View Full Version : Pop goes my cocktail!

26th June 2006, 11:10 PM
Hey there

I have just spent the past two hours buidling a new cradle for the new power supply to be fitted into my Ghost munchers/uniwars cocktail which I have just got the board going for (my first fix - yay)

All the wiring is done, the power supply has been booted without the 5v and 12 v lines - getting nice output when tested with the DMM

ok - attach the 5v and 12 - boot and test again - all is smooth

attach board (don't plug in switching rom board - maybe that was my mistake?)

boot - and hear a pop - screen goes on with nothing, the LED has gone off on my power supply

turn off the power, disconnect 5v and 12 and try again, still no LED on my power supply.

I heard what sounded like a pop but all fuses in tact. Open up the power supply and the fuse is ok and no parts look burnt/ charred.

I bought this game from a guy who told me the power supply had died. I have also killed a computer power supply on this game when i was fixing the board but i tohught that was my own error. I am seeing a nasty pattern. Does this puppy need a full rewire?

Board is fine :) - plugged it into my test rig

Screen is fine :)

can anyone help - loose wire shorting something?

Is there anyway to resurrect my new power supply or did i just watch 40 bucks up in smoke (no smoke even)? :unsure



Arcade King
27th June 2006, 06:14 AM
Cab fuse?

The poping sound could have been the 2 big transistors in your power supply, I know this sound all too well.

27th June 2006, 07:47 AM
I can recommend Jomac's power supplys ;)

27th June 2006, 08:58 AM
will give them a look

will also test the transistors tonight - can anyone tell me what is used - maybe I can see if i can by one at lunch?

i have a feeling this is not line voltage related for some reason, can't see why everything else would stay on and i still get 240v but the supply fries

confused and tired (watched soccer and had wiring diagrams going in my head)


27th June 2006, 01:10 PM
can't see why everything else would stay on and i still get 240v but the supply fries


They do that. Remember that the power supply only supplys the power to your harness e.g for the game board and coin mech. It doesn'r run the monitor or fluro lights.

27th June 2006, 01:56 PM
i am going to check the the 5 v grd and 12v lines tonight - feel I am going to have trace every one or even replace them.

However I can't see how a short on these lines can blow the power supply, I would have thought it would have blown the board as the short would have gone down the line.

This makes me dread that it is the line going in - however this appears to be constant and measures ok - which makes me think that something goes to hell when a current is drawn - however I wold have thought that would have blown the fuse.

will be spending more time tonight trying to figure this out - no power supply though - ned to fix this now - another project

27th June 2006, 02:04 PM
I doubt you would have a short, but it wouldn't hurt to check. But these things just go with age and that's why I always like to have a spare around. The supplys aren't really worth fixing, best to buy a new one, I'm sure Joey will give you a good price ;)

27th June 2006, 02:06 PM
this was a brand new power supply bought from AMD a couple of months ago - hence my head scratching, particularly since the line fuse and power supply fuses are not blown

I think some pics may help

The AC line in use very small wires which may be part of the issue - the current can't be sufficnetly draw through them?


27th June 2006, 02:29 PM
Oh I see, I didn't know it was new. Send the thing back. On a side note I spoke to Joey before I purchased my last couple of power supplys and he talked me out of buying one type as he had too many problems with them. Is yours one of these? http://www.highway.net.au/parts/power_supplies/2937.html

27th June 2006, 03:04 PM
no looks similar but different.

will check wiring again before looking at refund.

27th June 2006, 06:27 PM
Is there a harnes between the main loom and the pcb??

Have you tried without the 12v?? You only need the +5 and gnd to power the pcb up. +12v runs the amp

27th June 2006, 08:25 PM
Hi there

the PCB is fine, checked it on the test bench

The power supply is completely shot at the moment. Am going to read up before frying myself


27th June 2006, 10:58 PM

I have gone through the power supply tonight and Trav was right, i heard the sound of one of my transistors popping.

Can get this at Wagner so not TOO stressed

Everything else appears ok on the PCB but will double check to be sure.

Otherwise I went through my cab tonight and all the wires from the harness appear to be in tact. dusty, but no cracks in the insulation. Is it worth just ripping them out and re-wring. At the moment all 5v lines (and ground lines) are tied to a central spade connector which was wired to the power supply fro their respective connector. Long shot but could this be it?

Saga continues

Thanks for all the help


Arcade King
28th June 2006, 06:15 AM
I found this document to be most helpful written by Randy Fromm.

Remeber you're dealing with high voltage when poking around inside a power supply.
I've fixed quite a few power supplys now, much cheaper than buying a new one :)

28th June 2006, 08:39 AM
Thanks Trav

This is also on the SPIES archive. Had a read last night.

I have come too close to be shocked before to play around with something like this in jest.

It is compeltely disconnected and disassembled at the moment. definitely a blown transistor. Everything else looks ok but will continue to poke (carefully) around.

one odd thing I founf was that testing the continuity between the GRD and 5v point insid ethe supply was that it would quickly short and then build to 50ohm resistance. Is this normal?


29th June 2006, 11:05 PM

I think i only blew a powe rtrnasistor on my powe rsupply. Yanked a couple of diodes that weren't happy in circuit and they sprung to life, parituclarlt eh two big 5v diodes.

went back to the cab to try and work out what the hell is wrong

After playing around, I saw a pair of wires that had been tied together but were unnecessarily long.

I traced this back and found that this was a gorund wire that had been rigged up to a test switch of sorts that had been removed and the wires tied together.

Back at the harness, I found that the coin mech and gorund were shorting as a result of the test setup being tied. So will install a proper test switch to remove the short.

I also found that the diode across the coin counter was blown.

will fix these and see how we go, fingers crossed


3rd July 2006, 08:15 AM
Disconnect the coin counters. These could be shorting the 12v and aren't nesecary in a home enviroment.

3rd July 2006, 08:45 AM
am going to do that

I have a feeling the counter is blown, parituclarly since the coin switch was permanently grounded - the counter would have been continually energised and probably has blown, shorting the coil (i assumeit is solenoid driven) and the power going to it.

didn't get to attack it on the weekend other than to buy replacement transistors from WES/Wagner