mvs problem

mrbill2084

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I picked up a few mvs 4 slot boards. This one has a weird problem. Game works fine, but it has some weird video issues on the left side of the screen. 1st screen and 3rd screen (winners don't use drugs) look fine but 2nd screen (mvs boot screen), and game play are messed up. I swapped top boards and no change. Any ideas?

here are some pics (2nd screen did not come out).


screen1
screen1-123.jpg


screen 3
screen2-103.jpg


game screen
screen3-73.jpg
 
2nd board has a different graphic problem. I have not tried swapping top boards on this one.. here are pics of its problem(I cleaned the cart slots on both boards and cart is known good).

screen 1
screena-8.jpg


screen 2
screenc-6.jpg


screen 3
screenb-8.jpg



game screen
screeng.jpg
 
Screen 1 is normal for both boards. First thing to do is to remove the onboard battery. There may be corrosion under it that can cause problems. Report back once you've done that.
 
If i recall correctly ive had both issues in the pas the way i fixed mine was cleaning the carts. and blowing into the slots. Also I would wiggle the carts when placed in the slots and i believe i fixed one of those problems like that. And like mentioned above check under the battery and see if theirs no traces that are cut from he battery acid. also I would solder wires onto the battery so the battery isn't near the PCB in case it leaks in the future..
 
Screen 1 is normal for both boards. First thing to do is to remove the onboard battery. There may be corrosion under it that can cause problems. Report back once you've done that.

I have a mv1fz board, I seen a couple people mention leaky batteries, I checked mine over/under no signs, but some people mentioned switching to a coin cell non rechargeable battery. Is there a site that sells the correct holder for this setup that you recommend? Also do I simply desolder that one 300 ohm resistor off the board or do I have to build a trace between the two points that the resistor was connected too? I'm not to sharp on the science of resistors but I can desolder/solder good enough to do this mod with a little clarification.
 
Both are mv-4 boards if it makes a difference.. I will try taking out the battery and checking the traces. underneath. I had one board before with bad traces(grid would only come up). raymond fixed it for me last time..

I cleaned the cart slots and all 4 slots are pretty much doing the same thing for both bad boards. I swapped top boards on the 1st one with a know good top board and no change to bad graphics.

I have another board, mv4ft3, that will show a grid with no carts, but stick a cart in it and it never gets to 1st screen. Going to take apart and clean that one this evening..
 
sorry, I have been busy with other projects, I not gotten back to the neo geos yet. Problems are consistent with any slot on both boards.

I did mess with the 3rd board(mv4ft3) a bit. I cleaned slots and lifted the battery. traces looked good around and underneath. After cleaning no change. Grid with no cart. I see the 1st screen with a cart(green with blocks), but then it does not get to the 2nd screen.
 
Is it stuck on green? If not, tell us how you are cleaning the slots and the carts.
 
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