Dead iMacs (CRT)

Posted by Pierre Igot in: Macintosh
August 11th, 2003 • 11:27 pm

As a Macintosh tech support person for the local community, I am starting to see more and more hardware problems with CRT iMacs purchased 3 to 4 years ago. The most common (and least problematic) issue is a dead PRAM battery. The symptoms are often rather obvious (the system forgets the date and time after a restart, there are occasional startup problems, etc.) and fortunately the problem is relatively easy to fix (although the slot-loading iMac isn’t exactly the easiest Mac to take apart).

More problematic are the incidents I have seen in the past couple of weeks. One friend’s iMac suddenly started making horrendous noises, and it turned out that the hard drive was damaged beyond repair and had to be replaced.

Then last week I was called in to take a look at another slot-loading iMac which had started to behave erratically. The hard drive had problems that Disk Repair couldn’t fix, but I was able to fix them with DiskWarrior. But then I also noticed that the date and time had been reset. So I started suspecting a dead PRAM battery again. I tried turning the machine off and back on once more to see if it would forget the date and time again, and… it wouldn’t start at all.

It turns out that it was a second-hand machine that had an existing problem with the power button itself. (There was a coin taped on top of it, and the customer was using the power button on the keyboard itself. When I removed the coin, I found that the power button was not “clicking” properly half of the time — and it definitely was not able to make the machine start up again.) But this was obviously a more serious problem.

I came back the next day with a new battery, and took out the existing one. My tester indicate that it was indeed dead, so I hoped that the new battery would revive the iMac. No such luck. It still wouldn’t start. No noise, no chime, no nothing. Dead. I tried pressing the “PMU” reset button on the motherboard, but that didn’t help either.

Unfortunately, that’s the limit of my knowledge of hardware problems. The information I was able to gather online and from a colleague is that this iMac probably has a more serious problem, such as a defective power supply unit or even a defective motherboard, and that it would involve expensive repairs by an authorized technician.

I just find it strange that it would just happen as the PRAM battery was clearly in its last stages and was the most likely source of the cascade of events that had prompted the customer to call me in the first place. But I don’t know what else to try to revive the iMac. I left it unplugged and without a PRAM battery for 48 hours, and tried again. Nothing. I pressed on the PMU reset button for 30 seconds. Nothing.

All I could do was assure the customer that the hard drive contents were probably safe and that I would able to retrieve them if they decide to get a replacement machine.

Still, that’s quite a few problems with slot-loading iMacs in the past couple of months.

43 Responses to “Dead iMacs (CRT)”

  1. MacDesigner says:

    If a system has a bad power button, you can always add a onCue power button. It attaches between the keyboard and computer. My G4 was one of a line of AGP G4’s that had defective power button boards. Unfortunately, due to various reasons, it was not repaired before the warranty expired. I also needed it as I was purchasing a new keyboard that didn’t have a power button and would have not been able to start my computer.

    You could use the onCue as another way to make sure it is not just a bad power button on the computer or a bad keyboard power button.

    Here is an link for the onCue at MacWarehouse:

  2. Pierre Igot says:

    Thanks for the tip. However, if the power button on the keyboard doesn’t do anything, I don’t see how this particular accessory could have more success.

    FWIW, we also tried with another USB keyboard, and it wouldn’t work either.

  3. MacDesigner says:

    “However, if the power button on the keyboard doesnít do anything, I donít see how this particular accessory could have more success.”

    My tip was aimed at allowing you to check if the power button on the original keyboard was working properly. It’s smaller and easier to carry than a second keyboard.

    I needed to get an onCue because my keyboard’s power button was becoming erratic. Combine that with the bad power key on the tower and I was having problems starting my computer. One day after installing an update I clicked shutdown instead of restart, and couldn’t restart my computer for over 20 minutes. Not a fun time.

  4. Pierre Igot says:

    OK, understood. Thanks.

  5. ssp says:

    A friend of mine has a ‘dead’ (slot-loading) iMac with a dead display. Actually he suspects the whole video board may be broken. He’d quite like to just continue using it as a server, say, but after starting up – with chime and all – the machine will just turn itself off again.

    Have you seen that behaviour before? Any hints?

  6. Pierre Igot says:

    Haven’t seen that particular behaviour, no, but have had an iMac (original Bondi Blue) which needed a new video board.

    In my case there is no chime, nothing. It’s really dead :-/.

  7. Pierre Igot says:

    Sorry, apart from checking the PRAM battery and using the PMU reset button, I don’t have any suggestions.

  8. Man says:

    trying to fix my friend’s imac. it’s tangerine and according to a site it’s of the rev C (no bump on the mouse). problem: starts up with no chime at all and the power button would go “amber” or “orange”. the screen stays blank. hard disk seems to be spinning (according to the noise made). can you help?

    thanks in advance,


  9. John Miao says:


    When you have a chance can you please tell me where the CUDA (or PMU reset) button is on my iMac?


  10. Pierre Igot says:

    It depends on whether you have a CRT or FP iMac. Seeing that this thread is about CRTs, I am assuming it is the former.

    Unfortunately, that means that you have to take the iMac apart (if you haven’t already). It’s right next to where the PRAM battery is located, on the motherboard. It’s a small round button and I believe there’s something written on the board right next to it.

    For instructions on how to take the slot-loading iMac apart, please refer to:


  11. David Anderson says:

    For those with dead video on their CRT iMacs have a look at
    for instructions on how to replace the Flyback Transformer.

  12. Tor Sigurdsson says:

    There’s always the iMac service manual to help you out:

    You should be able to go far with those.

    I unfortunately have a slot-loading iMac that chimes but stays dead past the chime.
    I have replaced the battery, and tried the PMU switch to no avail.

    Wonder if I’ll be able to revive it :

  13. Pierre Igot says:

    Thanks for the link. However, as far as I know, these manuals are not supposed to be freely available on the web, are they?

    Since I first posted this item, I’ve had to deal with another slot-loading iMac. However, replacing the battery in that one didn’t fix it. I’m still getting nothing – no chime, no response of any kind. Tried the battery, the PMU switch, etc. Nada.

  14. John Miao says:

    Any suggestions on how to fix this problem?

    Thanks, John

    Pasadena, CA

  15. Pierre Igot says:

    Nothing. Sorry. (I’m still looking myself.)

  16. John Miao says:

    Any suggestions as to where in Pasadena, CA to take this to get it repaired?

  17. Thomas says:

    I¥ve got a problem with an imac dv 400 se. It doesn¥t connect to firewire devices any more. It loads my ipods battery, but doesn¥t mount any firewire harddrive or doens¥t connect to firewire cd-burners any more.

    Any ideas?


  18. Pierre Igot says:

    Could be a dead FireWire port. Did you try running the Hardware Test CD?

  19. Thomas says:

    I already thought of this, but i have no hardware test cd for this imac. Should i have one ?

  20. Pierre Igot says:

    It seems to me that all Macs come with a Hardware Test CD. At least it has been the case for quite a while.

    Not sure what else you could try.

    Are you running OS 9 or OS X? Have you tried with different cables? Do you remember the exact time when it stopped working?

  21. Thomas says:

    I think apple just startet sending a Hardware Test CD when the 500 Mhz iMac came out. So i don¥t have a Hardware Test CD. I¥ve tried several cables, several devices (ipod, cd-burner,…), several systems (os 9.2.2, os x 10.2.4, 10.2.6, 10.2.8) and even tried to fix it as a hardrive problem (diskwarrior, first help, fix the rights on the harddrive)and it still doesn¥t work. The problem is, i don¥t remember when it stopped working and what i was doing at that time. Thanks for your help, perhaps i just go and get an eMac…

  22. Pierre Igot says:

    You might find the following interesting:

  23. Thomas says:

    Ye, pierre, quite interesting, but does it in fact say anything,how to repair the damage yourself if you¥re out of warranty? I think it leaves my ipod useless unless i buy a new mac… Have you heard of a way to exchange the firewire-ports and electrics yourself? Perhaps i just try to get an old motherboard via ebay.

    Thanks for your help…

  24. Pierre Igot says:

    Yes, I suspect that the only way to work around the problem is to swap the motherboard. If your computer had expansion slots, you could install a PCI FireWire card, but obviously that’s not the case here.

  25. Thomas says:

    So i¥ll try some other tricks i¥ve read in the last days first: switch back to 10.2, let the imac unpowered for a day, try to reset all again and then check for a motherboard at ebay…

    Thanks so far.

  26. John Miao says:

    I’ve given up trying to fix my slot-loading IMac – as it will not start.

    Is there a way I can get the contents of the memory on my IMac without repairing the machine?


  27. Pierre Igot says:

    You mean the contents of your hard drive. Yes, the hard drive is pretty easy to remove and can then be installed inside any computer that supports IDE/ATA drives, with minimal work. You can also buy an external enclosure that would turn it into a FireWire drive.

  28. John Miao says:

    Thanks Pierre!

    Do you know where I can buy such an external enclosure for the hard drive?

  29. Pierre Igot says:

    Other World Computing has been pretty reliable for me over the years, although their shipping options are somewhat limited. You can probably find such enclosures there.

  30. iMacUser says:

    I have noticed many problems with some of the CRT iMacs that ive had at work over the last year. After about 2-3 years of working fine everything is going wrong. I have to say I hate every one of them….. given up completely. The first problem i’ve found is that the CD drives (the slot loading ones) slowly cease to operate as they should…. PS, NEVER PUT THOSE CARD SHAPED CDS IN A SLOT LOADING IMAC, this will kill the cd drive pretty quick. Then I had a problem with the screen rolling until it just gives up and goes black. This is a huge pain because theres no real fix for this, hardware test does nothing, the tune up dials at the side(under the shell) are only for brightness+contrast and if to manage to get through the laborynth of hidden fixings to get the top shell off the iMac to get to the CRT itself…. you will find that the adjustment screws on the top of the ray tube wont help with the tracking at all.
    The only thing i can suggest in this situation is to go and buy an external monitor and forget about the iMac CRT.
    Nothing seemed to fix it, full reinstall, firmware updates etc etc. Dead.

    Does anyone know if it is possible to use the DV imac in target disk mode by connecting to another mac through firewire and holding ‘t’ at stratup?
    Doesnt seem to be working for me?

  31. sam says:

    Not sure if you still need the info. but here it is

    Target Disk Mode
    The user has the option at boot time to put the computer into a mode of operation called Target Disk Mode (TDM).

    When the iMac is in Target Disk Mode and connected to another Macintosh computer by a FireWire 400 cable, the iMac operates like a FireWire mass storage device with the SBP-2 (Serial Bus Protocol) standard. Target Disk Mode has two primary uses:

    high-speed data transfer between computers

    diagnosis and repair of a corrupted internal hard drive

    The iMac can operate in Target Disk Mode as long as the other computer has a FireWire 400 port and either Mac OS X (any version) or Mac OS 9 with FireWire 400 software version 2.3.3 or later.

    To put the iMac into Target Disk mode, you restart the iMac and hold down the T key until the FireWire icon appears on the display. You then connect a FireWire 400 cable from the iMac to the other computer. When the other computer completes the FireWire 400 connection, a hard disk icon appears on its desktop.

    If you disconnect the FireWire 400 cable or turn off the iMac while in Target Disk Mode, an alert appears on the other computer.

    To take the iMac out of Target Disk Mode, you drag the hard disk icon on the other computer to the trash, then press the power button on the iMac.

  32. Pierre Igot says:

    sam: Thanks, but in this case it was impossible to start the iMac altogether, so the TDM was not an option.

  33. EXO2 says:

    Hi pierre!
    no speak spanish?..
    my english is bad..i’m try to translate…
    my imac 350 blueberry slot loading is gone…
    is my first imac in the year 2001,
    and have the same problem,the analogic board ($200us)
    you can try this,the 2 possible things,
    the little fuse in the front of the card,above in the crt,
    this is a resistor-fuse alone,and cut the voltage to the
    conmmuted transistor in the tube crt,
    ok? is good?
    change the transistor, is the big one in the dissipation
    aluminium, no work?change it,is difficult to buy,
    apple don’t sell it!
    my imac alive 6 months more and died again,
    the last chance,change the analogic board…..
    saludos amigos!

  34. Pierre Igot says:

    Sorry, don’t speak Spanish :). Thanks for the additional tips. They might be useful to some…

  35. TheMacGuru says:

    update the firmware
    use external monitor if you have too to get the job done
    tap the power button on the front 1 time and then hit the space bar…..(should take you out of sleep mode which may be a by product of the firmware issue)

    note: this happens usually after people have tried to install OS X before updating firmware

  36. Kathi says:

    I have a slot 300 imac

    It would not start up so i opened up checked the battery, its ok
    then I reset the computer

    I started the computer and zaped the pram

    The computer started up but the screen was blank.
    the computer beeped and i hit the return key and it shut down.

    is there a was to set this up to an external monitor?
    it is not like an older imac where i can see the chords, so i am looking for the location of where to hook up if possible an external monitor to save the computer.

    Thanks in advance.

  37. arnie says:

    There are to my recollection two forms of imac. One with an external svga connector and one without. The imac without the ext connector looks to me to use the old world apple DB15 monitor connector that’s built into a dist board to the rear of the cdrom drive. I believe you can connect an external monitor to this, but would have to remove the bottom plastics so it’s not really viable. The latter imacs have a hinged plastic latch to the rear that can be undone and behind it will be the svga connector for an external monitor.

  38. arnie says:

    I’ve got two imacs in at the moment, an old world imac 266 and the newer imac 450DV. Anyway, they’re both dead. The older imac won’t even try and start and the newer one is well…. toast. I plugged the newer one into a power source and the rear circuitry to the CRT tube, which is housed in it’s own circular faraday cage lit up like a christmas tree, buzzed loudly and scared the living daylights out of the respective other half becuase of the smell. Basically, having been fixing macs for years, I reckon the imac isn’t as hot as it was originally made out to be. It’s not the built in obsolescence that gets me, but the fact that with the crt built in, there’s yet another item that can fail as and when.

  39. Fred Talbot says:

    I have a similar problem to ssp’s on a Imac 266 tray strawberry. Startup chime and 1 to 3 seconds of life after the power button turns from amber to green, then goes black. Startup action keys, reset and CD’s have no effect. I have done professional equipment repair and amateur tv, I am about to go beyond the belly of the beast, where I found a suspect surface-mount (box-shaped) resistor,with a dark oval discoloration on its top face, on the logic board. Help diagnosing if this is a CRT problem would be encouraging, service manuals are inaccessable to an unpurchased apple devotee. You are my ballpark.

  40. jeannemrm says:

    At work, they bought 2 imac dv 400s a few years ago…and they recently needed new batteries. Both, however, refused to start again even with new batteries and resetting the motherboard. however, thanks to a kid who wouldn’t give up, one of them eventually started after lots of button pushing…The second machine did the same….after about 10 to 15 min furious button pushing, it goes from a blink of the light+whir/click to eventually making more clicks (screen trying to come on) and eventually a chime and then it will start and quit but eventually will come up and continue working, can be restarted, shut down briefly and restarted etc. however, if you have it shut down for more than a few minutes, you have to go through the whole mess again!!!! I’ve seen people all over the net complaining about this, and the fact that two of this same machine, bought at the same time, have done the same thing tells me one thing: Hardware/design flaw for this model! There are too many examples out there of this to be coincidence. Of course, it doesn’t show up until well after the warrentee has run out, but I think Apple needs to be made aware of this (though I’m sure they are) and give some responsible answers and solutions or even recalls!

  41. jeannemrm says:

    forgot to mention one thing regarding the imac dv startup problems. It almost seems like it needs to let the electricity seep into the motherboard little by little until it finally reaches the booting protocals….so that when it is off too long, or unplugged, the charge in the board dissapates and you have to begin again.

  42. shadowfax says:

    I have a imac 600 running 10.2 on a 6 GB HD
    I wanted to install a larger HD either a 30 or 60 but I run into the problem that the HD will not spin up. I can put the old 6 back in and everything is ok but if I put the larger one in nothing.

    I should mention that I had the 60 working for a short time until I upgraded to 10.3. the install went great and I was using the machine the first day and I shut down. Big mistake, I got the blinking question mark. I tried everything to get it going but eventualy put the 6 back in and it started.

    I put the 60 in my B&W and it started right up in 10.3 except for one small problem, it was all grey colors. Very hard to read. I changed the startup disk to 9, rebooted and everything was peachy again. I was able to do this 3 times.

    Has anyone seen this before?
    IF so how did you fix it?

    I need a larger hd and at least 10.2.8 to run photoshop cs

    thanks in advance

  43. Pierre Igot says:

    shadowfax: Did you check the drive compatibility reports at I always check them for the machine that I am upgrading, to see if other people have experience with the same brand of HD.

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