Gauntlet graphics issue...

75ohm

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Helping a friend out on this one so troubleshooting will not be near real time; thanks in advance.

Background:

Gauntlet 1 machine is great shape but came with a G2 board. No problem, pick up a G1 to have both!

Issue:

After a few months the graphics starting getting goofy with what appeared to be missing pixels/colors on the background and characters.

Troubleshooting performed:

Checked ground connections
Checked solder joints and connections
Checked seating of the DIPS, PROMS, and ROMS

Nothing yet.

Wiggle the board or put a little pressure somewhere, full display.

This is a never ending cycle of frustration.

Reseated most of the chips in the sockets...

Same thing.

Not sure if there is something we're missing or if a chip is going bad. Some of the chips seem rather warm as well.

Additionally, there are three ground points on that board, should all three be connected? Originally it had only one and we chained all three points together, no difference.

Put the G2 board in, perfect.

Thoughts?

Thanks again...
 
Did you check the +5V voltage? If it's fine, try to find specifically where flexing the board fixes the problem, and look for hairline broken traces, or bad sockets there.

DogP
 
Nope, but we certainly can.

Would there be any reason why the G2 board works fine and the G1 wouldn't though?
 
If the +5V is low, anything can happen... it just depends on the random tolerance of the individual chips, and widely varies from board to board. When things just start to act funny, the voltage is one of the first things I check.

DogP
 
OK, just in case anyone in the future has this problem: MIGHT have been a cold solder joint on the video pins. One didn't look great and I gave it a little heat, and it there weren't any missing lines on motion objects when I turned it back on. I'm hesitant to say it's 100% fixed, however.
 
Turned it on 24 hours later, and of course the problem came back. Of course it did. I am so f%$#*ing sick of having my games working 100% when I go to bed and seeing the same god damn problem come back the next day.

Has anyone seen this and solved it? I mean:

Wiggle the board or put a little pressure somewhere, full display.

This is the EXACT problem I have to the letter.
 
It definately sounds like you have an intermittent connection. You are on the right track, just haven't found the loose part yet.

The fact that it worked after reflowing the solder on the PVID pins is a good sign that you either flexed the board correctly or squeezed the correct part back down tight for a few hours when you worked on it.

Unfortunatly, the best advice I have is to keep looking for that cold solder joint or loose pin. The size of a Gauntlet board makes trace and pin cracks pretty darn easy.

Brian.
 
It definately sounds like you have an intermittent connection. You are on the right track, just haven't found the loose part yet.

The fact that it worked after reflowing the solder on the PVID pins is a good sign that you either flexed the board correctly or squeezed the correct part back down tight for a few hours when you worked on it.

Unfortunatly, the best advice I have is to keep looking for that cold solder joint or loose pin. The size of a Gauntlet board makes trace and pin cracks pretty darn easy.

Brian.

Thanks, man. I know it sounds like I wigged out and sprinkled steroids on the board, but I was just letting off a little bit of steam. I appreciate it.
 
Thanks, man. I know it sounds like I wigged out and sprinkled steroids on the board, but I was just letting off a little bit of steam. I appreciate it.

I know exactly where you are coming from. :p I have been in the same situation many times. For example with a PCB that only powers up about 75% of the time, finding a SMD RAM chip that makes the board work if you hold it down. I touch up the solder, board now works perfectly..... After about 3 power cycles, the board stops working altogether.

When my repair efforts take me from working 3 out of four times to 0 out of a hundred, I tend to let loose a long string of swear words as well....

Brian.
 
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