Powering Up Question

FlashbackArcade

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When I power my machine up, the screen is scrambled but if I turn it off and then back on again immediately it will power up correctly. Anybody have a guess as to what is going on with my machine? This happens every time so the behavior is consistent. Any insight would be great!
 
Sounds like the machines is starved for power. Are you running a switching power supply in there? I'd double check to make sure the 5v line is adjusted properly.

Also, how many games are you running on the same circuit? I had one game that wigged out on me when it had to share power with more than 2-3 games at once.
 
That's what I though but when I measured the voltage, I have 5.3 V at the board and 5.43 V at the power supply. Only using 1 board a 60-1.
 
OUCH.

Turn the voltage DOWN!

It should be 5.1 at the board itself and no more.

If it still doesn't power up the first time then you probably have a power issue in which it's not stabilizing at 5v fast enough.
 
Backed down the power supply to get voltage at the board to 5.1 V. Still no change in the powerup. When it powers up, the images on the screen are scrambled but if I hit the switch activated by the back panel two or three times, the board powers up no problem. Didn't have this problem before I switched over to jamma harness. Anybody got a clue what's going on?
 
Do you have another power supply you can swap in? I had a similar issue on a game that cleared up when I put in a new supply.
 
I've seen PCs do this, including arcade PCs. It's always one of two things:
  • bad capacitors on the motherboard in the Vcore (CPU power) section, resulting in the CPU receiving a low/high or rippling voltage.
  • A PSU that raises PWR-OK without any self-tests (in violation of the ATX standard, but a lot of cheap chinese PSUs do it), and is slow to stabilize +12 (which is what powers the regulators for Vcore). To clarify: the PSU raises PWR-OK before +12 is ready, signalling the motherboard to start code execution, but Vcore isn't stable yet, so the CPU barfs and the system freezes
I second trying a different power supply. I'd also examine the caps on the game board itself -- it may regulate a different voltage for its CPU off the +5 or +12, and there may be a problem with that regulator circuit like a bad cap. (ESPECIALLY if the board was made in 1999-2007.)
 
I would continue to isolate the issue down. Do you have another jamma board you can try. If the problem still exists I would try another jamma harness. You have a bad crimp in the harness effecting the +5. If it does go away it may be a fault in the board itself.
 
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