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Tell me why this wouldn't work: replacing arcade power supply with PC pwr suppl

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quarterback:

I've got a 'dead' cab that I bought last week at an auction.  After taking my multi-meter to the switching regulator power supply terminals, I've found that I'm not getting the voltage I'd expect (only 1.6v from the 5v terminals and only 4v from the 12v terminal)

This leads me to believe that the PS is bad/needs replaced/repaired.  

But riddle me this... I have an extra computer power supply somewhere in the basement, and PC power supplies ALSO put out +5v and +12v.   Would it be possible to hook up a computer PS instead of buying a new 'arcade' power supply?  Has anybody done this?  I searched the forums but didn't find anything.

My biggest concern is that the existing arcade power supply has 220v (212v actually) going into it and the 12v output also says "25A".  I don't think a PC power supply could crank out that kind of amperage so maybe it's not strong enough.

Anybody?

menace:

You pretty much answered your own question--the computer power supply may not supply the amperage as well as the fact that some power supplies need to have current drawn relatively evenly across the 12V and 5V lines--for instance if the game drew heavily on the 5 sometimes the 12 will dip and if the  game drew heavily on the 12 then somettimes the 5 will dip--you should just crack open the arcade power supply and see whats the problem--i fixed a couple that just had bad fuses and one blew a cap--no big deal at all.

quarterback:


--- Quote from: menace on November 12, 2004, 01:23:23 pm ---you should just crack open the arcade power supply and see whats the problem--i fixed a couple that just had bad fuses and one blew a cap--no big deal at all.
--- End quote ---

Yeah, but I suck at soldering and I really don't know if I could even diagnose the problem since I'm so new at this.

I was able to find some other things via Google that imply that people have done this with a PC supply.  Both here and here

I bought the cab assuming everything inside was dead.  This was fine because I was really only looking for an empty Mame cab anyway and figured I'd use a PC monitor or TV.  BUT, if the arcade monitor DOES work, then I want to use it.  Right now I can't tell if the monitor works or not because I can't even get the game to power up.   I'm not really interested in spending any more money on parts only to find out that the monitor doesn't work, so I'm looking for a way to figure that out first.

How about this question:  What exactly is the switching power supply powering?  Is it just the PCB and lights?  If so, then I can't imagine it pulling that much power and a PC supply might work.

So, anybody think I'll do myself/my machine any irreparable damage if I try a PC power supply? :)

quarterback:

Okay, a new wrinkle here.

I took the power supply out of the cabinet (disconnecting all the wires except for the AC Input) and powered it up again.  NOW, with nothing cconnected to the 12v and 5v terminals, I'm getting the correct voltages (12 and 5 respectively)

So, is this normal?  I expected that I'd get 12v and 5v readings with everything attached, but I did not (I got 4v and 1.6v) but with all disconnected, I'm getting the correct readings.  

Is this a result of:
A PS problem? If so, anything in particular pop to mind?
or a problem elsewhere in the cab perhaps?
Thanks

paigeoliver:

Thats a power supply problem, I have an AR 3 board that does the same thing. Tests fine with no load, and drops to minimal voltages with load.

If it is a game with a normal switching power supply, then you can USUALLY replace it with a PC power supply. Most boards are fine with them, although you can forget anything from ATARI that had an AR board in it.

The downside to using PC power supplies is that they are non-adjustable, and some boards are REALLY picky about voltages (pickiest I have ever seen is super strike, which has only a .1 volt window that the ball sensors work properly in).

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