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Thread: Powermac G4 MDD shut down

  1. #1
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    Question Powermac G4 MDD shut down

    Hi to all from Portugal.
    Just bought a Powermac G4 MDD 1,42Ghz / 1,5Gb Ram, Without HDD and a blown power supply.
    After a full disassemble and full clean up, installed a atx power supply and its running. When OS X installation begins and after a few minutes cpu fan goes to maximum and a few moments later it shuts down. New termal grease was used ( Artic Silver 5 ). Temperature seems very low as the cpu heatsink is only warm.All fans working and with an increase of two more fans between the cpu heater and the back of the case.
    New battery, already done a pmu reset and the problem remains.
    As for the ATX power supply, the only voltage that is not present is the 25V, and it seems that voltage is only used for a mac display.
    Help needed .
    Many thanks to all .
    Braga

  2. #2
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    Howdy -

    Hmmm, could be a few things I suspect.

    Could be a sensor is reporting incorrect readings, causing the shut down. Does anything too warm?

    What OS are you using? If it is an OEM disk from a different model (gray), this can cause a similar high fan situation, though I don't think I have ever seen one shut down all the way. Also, a retail OS disk (black) that is older than the G4 will not work either, though usually will not install or not boot correctly.

    Some MDDs need a voodoo reset. Not quite the same symptom, but worth trying?

    Check and recheck voltages? Never done the ATX PS mod, so not much help there.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  3. #3
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    Default Powermac G4 MDD

    Hi,
    Thanks for the reply. ATX power supply is ok, all voltages correct. Temperature is very low all around the cpu and heatsink, also case temperature is normal?!
    Will give it a try on your "Voodoo "
    Thanks once again

  4. #4
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    What OS did you install?

    When booted to the OS install disk - if using a DVD - does it behave normally, or do you get the same issue?
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  5. #5
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    Default Powermac g4 MDD

    Hi,
    Im trying to install OS X 10.4 ( Tiger ) with a dvd install disk. Issue remains.
    Is there a thermal sensor on the logic board ?

  6. #6
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    None that I am aware of.

    So, just to confirm it is hardware (sensor, etc.) Is there any other OS that you can install/boot from to test? If it behaves the same with more than one compatible OS, that would likely rule out any software. Is this a black retail OS DVD, or a gray model specific DVD?

    Any other similar Macs handy that you could use to install the OS on?

    What happens if you put it in Target Disk Mode? Does it run for hours with no problems, or does it shut down again?
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  7. #7
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    Default Powermac G4 MDD

    I have images for installation of jaguar,puma, tiger and leopard OS X, does the same thing with all. This was bought without HDD and so i cant get to install the OS because of this issue.
    Temperature is only slightly warm and it shuts down. Oh and by the way every times it starts i have no tone start. Just boots the disc , i have acess to disc utility to erase and format and begin installation ( verifying install dvd and installatio itself ) with no sucess as after a few minutes it shuts down.
    Already disassembeld once again and aplied once more new termal grease without sucess.Re-check temperature imediatly after shut down and temperature is very low ????

  8. #8
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    Once booted or on boot you can try this. I won't hurt anything. It's a shot in the dark without more info. Have these disk images been tested on other drives/computers? - make sure they are good.

  9. #9
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    Default Powermac G4 MDD

    Quote Originally Posted by unclemac View Post
    None that I am aware of.

    So, just to confirm it is hardware (sensor, etc.) Is there any other OS that you can install/boot from to test? If it behaves the same with more than one compatible OS, that would likely rule out any software. Is this a black retail OS DVD, or a gray model specific DVD?

    Any other similar Macs handy that you could use to install the OS on?

    What happens if you put it in Target Disk Mode? Does it run for hours with no problems, or does it shut down again?

    Ok, just did " voodoo " and all the same.
    Can even get to reach installation menu, shuts down and sometimes i get Kernel panics like unresolved kernel trap ( CPU 1 ) 0X300 data acess; received emergency temp signal, going to sleep;Panic CPU 0 Caller and sound legacy errors.
    Cpu card going ? Logic Board ???

  10. #10
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    Unfortunately, generally speaking, the Apple method is to replace parts until you find the answer. There is not really a test method except to swap out parts. Unless something in the panic log specifies a processor, otherwise it can be processor, motherboard, memory, power supply.

    Apple's Service Manuals use that method. Speaking of which, do you have the service manual? It is a readily available item. If you don't, send me an email on the contact page and I will email it to you. Or figure out a way to link it for you. Once in a while a service manual will have a tip, like one of the motherboard LEDs is flashing.

    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  11. #11
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    Quote Originally Posted by ricks View Post
    Unfortunately, generally speaking, the Apple method is to replace parts until you find the answer. There is not really a test method except to swap out parts. Unless something in the panic log specifies a processor, otherwise it can be processor, motherboard, memory, power supply.

    Apple's Service Manuals use that method. Speaking of which, do you have the service manual? It is a readily available item. If you don't, send me an email on the contact page and I will email it to you. Or figure out a way to link it for you. Once in a while a service manual will have a tip, like one of the motherboard LEDs is flashing.

    Rick
    Rick,
    Many thanks for the reply. Yes i do have the service manual.
    Already put the missing 25V on power supply to get some conclusions, but remains the same.
    This was bought so cheap and for the case, was not expecting that a sign of live will apear ! Think im about to give up and procede to a Intel cpu on this chassis .
    Once again many thanks and the best regards to all.
    Braga

  12. #12
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    Default opps,

    I intended to paste this on my last post... my apologizes. Once booted or on boot you can try this. I won't hurt anything. It's a shot in the dark without more info.

    Zap the PRAM. On Startup hold the (command + option + P + R) keys. Hold them until you hear the first startup "bong/chime" and keep holding them for about 3-4 more "bongs/chimes".

    Open Firmware reset -

    Hold the Command+Option+O+F keys during startup. This will put you in the Open Firmware Interface. At the end of any text you will get a '>' prompt. At that prompt type:

    reset-nvram -Hit Return
    set-defaults -Hit Return
    reset-all -Hit Return

    That should cause a reboot.

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