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Help! Game Board Repair (Super Pang)
CHRIS-F:
Hi All,
I only bought my Super Pang (Bootleg) PCB a week or so ago and it worked normally, I removed my joysticks to clean out the gunk and swap a few Switches, everything worked with the machine open, I unplugged it and all I did was push the PCB back a little on top of it's plywood shelf and close the machine up, after switching it on again there was a horrible sound coming from the speaker and the screen showed a corrupt white screen with light blue blocks, I switched it off and on again and I saw a message saying RAM OK with lines across the screen, after switching it off and on again a few times I get different screens with corruption and sometimes the game seems to work, but there is no sound, about one time in ten it will start and work normal, sometimes at switch on it seems to be making corrupt sounds like in attract mode, but AFAIK attract mode sounds is off so it shouldn't be doing sound anyway until a coin is inserted, my initial thought was I may have pulled a solder point loose when sliding the board along the wooden shelf, but I can't see any loose.
Where do I go from here to try and diagnose the fault, I have a multimeter, (I think it has logic test) and I have checked I'm getting about 5.1V at the chips and just over 12V (forgot the exact voltage) but the voltages seem to be correct.
Thanks,
Chris.
Mike A:
I am not an expert at this, but the first thing I always do when a board suddenly stops working is clean the edge connector and plug it back in. That has worked a surprising number of times. I have had two boards where I cleaned and re-seated any chips in sockets. That fixed them up. This would be a good starting point.
CHRIS-F:
--- Quote from: Mike A on June 12, 2019, 06:47:47 am ---I am not an expert at this, but the first thing I always do when a board suddenly stops working is clean the edge connector and plug it back in. That has worked a surprising number of times. I have had two boards where I cleaned and re-seated any chips in sockets. That fixed them up. This would be a good starting point.
--- End quote ---
Thanks Mike,
I have cleaned the edge connector with a scotch pad and IPA and wiggled it on and off a few times, still no change, also I have re seated all the EPROMS. I'm leaning towards a logic fault maybe as the only thing that makes it work is powering it on and off a few times, each time is different but it occasionally works ok.
Mike A:
Yeah. It is time to get down and dirty then. Pretty much anyone will know how to proceed better than me.
opt2not:
It's possible you might have scratched a trace when moving it around in your cab. I would go over it with a magnifying glass and look for scratches or gouges that might have torn traces.
Another possibility, shifting around an older PCB can sometimes knock the legs of the surface mount chips loose. I've had this happen to my Smash TV board, when it was shipped to me.
One way to check this is by turning the game on and tapping or lightly pressing on some of the surface mount components. If you see a change on-screen, there could be cold solder on those components, or they're failing.
One last "physical" test you can try is light bending the PCB a bit when it's running. Sometimes these boards get flexed over time, especially if they're stored improperly (horizontal storage should be avoided as gravity will eventually make your PCB's sag).
If something changes on-screen while you're lightly bending the board, there is most likely a cold solder joint somewhere.