Hi,
This is going to be a slow burning thread, so patience required (!), but I thought it might be of interest and worth a post or two.
Recently I got hold of two defective G5 2.7GHZ dual machines. From these two I actually got one working really well and have overhauled for sale. The other though is dreadful.....a nice case (well, that's what I bought them for really) but a cooling system malfunction took out the power supply big style.
The thing is though having only seen air cooled Mac.s I was really interested by the lovely looking water cooler in both machines. The working one I re-furbished, but on the spares machine I decided that the water cooler is too good to throw away. It has a brilliant little 140 mm aluminium radiator that looks bullet proof (pic attached). It also has an interesting pump. The pump is labelled Delphi, but in reality it is a Laing pump which is the standard for most proper water cooling projects and is fairly expensive ( the retail version is about £60). I am replacing the seals on mine and going to see if it does the business.
From testing, the usual black Apple wiring to the pump plug is a six pin connector with 2 blanks. When looking at the connector to the pump end on, the pins are like this:
1, blank, 2, blank, 3 , 4.
The connections are as follows: 1 = ground, 2 = V mot (variable), 3 = Tach output, 4 = 12v motor.
To test, connect 1 to ground and 2 and 4 to 12 v. If testing dry then only run for a second as the pump uses the coolant to lubricate itself.
The failure mode of these pumps is the O-ring seal which costs £1.20 to replace. Failure can also be due to burn out of the PCB (fortunately this is not the case for mine), but there is a guy on eBAy who occasionally sells new PCBs that he makes from new surface mount components.
I'll let you know how I get on.
Oh yes and one other thing I have NEVER seen before. This G5 still had the little grey rivet in place in the processor cover. I managed to extract it without breaking it and have saved it. It's a silly little thing but finding one that has not been broken at some point is about as rare as finding a hen with teeth.