PSU voltage concern / when can damage occur?

F4U57

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At what voltage can you start causing damage to boards?

The reason I ask is I had a known good PSU (cheap Chinese brand) powered on my game, nothing displayed but a white screen. Switched off the game checked the PSU and measured a voltage of 6.4v. Attempted to turn it down and at its lowest it was at 6.04v. I swapped out with two known working PSU's (Peter Chou's) and at their lowest they are around the same, one at 6.1v the other at 6.4v.

It can't be a coincidence that all three PSU's are at the same voltage, perhaps a spike in the house? Could something in the cabinet be causing the problem? Everything was working fine yesterday, the only change has been powering off to swap games.

Lastly, what's the possibility I have damaged my game when I first noticed the problem? The cab would have been on for 10 seconds before I switched it off.

Any recommendations to troubleshoot? I don't want to fire it up with anything running in it until the voltage is back down to a suitable level.
 

Westcb

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Damage to boards depends on the game, I have had a psu run well over 6 before on a board for a short time and no damage. Some boards can start having problems at much lower. Is it possible your multimeter is having problems? Where are you testing the voltage? Is it under load, at the jamma edge, or on a chip on the board? Seems suspect that all are doing it, I would assume the power outlet would not be at fault as the psu can accept a wide range of AC current.
 

F4U57

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Turning all three power supplies down to their lowest threshold were giving readings of +6v, that can't be right. I would think that without Load, at their lowest they would read under 5v.

I could be wrong, but it seems like something else is to blame. This particular game was working fine last week, it is also CPS1, with potential to suicide, I'd hate to think I've fried it.

With the game powered I testing at 6.1 at the PSU and 5.8 at the edge connector, this is with the PSU at its lowest threshold. Something's not right.
 

Westcb

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Turning all three power supplies down to their lowest threshold were giving readings of +6v, that can't be right. I would think that without Load, at their lowest they would read under 5v.

I could be wrong, but it seems like something else is to blame. This particular game was working fine last week, it is also CPS1, with potential to suicide, I'd hate to think I've fried it.

With the game powered I testing at 6.1 at the PSU and 5.8 at the edge connector, this is with the PSU at its lowest threshold. Something's not right.


At this point does the game come up when your testing? Or is it a blank screen? One thing that happened on my multimeter is when the battery is low the read outs are all over the place. You could try switching the battery but would be ideal to test with another multimeter just to fully rule out s problem with that. At this point though make sure you are using a beater board to test as cps1 boards have enough problems under the right voltages and I can't think of too many cps1 boards that are cheap these days to risk killing it.
 

F4U57

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At this point does the game come up when your testing? Or is it a blank screen? One thing that happened on my multimeter is when the battery is low the read outs are all over the place. You could try switching the battery but would be ideal to test with another multimeter just to fully rule out s problem with that. At this point though make sure you are using a beater board to test as cps1 boards have enough problems under the right voltages and I can't think of too many cps1 boards that are cheap these days to risk killing it.

That's a good idea thanks, I'll try swapping the battery on the multimeter, I've noticed I'm not getting a stable reading, only after holding the rods there for a good 5 seconds...


Ok, just had another look now and there is a battery symbol display on the multi. Guess I'll swap out batteries and go from there.
 

skate323k137

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Generally you do not want to run anything over 5.15. Once you start pushing past 5.2 you can damage more sensitive ICs. Some boards are more tolerant than others... when I got my first neo cab the owners had it set to like 5.9 and there was just some graphics glitching. Once I got it set right at 5.1 at the jamma edge the board was fine for years (and still is).
 
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aha2940

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I also have a chinese PS, and it also gives 6V at its lowest point. I have never tried any board on it, only a voltmeter, but I suspect that it is designed in such a way that under load (like a JAMMA board) the load will cause the PS to lower its voltage output and get to about 5V? Just a thought.
 

Westcb

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I also have a chinese PS, and it also gives 6V at its lowest point. I have never tried any board on it, only a voltmeter, but I suspect that it is designed in such a way that under load (like a JAMMA board) the load will cause the PS to lower its voltage output and get to about 5V? Just a thought.


This ^ under load it's a big drop then nothing connected at all. Gotta keep a crap jamma board for testing purposes so you don't see magic smoke on a good game.
 

Xian Xi

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This is why you buy a "smoke" PCB, a game for testing these things out that you don't care if it dies. I highly recommend, Superman.
 

F4U57

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A "smoke" PCB. Ha, indeed.

Luckily, I didn't damage any of my boards. It was in fact the multimeter. It was screwed anyway so I invested in a better model that also checks continuity.

All is well again. Thanks for the advice fellas.
 

Syn

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This is why you buy a "smoke" PCB, a game for testing these things out that you don't care if it dies. I highly recommend, Superman.

I've got The Main Event that's screaming to be a "smoker" board.
 
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