec]

Trying to decide if I should desolder the roms or replace the PCM first. I'm not positive the PCM chip is the problem, and I'm not very confident I won't break it, so I'm leaning toward desoldering and checking the roms.

 

[pierpa86]

Trying to decide if I should desolder the roms or replace the PCM first. I'm not positive the PCM chip is the problem, and I'm not very confident I won't break it, so I'm leaning toward desoldering and checking the roms.

i think desolder v rom can be easier, with desolder station you can do in 5 min, there is no risk of breaking the rom, instead with hot air on the pcm chip it could damage it.
the snk boards are very solid but don't turn up the heat too much and don't stand too still on the spot.
Use flux if you need on Ground point.
I use 400° on my desolder station (a too high temperature I know, you have to be quick)

I repaired the v2 of my bootleg Irritating Maze a few days ago.