MV1A not playing specific games

littlecharlie

Lazy SNK Employee
Joined
Jan 10, 2018
Posts
57
I have a board (mv1A) that is playing fine all my originals carts (MS, MS2, MSX, Shock troopers, Neo turf masters) but this board has a problem with also original MS3 and the multicart 161.
With MS3 it boots nice, but when it gets to the main screen I get the following screen, and then after 5 sconds or so I get the UNIBIOS error.

JEcHQhV.jpg


9SFSQ8I.jpg


I though that the problem was that my MS3 cart was dirty,but I cleaned really nice the connector (eraser + isopropylic alcohol) and still the same problem.
And this cart plays fine in other MVS boards that I have, including another MV1A board.

So maybe the problem was the slot part (the vertical part) of my MV1A, so I swap it with the slot of another MV1A, and the problem remains.

I've also tried a more powerful (up to 5A) power supply, and still the same problem.

So there must be something wrong with the board itself, that for some reason it won't play MS3 (and the multicart).
Maybe because MS3 is very demanding? I wish a had another original cart that was also very demanding and check if I have the same issue.

Anyway, have you encountered this problem before?

Is it possible that some of the neo-buf are damaged and producing this behaviour?

Thanks!!
 

maki

Krauser's Shoe Shiner
Joined
Jan 1, 2022
Posts
241
Try enabling the HW checks on boot in the UniBios, it disables it by default, so many of the seemingly working MVS are not really okay

if you can burn or get it though, get the DIAG Bios, it will help with identifying problems better
 

littlecharlie

Lazy SNK Employee
Joined
Jan 10, 2018
Posts
57
Hey Maki, thanks for the tip, didn't know it.

I did so, and when I reboot the system, I got a Calendar error

99fbojy.jpg


I then used the diagnose bios to get more info, but it showed all tests passed.
So wierd.

And funny thing is that know I can't get again the calendar error (with the HW checks enable, AES mode,. MVS Mode. .... ). I can't reproduce it.
I only saw it once (the first time).

I went to the hardware test, and set the calendar to today. And it seems it is working fine. After power off and on agian, the date remains.

Soooo, I though I was finally going somewhere, but I'm stuck again :LOL:
 

awbacon

Athena's Stalker
10 Year Member
Joined
Jan 28, 2009
Posts
3,985
Hey Maki, thanks for the tip, didn't know it.

I did so, and when I reboot the system, I got a Calendar error

99fbojy.jpg


I then used the diagnose bios to get more info, but it showed all tests passed.
So wierd.

And funny thing is that know I can't get again the calendar error (with the HW checks enable, AES mode,. MVS Mode. .... ). I can't reproduce it.
I only saw it once (the first time).

I went to the hardware test, and set the calendar to today. And it seems it is working fine. After power off and on agian, the date remains.

Soooo, I though I was finally going somewhere, but I'm stuck again :LOL:
that's the worst when you THINK you are getting to the root of the problem...but you just end up more befuddled than when you started
 

ack

Fio's Quartermaster
10 Year Member
Joined
Apr 9, 2009
Posts
483
I would bet its going to be an issue with the NEO-BUF to the right of the NEO-I0. It might be having issues or if your board was from china it might have been replaced with a bypass which will cause problems.
 

maki

Krauser's Shoe Shiner
Joined
Jan 1, 2022
Posts
241
Can you open it and take good pics of the interior?

Calendar problems are common (like Backup RAM problems) since its close to the battery, which will leak over time.
On the original BIOS a calendar error will show the green screen with some gibberish on it, and not keep booting past it, "calendar freeze"
 

littlecharlie

Lazy SNK Employee
Joined
Jan 10, 2018
Posts
57
that's the worst when you THINK you are getting to the root of the problem...but you just end up more befuddled than when you started
definetely, and now it's getting worse ...


Replace the uni-bios with an oem one and see what you come up with.
BB

I did so. And the result was equivalent. The board boots OK (no freezing), and then it shows the main MS3 screen, with the same graphic error, and after 5 seconds or so, it reboots.

Can you open it and take good pics of the interior?

Calendar problems are common (like Backup RAM problems) since its close to the battery, which will leak over time.
On the original BIOS a calendar error will show the green screen with some gibberish on it, and not keep booting past it, "calendar freeze"

27MxQd0.jpg


BKHLOb0.jpg


UFCkmq5.jpg


The board did not show signs of acid leakage or corrosion. In this board, backup RAM is fine.
Apart from the first time that I got the calendar error, It never showed again, nor any other error.
The calendar chip is gettting the voltage and the traces are good.
I want to check with the oscilloscope that the crystal is OK.
And I've ordered some NEC chips just in case.


I would bet its going to be an issue with the NEO-BUF to the right of the NEO-I0. It might be having issues or if your board was from china it might have been replaced with a bypass which will cause problems.
That was my guess also: I've had some mv1a board with a bypass instead of neo-buf GA11, and they show graphic glitches on 161 cart (and replacing the bypass with a furrtek replacement would solved the issue).

Sooo, I went and replaced the GA11 neo-buf with a spare (from another mv1a board that was playing MS3 fine, so the chip should be OK) and the result was a fiasco. Again, a wtf situation.

The first boot after the replacement showed exactly the same behaviour. Boots nice, but then main screen with glitches and unibios error screen.

I then power off, I recheck everything (not soldering, only visual) and power on and boom!, cross hatch screen. Come onnnn!

dipswitch 1 is off, the cart is super clean, same as the slot of the board (I know the cart and the slot are not the issue because I have tried swapping from my other mv1a board). Again diagnose bios shows all tests pass ... I've also clear backup RAM ...

So frustrating

pd: I have double checked the soldering on the new NEO-BUF, it all seems good. No bridges and continuity from pins to traces.
 
Last edited:

littlecharlie

Lazy SNK Employee
Joined
Jan 10, 2018
Posts
57
Well, I solved the new problem, replacing again the replacement NeoBuf with a furrtek board I had, and finally the board came back to the previous state, which is booting fine but still no possible to play metal slug 3.
I guess I must have fried the neo buf with the hot air or re-soldering it to the board.

So, still no real progress
 
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