Neo Geo with a gbs8200 vid board, clamp settings?

Leinhit

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I'm restoring a Neo Geo and using a gbs8200 video converter board to run it to a VGA monitor.
Does anyone know what the clamp settings should be? I'm having trouble with color and don't know if it's the neo geo board or my video board. Thank you
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Your clamp settings are fine.

There is no green signal on the video board. That means it is either a bad input on your converter or bad output from your Neo.

If you have a logic probe you can test the JAMMA edge to see if the green signal is present there and then correct the problem accordingly.

Brian
 
There is other stuff going on here besides missing green, your white is pink. I had a gbs give me weird color issues when it was under powered.
 
There is other stuff going on here besides missing green, your white is pink. I had a gbs give me weird color issues when it was under powered.
White isn't white if green is missing.

White is the the combination of all three colors, therefore without green it is just blue and red. The color I see is a pale purple, not pink.

Missing green is the only problem.
 
Your clamp settings are fine.

There is no green signal on the video board. That means it is either a bad input on your converter or bad output from your Neo.

If you have a logic probe you can test the JAMMA edge to see if the green signal is present there and then correct the problem accordingly.

Brian
Sadly I don't have a logic prob​e,
 
Do we know what the clamp settings are supposed to be? I read allot about if set wrong the colors mess up in a few minutes
 
There is other stuff going on here besides missing green, your white is pink. I had a gbs give me weird color issues when it was under powered.
I have it connect to+5 volts, is it ok to go to the+12 volts?
 
I really don't think it's clamp settings. IIRC, that's usually the problem where the entire screen gets washed out after a few minutes.

It's supposed to be powered by +5v, so no, DON'T connect it to +12V.

To figure out whether your green is bad from the Neo Geo, converter, or monitor, swap the green and blue wires from the Neo Geo to the converter. If you're still missing green, then swap the green and blue from the converter to the monitor. If you're still missing green, then it's your monitor. You could also rule out the monitor if you have another VGA monitor on hand that you can plug into the converter.

DogP
 
Sadly I don't have a logic prob​e,

Unfortunately, without a logic probe it is a little tricky to confirm where the trouble is exactly.

There are still things you can do. Do you have a multimeter or some way to check continuity? If so, verify that the wire on your JAMMA harness that is coming from the green signal line is good all the way to your converter board. The pin you want is on the side solder of the JAMMA harness, number 12 (or the fifth one past the key).

Do we know what the clamp settings are supposed to be? I read allot about if set wrong the colors mess up in a few minutes

I have used several different models of theses converters over the years, and to my experience, the clamp will make the screen go blank or flicker in and out if it is not on the correct adjustment. If your picture is stable and looks as good as the photo you posted all the time, it isn't the clamp settings.

I have it connect to+5 volts, is it ok to go to the+12 volts?

I also have never seen an issue with these Chinese boards if you are giving it a full 5VDC. Unless your +5 line is less than 5VDC, there is no need to connect it to the +12 line.

Brian.
 
Unfortunately, without a logic probe it is a little tricky to confirm where the trouble is exactly.

There are still things you can do. Do you have a multimeter or some way to check continuity? If so, verify that the wire on your JAMMA harness that is coming from the green signal line is good all the way to your converter board. The pin you want is on the side solder of the JAMMA harness, number 12 (or the fifth one past the key).



I have used several different models of theses converters over the years, and to my experience, the clamp will make the screen go blank or flicker in and out if it is not on the correct adjustment. If your picture is stable and looks as good as the photo you posted all the time, it isn't the clamp settings.



I also have never seen an issue with these Chinese boards if you are giving it a full 5VDC. Unless your +5 line is less than 5VDC, there is no need to connect it to the +12 line.

Brian.
Ok thanks, I did read that it needs 2 amps and some switching power supplies don't push 2 amps on the+5, but do on the+12

And the board is marked as accepting+5-+12 volts.

I will check what the+5 on the power supply is rated tomorrow.

I need also see you tube vids that if the clamp is wrong that the colors wash out after a few minutes,. I could test this by turning it on and checking immediately.

And yes, I have a dmm and I will check for continuity on that wire tomorrow as well.

I did have to splice in the vid board wire to the jamma harness so let's hope it's just a bad connection, knew I should have soldered it...

Thank you both again..
 
I really don't think it's clamp settings. IIRC, that's usually the problem where the entire screen gets washed out after a few minutes.

It's supposed to be powered by +5v, so no, DON'T connect it to +12V.

To figure out whether your green is bad from the Neo Geo, converter, or monitor, swap the green and blue wires from the Neo Geo to the converter. If you're still missing green, then swap the green and blue from the converter to the monitor. If you're still missing green, then it's your monitor. You could also rule out the monitor if you have another VGA monitor on hand that you can plug into the converter.

DogP
Will do,. And report back, I also have a multi jamma board I can put in and test everything at once, I would assume if color is good with another board then it is this neo board.
 
All thank you for your continued assistance.

I got called into work the last couple days on my days off so no time to play with this.

However today I did try a different VGA monitor with the same result, missing all green Color.

I then began continuity testing and I narrowed it down to the wire harness that came with the new GBS 8200 video board doesn't seem to have continuity between the end of the green wire and the green wire pin in this plug that you see here.

I have not tried pulling the pin out yet, is there a trick to it?

I do not have a pin extractor tool. And I d rather not cut the wire to see what's going on. I don't see any obvious flaws in it

The wire seems to be in good brand new condition as I just took it out the box with the video board. However I need to get the green wire out with the pin to Futher test it

I'm wondering if they did not connect the green wire to the pin inside the plug at the factory? Is this possible?

I will report back more, I have not tried putting a different multi board in the game to see if that helps or connecting the vid board to 12 volts,, but with this new wire video connector possibly being messed up it's not going to help.
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Ok an update, partial success.

I found the green wire did not have continuity, that will hopefully fix the color issue

I say partial cause I get to that same grid screen, but now the player one button isn't taking me to the test screens.

I also borrowed a mvs cart and I get to the same grid screen.

While fooling with it, the cabinet power switch did on me. Have to find a replacement before continuing.

Will report back.

Ideas why I can't get back to the test screens or only a grid with a borrowed cart? Lender said cart work long time ago and has been sitting since
 
Take the cart apart and clean the edges with rubbing alcohol. Do the same for the PCB, clean the slots with a tooth brush and alcohol. Try cart in each of the two slots. These games are very temperamental. Some carts won't work in some slots, etc.
 
More success! Cleaned contacts on cart, didn't seem dirty but clean soft rag and rubbing alcohol would come out black.

Cleaned the board contacts as well after I confirmed player one button does indeed work with a multi board.

Bypassed the power switch without a cart and got to the grid and then the setup menus.

With a cart and I was soon testing and playing bust a move!

Phone died after the first pic, but u can see the color screen now below.

Not 100 percent I trust it yet to work 100 percent of the time, but good start.

Recommendation for a neo multi cart? And not the $400 dark soft one...

I set the clamp settings as suggested above..

Thanks for the continued help

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Great to see you got it working! AFAIK, the 161 is probably still the best bang for the buck (it's cheap, and pretty good with around 100 different games).

DogP
 
Thanks, who thought the connector from the factory would be bad?

So who has said 161-1 carts? Price? Little more testing and I'll put a 24" led in this

* Also in the setup, it doesn't seem to be keeping the time I set very well, dunno what I would need this for, and what is this " insert memory card" option in the setup, didn't know it took one. That anything I need?

Thanks
 
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