Need advice on fixing 2 MV-1F boards...

One of the systems does power up, but displays Video Ram Error at 8000 01FF should be FFFF... (But I got a new Sony video ram chips. In this kit, you get two of the Sony Chip and a pair of sockets to replace the old chips)

The other powers up, but displays Z80 Error (But I got two 27C1024 EPROMS (used for BIOS, since the system does not include a working BIOS), and a replacement Z80 CPU).

I also got another MV-1F that I can use for parts.

Any advice or links to similar issues would be a great help. Thanks

Actually, the ram address should read 5555 (not FFFF). 01FF or FFFF would indicate that both of the video sram chips are bad, or there are multiple cut traces. These ram chips will be 24 pin pdip, and labled on the board next to each will be '5814'. Just desolder, solder in socket, and pop in a new one.

I know nothing about the z80, sorry. Maybe this post by nightmare tony will help a bit?? http://www.neo-geo.com/forums/showpost.php?p=128141&postcount=8

cheers,
-DT

It could be the Z80, the Sound ROM, the 6116 Static RAM, or the interface IC that connects the sound circuit to the rest of the board.

It could also be dirty cartridge contacts or a dirty socket if the sound ROM in use is on the cartridge.

The error message is very generic. It just means "there's a problem somewhere in the sound processing circuitry" and doesn't really give you any more information than just that.

As for the video RAM error... Look at the legs of the chips you removed. Make sure there isn't any copper stuck to the legs. If there is then maybe you pulled out part of the plated through hole or part of a trace. Either way, that's bad.

If you didn't pull those chips off the board then desolder the sockets and check under them for missing traces, broken traces, or missing solder pads from the board. You can also shine a flashlight through the holes from the bottom and check to see if any of the plated through holes are damaged. You should see shiny solder uniformly covering the insides of the holes. If you see strips of black or green then the plated through holes are damaged.

If you see board damage to the traces or the plated through holes you will need to carefully solder in some jumper wires. I would recommend using wire wrap wire if you need to do that.

RJ

That advice would have been more useful nearly a year and five months ago.