Any tips on where to start troubleshooting? (MVS MV2F) - garbled graphics /boot

[mawrick]

Anyone have any tips on where I should start troubleshooting this problem with a MVS 2 slot MV2F, have some battery damage around neo-ZMC2 chip, tried to clean it up but not sure if this area is what's causing this behaviour ?. on some boots it seem to have a slight different color palet (the green seem to be gone on those boots, and it's more of a brown/grey color).

 

[pierpa86]

Any sound out of it ?
Did you try with Diagnostic bios ?
Take some picture of the board aroud the battery, i replace a lot of ZMC2 that fix garbage graphics.
But here seems not booting..

 

[mawrick]

I'l try to take some more pictures of if, there isn't realy any sound from it, other than if I hook up headphones directly to the board I just noted it gives a constant "ticking" sound......tick tick tick.....

Have some eproms on the way so hopefully able to put in a diagnostic bios in the near future...

 

[pierpa86]

I'l try to take some more pictures of if, there isn't realy any sound from it, other than if I hook up headphones directly to the board I just noted it gives a constant "ticking" sound......tick tick tick.....

Have some eproms on the way so hopefully able to put in a diagnostic bios in the near future...

So if you hear the soud click of watchdog and board is not booting:
This is the page for you:
https://wiki.neogeodev.org/index.ph..."Click of Death" is,volume is set high enough.

 

[mawrick]

Now that I took a closer look at it I guess I can spot one of a major problem - seem like someone have had a fiddle with this before - hiding in plane sight (if there isn't any good reason fot the bios to be in opposite direction that the silkscreen indicates?)

I guess this means a fried bios?, would it be safe to put it the right way and test or should I just wait til I get my hands om some eproms ? (can this have caused additional damage or would it only affect the bios chip itself ?)

 

[Neo-Alec]

Yep, just put it in the right way. No danger beyond any possible damage already done.

 

[mawrick]

Yep, just put it in the right way. No danger beyond any possible damage already done.

yea, tried to no avail, still garbled graphics, but seem like the green colors are gone, guess I'l wait for some eproms to get a known good bios....


Found a image showing some pinouts on the net, anyone know if these are correct on the M2F ?, most seem to be ok here, but connections to the NEO-E0 chips doesn't seem to be alright, but not sure if these are correct on the M2F

 

[pierpa86]

I think its mandatory try to read bios eprom in order to check integrity first.
Check this out:
https://wiki.neogeodev.org/index.php?title=MV2F

 

[Dloop]

There seems to be quite some areas to check for corrosion / battery leakage in one of the picks if I am not mistaken

 

[mawrick]

There seems to be quite some areas to check for corrosion / battery leakage in one of the picks if I am not mistaken

Yea, there is some acid damage, haven't yet found any broken traces though, but will still do some more cleaning on the ZMC2

 

[pierpa86]

Yea, there is some acid damage, haven't yet found any broken traces though, but will still do some more cleaning on the ZMC2

Remember that the hole go to other side of pcb.
My last repair on this MVS model has the same corroded hole i had to fix them.

 

[Dloop]

There’s a lot more places than I pointed out, even on the same picture now I see. So try to actually beep test between points

 

[mawrick]

Remember that the hole go to other side of pcb.
My last repair on this MVS model has the same corroded hole i had to fix them.

yea, will be digging some more, it's the only area of the board that seem a bit "scruffy", the rest seem quite mint

 

[mawrick]

There’s a lot more places than I pointed out, even on the same picture now I see. So try to actually beep test between points

Yea, been trying to go thru all of that area, but not found any broken just yet , haven't really looked much at the bottom side yet, but see there is some crusty areas there as well....

 

[mawrick]

Tried to check the traces underneath as well and seem to check out, except for one I wasn't able to beep, either a broken trace, or corrosion causing it, but seem to go from the area around ZMC2 to an area below a small IC called hd74ls157p (if I found the right location), other than that all seem to check out, guess I'l wait til I get some new proms for bios/diagnostic....

and clean it a bit better

 

[mawrick]

Just thought I'd give an update on this one, cleaned some more, retraced the lines, and the one I though was missing was actually just me having probed the wrong via

programmed a unibios and the thing booted up to cross-hatch test, inserted a game and it fired up, so seem to be ok. Tried the second slot - there it seem there is some "black bars" thru the neo-geo logo, and the sound seem to be missing when using slot 2 - not sure what that would indicate but at least it seem to be somewhat operational.

Also did a run with a diagnostic rom - I'v just booted that without any cartridge in the slot so not sure if that means it does all the tests or not, but it comes up with all test passed - is there more tests this one will do ? (have't hooked up a controller yet so realy haven't been able to dig around much)

 

[mawrick]

I also have a second one which is a mv2-01, that one seem to be in watchdog modus, it only "flickers" white screen with the unibios, but with the diagnostic I get a quick blackscreen with the text that it's stuck in watchdog, before it resets. one of the 257 chips have a broken leg, can this cause such an error or should I first look elsewhere ? (I thought the 257 mainly was for switching between the slots ?)