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Power Mac G5 1.8/DP/3GB400/160/SD/FX5200/PCI-X start up problem

4150 Views 25 Replies Latest reply: Jul 16, 2011 8:32 PM by BDAqua RSS
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Jul 13, 2011 11:59 AM

Please help, having problem with start-up of my Power Mac G5. Its a Power Mac G5 1.8/DP/3GB 400/160 HDD/SD/FX5200/PCI-X.


Mac doesnt want to start.




1. when press the power button there is no sound at all

2. LED diod above power button flesh three times in a row in white colour after 5 second pause

3. I am sure it is not a problem with RAM, HDD as a have similar Mac at job and tried to interchange those elements between computers but it doesnt help!


I had the same problem today in the morning but it finally started normally after couple of tries but in the afternoon there is no way to start the POwer Mac G5. I tried minimum 50 times to start it up and no way to do it.


Can anybody help me please!

PowerMac, Mac OS X (10.5.8)
  • BDAqua Level 10 Level 10 (114,695 points)

    Hi, it very likely is the RAM slots/lead free solder issue.


    If you're sure the RAM is good, try the Hair Dryer trick...





    It can show on any G5, and even many other computers & electronic devices of the period.


    Some people hae even had success not using the inner pair of RAM sticks & such.

  • BDAqua Level 10 Level 10 (114,695 points)



    "Bingo !!


    Hairdyer 4 mins (to the point at which it became worryingly hot) and its back to life"


    "Awesome!!!! That's insane that it actually worked! Thanks for the help!"


    "I was not using the hair dryer long enough. 4 - 5 minutes did it.


    I am back up and all memmory is good. I used a Conair 1875 watt. "

  • BDAqua Level 10 Level 10 (114,695 points)

    Great news, thanks!


    Right, you did great.


    PS. As a rough estimate I'd say that has worked 80-90% of the time, & roughly 20-30% of the time more or less permanent.

  • BDAqua Level 10 Level 10 (114,695 points)

    You're correct Robert, the initial lead free solder, (mandated), had a tendancy to lose contact due to repeated heating & cooling over time.


    And you're very welcome, I'm very happy that I could help.

  • japamac Level 7 Level 7 (24,390 points)
    Is there any SW tool to exactly isolate where is the problem


    could it be a one of the processors failure ?

    It could also be a processor.

    Processor BGA failure is also a result of RoHS mandated changes in connection material used.


    Logic board memory controller BGA is a likely suspect, as well as RAM slot attachment.


    The board needs replaced or a reflow.

    DIY reflow in an oven or with a heat gun (latter good for component level flow).

    Google will reveal many ideas for DIY reflow.


    Personally, I'd try a reflow of the memory controller.....

  • japamac Level 7 Level 7 (24,390 points)
    is it possible to somehow disable lower or upper processor in order to eliminate the reasons if processor is a cause of a problem?

    CPU 1 may be disabled. CPU 0 cannot be disabled.

    Physically remove and switch the processors to use disabling as a troubleshooting technique for both processors.

    (Removal and reversal will require Thermal Calibration. Use ASD 2.5.8).


    While booted normally, in Utilities, open Terminal and enter the following:


    $ sudo nvram boot-args="cpus=1" (To re-enable the 2nd cpu set boot-args="").


    Alternatively, in Open Firmware do this:


    • Boot while holding down Command-Option-O-F
    • At the command line prompt enter: setenv boot-args cpus=1
    • Return
    • Enter: mac-boot
    • Return
    can I run the pc on only one processor?


    what about video graphic card, could it be due to the malfunction  of the video graphic adapter card?

    Anything is possible, but the POST error that your machine gives you (three flashes) tells us otherwise.

  • japamac Level 7 Level 7 (24,390 points)
    CPU 1=lower processor?


    so first step in investigation of the problem would be disabling CPU 1 in terminal mode, how could I enter terminal mode? more details please

    Open the Terminal application located in your OS X Applications/Utilities folder.

    second step is physical interchange of the processors and in that case I have to do Thermal Calibration?


    Sometimes that is all that is needed to correct things.

    where to download ASD 2.5.8?

    Google will give you some options.

    You can email me via my profile/website and I can steer you to a working download.

    third step would be heating the logic board with hairdryer-which exact logic board location should I heat and for how long?

    The area around and between the RAM slots.

    The large, square area of many solder connections is important to heat thoroughly.

    Heat long enough to make things HOT.

    Solder doesn't melt until 415ºF (or so). A hair dryer won't melt anything, so let things get hot.

    if you were me what would you do in order to solve this problem?

    First I would complete the CPU diagnosis.

    Failing improvement there, with nothing to lose, I would remove the logic board and reflow the solder using a heat gun or oven.

    If that failed, I would look for a parts machine or sell the parts that I had.

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