MV1ACH graphical glitches and Exeption Error Handling

moldov

n00b
Joined
Jan 20, 2022
Posts
1
Hello everyone!

I know, you are experienced guys, much more than me, so you probably was facing similar issues before and know what to do, or just can give me a clue.

I recently received couple of MVS's boards along with 161 in 1 banana cart from friend of mine.

MVS-1B has the sound issue (only coin and SSG sound works) but with the scope I found that YM3016 is failing. Pin 4 is active and I see synchro pulses coming from YM2610 and those pulses change when music should play and there is no activity on pins 10,11 on YM3016 - so it's apparently YM3016 (I ordered 2ea from Ali with dip socket).

The second board failing is MV1ACH. While inspecting the board I found that slot board is SLOT1AX instead of SLOT1ACH as it mentioned here and here. However slot boards look almost identical having 74LS245, so I guess it's not the issue.

I have SNKDAN diagnostic BIOS which shows that all test passed but I have graphical glitches listed below. I inspected traces and didn't find anything coroded or damaged. Just few traces are sligtly screched, but I checked the continuity and isolation from the traces beside. As it passes all the DIAGBIOS tests looks like it's slot and slot related IC's issues as I understood through internet searching and posts reading.

Below is troubleshooting had been done.

- I have 2 banana carts so I checked them both - both has similar issues, so it's not cartridge issue.
- I cleaned slots with alcohol and folded piece of paper. Paper was not dirty so I don't expect slots to be so dirty.
- While cart is inserted, I was trying to move it a bit to check the slot connectivity - looks like all good as no additional glithes appear while moving, so looks like the issue is permanent and not intermittent.
- I have supergun with voltmeter - so it's not a power issue.

There are few clues which experienced guy will recognize fore sure. I made them CAPS locked

This is Metal Slug start screen. "Slug" looks NEGATIVE and the whole logo is BLINKING.


These are UNIBIOS start screen and Exception handler from UNIBIOS which I see after game starts. All the games I was trying have similar handler appear. If I start Metal Slug it appears right after game starts. If I start Metal Slug 2 it appears after I run couple of dunes in the beginning of the game. Also there are some wierd graphic glitches which I cannot describe exactly as they are different. Neo Geo start sound is OK when game starts. Also I don't see any glitches when I see 161 in 1 menu on the screen and scrolling through it.


Any information for troubleshooting would be really appretiated.


glitch.jpgglitch1.jpg
 

maki

Edo Express Delivery Guy
Joined
Jan 1, 2022
Posts
332
The second board failing is MV1ACH. While inspecting the board I found that slot board is SLOT1AX instead of SLOT1ACH as it mentioned here and here. However slot boards look almost identical having 74LS245, so I guess it's not the issue.

I have SNKDAN diagnostic BIOS which shows that all test passed but I have graphical glitches listed below. I inspected traces and didn't find anything coroded or damaged. Just few traces are sligtly screched, but I checked the continuity and isolation from the traces beside. As it passes all the DIAGBIOS tests looks like it's slot and slot related IC's issues as I understood through internet searching and posts reading.
IME if the DIAG bios passes, it is often related to the slot traces, as they are not tested.

You can plugin the MVS without cart, the signals should be still present, might be easier to test them this way (for the AES it is), measure the voltage against ground

you should not get 0V if there should be a signal
lots of signals can be found here: https://wiki.neogeodev.org/index.php?title=Signals
otherwise look for the actual ICs, they will have the signals

my guess is to focus on the PROG board, could be the CHA as well, but the later would rather result in sound and graphic problems IMO
 
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