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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > Late 2006 iMac Potential PSU Failure

Late 2006 iMac Potential PSU Failure
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Tallest Skil
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Apr 30, 2018, 04:25 PM
 
Hey guys… so your site seems to be dead now. Damn shame, it was always good for tech support.

Speaking of which, I have a Late 2006 Core 2 Duo 17” iMac running Lion that is now shutting itself down both while running and while asleep. I have used it as our iTunes media server for about 5 years now, because Apple is too stupid to figure out that people would like to just plug a hard drive (with media formatted in iTunes Library folder structure) into their AirPort (which is now discontinued entirely) and access it from ANYWHERE on a home network (say, from an Apple TV). I’m unable to run Apple Hardware Test on it because I’ve somehow lost my Snow Leopard retail disk and can’t restore that functionality. I have reviewed both temperature and fan data, and it’s running at the lowest speeds and the coolest operational temperatures right up until the moment the power cuts out. I have also reviewed shut down logs in the Console, and all shutdowns are returning 0 (meaning “loss of power”), as opposed to 1 (hard shut down by holding the button), or 5 (normal software shut down).

With no software glitches in sight, I’m worried this is the PSU. Worried because I’m not ****ing dropping $500 on a FOUR YEAR OLD “new” Mac Mini to replace it, and… there’s no Mac Mini update in sight still. What’s left for me to do to definitively pin down whether or not the PSU actually is at fault?

Thanks for any help, those who still use the site. I see a few posts from just a few days ago, and the forum list says “20,000 threads” but I can only see two of them when I go to any subforum.
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andi*pandi
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Apr 30, 2018, 05:03 PM
 
We're still here! more people chat in the lounge than ask for help. Someone who knows something about PSU will be along shortly.

Do you have a power surge protector?
     
reader50
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Apr 30, 2018, 05:10 PM
 
Forum menu bar -> quick links -> today's posts. Traffic is down since the News site closed, but we're hanging on here.

My first suspicion is failed capacitors, most likely in the PS. Have you opened your iMac up for cleaning? Pull it open, blow everything out, and look over the electrolytic capacitors. Both on the logic board, and in the PS.

A single failed cap is easy to replace if you have soldering skills. If a bunch are gone ... there used to be recap sets sold on eBay. But swapping all the caps is a lot harder than doing one. Especially since Apple used to overdo the hush gum smeared around the PS board. Officially to make it quieter. Unofficially to keep you and I from fixing things instead of buying new.

Replacement power supplies that had already been recapped were also sold. I haven't looked for either in a long time.

psst ... did you check the power socket it's plugged into? Say by trying your iMac in a completely different socket for a day?
     
Waragainstsleep
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Apr 30, 2018, 05:50 PM
 
The G5s were the ones that suffered most from bad caps which means you ought to be able to source a donor PSU cheaply enough, recapped or not. Might be even cheaper if you can find a donor machine with a dead logic board or other fault.

That said, the ~2008 iMacs are prone to blowing PSUs too but I don't know if thats the caps or not.
I have plenty of more important things to do, if only I could bring myself to do them....
     
Tallest Skil  (op)
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Apr 30, 2018, 10:02 PM
 
Thanks for the replies, guys.

Originally Posted by andi*pandi View Post
Do you have a power surge protector?
Sure do; it’s plugged into one when it’s in the basement, but the problem persisted when I brought it upstairs for testing and directly used a wall socket.

Originally Posted by reader50 View Post
Have you opened your iMac up for cleaning? Pull it open, blow everything out, and look over the electrolytic capacitors. Both on the logic board, and in the PS.
I’ve mostly been afraid to do that, but I think I have all the tools I need to do it. At least it’s not like the aluminum ones that need suction cups to get it apart. I’ve vacuumed the bottom grille and figured that was the best I could do from the outside since compressed air would likely cause more problems. As for the capacitors, will it be visibly apparent if there are problems? I only have a multimeter and wouldn’t be able to really test them individually, I guess.

psst ... did you check the power socket it's plugged into? Say by trying your iMac in a completely different socket for a day?
Technically yes, but only one other socket. I have an older house and the plugs throughout are of varying and indeterminate age (the basement’s are the newest). I can make room for it in a few other places and see what’s what, I think.
2009 Mac Pro: whatever hardware I need
LC575: 12”, 66Mhz Motorola, 64MB RAM, 180MB HDD

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reader50
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Apr 30, 2018, 10:33 PM
 
Originally Posted by Tallest Skil View Post
I’ve mostly been afraid to do that {open for vacuuming}, but I think I have all the tools I need to do it. At least it’s not like the aluminum ones that need suction cups to get it apart. I’ve vacuumed the bottom grille and figured that was the best I could do from the outside since compressed air would likely cause more problems.
If it's never been opened, it's way overdue for cleaning. And yes, compressed air from outside doesn't do it. You need to blow out the fans and heat sinks directly. I don't recall if the PS had a temp sensor, so it could well be plugged with dust. And turning off to protect itself, while Lion thinks everything is cool and fine. If memory serves, you need an old credit card to release the upper corner latches. It helps to squeeze the case together while pushing with the card, to reduce sticking.

Originally Posted by Tallest Skil View Post
As for the capacitors, will it be visibly apparent if there are problems? I only have a multimeter and wouldn’t be able to really test them individually, I guess.
You can't reliably test caps in-circuit. Follow the wikipedia link I posted - this is one kind of problem that's easy to see. @War is right, the G5 iMacs (2004-2005) were most affected. But your 2006 is only a year later, and it's a problem that's easy to see. And reasonable to fix.
     
Doc HM
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May 2, 2018, 11:50 AM
 
The white iMacs suffered from the same caps issue as the G5's did, just not as badly. I suspect it might be hard to track down a replacement now as past failures have eaten up all the stock, likewise the screens on these which are also prone to failing and now cost a fortune if you can find one.

That said I have had more than one client who reported their iMac switching off and the cause turned out to be trapping the power cord between desk and wall and then pulling the cable out of the back of the mac when adjusting the screen angle. Sounds silly but not uncommon.

If it is the PSU I would look at maybe one of the last of the 21in iMacs with the removable screen as a replacement rather than a mIni. The Minis are wiiiiiildly over priced, underspecced and soldered together for no reason at all. The 2012 iMac 21 is a great machine with loads of life left in it, much more powerful than your old war horse and pretty cheap now as well. What's not to love?
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Tallest Skil  (op)
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Jun 14, 2018, 01:49 AM
 
Thanks a ton for the help, everyone. Just a quick final post to close out the troubleshoot in case someone else has this problem. Yes, it was the capacitors. I got over my fear of cracking it open and lo and behold, leaking.

https://s22.postimg.cc/crpk6p373/773_D1_CAD-_A997-4_D0_E-93_AF-271_A76_D496_A3.jpg

I’m just now noticing that it autofoused incorrectly, but I’m not stripping exif again.

So now we know, and now I wait for Apple to care about the Mac line again, because not only is this sucker fully dead now, I’m posting from my iPhone because my 27” Cinema Display has had its backlights and LCD die. I know that displays have a liefespan, and I know I bought it on launch day, but this is still upsetting.

EDIT: for anyone popping open these white iMacs, I discovered that a handled cheese slicer makes credit cards obsolete and dramatically cuts down on opening effort.

http://cdn0.rubylane.com/shops/hoosi...s/13586.1L.jpg
( Last edited by Tallest Skil; Jun 14, 2018 at 02:03 AM. )
2009 Mac Pro: whatever hardware I need
LC575: 12”, 66Mhz Motorola, 64MB RAM, 180MB HDD

Ah, the good old days of signatures.
     
Doc HM
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Jun 14, 2018, 05:33 PM
 
its nice when people report back.

Good job.
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Waragainstsleep
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Jun 18, 2018, 09:03 PM
 
Which caps are leaking?
I have plenty of more important things to do, if only I could bring myself to do them....
     
   
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