Update: Fixed! 4 slot mobo, cross hatch of death (bottom board is problem)

Update, got a hold of a cheap multimeter from radio shack. Checked all the pins on CN10. Continuity was good for all except B5 to B9 (18). Soldered in a jumper, popped it in my 4 slot big red, and it fired up great. Sound works and no graphic glitches. Thanks again MKL. Your contributions to this board are greatly appreciated. One last question, did SNK ever release a detailed schematic of the 4 slot? The manual on hardmvs doesn't include a indepth one.


Like topic says. I have a spare 4 slot mobo that has a permanent cross hatch. The board worked flawlessly prior to displaying this screen, it sat idle in a cab for a few months before a new monitor was installed. I'm not tech savy when it comes to PCBs, but I've isolated the problem to the bottom board by swapping the top (slot portion) with the bottom of a working mvs-4, and that worked fine.

Any trouble areas I should be focusing on? Jamma edge was cleaned, and power supply issues are not the problem as I've tried it in numerous Neo cabs.

If it's the bigger 4-slot model this thread could be useful:

http://www.neo-geo.com/forums/showthread.php?t=131636

There is a complete trace mapping from the top-bottom interconnects to the chips on the bottom board. Check all those traces. If however you have the newer model that info can't be used.

MKL said:

If it's the bigger 4-slot model this thread could be useful:

http://www.neo-geo.com/forums/showthread.php?t=131636

There is a complete trace mapping from the top-bottom interconnects to the chips on the bottom board. Check all those traces. If however you have the newer model that info can't be used.

Click to expand...

Wow, great thread. Book marking now. The trace layout looks identical to my board, I'll give it a closer look. Corrosion sounds like the most likely cause.

Thanks.

Make sure you remove the old battery and clean up the corrosion and leakage as well as you can.

RJ

looks like your diagnosis was correct. The board is fairly filthy, but from what I can tell most of the traces appear intact, except:



At least 6 are almost completely eaten away. I'll post some results as soon as I can solder in some jumpers.

Have you actually checked continuity between pins on the connectors and chips? Visual inspection of the traces is not reliable. Sometimes the solder mask coating covering the traces is just discoloured but the trace could be good.

MKL said:

Have you actually checked continuity between pins on the connectors and chips? Visual inspection of the traces is not reliable. Sometimes the solder mask coating covering the traces is just discoloured but the trace could be good.

Click to expand...

don't have a multimeter on hand. I do at work though. Will probably have time this week to mess around with the board.

bump