Changing the power supply unit on a powermac g5, after it blows up!
November 27th, 2007
If the PSU on you’re powermac g5 has gone, or you think it may have, you aren’t the only one (see macintouch forums). When I was reading around on the subject I read the failure rate is around 11%, I can’t remember the exact figure but hopefully I’ll find it again later. Luckily Apple did acknowledge the problem and has extended the warranty on the power supply, which you can claim here: Power Mac G5 Repair Extension Program for Power Supply Issues
A relatively new customer phoned us up last week in a panic, claiming his server (the powermac) had stopped working and wouldn’t even switch on. We’d recently set-up a remote backup solution for him and installed an extra internal hard drive in the powermac for local backup. I’m guessing the extra load of the hard drive took it over the edge. Needless to say he needed the server back up asap.
Phoning around we found one supplier with a spare powermac psu in stock. None of the local apple stores did and most companies sounded confused, as if I was asking a silly question. We ended up paying £150-£200 for the psu, a little on the expensive side but desperate times call for desperate measures.
I’m definitely not an expert with mac hardware and I don’t have special tools for taking apart a computer - this scared me - because everybody I spoke to or every article I read said not to change the psu yourself and to take it to a professional. My advice would probably be this too, it isn’t for the faint hearted or impatient. But if you’re up for a bit of a challenge you can’t do too much damage, read on.
Get hold of a guide to taking apart the mac, such as this one. I found a few discrepancies but it gives you a basic idea on how to remove things. To start with, remove everything. At first I tried to remove things that looked as if they would be in the way, leaving a few parts behind. Unfortunately the psu is so awkwardly positioned and large that the only way to get it out was to take out everything including the motherboard.
Having removed everything, switch over the psu and put everything back - simple. In total the changeover took about 2 hours. I used a standard toolkit but struggled with the screws for the processors because you need a very long, very thin screwdriver that will fit through the holes in the heatsink. I got by with a pear of pliers, a screwdriver bit and some brute force but it took forever.
I think as long as you keep the parts and accompanying screws separated in to the order they need to go back in the task becomes less daunting. The case on these powermacs aren’t small but then neither is the space left over. There are a lot of tightly packed components in the machine and it’s a bit of a puzzle to put back together. Good luck!
Also worth noting: When you’re finished with the broken psu most suppliers told me they’d buy it back for about £50 - worth a try.
May 4th, 2008 at 8:03 am
You talk about how hard it is to remove the PSU and yet you give no instructions that may be helpful.
You tell us to get a hold of a doc that explains how to take apart a PowerMac and yet you give us not information on where to get such a document.
Do you remove the mother board first? Don’t think so, I can’t get to it at this point until I remove the PSU. So how do I remove the PSU?
That is what your site is all about.
Give me some info please. I removed the CPU’s without a problem, now I need some help with the PSu in order to continue.
Can you help me?
Please.
Gratefrully,
Donna
May 22nd, 2008 at 11:14 pm
Hi Donna,
Sorry it has taken a while to get back to you. The post does reference one manual for taking apart the g5, it was this one: http://www.sharpeningbeneath.com/g5guide/
I’m sorry but I can’t remember whether or not you remove the motherboard. I know that both seemed to get in the way of each other and in the end it took some force to get one of them out.
I did the replacement with a colleague so I’ll ask him if he remembers.
Sorry my post couldn’t be of more help.
Cohen
June 25th, 2008 at 10:43 pm
You do not need to remove the motherboard. That would be a lot of extra work that is completely unnecessary. On my G5 2.7 dual water cooled, you do need to pull the processors off. remove the front fan. take the plastic front cover off the radiator. Purchase a long extension with 1/32 allen. loosen the two bolts holding front of radiator, two bolts just in back of the radiator, two outside bolts at the very back of the aluminum plate holding both processors, and the two middle bolts at the back of the aluminum plate holding the processors. These bolts do not have to be removed completely. It is a bit easier to leave them. They are on expanding pegs that hold the processor in place and center it.
Gently tug back and forth on the processor/radiator assembly. If it does not go fairly easily, check again for missed bolts. (Oh yeah, and disconnect the black wire connector)
Once the processors are removed, un bolt the two screws on the steel plate at the bottom of the case. Wiggle this plate out, which will expose the power supply.
At the bottom of the case, there will be four screws. Remove the four screws. Now disconnect all three wiring harnesses that connect to the power supply. Leaving the side of the power supply nearest the motherboard in its current position, pull the other side of the power supply so it tips at an angle. This will put just a bit of pressure on the mother board where the harnesses come out of the power supply. You should be able to pop out the clear side of the power supply out of the case.
This is easier than removing all the screws for the motherboard, and detaching all the wire harnesses going everywhere else.