Power supply or logic board?

We had a funky power failure last night, and now my iMac G5 (17", 1.8 GHz, about 2 years old) is dead. Push the button, nothing happens.
I opened the case. The #1 LED is on, but it's not on solid. It's varying in intensity at a rate of a few cycles per second. Not really flashing on and off, but flickering. I've never noticed that before--I thought it was on solid when I've looked previously. Am I right about that?
The internal power button and PMMU reset button have no effect. Also, if I put my ear close to the power supply, I hear a "chirping" noise.
Any thoughts? I'm guessing it's the power supply. Any ways to test it aside from substitution? I have voltmeters and an oscilloscope and know how to use them, but I don't know where the test points might be.
TIA,
Neil
iMac G5 Mac OS X (10.4.8)

rbneil-
Take a look here.
It sounds like your power supply is dead. Apple will
repair it under the extended repair program if you
are covered.
The light should be on steady from what I remember.
That is a clue for sure.
Luck-
-DaddyPaycheck
Checking the link, it seems that the recall program only applies to the 20" model. Mine is a 17". Are you aware of Apple extending the warranty at all on that one?
Neil

Similar Messages

Power supply vs. logic board? turns off in sleep mode.

My imac g5 (2004 - 1st generation?) is either turning completely off or going into some un-wake-up-able mode after it's put to sleep. (I have to switch off/on the power strip and turn the computer on all over again.) And sometimes if it's sleeping (power light pulsing on front) it may or may not wake from sleep by pushing the power button. Often touching a key in that circumstance will cause it to crash, so I've quit using that altogether as a method of waking it up. I've reset the SMU a number of times throughout the past few months and it has not cleared up this problem.
Last night after I put it to sleep it switched in to the un-wake-up-able mode. I could still hear something running (not a fan, just an electrical hum) where it seems like it's crashed and can't shut itself off. I had to turn off the power and try to turn the computer back on. It wouldn't respond the first couple times. Then the power light glowed for a while but it still didn't turn on completely. After a few more minutes I tried again. Maybe I held the power button for too long, but I heard a long single beep, the fans whirred, and then everything started up as usual.
I've read a number of threads seemingly related to these issues, but am now not clear about whether this is a power supply issue or a logic board issue. I have yet to open the back and check for bulging capacitors. Just thought I'd ask here first.

I am having a very close issue too (posted also in a more recent thread about power button not functioning). My old iMac G5 20 inches got a power supply that went bad two years ago. I had it replaced and all went fine until two weeks ago.
My wife was using it, while I was away: machine shut down with a 'pop!' sound.
She tried to start it up again, but after pressing the button a couple of times - the last one longer - she had a long strong peep. The machine went on for a while and then off again. Scared, she left it off.
After checking, no reported issue seems to fit to the problems shown: power supply is working; logic board too. The machine is working fine, but on sleep, it dies out. While doing tasks, at undetermined times, it shuts down with a 'pop!'. Sometimes you can restart it immediately. Sometimes you can't and have to wait one or more hours. No evidently bad caps on board, led check returns 1 (no 2 flashing or attempting to turn on) with dead computer, otherwise all working fine. Hardware test also passed. Console messages have nothing relevant or clearly understandable to offer.
Still can't figure out a solution. Many user are pretty fast in suggesting to bringing the machine to Apple. Unfortunately not all around the world we have/need cars. And getting the 20 kg of iMac by feet/metro to the shop it ain't such a nice walk. When I fried the power supply, there was no sufficiently large box on sale to pack the computer and have it send to the shop. I had to wait for the technician - on a convenient day - do drop by and take it (and he knew he was going to repair it)!
Will post, if I have further developments.

Power supply or logic board failure

First time post, long time Mac user (since 1983). My older iMac G5 1.8 GHz Power PC (ALS) occasionally fails to start when I press the power button or the internal power button on the logic board. The only solution is to unplug/plug the external power cable where it meets the power supply housing (not at the outlet). None of the capacitors seem to be bulging on the logic board, LED1 always lights up, LED2-4 fail when there is a problem but are normal after unplug/plug routine. Noticed that there was no internal Lithium battery where one is supposed to be, but this has been the case for 5 years, so this is probably not the issue. I suspect the power supply. It's an old iMac with plenty of leg left and will be used as a second computer in the home. Any ideas? I don't have a volt meter, but am willing to get one if the test points are easy to get to (I'm not an electronics wizard).

Welcome To Discussions - If resetting the SMU, which is in effect what you are doing, solves the problem and the caps look ok, then the prime suspect would be the power supply unit. They are not expensive, check out [synaptech.com] for prices or[welovemacs.com] whcih will also give you instructions on how to replace it.
It would probably be a good idea to replace the battery it's CR2032 3 volt lithium button, easily obtainable at Radio Shack or similar places.
Let us know how you make out,

What do you think-Power Supply or Logic Board??

I came across a used dual 1.0 GHz MDD G4 that will not start. When the power button is pressed, the power LED will light and then go out. There is no chime and the fans all come on incredibly loud and fast. The logic board has a small red LED between the CPU and RAM slots. Does the red light mean the board is working or good?
I've swapped CPUs and got the same result. If it was a power supply issue, would the fans and logic board power up like they do? I've put a disc in the drive and can hear activity, but nothing ever happens. Also the power supply looks to be smaller than the other MDDs I've used. It also has a large separate fan at the end towards the front/speaker area.
At the same time since the logic board has the red light, it would seem that it's working also. Right? I just need help deciding what to replace next. Thanks in advance.

Here is a link to the front panel issues in general:
http://www.xlr8yourmac.com/tips/MDDps_mods/MDD_PSMods.html
The front panel with the mirror doors was off. I used a small screw driver to >push the small start up button
Thus you did not disconnect the front panel BOARD. It has it's own connector to the motherboard. If you disconnect it and then short the green lead (Powerup) on the PSU connector to the adjacent black one (GND) you are bypassing the front panel button for booting. Do this only at your own risk if you have a solid electronic experience.
Here is a helpful pinout scheme:
http://www.smalldog.com/newsarchive/techtails_display.php?id=44
Hans

Power socket on logic board

I've just put a new optical drive in a 12" 1ghz Powerbook and in the process have had a bit of a mishap...the power socket came undone from the logic board. This is the bit that connects the cable that runs from the power button to the logic board. The connector didn't come out of the socket, the whole socket came off. Seems like a large problem...any ideas what the best coarse of action is? Hopefully don't have to replace the entire logic board. Good repair places in the UK would also be welcome.
any help will be appreciated.

hi david,
I just found out today that it's been repaired. Basically, there was no way I was going to try and fix it, so I brought it in to one shop that said "nope, gotta replace the logic board," but i didn't trust them, and so i sent it off to another repair place, who fixed it today--tested, all back in action.
BIG sigh of relief. £80 instead of around £400.
So basically, it depends on how bad the board was damaged when the connector came off. I happened to get lucky (after persevering with a second opinion!)
If you find a GOOD repair house, not a lazy one that just goes for the easy and expensive fix, then you may be in luck. I'm in the UK, and I can HIGHLY recommend VIS Mac Parts as a repair house.
http://www.applemacparts.com/
In fact, nearly everyone I spoke to along the way said it would require a new logicboard, so: don't listen to them, and find someone who has the knowhow (and honesty) to repair it.
hope this helps & best of luck!!!
david

Anyone else waiting on a replacement Power Supply & Logic Board from Apple?

On Dec. 26, I took my iMac G5 to my local service provider to resolve some power issues under the Repair Extension Program. They ordered the part (new power supply and logic board) from Apple that very day, yet I'm still stuck here waiting 16 days later.
Anyone else out there waiting for this part to arrive? How long should it take? Can I call Apple directly in order to get a better estimate?
Thanks!
1.8 GHz iMac G5 Mac OS X (10.4.8)

All right, so here's the latest plot changes in the ongoing saga of my iMac G5...
I spoke with two very kind and helpful women at Apple this afternoon. Both agreed that this sort of behavior from my AASP was certainly unacceptable. I was able to lodge a formal complaint against my AASP, as well.
My particular part order was given some sort of high priority status by Apple. I was asked to call back on Friday to receive an update on the order's status.
I was also asked to send a letter to Apple's Corporate Customer Care division explaining my situation in full. I'll try to send out this letter within the next few days.
So that's where we stand right now. No computer yet, but at least SOME progress is being made.

Logic board and power supply symptoms on a Mid 2007 I Mac Intel

does anyone know what would cause my Mid 2007 Imac to quit abruply? On tun on the super drive spins up for about 5 sec and then spins down. No display No Nothing!! It was working fine up to this point. Could it be the power supply or logic board?? What other componants are in there that would cause this problem.
It is my daughter- in- law's Mac and they don't have alot of money to fix it so if I could fix it that would help.
THX for Ur Time!!

Unfortunately no one hear can truly diagnose the problem.
1. Run the Apple Extended Hardware Test using the original Install DVD 1 that came with that iMac.
Intel-based Macs: Using Apple Hardware Test
2. Call your local Authorized Apple Service Provider and have them test it.
How to find your nearest Apple Authorized Service Provider (AASP) or Apple Authorized Distributor (AAD)

6-month old Mac Pro has already had a new logic board and power supply

At a cost of $400 in shipping and a one-month wait, my 5-month old Mac Pro got a new power supply and logic board
Now I keep getting kernel panics, runaway kernel_task in Activity Monitor, and corrupted boot drives
External Firewire drives work some of the time, and occasionally my USB devices dont work either
This computer is a nightmare - how do I begin to figure out if this is OS (10.6.4) or hardware related?
The extended AHT test reports that all is OK - as does an extended memory test using Applejack
Should I do firmware updates and re-install the 10.6.4 combo pack, or am I just wasting more of my time?
I've got 4 macs and this is the only one that works badly - I think Apple's OS updates are getting as bad as Windows updates

My first question is why you spent $400 to get a 5 month old system fixed. That should have been covered under the warranty. So someone ripped you off, or you left out some key details.
And if you had both the logic board and PSU replaced, did you ever stop to think that maybe the problem lies with the power coming into your house? It's not really the big power spikes or blackouts you need to worry about, since those are pretty rare. What you need to worry about are the small fluctuations in voltage that happen several hundred times a day, if not an hour. Sometimes there's not quite enough power, other times there's a little too much, and all of this takes a steady toll on the PSU. It will do what it can to try and feed the rest of the computer a steady diet of electricity, but sometimes a jolt will get past it and start damaging other components. It could even cause data corruption on your HDD.
If the PSU and logic board already went, who knows what damage it may have caused to anything else. It may just be taking longer to show up.
It might also be that whomever ripped you off to the tune of $400 simply traded you one defective logic board for another. Or maybe they don't really know how to protect against ESD. I once saw a repair shop where the techs smoked in the same room they did the repairs. Sadly, for every one good tech out there, there's probably at least 3 complete idiots. Kind of like auto mechanics.
And I never have problems with Windows or Apple updates. Seems like on Windows the majority of people who have problems with updates are either running some program designed to change the way Windows looks or messes with low level system files, or they have a malware infestation they were unaware of/oblivious to. Most of the people who have problems with Apple updates seem to be the same way. They're running some truly bizarre programs that mess with the system in ways programs were not intended to mess with the system. There's generally a reason OS vendors provide an API for developers. You deviate from that at your own peril.

IMAC (Early 2006 20-inch) Power Supply, Logic Board

Has anyone had problems with the new 20inch iMac Intel Processor computer? Purchased the new iMac and in a month the compute was wouldn’t startup. Repair was diagnosed as Power Supply, Logic Board. Apple store switched out a new iMac computer after 2 weeks trying to get parts. The new iMac was plugged in a power strip protector. Now 2 weeks later the new computer is dead and Apple store is saying Power Supply and Logic Board is bad. I am not getting any power surges at the office and it is on a new power strip. Has anyone else had problems with the new iMac?

I got the same problem... I buyed it 2 days ago, plugged it yesterday and it worked. Today, I unplugged it to arrange all my connections(tv out, optical sound, printer, etc...) and it replugged it and pressed the power button and then... nothing... I was so frustrated... I switched to mac 2 month ago and I seem to keep having problems
Ne ways, I went to an apple store and I'm waiting for the diagnosis I'll post more news when I get some!
Ian
ps I'd like to add that the imac was plugged on a powerbar with surge protection.

1st Gen iMac Power Supply Issue

I just got my iMac G5 back from Apple after having the power supply and logic board replaced for the second time in two years.
It is apparently a fairly common problem with the first generation iMac G5s. I've basically been told it's a problem with no real solution and that they'll fix it for free (for the first three years). It's great that I'm within the three years, but if it happens again after October, I'm likely going to have to foot the bill to get it repaired.
Does anyone have any more detailed info on this issue (other than Apple's Repair Extension doc)? Would turning off the computer each night prolong the life of those parts? Would turning it on/off everyday reduce the life of those parts?
Any thoughts/comments?
Thnx...CN
iMac G5 Mac OS X (10.3.9)
iMac G5

Just to add to BB's comments, I doubt that leaving the computer on will have any benefit at all for you in terms of longevity. If you have problems with faulty capacitors , and the like, in fact it will probably make the issue worse rather than better (though I doubt this will be a problem for you if your logic board was replaced after about April 2005). Doing so will probably also add a little extra wear to the bearings of your HD (unless you have it set to spin down when not needed) , and will cost you a little more (but not a whole lot - though when we all leave them running the environmental costs continue to mount) in electricity over time.
You should probably also shut down every so often anyway - maybe once a week or so, to help clear some potential memory issues that can persist with some applications even under OSX, and you should certainly shut down at and start up again at any time when you notice slowdowns, program "hangs" or other problems.
Cheers
Rod

Mac Pro 2,1 Spontaneous Restart with No Boot - Power Supply PSU Problem?

One day I was working away on my Mac Pro 2,1 Quad Core 3.0 (2007) with 8 gb ram running Lion and it just shut itself off like someone pulled the power cord (but no one did of course). Then it attempted to restart, but wouldn't boot. Basically I haven't been able to use it since as I can't get the computer to stay on for any length of time.
I'm thinking its either the power supply or the, oh no, logic board.
Symptoms have been like this so far:
Initially I would get a chime and a boot start but then I would find the computer would shut itself off somewhere in the process and try to restart. Usually the next time I would get no chime and a horrible repeated clicking of my optical drive with a rythmic fan whirring up and down on the original ATI x1900 xt graphics card. I would have to manually power off with the power button to make it stop. Sometimes it would try to restart again anyway. The only way I could get a chime again was to unplug and wait (longer the better). But even if i got a chime and a start of a boot, invariably the computer would turn off again.
I couldn't boot from another source, I couldn't run apple hardware test, I couldn't run diagnostic,... it just wouldn't stay on to do it.
I hauled my mac pro (out of warranty) to the apple store genius bar and the problem presented itself, continuously. The gent was able to get fsck to work long enough to determine my hard drive was ok and said it was one of three things - the power supply, the graphics card, or the logic board. He said because the comp powered on and then shut off, and because there was intermittent chiming, he didn't think it was the power supply. He thought it was the graphics card and said I could leave my Mac for 10 days and they could take a looksy, or I could just install a new graphics card on my own.
I chose the latter, bought a ATI Radeon 5770 from the apple online store for $275 and installed it.
Problem persists.Exactly the same as before. Got initial chime, then next time no chime, optical drives clicking and graphics card fan whirring up and down rhythmically.
I had a touch of time to disconnect everything and I get a chime consistently now when I have my boot drive, graphics card, 4 gb ram, and monitor attached. (As well as wireless mouse, keyboard, trackpad). I even got to logon once only to have a prompt shut off and restart attempt. also I verified it was at least one optical drive clicking (when I removed them both) during these boot attempts.
The improvement in chiming seemed to be when I unseated one ram riser ( I have to with 2 x 2g ram modules each).
I also checked the diagnostic leds on the logic board and all was as it should be... says I got trickle power and rail power etc.
Is there anything else I can do to determine what's wrong? What do you guys think is wrong? Could it be bad RAM? Power Supply? Logic Board?
All your help is massively appreciated in advance!

Well I ran as many tests as I could with no definitive results to the point I would have to start buying replacement parts and testing that way. I opted to take it back to the apple store and they said it's (dun dun dun dunnnnn) the logic board.

Recently replace logic board. Cannot open software purchased from Ap Store.

The Power supply and Logic Board were replaced. Now I cannot open software purchased from Ap Store. Computer gave message this was purchased for another computer and go go Ap Stor.   I did, and nothing suggested what to do??? Suggestions?

You only know a very small part of the story.   THE ORIGINAL iMAC WAS ONLY JUST OVER A MONTH OLD! The original Appointment was screwed up by Apple Support(?). I was told to drop it off in the morning and return for the 3:15PM appointment, which I did only to find there had been no appointment made, but the case number was in the system. I was told 3-5 days only to be notified by e-mail on the third day the logic board (motherboard) was bad.   Another wait. A week later it was ready and it ran from about noon until the next day about 11 AM when it had an update that required a restart where is promptly died during the restart. The Mgr of the Apple Store was gracious and had the computer replaced with a new one rather than trying something else.   Perhaps, you think it is fun to sit in a noisy store for half an hour or more, but I sure don't. Where is Apple's QC??? China!
I owned a computer business for 15 years and never once made a customer go through this much trouble.
If my computers made it through a 72 hour burn-in and did not have a problem in the next couple of weeks it never did have a failure.   My 15 year record of building computers had less than a 1% failure rate.
By the way, for your information if a new logic board is installed (I seemed to see several being done each visit) and the App does not recognize it, just uninstall it and go to the App store and re-install it.

Troubleshooting power supply failures

I'm branching out this thread as a continuation of <http://discussions.apple.com/thread.jspa?threadID=2418851> since the topic has evolved and the subject is no longer accurate.
I have a 2.1GHz iMac G5 (iSight) that does not boot reliably and sometimes goes into deep sleep and can't be awakened. I have ruled out software and RAM issues, leaving power supply and logic board as the likely suspects. I'm leaning towards the power supply. I'd like more info on the symptoms of power supply failures and see if my symptoms are consistent with it.
*Reasons to believe it's the power supply:*
• symptoms are consistent with the computer not getting enough power.
• it's a more common failure.
• Computer has 4+ years of continuous usage.
• the left side of the vent had been warm lately (that fan pushes air over the HD then the PSU)
*Reasons to believe it's the power supply:*
• visual inspection showed no damaged capacitors (although there could be hidden damage)
• in my previous experience with power failures, the Mac shut down completely, not half way.
*Reasons to believe it's the logic board:*
• problem triggered by adding RAM (although that's not the only trigger and removing the RAM didn't • instantly solve the issue. Timing may have been a coincidence)
*Reasons to believe it's not the logic board:*
• It passed all the Apple hardware and Techtool Pro tests.

FYI, you can access them in /private/var/logs, but you need to use a utility to show invisible files first.
The last system.log entry is
May 8 13:19:33 eric kernel[0]: IOPMSlotsMacRISC4::determineSleepSupport has canSleep true
So it looks like it went into sleep normally, but couldn't wake up or shut down without recording any more log entries.
windowserver.log had a few errors 20 minutes earlier:
May 08 12:56:56 [66] Server is starting up
May 08 12:57:00 [66] CGXMappedDisplayStart: Unit 0: boot screen
May 08 12:57:00 [66] CGXMappedDisplayStart: Unit 0: no display alias property
May 08 12:57:00 [66] CGXMappedDisplayStart: Unit 1: no display alias property
May 08 12:57:00 [66] AGCAttach: Couldn't find any matches
May 08 12:57:00 [66] CGXPerformInitialDisplayConfiguration
May 08 12:57:00 [66] Display 0x4271440: MappedDisplay Unit 0; Vendor 0x610 Model 0x9c51 S/N 0; online enabled built-in (0,0)[1680 x 1050], base addr 0xb0018000
May 08 12:57:00 [66] Display 0x3f003d: MappedDisplay Unit 1; Vendor 0xffffffff Model 0xffffffff S/N -1; offline enabled (2704,0)[1 x 1], base addr 0xb0018000
May 08 12:57:03 [66] GLCompositor: GL renderer id 0x00021802, GL mask 0x00000003, accelerator 0x0000281b, unit 0, caps 0x00000003, vram 128 MB
May 08 12:57:03 [66] GLCompositor: GL renderer id 0x00021802, GL mask 0x00000003, texture units 8, texture max 2048, viewport max {2656, 2656} extensions 0x0000000f
May 08 12:57:22 [66] kCGErrorFailure: CGXDisableUpdate: UI updates were forcibly disabled by application "Finder" for over 1 second. Server has re-enabled them.
May 08 12:57:22 [66] kCGErrorFailure: Set a breakpoint at CGErrorBreakpoint() to catch errors as they are returned
fsck_hfs.log shows the disk is fine:
/dev/rdisk0s3: fsck_hfs run at Sat May 8 12:56:40 2010
/dev/rdisk0s3: fsck_hfs run at Sat May 8 12:56:55 2010
/dev/rdisk0s3: ** /dev/rdisk0s3 (NO WRITE)
/dev/rdisk0s3: ** Root file system
/dev/rdisk1s3: fsck_hfs run at Sat May 8 12:56:55 2010
/dev/rdisk1s3: ** /dev/rdisk1s3 (NO WRITE)
/dev/rdisk1s3: QUICKCHECK ONLY; FILESYSTEM CLEAN
/dev/rdisk1s3: fsck_hfs run at Sat May 8 12:57:06 2010
/dev/rdisk1s3: ** /dev/rdisk1s3 (NO WRITE)
/dev/rdisk1s3: QUICKCHECK ONLY; FILESYSTEM CLEAN

Exploding Power Supply

Last week the power supply of my 9 month old Mac Pro exploded with a huge bang. I was really scary. No visual damage, but the whole system is fried.
Let me give you a summary of the history:
first repair - Audio failure --> Logic board replaced
second repair - Mac was dead --> power supply replace
third repair - Mac was dead --> no problems found
fourth repair - Power supply exploded --> Logic board, power supply, etc is going to be replaced.
I called Apple and they want to repair my Mac Pro again. My question to Apple was: "How many times do you have to replace parts until I get a new Mac Pro?".
I'm really sad with the quality of my Mac Pro. It's a great system, but it's not reliable. Luckily I've purchased a MacBook some months ago, but I need my Mac Pro to do my job.

Looks like I'm joining the exploding PSU club. I powered down my Pro after work last night (I usually leave it on all the time) and when I came into the office this morning and pressed the power button I got a flash of bright white light from within the case in the PSU area and a loud snapping noise. The thing that I'm not sure about now is how the repair's going to go. Since I work at a University, I have to take the machine back to Tech Services and I'm just praying that I don't get personnally stuck with the repair bill.
Oh, and I've popped out my 3 data drives -- I'm not sending those to tech services with the machine!

New power supply and sleep light question

I just got my iMac back with a new power supply and logic board installed under the Apple repair extension program. I had diagnosed the problem using the Apple troubleshooting assistant online. When I did this I also reset the SMU (system management unit) per the instructions with the troubleshooting assistant.
My computer is now working correctly but when I run Software Update I am prompted to install the iMac G5 Sleep Light Update version 1.0. I had previously installed version 2.0.0 back in July/05. I don't have the ambient light sensor iMac. I am a little nervous about installing this version or reinstalling the version I alreay have in my utilities. I realize this is a firmware update and cannot be reversed.
Anyone else experience this with 2 different versions of the Sleep Light Update, I don't seem to be able to find any info on the Apple site.
Thanks for any info
Scott

"reinstalling the version I alreay have in my utilities"
Please correct me if I'm wrong, but if you have it in your utilities folder, I believe that means that the installer folder has been downloaded, but the install was not done. I am thinking that once installed, it disappears from the Utilities folder.
I see no reason why you would need to do that firmware update if you don't want it. In the future, if you or someone else wants to do the update, it'll still be available on the Apple website.

Power supply or logic board?

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