Screen is grainy

AdamUnRama

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This post may not need to go in the monitor section, as I do not believe it is the monitor, or TV. I have just started restoring this cab, two days ago I connected the GBS-8220, plugged it in to the TV and it looked freaking fantastic. Now when I turn it on it looks like the images below. Do I need a new GBS board? Could one of the wires be bad? The GBS hasnt touched metal, or had a short in any way. Should I drop the

Also, my JAMMA harness only as five video wires, should I upgrade it to a newer harness which has the six video wires? Would/could that give it a better image?

I couldnt really find a threat that had this general question; most of the answers to threads that are similar to this question go something like 'eff the BGS-8220, classic games weren't meant to be played on an LCD.'
 

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This post may not need to go in the monitor section, as I do not believe it is the monitor, or TV. I have just started restoring this cab, two days ago I connected the GBS-8220, plugged it in to the TV and it looked freaking fantastic. Now when I turn it on it looks like the images below. Do I need a new GBS board? Could one of the wires be bad? The GBS hasnt touched metal, or had a short in any way. Should I drop the

Also, my JAMMA harness only as five video wires, should I upgrade it to a newer harness which has the six video wires? Would/could that give it a better image?

I couldnt really find a threat that had this general question; most of the answers to threads that are similar to this question go something like 'eff the BGS-8220, classic games weren't meant to be played on an LCD.'

I don't know anything about LCDs or the adapter boards involved with them, so we'll move on to the next step. :)

the JAMMA video wiring consists of red, green, blue, sync, and then ground. considering you have all 3 primary colors in your pictures and it's garbled up, but synced properly, I'm going to say the wire you claim to be missing is ground. the good news is you can use any one of the other logic grounds coming off your power supply for this, although I am not entirely sure if that would help your video problem. it might affect the adapter board at least, but the part that doesn't make sense is that this worked fine before and now it doesn't, right? I'm not a proponent of LCD either, but if it's just for your home use then I don't see much of a problem, especially if you're doing like a supergun or something.

now it could be a problem with your MK2 board, won't be anything ROM-related, but possibly RAM-related, does it give any errors on the power-on test? (assuming that dipswitch is set to do the power-on test, otherwise you can do it from test mode too) otherwise your best bet is to try plugging in another game and see if you get the same artifacts on the screen.

if the artifacts go away, it's a problem with your MK2 board.
if the artifacts stay, then it's a problem with your LCD.

hope this helps.
 
Last edited:
Mecha,

Thank you for the reaply. I am stumped as well. I understand some of the games will be pixilated; TMNT, UN Squadron, even MK, it looks like a color is missing. I'll figure it out, thanks again!
 
That looks more like a video RAM failure. Can you plug the board back into another cabinet? You might also want to make sure you have +5/-5/+12 on the edge connector.

Matt
 
I was afraid the PCB was bad. I went in through the RGB ports as opposed to the VGA, it made the pic a little better.
 
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