Power Mac G5 power issues...

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Level 1

8 points

Power Mac G5 power issues...

Hello, on a quest to find a G5 powered computer, I found an early 2005 Power Mac G5 (2x2.7GHz). The first time I plugged it in and powered it on, it worked just fine. The second time, I pressed the power button and heard a loud pop from the power supply. I replaced it, and here's what now happens:

When I plug the power cable in, there's a small click noise about a second after plugging it in, and the power light on the front of the machine flashes along with the click. However, it does not turn on at all when I press the power button. When I unplug the cable, it makes the same noise about a second after I unplug it. I can see a faint flicker from the power light after unplugging it.

Does anyone have any suggestions to fix this? It's part of a collection which is why I want to get it up and running.

Power Mac G5-OTHER

Posted on Jun 27, 2016 7:33 AM

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Answer 1

K Shaffer

Level 8

36,058 points

Jun 27, 2016 5:32 PM in response to Wind5387

There may be failed capacitors or other power supply issues, including

overheating due to dust inside the power supply or air channels. And

if the unit is liquid cooled, other things can be involved.

Since all the PowerMac G5 power supplies are considered Custom,

to get a good replacement is a hoped-for way to improve the situation.

Unlikely it may be, to actually locate an inexpensive working one.

Did you try a SMC power management unit reset? Or PRAM reset?

• How to reset the SMU on a Power Mac G5 (Late 2004) or Power Mac G5 (Late 2005) - Apple Support

For NVRAM (PRAM) reset see:

• How to Reset NVRAM on your Mac - Apple Support

Several links appear in this search result; some look promising:

https://duckduckgo.com/?q=troubleshooting+G5+PowerMac+power+supplies&t=ffsb&ia=web

I've read about the noise the G5 PowerMac can make when some power component

fails; troubleshooting is involved. Somewhere I had a link to a source for official PDF
service manual, to download one for offline use. -- I may see if I can locate the item...

Apple Power Mac G5 (Early 2005).pdf manual

Apple Power Mac G5 (Late 2005).pdf manual

Apple Power Mac G5.pdf manual

Good luck! 🙂

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Answer 2

Wind5387 Author

Level 1

8 points

Jun 27, 2016 6:23 PM in response to K Shaffer

Hi

I did try resetting the SMU earlier, but it still didn't power on. I looked at the instructions for resetting the NVRAM, but because that involves booting the machine up (which mine won't do) that may not work. Plus, there is no operating system on the hard drive. 😕

A minute ago I removed the graphics card and processor and reseated them, and even unplugged/replugged the power supply from the board, but that hasn't worked either. I'm hoping the power supply I got isn't defective, but that may be a possibility...

Also, if you want to hear the pop noise I mentioned above, I happened to get it on video https://www.youtube.com/watch?v=91_aWog2OhU

This is an early 2005 G5 that is liquid cooled. While replacing the power supply, I did have to clean off corrosion from the processors. Even with the corrosion, the computer still powered on the first time I got it (before the first power supply went), so this thing definitely has no problems other than the power supply (maybe)...

I will update when I've tried some more methods! Thanks for the reply.

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Answer 3

K Shaffer

Level 8

36,058 points

Jun 28, 2016 11:56 AM in response to Wind5387

When I looked into the specs, the fact your model is a LC became apparent.

Not sure if the service manuals (two have applicable info, one does not) can

a help to you now or in the future; if you haven't either, download both as the

link(s) may not work at some point or their host may go offline, as some have.

Those can be a good reference. I tested all the links and read through each.

(By default, for some reason, they opened in a browser for me; as reference

they're best downloaded & kept on archive for offline access.)

Good luck in this matter! 🙂

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