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Shock Troopers black screen / self rebooting

gamezer0

gamezer0

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So I have this Shock Troopers 1 cart I've owned for many years which worked well back in the day, but doesn't now :(

I have 2 MVS boards, and the issue is different on each:
- Long board (I think it's a MV1F): boot up (classic green screen with artifacts) -> Neo Geo logo with music -> reboots to green screen (back to step 1)
- Short board (MV1B1): boot up (green screen with artifacts) -> small graphics glitch -> black screen (no reboot, stays here forever) EDIT: Fixed, now it reboots like the other one (I enabled dip switch 8, pause, by accident)

I've tried cleaning the contacts with isopropyl alcohol and cotton earbuds, also with a toothbrush, but nothing changed. Other games work perfectly on both bases.

I opened the cart and didn't spot anything obvious that could be the culprit. Some sides were quite sticky (despite the rest of the cart being pristine), presumably that's soldering flux used in the factory? I'm attaching some photos of the boards

Coincidentally, this week I got a Unibios 4.0 (which I need to install on the long board), and I've seen it has some diagnostics, so maybe I can use that to get more clues of what might be happening? With the regular BIOS I can access the service menu. The game shows up in the game list, although some settings have typos (e.g. it displayed something like "LANGUAGE: ENGWLISH"), not sure if actual typos, or an error when reading some ROM.

Anything else worth checking out other than the Unibios test?
 

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Sticky boards are indeed from factory flux. I don't see any issues, but I would check for shorts across the capacitors. UniBIOS can display the CRC32 of the cart, that might indicate a problem but a reboot sounds like a short to me... would be unusual, but not impossible.
 
Kujako said:
Sticky boards are indeed from factory flux. I don't see any issues, but I would check for shorts across the capacitors. UniBIOS can display the CRC32 of the cart, that might indicate a problem but a reboot sounds like a short to me... would be unusual, but not impossible.
Click to expand...
But there are no caps in the cart, right?

The 2 boards I have work well with all the other games I have
 
There are some ceramics but it's very unlikely they are bad
Since it does some kind of boot, P1 might be fine.
P2 is a Toshiba and these have decently high failure rate in either carts or boards (bios)

Unibios CRC check is a good start. And if a P rom is bad the good thing is they are compatible with 27C322 in the case of your P2
 
my Shock Troopers cart was absolutely pristine when I got it but there were some weird gfx glitches.

Went all over the boards and everything looked alright apart from 1 trace that didnt' look corroded or anything but it just wasn't quite as good as all the others. checked continuity and it was busted. small jumper wire later and I was back in business.

My point is that even the smallest things here can affect stuff so being extra vigilant across the boards may turn something up that you'd missed before. CRC is a good place if another visual inspection doesn't bear fruit.
 
gamezer0 said:
But there are no caps in the cart, right?

The 2 boards I have work well with all the other games I have
Click to expand...

There are surface mounted capacitors as @fraggle200 said. It's not that I suspect the capacitors of being bad, but that a short across them can be an indication that a component near them has failed.
 
You mentioned getting a Unibios recently. Did you reset the backup ram after installing it?
 
Thanks all!

I haven’t installed the Unibios yet, so it can’t be that. Hopefully I can do today, otherwise after my holidays. I’ll keep the post updated as I try stuff.
 
I just installed the Unibios, ran the CRC and this is what I got. That “NG” doesn’t sound good?
 

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nem said:
Correct, NG = Not Good
Click to expand...
Any suggestions? What does “ROM Region” mean?

BTW I discovered the issue with the short board (black screen instead of reboot was caused because I enabled dip switch 8, which is “pause” by accident) now both of them self reboot.
 
Today I spent a while looking for broken traces on P1 and SP2, but couldn’t find anything with the multimeter (my skills aren’t the best though 😅)

Before I try the reflow option for those 2 roms (or is P1 enough?), is there anything else worth checking? like maybe checking continuity between the rom legs and the solder on the other side of the board? 🤔
 
You can reflow the P1 but you most likely will have to burn a replacement.
There are two versions of the program rom.The P1 is the long life bar version that your heroes share and PG1,the updated version where each hero gets a separate life bar.
BBH has a big write up of the differences.
The PG1 version was introduced with serial# starting at 007 which is
one fact I discovered around the time of this games release.
You can choose to use either version as a replacement.
BB
 
BIG BEAR said:
You can reflow the P1 but you most likely will have to burn a replacement.
There are two versions of the program rom.The P1 is the long life bar version that your heroes share and PG1,the updated version where each hero gets a separate life bar.
BBH has a big write up of the differences.
The PG1 version was introduced with serial# starting at 007 which is
one fact I discovered around the time of this games release.
You can choose to use either version as a replacement.
BB
Click to expand...
Thanks for the info! I was aware there were 2 versions but didn’t know the differences. My serial is 004xxx so if I want to keep it original I should go for P1.

What is BBH?
 
gamezer0 said:
Thanks for the info! I was aware there were 2 versions but didn’t know the differences. My serial is 004xxx so if I want to keep it original I should go for P1.

What is BBH?
Click to expand...
Over the years PG1 boards have been swapped out for nicer looking MVS shells so the serial number thing is not consistent nowadays and you just have to refer to the chip as to what version you have.
BBH is a member in the community.
Just Google bbh shock troopers and you'll get all the info you need to know about this game.
BB
 
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