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  1. #1


    Member Since
    Apr 25, 2007
    Posts
    26
    imac g4 flat-panel
    Hi guys,

    I have an imac g4 flat-panel 800mhz, the usb ports appear to have suddenly stopped working, the system boots up, but I cannot log in or change the boot mode as I cnanot use a keyboard.... any advice before I crack it open? I'm familiar with mac innards, I have repaired about 5 now, but I haven't come across this problem before, any advice at all would be great.


    Regards,
    Baris

  2. #2

    bryphotoguy's Avatar
    Member Since
    Feb 02, 2007
    Location
    Chicago, IL
    Posts
    3,978
    Specs:
    Quad 2.8GHz Mac Pro, Edge iPhone
    Do you have the restore discs? I'd startup with it and try fixing the permissions and check for errors on the hard disc.
    Pop the disc in and restart the computer. Hold option right after you hit the power button to bring up the boot menu. Choose the CD and click the right arrow. When the computer restarts, it should start with the CD. See if you can fix the permissions and such.
    Or try resetting the PRAM... Apple, Option, P, R during startup. Hold till computer chimes a second time. Or do it till it restarts a 3rd time.
    I've never seen this, these are simple easy fixes before you open up the case.
    Hope this helps!!
    Bryan

    January 2008 Member of the Month

  3. #3


    Member Since
    Apr 25, 2007
    Posts
    26
    Quote Originally Posted by bryphotoguy View Post
    Do you have the restore discs? I'd startup with it and try fixing the permissions and check for errors on the hard disc.
    Pop the disc in and restart the computer. Hold option right after you hit the power button to bring up the boot menu. Choose the CD and click the right arrow. When the computer restarts, it should start with the CD. See if you can fix the permissions and such.
    Or try resetting the PRAM... Apple, Option, P, R during startup. Hold till computer chimes a second time. Or do it till it restarts a 3rd time.
    I've never seen this, these are simple easy fixes before you open up the case.
    Hope this helps!!
    Bryan
    Hi, thanks for the enthusiasm unfortuantely as I said above, the usb-ports don't seem to work, therefore I can't do anything that involves using a keyboard. I was hoping there might be other options, maybe remove a battery temporarily or similar? A kind of manual purge.

    Thanks again.
    Baris

  4. #4


    Member Since
    Oct 27, 2005
    Posts
    4,702
    .:edit:.

  5. #5


    Member Since
    Apr 25, 2007
    Posts
    26
    Quote Originally Posted by Pulse-8 View Post
    .:edit:.
    Perhaps you have read my mind! Of course I won't know unless you supply some context for that statement...

  6. #6


    Member Since
    Oct 27, 2005
    Posts
    4,702
    Lol, I was just trying to wrap my mind around your issue of non-working USB ports and it's getting late here and I'm tired ... those two don't mix.

    I spent about 10 mins on google but couldn't find anything and when I did post something I realised it wouldn't/couldn't work anyway.

    I had this crazy idea about a FireWire to USB adapter ....

  7. #7
    MacHeadCase
    Guest
    Right off the top of my head, I can see two options here.

    If you have another Mac, you could always use use FireWire target disk mode and run the Apple Hardware Test in extended mode through the optical drive of the other Mac so it can check all the hardware components on the iMac.

    If you have another keyboard lying around you could plug that in to make sure it isn't the keyboard acting up instead of it being the USB ports.

  8. #8


    Member Since
    Apr 25, 2007
    Posts
    26
    Quote Originally Posted by Pulse-8 View Post
    Lol, I was just trying to wrap my mind around your issue of non-working USB ports and it's getting late here and I'm tired ... those two don't mix.

    I spent about 10 mins on google but couldn't find anything and when I did post something I realised it wouldn't/couldn't work anyway.

    I had this crazy idea about a FireWire to USB adapter ....
    Well Pulse, that was probably good thinking because that's the best I could come up with too and I'd like to think between us we're pretty smart. Might give it a go if the below option doesn't work out...


    Quote Originally Posted by MacHeadCase View Post
    Right off the top of my head, I can see two options here.

    If you have another Mac, you could always use use FireWire target disk mode and run the Apple Hardware Test in extended mode through the optical drive of the other Mac so it can check all the hardware components on the iMac.

    If you have another keyboard lying around you could plug that in to make sure it isn't the keyboard acting up instead of it being the USB ports.
    Now this... is a pretty good idea. It just so happens... I do have another imac of almost identical build. You are a genius. I am a little confused as to firewire disk mode however, I need to tell the busted mac to use the good hardware, will simply plugging in a firewire cable do this? If I have to hold any keys on the busted mac, it's not going to work haha!

  9. #9
    MacHeadCase
    Guest
    Just follow the instructions at Apple's site (the link I posted). The working computer being the Host computer, the broken one being the Target computer.

    Mind you, I've never tried this before, but hopefully it can work.

    Just pop in the working computer's optical drive the broken iMac's Hardware Test CD (this could be confusing: in some previous Mac models, the Hardware Test was on its own CD, some other Mac models have the Hardware Test on one of the CDs or DVDs that came in the kit with the Mac) and once you get the broken Mac in Target Disk mode, try to launch the Hardware Test from the working Mac and ask the diagnostic software to check the hardware components on the broken iMac.

    Let us know if it works and what the results are. If not, report back anyway: maybe someone else has other ideas.

  10. #10


    Member Since
    Apr 25, 2007
    Posts
    26
    Still haven't had a chance to diagnose the problem or start working on it, but I did notice that the mouse still lights up. This would indicate the bus is still working to some degree.

  11. #11

    SpindleX's Avatar
    Member Since
    Jan 04, 2007
    Location
    Asheville, NC
    Posts
    80
    Specs:
    iMac Alum 20'' 2.4GHz | iMac G4 | iPod Silver Nano 2GB
    You've tried another keyboard? Does the mouse work properly while booted up?

  12. #12


    Member Since
    Apr 25, 2007
    Posts
    26
    Quote Originally Posted by SpindleX View Post
    You've tried another keyboard? Does the mouse work properly while booted up?
    Hi there, no it doesn't the mouse and keyboard do not work properly although the mouse lights up which means at least the power signal is available. However the keyboard and mouse do work perfectly fine on another machine, so I am ruling them out.

    I can't do a hardware test because I can't eject the item, which in turn suggests it could well be the hardware. Annoying as heck. Why can't they product firewire mice and keyboards haha! That would be awesome.

  13. #13


    Member Since
    Apr 25, 2007
    Posts
    26
    Okay well I have disassembled the imac with dysfunctional usb, a comparison of the board to another board shows nothing particularly unique, the solder contacts seem to be fine, although I may attempt to apply a little heat to make sure.

    I have also ordered a firewire to usb cable to see if that will allow me to get at least a keyboard running, then I can try the hardware test. No joy as far as target disc mode, it works, the only thing it checks remotely is the harddisk, which seems to be in fine condition. So for future reference, you cannot boot from one mac to diagnose another via the hardware test in this manner.

    Any other suggestions welcome... here's the status

    None of the 3 USB ports works, but all will light the apple mouse optical laser up. Suggests power is available... could the controller be dead? Where would I find it?

  14. #14
    MacHeadCase
    Guest
    Just a thought... Did you try resetting the PMU?

  15. #15


    Member Since
    Apr 25, 2007
    Posts
    26
    Quote Originally Posted by MacHeadCase View Post
    Just a thought... Did you try resetting the PMU?
    Always got an idea haven't you? Don't want to let it die? Heaven forbid poor web should get a break! Haha, I hope this works, if it does, I'll paypal you 10GBP, you will recognise it as 20USD!

    Many thanks for you continued attention.

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