Resetting PMU in a IMac G5 3rd generation

Question

Resetting PMU in a IMac G5 3rd generation

Okay I am trying to reset the PMU on an IMac that i believe is a G5, (which it doesn't really say but when I check the serial number it says it is) and it's a 3rd Generation and has a Motorola Processor. The problem is I can't find a service manual or anything else that will show me pictures of where it's located or how to even take the IMac apart. I would be grateful to any suggestions! PLEASE! Thank You!

IMac G5, Other OS, i need help LOL

Posted on Oct 22, 2008 11:16 AM

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Answer 1

MGW

Level 7

27,041 points

Oct 22, 2008 11:52 AM in response to no_im_awesome

Welcome to Discussions - you don't need to take it apart if it's the iSight, here are the instructions:

1. Turn off the computer by choosing Shut Down from the Apple menu, or by holding the power button until the computer turns off.
2. Unplug all cables from the computer, including the power cord.
3. Wait 10 seconds.
4. Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer.
5. Let go of the power button.
6. Press the power button once more to start up your iMac.

Hope this helps,

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Answer 2

Oct 22, 2008 12:24 PM in response to MGW

Okay I have done that but that didn't work. So it says the next thing to do is reset it enternaly by pushing the PMU button inside on the logic board. But I don't know how to even go about labeling things or knowing where or what to push. Thanks again!

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Answer 3

MGW

Level 7

27,041 points

Oct 22, 2008 12:36 PM in response to no_im_awesome

If you have an iSight, there are no user accessible parts, and you can't open it without voiding the warranty. In any case, opening an iSight is really difficult, and carries with it the likelihood of damaging some of the components.

What exactly is the matter with your computer?

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Answer 4

Oct 23, 2008 6:20 AM in response to MGW

Yea there isn't a warranty for it...i got a refurbished one from amazon. I have it already took apart. I got that far from using IMac G5 service guide but I noticed after I opened it, it isn't the same as the guide shows. The service guide that I have is for an Intel-based IMac G5 and I have a IMac G5 with a Motorola Processor (which I can't find a service guide for). And the problem is- when I start the computer it starts up and I log-in and it "seems" fine, but after like a min. or so it locks up and the fan comes on and stays on and you can't do anything, you can't move the mouse, push any buttons or anything. It totally locks up and the only way I can get it to stop is hold the power button til it shuts off or do the worst unplug it. So that is why I would like to reset the PMU internally.

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Answer 5

MGW

Level 7

27,041 points

Oct 23, 2008 6:35 AM in response to no_im_awesome

Resetting the PMU externally does the same thing as an internal reset. The problem is probably in your power supply unit, and you need to take the computer in to a tech and have it diagnosed and repaired.

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Answer 6

Oct 23, 2008 7:13 AM in response to MGW

Well we won't take it to any place. The computer is one that is at the Tennessee Technology Center @ Paris, me and my Instructor where wanting to reset the PMU internally. That is why I got on here to see if anyone had the same kind of computer and could help me out with that. But thank you for your input. It is gratefully appreciated.

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Answer 7

Oct 23, 2008 8:08 AM in response to no_im_awesome

I have the iSight model. You never confirmed if that is what you have other than 3rd generation (iSight models).

AS MGM already pointed out, the iSight models are NOT user repairable except for RAM installations. There are no G5 iSight model service manuals (for the public). You will need to take the computer to a local repair shop.

The only way to reset the PMU on the iSight models is externally.
http://docs.info.apple.com/article.html?artnum=2238 Resetting your Mac's PRAM and NVRAM

FYI: No such thing as an Intel G5 iMac. An Intel iMac and a G5 iMac are 2 different types/model computers. See the following Knowledge Base Article: http://docs.info.apple.com/article.html?artnum=301724-en How to identify your iMac

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Answer 8

MGW

Level 7

27,041 points

Oct 23, 2008 9:11 AM in response to Baby-Boomer-USofA

AS MGM already pointed out

Thanks again for the movie star status, Baby.

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Answer 9

Oct 23, 2008 10:37 AM in response to Baby-Boomer-USofA

well as i said Intel-BASED 🙂 but thanks for the Input. I located a place and found the PMU reset and followed the instruction and now it works. But Thanks Again for the suggestions :)!

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Answer 10

Oct 23, 2008 10:39 AM in response to no_im_awesome

i searched and found what i was looking for, from outside this website. Thanks Tho

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Answer 11

MGW

Level 7

27,041 points

Oct 23, 2008 11:07 AM in response to no_im_awesome

Could you please explain how the PMU reset you found differed from the one I gave you? I always like to learn new solutions.

Thanks,

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Answer 12

Oct 23, 2008 1:18 PM in response to MGW

Miriam, you are a star!! 😀

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Answer 13

MGW

Level 7

27,041 points

Oct 23, 2008 1:22 PM in response to Baby-Boomer-USofA

Thanks, and I would still like to know what the alternate method of resetting the PMU/SMU is on the iSight G5.

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Answer 14

Oct 27, 2008 8:28 AM in response to MGW

Sorry the server went down and I hadn't be able to get back on here...but now I'm back YAY! Anyways, you open the IMac G5 (isight) and you will see on the logic board a small black button that is the PMU and I pressed that and it reset it and TaDa... it worked. But i wouldn't suggest to anyone to do with if they got a warranty 🙂

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