Neo Geo MV-1H z80 error

[Martyken]

Hi guys, trying to diagnose the z80 error on a MV-1H motherboard i've received a while back, so far I have only looked/tinkered with it on a surface level checking soldering and traces.
On a surface level to my eyes it looks like it's in okay condition, nothing that stands out such as battery leakage or iffy traces.
It seems like the volume control for headphones, speakers and mono/stereo switch have been re soldered at one point? i think there is still flux(or maybe corrosion lol...) left over as seen in the pictures. I also noticed a little hole within one of the 1k resistors legs solder, not sure if that would fix anything though.
I get no check board when no cart is inserted however today I managed to get my 161 in 1 to boot, not sure if it was by coincidence however I was moving the sliders to different positions and switching between mono/stereo to test out if it effected the error at all (would turn off to make changes then turn back on).
My speaker dial was set to the lowest position, once in game I tried moving it to the right a little bit and tried to change games on the cart, only to get a z80 error.
Would these volume controls related to the z80 error in anyway or am I looking at the wrong things and it was pure coincidence that I got it to boot while tinkering with them.
I have attached some pictures, not sure if they would be of any help.

Thanks

 

[DarthMig]

You should check out this guys youtube channel. Here is the address https://www.youtube.com/channel/UCRBWJ9JeJ3Q8ssn_ibii-Cg . He has gone over z80 error, how to trouble shoot and fix. Also has multiple videos. Hope it helps. Make sure to got through his videos since he has multiple vids.

 

[Martyken]

You should check out this guys youtube channel. Here is the address https://www.youtube.com/channel/UCRBWJ9JeJ3Q8ssn_ibii-Cg . He has gone over z80 error, how to trouble shoot and fix. Also has multiple videos. Hope it helps. Make sure to got through his videos since he has multiple vids.

Thanks for the link, seems like it can get quite daunting on where to start diagnosing the problem without diagnostic eproms. I'll take my random boot as coincidental

 

[DarthMig]

No problem. Yeah you would have to have extra eproms to swap with. If you can find a board for cheap that has issues but not z80 error would be a good way to go. If you want volume control get yourself a 2 slot baord that has volume controls, memory can slot and controller ports. I have the two slot board.

 

[Martyken]

I've gotten the motherboard to bypass z80 error atleast twice now by turning it on a few hours apart, however once turned off it will still give me the z80 error if i try to turn it back on until i've left it for a few hrs or so lol.
Volume does seem to be working, however the only audio it plays is the Neo Geo jingle during certain parts of a game when it calls for some particular sound? no other sound effects are coming through the speakers (cart's sound works as it should on other mobos).

Just wanted to update to see if anyone else has come across this issue or would know what it could be attributed to e.g dying z80

edit: tested samurai shodown 2 and some game sound effects do make their way through for the duration of the startup jingle, mostly the vocals for special moves
not running into error as frequently as I was before however sound still the same, took case off mobo and saw iffy traces - have attached pictures wondering if they could be related to my issues