William R Rudloff

Q: iMac G5 2Ghz won't do a cold startup off the harddrive, but will boot off of CD and then on a restart.

So this is what my iMac has been doing for the past couple of weeks.  When I do a normal startup, the iMac turns on and goes to the gray screen.  After a few minutes longer then it's supposed to boot up, the fans in the iMac run at full speed and the iMac won't go any further on the boot.  I then have to do a hard shut down (I miss the restart button).  I now keep the System Disk in the machine because I then have to start the iMac back up, hold down the C key until the iMac goes through the booting process off the disk.  I can usually then quit off the Disk and do a restart.  And then usually the iMac will boot normally off the harddrive.  Neither Disk Utility nor Disk Warrior 4.1 have found anything wrong when I do the diagnostics.  Any ideas?  I aleady had the power supply replaced within a couple of weeks of getting the machine, so I'm sure it's not that.  Many thanks.

Bill Rudloff

iMac, Mac OS X (10.5.8), G5 20" 2Ghz

Posted on Feb 12, 2012 4:40 PM

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Q: iMac G5 2Ghz won't do a cold startup off the harddrive, but will boot off of CD and then on a restart.

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  • by William R Rudloff,

    William R Rudloff William R Rudloff Mar 15, 2012 9:40 PM in response to steve626
    Level 1 (5 points)
    Mar 15, 2012 9:40 PM in response to steve626

    Here's the thing, if I could have affored a new or used newer iMac, I would have done so.  I needed something better than my Power Mac G3 350mhz and iBook G3 600mhz.  However, I could only afford a machine of this kind.  That said once the power supply was replaced, it was working pretty fine.  But since this boot issue started and got progressively worse, it can't be the harddrive nor the System CD.  I copied the retail 10.5.6 I had from work as that system was already preloaded onto the machine, but I also used the original disc too but have the same booting issues.

     

    The PRAM battery is the same used in our bathroom scale, a 2032.  Replacing that didn't do anything nor trying to reset the PRAM a couple more times.  I left it unplugged all last night and today, and now it's does either a series of 3 beep, the power light blinks in a series of 3, and blast the fans on high, or it partially turns on, but won't bong, the light stays on and there is a little whirr as some of the electronics run, but not the whole machine.

     

    It's a hardware issue for sure, but I've been hoping someone will be able to say what it might be so I can fix it.  So far, I've tried most of the suggestions that I can do, but nothing's working.  It won't even boot off of DiskWarrior 4.3 anymore.  It's not finiding either the harddrive or the DVD drive when I hold down the option key (assuming it doesn't freeze right off the bat).  But the fact of the matter is, I can't afford another Mac, new or used.  I have to fix this one.  Oh and gere's a link for hi res images. http://dl.dropbox.com/u/65215981/iMacG5.zip  If anyome can transcribe what kernel panics mean in normal English, that'd be great.  Again I thank everyone for their help thus far.

    Bill Rudloff

  • by noondaywitch,

    noondaywitch noondaywitch Mar 16, 2012 6:03 AM in response to William R Rudloff
    Level 6 (8,147 points)
    Mar 16, 2012 6:03 AM in response to William R Rudloff

    Three beeps usually means bad RAM or a bad RAM slot.

     

    Depending which model you have, access to the RAM requires either the back of the computer removing, or for later models just an access plate on the bottom;

     

    http://www.ifixit.com/Guide/Installing-iMac-G5-20-Inch-Model-A1076-RAM/872/1

    or

    http://www.ifixit.com/Guide/Installing-iMac-G5-20-Inch-Model-A1145-RAM/1135/1

     

    For the earlier models with two slots, remove the RAM from one slot and try to start. If that's successful, it suggestd that the remaining RAM stick and it's slot are OK. If not, one or other is faulty.

     

    Swap the RAM to the empty slot and try again. If that works, you know that RAM stick is OK and that RAM slot is OK. If not, it's likely to be the slot if the RAM worked in the other, but the RAM if it didn't.

     

    Finally, take out that RAM stick and repeat with the one you removed at first. This should isolate the problem to one slot or one RAM stick.

     

    For the later model with only one user-accessible slot, it's a bit more difficult. Remove the RAM in that slot and try to boot - there's a built-in RAM stick of 512MB. If that boots at least you know the difficult one is OK.

     

    Reinsert the RAM being sure to seat it fully and try again. If you're off with beeps again either the RAM or the slot is faulty, but the only way to find out which is with a new RAM stick.

  • by noondaywitch,

    noondaywitch noondaywitch Mar 16, 2012 6:30 AM in response to William R Rudloff
    Level 6 (8,147 points)
    Mar 16, 2012 6:30 AM in response to William R Rudloff

    Just checked with MacTracker and you appear to have the earlier one with two RAM slots.

     

    As for the pics, the first one's not really specific. The third one says it can't find a driver for the platform - that suggests a damaged OS installation, probably corrupt firmware (hence the boot to Open FirmWare (second Pic) I think).

     

    Try the RAM first - if you can get it to start you can at least try to re-install, but I would suggest with the original OS disc, after re-partitioning and erasing the HD.

    APM partition map, Mac OS Extended (Journalled)

     

    Beyond that, I suspect it would be cheaper simply to write it off to experience and replace it.

  • by Scorpio66,

    Scorpio66 Scorpio66 Mar 31, 2012 11:02 AM in response to William R Rudloff
    Level 1 (0 points)
    Mar 31, 2012 11:02 AM in response to William R Rudloff

    I think you're dealing with two unrelated issues.  One caused by incompatible OS version, the other caused by a faulty power supply unit.

     

    First problem: I have the same computer (2004 iMac G5 20" first gen, PowerPC-based) and I'm fairly certain it can't run anything higher than 10.4.11 TIger.  It's a hardware limitation.  My understanding is that only Intel-based Macs can run OS 10.5+

     

    Second problem: I'm having the same problem with sudden shutdown at the Apple screen. This is after 7 years of flawless performance.  Weird thing though, the shutdown happens only when the machine is cold, i.e. powered down overnight.  It also happens when I boot from DVD, but again, only from a cold start.  But once it warms up, it's all good. I immediately thought it was hard drive 'stiction,' but first I made sure software wasn't the culprit.  Not software.  Replaced hard drive, didn't help.  My research leads me to believe it's a bad power supply unit, possibly bad capacitors (look up 'capacitor plague', but I'm still investigating that.  In the meantime, I let the computer warm, or 'prime' (like priming a pump). How do I prime it?  Power up holding the Option key, leave the computer at the 'Startup Disk' screen (fan running at full speed is normal BTW), then after about 20 seconds click the arrow so it continues booting.  My theory is that the electricity running through the components 'primes' the system enough to prevent the failure you and I have been experiencing at the Apple screen. Until I figure it out, I just leave it running, or go through the warming/priming routine. (Yes, I've backed up everything.)

     

    Check these links discussing power supply:

     

    https://discussions.apple.com/message/2440643?messageID=2440643#2440643?messageI D=2440643

     

    http://support.apple.com/kb/HT2173

  • by MGW,

    MGW MGW Mar 31, 2012 11:26 AM in response to Scorpio66
    Level 7 (27,026 points)
    Mar 31, 2012 11:26 AM in response to Scorpio66

    The Rev A iMac G5 can certainly run 10.5.8, but nothing beyond that, it was the last PPC update.

     

     

     

     

     

     

  • by Scorpio66,

    Scorpio66 Scorpio66 Mar 31, 2012 12:03 PM in response to Scorpio66
    Level 1 (0 points)
    Mar 31, 2012 12:03 PM in response to Scorpio66

    Edit to my previous post: as Miriam pointed out (thank you), iMac G5 PowerPC can run  10.5 Leopard. 

  • by William R Rudloff,

    William R Rudloff William R Rudloff Mar 31, 2012 12:18 PM in response to Scorpio66
    Level 1 (5 points)
    Mar 31, 2012 12:18 PM in response to Scorpio66

    I think somewhere in my posts, I have already repaired my power supply. I think it may be the logic board as I am getting more firmware bios screens like the one I posted earlier. I now have in my possession an Apple System Diagnostic disc that is supposed to work with my iMac but I can't boot off of it because of the variation of the bios screen asking to enter either Mac-boot or shut-down. I've even tried to boot from an external harddrive via FireWire, but it either freezes or gives me the bios screen. I might consult with the chap who repaired my power supply and see what he thinks.

    Bill Rudloff

  • by William R Rudloff,

    William R Rudloff William R Rudloff Mar 31, 2012 12:23 PM in response to William R Rudloff
    Level 1 (5 points)
    Mar 31, 2012 12:23 PM in response to William R Rudloff

    Oh and my internal harddrive still does not come up on the Option Key loading screen (when it doesn't freeze up). I took it out only to discover that it is SATA and my external drive case is traditional ATA, so I can't test it from my iBook or try and boot from it outside of the iMac.

    Bill Rudloff

  • by William R Rudloff,

    William R Rudloff William R Rudloff Apr 7, 2012 1:02 PM in response to William R Rudloff
    Level 1 (5 points)
    Apr 7, 2012 1:02 PM in response to William R Rudloff

    Well I got a SATA external harddrive case, put the iMac harddrive nt it, hooked it up to my iBook and there it was in all its glory.  Nothing missing or damaged according to disk utility.  Hooray!

     

    So I know am certain the harddrive was never the problem.  It most definately is the logic board.  It seems anytime I am able to get it to boot off a CD, it throws me into the Firmware Bios screen asking me to mac-boot or shut-down. I tried resetting the NVRAM via the Firmware Bios, but that didn't do anything.  It also will not recognize my external harddrivesn via Firewire.  Neither the one where I cleared off and added 10.4 nor the internal drive in the external case.  So, where's an inexpensive place I can get a replacement logic board?

    Bill Rudloff

  • by steve626,

    steve626 steve626 Apr 8, 2012 10:30 AM in response to William R Rudloff
    Level 4 (1,551 points)
    Apr 8, 2012 10:30 AM in response to William R Rudloff

    You can search on the internet and find (used) logic boards for iMac G5 PPC's -- I found a whole passle of them ranging from $50 to $200. You'd need to make sure you are getting the exact correct one. Some of the vendors seem a little sketchy, maybe not much better than ebay.   I would not pursue this route myself, it's sort of like a 90-year old person getting a heart/lung transplant from another 90-year old ... not the best prognosis.

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