MVH-MV4 Repair issues

Neogeoman106st

Crossed Swords Squire
Joined
Aug 29, 2017
Posts
191
'Hello All

So i recently picked up A 4 slot was was "last used 10 years ago" and the joker let the original battery on it sadly(Spilled its guts all over). So after some clean up and trace repair i go it to go from a watch Dog type garbled GFX to Displaying a WRam error Address 00101008 Write:AAAA Read:BAAA. This lead me to think the issue was the upper Wram. i got a replacement( M5M5256BFP-10L) After the replacement the Neo Diag bios says all test passed . So i put in the Unibios 4.0 and got to the crosshatch. So i decided to place the top board on and try some games. well it will not get passed the crosshatch. I tried with two games in different slots. i tried cleaning the Slots no luck . Sometimes it will no go to the crosshatch and it will be a Flashing black Screen. in addition to that it does not boot to the Mem test in cross hatch. When i try that it just Goes black and nothing more.

i did have to do Trace repairs on the connector by the battery that connects the Top board to the bottom but i am pretty sure i got all the traces and all should be fine but i will double check that.

Anyone have any Ideas what it might be besides the slot being Dirty?
 

maki

Edo Express Delivery Guy
Joined
Jan 1, 2022
Posts
332
I have a MV4 here for repair, still waiting for the power supply to run it, the ones I have here aren't strong enough

it also had the Battery still in place and of course it leaked

Instead of running wires from back to front, I've took the connector off (bismuth based solder, push the pins, don't pull the connector) and ran the jumper above the former traces
so thats how it looks underneath if it helps you to double check the connections
 

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Neogeoman106st

Crossed Swords Squire
Joined
Aug 29, 2017
Posts
191
Thank you for the pictures. I looked and am pretty sure all my connections are good.
After looking at the top board I did find a trace that was bad above the leaking battery. Seems like it creeped to the top. After some testing I was able to get to the mem test but only if a game is in Slot 4 and if the connector near the battery is not seated in. The men test looks like the below along with the crosshatch. Again this is only when the connector is not seated near the battery. When everything is fully seated and Carts are in any slot it just boots to a flickering black /off gray screen

ACCDE173-2818-42D7-B794-BD44BC872A4C.jpegD7FF4FC8-2254-46F1-AB8A-D875501B1ECE.jpegC0D67696-97CE-4139-BFE8-17EB569E7C51.jpeg96FBB1AE-36B7-49B0-969C-F333BE374C74.jpeg
 
Last edited:

Neogeoman106st

Crossed Swords Squire
Joined
Aug 29, 2017
Posts
191
Did some more messing around and when I slowly reconnect connector cn10 while in men viewer I get the following 3CB155A5-F892-4BDF-A3FD-ECDBD51C1CF3.jpeg
But only in slot 4
 

Neogeoman106st

Crossed Swords Squire
Joined
Aug 29, 2017
Posts
191
Ok So after more troubleshooting i found a few more traces i though had been ok near the c11 & d11 logic chips. now with these sorted i only get the flashing Black and very light gray screen no sound when the top board is connected. with it removed it books to the crosshatch. games or no games it only boots to the cross hatch once the Top board is removed. any ideas from anyone on this?
 

Neogeoman106st

Crossed Swords Squire
Joined
Aug 29, 2017
Posts
191
Ok so finally had sometime to work on this a bit more. I fixed some more questionable traces but also put back in the neo diag bios and with out the top board I get all tests pass and no issues . But when I first put on the top board with the diag bios I got a watchdog error then after reseating the top board it says
Testing bios CRC32 then just locks up and does not go any further. So maybe my issue is either the top board. Not sure what it could be. I will keep looking.
 
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