Dead PMG5 (June 04, LCS dual-2.5)

[computiNATEor]

Hey there,

I need some advice regarding my next course of action with my June 04 PowerMac7,3 (dual-2.5 w/ Liquid Cooling System).

I recently replaced all the hoses and the coolant, and reapplied thermal paste after a thorough cleaning. I blew the case out with some compressed air, too.

I haven't used this machine at all in at least a year, and before I started it up, I saw some signs of liquid cooling system leaks, so I wanted to freshen it up a bit. I replaced all of the cooling hoses with 3/8ths automotive fuel line, and replaced the o-rings with Viton rubber o-rings (#026).

Currently, when I press the power button on the front panel, I get nothing. No power LED (the one above the power button), no fans, no clicks, nothing. I've tried a couple things; namely, a different power cable (known working), hitting the PMU reset button (nothing), and a couple (unknown charge) PRAM batteries (still nothing).

When I replaced one of the PRAM batteries and reattached the power cord, I got a "click" sound, and a white LED near the front of the logic board flashed briefly.

My first guess will be to replace the PRAM battery with a new one and see if that helps, but assuming that it doesn't, what should be my next course of action? Power supply? The button itself?

Thanks for your help,

Nate

 

[computiNATEor]

When I plug the power cord in after hitting the PMU reset button, I hear a click and see the front panel/power light flash, but nothing else. Still unresponsive. I tried jumping the pins described in this video, too, but that also had no effect.

I suspect the power supply may be faulty. I'll try swapping it with some spares I have early next week.

 

[pl1984]

Where was the location of the liquid cooling leaks? Can you provide pictures of the leakage and location? It may be the liquid seeped into the power supply.

 

[computiNATEor]

Good point. They leaked at the o-rings, but as I haven't used this system in at least a year, the liquid may have evaporated before I noticed.

I did notice the residue on top of the power supply:

And with the processor cards removed:

 

[pl1984]

It doesn't appear to be extensive wrt the power supply, more like surface contamination. I recommend cleaning up the processor heat sink connections and moving forward with the power supply replacement.

 

[computiNATEor]

Yep, I've done that. Over the last week I fully disassembled the LCS, installed new Viton o-rings, cleaned off the surface corrosion with a brass wire brush and some alcohol, replaced the very brittle and seeping coolant hoses with 3/8ths fuel line, and refilled the cooling system with coolant.

 

[computiNATEor]

Update: I pulled everything out of the case; I think I didn't get the processors fully seated or something. The power supply registered proper voltages when I checked it with my multimeter. I had it relearn the thermal calibration, and it's running faster than ever.