iMac 24” wont start after power cut :o(

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    Posted: 12 May 2009 10:13 AM

    Hi all,

    I’m hoping someone might have experienced this before or can offer some advice. The other day we had a power cut and since then my iMac won’t startup. The behaviour is iratic - sometimes I just get a grey screen, sometimes I get the flashing folder with a question mark, sometime the mac will recognise start up keys like holding C to boot from optical or D to run hardware test. Sometimes it will not recognise the startup keys and stays on the gray screen.

    One time I got lucky and managed to boot from the optical, but it couldn’t see my internal drive, following that I did a hardware test (extended) and then booted from optical, it saw my disk. I formatted it, re-installed Leopard and restored from my TimeMachine backup. Ran repairs on the disk and the permissions just to be safe. On reboot it wouldn’t start again. I went through the same hit and miss of getting it to boot from optical, HW test etc. Eventually managed to format the disk again, reinstall Leopard, but this time I didn’t restore from TM. I Just used TM to restore files I wanted to my docs, itunes, etc. I also re-installed my apps using the installers (not my just restoring to applications or restoring the libraries). I thought I had it all sorted, switched off for the night. In the morning same story! Hardware Tests say all is well…

    Thanks for taking the time to read this, any help is appreciated

         
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    Posted: 12 May 2009 11:02 AM #1

    How old is the machine?

    Might try two things. First, zap the PRAM by holding down cmd-opt-P-R during startup until you hear the chime for the third time.

    Second, see if your battery needs to be replaced. There should be one on the motherboard. You can look up how to replace it online.

    It is very likely however, based on the symptoms, that the motherboard has a problem. You may want to drop it by an Apple store.

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    Posted: 12 May 2009 03:42 PM #2

    Hi Intruder.  Thanks for your advice.  I tried the PRAM thing the first sound I heard was a low tone - reminded me of error beeps you get from motherboards on PCs sometimes.  I then got the three chimes when i released the keys it stayed on the grey screen.  I reset the power, I got the flashing ? folder and.  I reset again with the keyboard and everything else but the network cable unplugged - grey screen again :(

    I bought the iMac in October 2007 (didn’t take out AppleCare - a bit too confident in Apple’s reliability!).  I’m reluctant to take it into the apple store because of ???.  If there is a mobo problem anyone have any idea what this might cost?

    In the meantime I’ll take a look at the battery replacement procedure.

         
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    Posted: 12 May 2009 05:23 PM #3

    OK I tried the PRAM reset again - this time only waited for two chimes.  So far so good.  I’ll confirm if this does the trick or not.

         
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    Posted: 19 May 2009 03:43 PM #4

    OK.  The PRAM trick did not work after all.  Subsequently I found that the Mac seemed to crash whever it went to sleep.  As a workaround I set the mac not to sleep and it stayed up for about three days - then the finder stopped responding and from then on it is properly deaded!

    I ran the symptoms past a Genius at my local apple store and they suggested that it sounded like a logic board (motherboard) problem.  I enquired into the prices.  ?50 for diagnonsis, which would be waived if a fault was found and the repair was booked.  Price for motherboard ?500 plus labour.  Ouch.

    I must admit that being a switcher from PCs I am now wishing it was easier to replace parts myself.  Whatever - Although this has happened I still prefer the Mac - this is the first problem I’ve had in nearly 2 years and it was caused by an external event.  Luckily my home contents insurance should cover it :O)

         
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    Posted: 21 May 2009 12:17 PM #5

    Try unplugging all peripherals except the keyboard and mouse. I had a USB device that was causing problems such as you describe. It was one of those LED light sticks and I was using it to illuminate the keyboard drawer. Anyway, maybe the power outage affected a USB hub or something attached to it.

    From what I understand it isn’t so much the power cutting off suddenly, but the spike that comes through when the power comes back on that causes these types of problems. I have UPS devices for all of my computers because they offer better surge protection than power strips. I like the UPS products from apc.com, but there are other ones that do the job.

    I hope that you get your Mac up and running smoothly as quickly and as cheaply as you can.

    [ Edited: 21 May 2009 12:25 PM by Lee Dronick ]

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    Posted: 21 May 2009 12:20 PM #6

    Sir Harry has hit on something I’ve had a problem with in the past when using my iMac 24”.  Barring that if it is still unresponsive, take it to the nearest Apple Store and get it fixed properly and be sure to pick up a very *good surge protector to plug it into when you get it back (assuming you didn’t already have one)

    * a good surge protector should have a fuse.

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    Posted: 21 May 2009 12:38 PM #7

    ChoMomma - 21 May 2009 03:20 PM

    Sir Harry has hit on something I’ve had a problem with in the past when using my iMac 24”.  Barring that if it is still unresponsive, take it to the nearest Apple Store and get it fixed properly and be sure to pick up a very *good surge protector to plug it into when you get it back (assuming you didn’t already have one)

    * a good surge protector should have a fuse.

    A number of years ago I attended a lecture given by an electrical engineer and he explained that over time a “simple” surge protector becomes ineffective. What happens is that there are small electrical spikes coming through the wires all the time. The surge protector dampens those, but in that process it sacrifices itself so that eventually it becomes just a power strip.

    With an UPS (universal power supply) unit not only do you get some battery backup time, but it breaks the electrical circuit when a spike comes in.

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  • Posted: 21 May 2009 12:43 PM #8

    ChoMomma - 21 May 2009 03:20 PM

    Sir Harry has hit on something I’ve had a problem with in the past when using my iMac 24”.  Barring that if it is still unresponsive, take it to the nearest Apple Store and get it fixed properly and be sure to pick up a very *good surge protector to plug it into when you get it back (assuming you didn’t already have one)

    * a good surge protector should have a fuse.

    A surge suppressor would not have helped avoid this problem in the first place. Buy instead a battery backup from APC or Belkin if you can still find them. A Back-UPS RS 800VA model should be enough for a 24” iMac plus a backup drive and cable modem and router. You could go cheaper and get a Back-UPS ES 700 Do not plug printers or scanners into the battery backed outlets.

         
  • Posted: 21 May 2009 09:16 PM #9

    If you’ve got DiskWarrior boot from it by holding down the “c” key on keyboard at startup. DiskWarrior doesn’t “repair” a directory it replaces it. Has the HDD been making any strange sounds?

         
  • Posted: 22 May 2009 04:07 AM #10

    I have an emac and had the same problem.  Turned out one of the 256MB ram was bad.  Took it out and the mac would start and not crash. Try swapping RAM to see if it helps.

         
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    Posted: 30 May 2009 08:06 PM #11

    markf21 - 22 May 2009 12:16 AM

    If you’ve got DiskWarrior boot from it by holding down the “c” key on keyboard at startup. DiskWarrior doesn’t “repair” a directory it replaces it. Has the HDD been making any strange sounds?

    Yeah I’d give DiskWarrior a shot too myself. It has brought back a Mac that was cut off short during an electrical power outage as well and exhibited the same symptoms.

     

    Since then, I have upgraded my DiskWarrior software and… I now have a UPS Back-UPS unit. This model right here. But you can get cheaper units too. We simply had two Macs to plug in it.  smile

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    Posted: 05 June 2009 04:11 PM #12

    Hi All,

    Thanks for your adviCe on here - it is much appreciated.  I wanted to update the thread, because I hate it when threads just tail off!

    I did have it plugged into a surge protector, but interesting what Sir Harry says about them deteriorating over time.  Could explain why it didn’t work.

    I tried unplugging everything and still have the same problem.  Intrestingly as well, as mentioned above - whereas I had a workaround for a while, because it would start or at least boot from optical or hardware test, or start in safe mode around 30% of the time, now it never starts and never boots from optical, safe mode, HW test etc.

    While I could boot from optical I tried disk warrior, I don’t think it made any difference.

    I wonder whether as intruder mentioned above it could be the battery…

    Anyway, my home insurance have come through and I will be replacing it - waiting for WWDC next week just in case Snow Leopard gets released or something like that! :O)

    As I’m replacing it, I’m very curious to have a go at fixing it myself - nothing to lose - right?

    I will try the battery first, they cost about GBP 2.00 Next, i will try to find a motherboard (logic board) at a reasonable price.  Has anyone got experience of this?  I have the 24” Alu from mid 2007 (model A1225).  I wonder if I have to put the exact same board in there, or if I can put a better one in - will all the leads be the right length, fit in the chasis, be able to use the same graphics card, memory, anything else i might not have thought of!

         
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    Posted: 12 June 2009 12:53 PM #13

    UPS also fail over time as the batteries age.  When they fail (and they will) they’re at least as risky as an old surge suppressor.  They have battery status lights but I’ll estimate not one in One Thousand is even located where it can be seen.
    My employer suffered a data loss that led to an email to check them.  Corporate wide 68% were dead.  Now we check the lights every month.

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  • Posted: 24 November 2009 01:59 PM #14

    Hi there.
    Can a power cut damage your hard drive? we are having quite a lot the last couple of day and it’s worrying. Also, could the cuts damage a router? thanks for your help!

         
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    Posted: 24 November 2009 02:03 PM #15

    Yes to both. Especially if they come with a surge.

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