Motherboard Neo Geo MVS MV1 non working,green screen......

[raggio252000]

Hi!!

I have 2 NEO GEO motherboards model MVS1 with the same problem,the motherboard doesn't load the games.
After inserting the game the system starts but I can see only a green screen.Of course I tested it for a while but nothing.
Anyone know what can I do??

[Lawrence]

Argh, I've seen this error before, but I can't remember the cause.

EDIT: seems pretty common, apparently it's a 'calendar error', and involves a failure of the RTC crystal or the RTC itself (real time clock).

Stuck on green is a calendar error, but before you blame the crystal next to the D4990 clock chip, you need to check that power is getting to the chip.

 Pin 14 on it should be around 3v even with the power off. With power on, it should be at +5v. If not, you'll get the stuck on green problem.

 If power is there, then check to make sure the crystal is working. An oscilloscope or logic probe will help here. If it's not, replace it.

 If the crystal is working and the chip has power then you need to check for corroded or scratched traces. I just fixed a 2 slot board with a calendar error that had 9 gouged traces on the bottom of the board. The clock/calendar chip was OK and the problem was that the system couldn't access it because of the trace damage.

Found on neo-geo.com.

[l_oliveira]

Calendar error will give an specific error message on the screen (same  text).

It's possible that there's traces cut by corrosion on the 68000 bus. If you get the monitor test pattern when you turn it on without a cartridge, the cut trace is towards the cartridge connector.

Now, there's a few things to test:

1- all dip-switches down, to force it to test the WORK RAM.

2- Place a MULTIBIOS (any version will do) on the BIOS slot to attempt to troubleshoot the issue

3- Track down any traces of corrosion, with SPECIAL attention to the backup memory area, because the battery is specially caustic and sometimes leak material, causing board damage (hence Laurence's suggestion).

[raggio252000]

Hi again!

I thank you for your info.
So I removed the old battery and I removed the old(and damaged I suppose) 32.768 crystal and replaced with a new one and video board now WORKS:buttrock:

However I have NO AUDIO,I checked the board and I found this other problem on the board,what do you think?





New crystal on the board below :buttrock: