Consolized MV-1B hw test failed

[Burning Fight!!]

Well I guess this was meant to happen at some point but it took me by surprise to see mine glitching out after being months unhooked from power.

I'm getting a hardware test failed for Backup RAM and the Z80 System... or at least that's what I think, because the screen reads more like

"HAPDUAPE TEQT DAILED - X80 QYQTEM"

any hints of places to look into to fix this? I'm assuming cold solder joints.

EDIT: ok, it seems z80 errors are meant to be normal since the MV-1B doesn't have the SM1 ROM. With a cart inserted I can bypass the Backup RAM error with A, and the games work, but the graphics are still all scrambled.

The graphics are OK, no doubled pixels or vertical lines or any of the sort, just being fetched from the wrong addresses I think. This affects both the sprite and fix layers.

 

[HeavyMachineGoob]

A bunch of different errors/problems all at once could happen from something simple like PCB flex damage. How was this CMVS stored? Was it upside down with stuff sitting on top of the bottom board?

 

[Burning Fight!!]

A bunch of different errors/problems all at once could happen from something simple like PCB flex damage. How was this CMVS stored? Was it upside down with stuff sitting on top of the bottom board?

It’s the one from China that had the AES shell. It just sat on my shelf undisturbed.

I reseated the weird Jamma board and the bram error is now gone, but the graphic errors still persist with no change. And I’m probably going to give up very soon on it and just reuse the shell unless the fix is half obvious.

I never had to mess with a MVS board so stuff is still new to me. Stuck address lines on the LSPC is my best bet for now.

 

[HeavyMachineGoob]

Ah, well you didn't specify exactly what kind of CMVS this was before.

Are the MV-1B top and bottom boards soldered together? Check the soldering, if there's lots of flux (clear crusty goop), clean all that with rubbing alcohol, paper towel and a brush. Flux is somewhat conductive and can cause random problems.

Or still using the original connectors? Take the two boards apart and spray electrical contact cleaner in the connectors and reseat them. Put contact cleaner in the cart slot too.

 

[Neo Alec]

I feel for you because I kind of wanted to try one of these, and you took a gamble on it. I'm sure someone could repair the board.

 

[HeavyMachineGoob]

Not that this would affect graphics but does the top board of ypur MV-1B have a replaced NEO-BUF? By replaced I mean wire jumpers or a little ribbon cable-type patch where the chip would be.

 

[littlecharlie]

Not that this would affect graphics but does the top board of ypur MV-1B have a replaced NEO-BUF? By replaced I mean wire jumpers or a little ribbon cable-type patch where the chip would be.

THis is typical from boards from Aliexpress, and shouldnt affect if the NEO-BUF replaced are in these locations:

NEO-BUF - NeoGeo Development Wiki

wiki.neogeodev.org

 

[Burning Fight!!]

I feel for you because I kind of wanted to try one of these, and you took a gamble on it. I'm sure someone could repair the board.

Nah, I had a good run with it for the price point.
Where's zeta to say "I told you"?

Not that this would affect graphics but does the top board of ypur MV-1B have a replaced NEO-BUF? By replaced I mean wire jumpers or a little ribbon cable-type patch where the chip would be.

The slot board has that passive replacement littlecharlie linked to, the top board has a QSB PCB with two 74HC245As and some smd caps/resistors.

Haven't looked at it much because I was fixing my PS1, but I'm going to dive deeper into it tomorrow.

 

[Burning Fight!!]

Oh yeah, I forgot to mention it connects both boards with ribbons. I resoldered the left one as it had the FIX rom lines going to it and that didn't seem to do a thing, despite the old opaque solder blobs it had.

For reference this is what the graphics output look like right now.




Again, since the graphics addressing looks like quite close to what its supposed to be I'm guessing lower addressing bits are getting stuck. But I have no idea where to look for it on the main board...

 

[Neo Alec]

Nah, I had a good run with it for the price point.
Where's zeta to say "I told you"?


The slot board has that passive replacement littlecharlie linked to, the top board has a QSB PCB with two 74HC245As and some smd caps/resistors.

Haven't looked at it much because I was fixing my PS1, but I'm going to dive deeper into it tomorrow.

No, I think you have every right to expect many years of reliable gaming for what these cost.

 

[Burning Fight!!]

No, I think you have every right to expect many years of reliable gaming for what these cost.

The great news is that if I have to end up dumping this board, the cool shell and serviceable supergunish board is probably a good fit for a MV1C, with some adaptation. Or I could get another MV1B and recycle the ribbon cables that go under the connectors.

------

I've desoldered the BIOS eeprom in this (a 29f040 SOP44) but I don't have the right adapter on my programmer to burn smkdan's test bios. This will have to wait a bit.

 

[Neo Alec]

I wouldn't think a completely different board like the MV1C would fit correctly without a lot of work.