PowerMac G5 Won't Power On

[eliplan312]

I have recently obtained a PowerMac G5 (Dual 1.8, Model A1047, EMC 1969, 2004), which won't power on.

I have tried reseating the RAM, resetting the PMU/SMU, re-plugging the cables, swapping the battery, removing the battery then holding the power button then replacing the battery, etc. It still won't show any signs of life whatsoever. Nothing happens when the power button is clicked, not any lights or any clicking noise.

I am hoping not to have to replace the PSU, as I don't have the money at the moment for that. The old battery measured at 2.4 volts, so I replaced it and the same thing happens. I am beginning to think that the front panel assembly might be broken, as there was a liquid spill on the front panel. The only thing other than replacing the front panel or the PSU I haven't tried is leaving it unplugged with no battery overnight, which some other post somewhere said might work.

Any help would be appreciated.

EDIT: The system was off when the spill occurred, and it has been months since that without being powered on.

 

[OrangeSVTguy]

Can you hear the PSU click when you first plug it in? If the power button board is shot, you can always disconnect it and just jump 2 of the pins with a screw driver to start it up.

 

[eliplan312]

I don't hear anything, but I'll try jumping the pins on the front panel connector.

 

[arogge]

Can you hear the PSU click when you first plug it in?

What does it mean if the PSU clicks, the room lights connected to the electrical socket dim, the power button lights up when pressed, the motherboard indicator light comes on but immediately shuts off, and the fans start to move but immediately stop once the motherboard light shuts off?

 

[eliplan312]

What does it mean if the PSU clicks, the room lights connected to the electrical socket dim, the power button lights up when pressed, the motherboard indicator light comes on but immediately shuts off, and the fans start to move but immediately stop once the motherboard light shuts off?

None of those happen. No lights, no fans, no external lights flickering, nothing. Also, sticking a screwdriver around on the front panel header doesn't seem to do anything. Does anyone have the pinout for it?

 

[OrangeSVTguy]

None of those happen. No lights, no fans, no external lights flickering, nothing. Also, sticking a screwdriver around on the front panel header doesn't seem to do anything. Does anyone have the pinout for it?

If you don't hear the clicking noise when you plug in the powercord then that means the PSU is most likely dead

 

[eliplan312]

I had a similar problem with a quadcore G5 that I was troubleshooting, and the PSU was also dead. I guess I'll have to get out my multimeter.

EDIT: I've just tested all the pins on the front panel header, and they're all <50mV, except for one which is 3.3v regardless of the power plug state, which is coming from the backup battery. I guess I'll have to test the actual power connectors.

EDIT 2: I tested the power connector which has the black cover on it, and 20-something pins or so, (the one between the CPUs and the front panel header), with the power connector plugged in, and there was no voltage whatsoever on any of them.

Looks like it's dead. I guess I'll have to either find a use for the case or somehow repair the power supply.

EDIT 9000: I just found http://damntechnology.blogspot.com/2009/02/rebuilding-powermac-g5-power-supply.html which looks promising.

 

[OrangeSVTguy]

PM if you need one. I have a 400w and 600w g5 power supplies.