NeoGeo 4 Slot MVS-4-25 video problems

Arm123

n00b
Joined
Nov 8, 2007
Posts
6
Its late and iv been testing boards all night. Thought i would post this one up while im sleeping.

I plugged in a 4 slot into my test rig and proceeded to test each slot. I was able to get all 4 slots working. However, i am seeing a graphical issue.

The video seems to flicker in and out (to black screen) at random times. I thought this may have been a grounding issue because i didnt connect ALL the grounds for this test. I proceeded to do so... with out success.

When i wake up, im planning to double check my video connection (already did that) and check all the voltages (+5,+12) at the power pins.

If that doesn’t work, i may pull of and test all the caps on the boards.

Anywhere else i should be looking ? Does this sound familiar to some of the techs out there ?

check back in a couple of hours.. need ZzZzZzzz... ;-p
 

ttooddddyy

PNG FTW,
Joined
Nov 29, 2001
Posts
8,335
Sounds more of an edge connect problem, what if you move the edge connect whilst the game is running. The 12 volts will not effect the gfx and the 5 volts may cause no/intermittent boot up, but not the symptoms you describe.
 

Arm123

n00b
Joined
Nov 8, 2007
Posts
6
Thanks for the reply...

I removed the cage and looked around. Nothing obvious.

I left it on for a bit and wiggled the edge connector (Pushed it hard to one side). The image seems to be more stable.

Gonna leave it on for a bit and do somthing else.

Thanks mate ;-)
 

Arm123

n00b
Joined
Nov 8, 2007
Posts
6
Ok... it seems that the wiggling of the edge connector was just a coincidence.

After the system was powered off for about 5 min and started back up again. The issue reappeared.

Seems to happen on screens where ther is alot of action.

However, it disappears on its own after about 3-5 min of being on.

I am just guessing, but does this sound like a cap replacement would help here ?
 
Last edited:

ttooddddyy

PNG FTW,
Joined
Nov 29, 2001
Posts
8,335
Does adding an additional ground from the mobo to the monitors video ground help ?
 
Top