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  1. #1
    G5 Power Mac No Boot

    Member Since
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    G5 Power Mac No Boot
    I am fairly new to macs so please forgive me.

    I have a G5 powermac 2.0 (2023 A1117) that recently gave off a loud bang and will no longer boot. A coworker suggested that the power supply is the likely problem with the system, so he supplied me with a spare part system that uses the same power supply. I am not 100% sure that the spare system is good to begin with.

    So I replaced the power supply, and put all of the parts back together. When I plug in the AC cord and when I press the power button I get a "click" sounds coming from the rear bottom of the mac (probably power supply). I also see a trickle light LED on the mobo light up when the AC cord is in. The silver light for the button comes on and then goes out right away (it sometimes stays on). The system shows no signs of life (no fans, beeps, display, nothing).

    I have tried all of the usual things, reseat memory, reseat cpu, smu reset, reseat video card (replace video card)...

    What can I do at this point? and how do I go about testing the power supply with a DVM?

  2. #2
    G5 Power Mac No Boot
    Chris H.'s Avatar
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    Your best bet for an older Power Mac is to take it in at an authorized Apple Repair center, or an actual Apple Retail Store and have them look at it. Not all power supplies fit in these babies.


    And that brings me to my next point- always (carefully) dust out the inside of your computer!
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  3. #3
    G5 Power Mac No Boot
    chscag's Avatar
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    To add to what Chris replied... The loud bang you heard was very likely an electro capacitor bursting in the PS. I've heard that noise many times during the years I was doing computer and electronic repairs for the US Govt. You might want to dig around thru the machine and also on the logic board to see if there is any other damage. When a capacitor shorts out and bursts, it usually causes other damage.

    And like Chris said, the PS you have may not be the one needed.

  4. #4
    G5 Power Mac No Boot
    pigoo3's Avatar
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    Quote Originally Posted by chscag View Post
    To add to what Chris replied... The loud bang you heard was very likely an electro capacitor bursting in the PS. I've heard that noise many times during the years I was doing computer and electronic repairs for the US Govt.
    Usually you also get that semi-nasty "electrical smoke" smell as well!

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  5. #5
    G5 Power Mac No Boot
    Mac SK's Avatar
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    Quote Originally Posted by Morial View Post
    I am fairly new to macs so please forgive me.

    A coworker suggested that the power supply is the likely problem with the system, so he supplied me with a spare part system that uses the same power supply. I am not 100% sure that the spare system is good to begin with.


    If your board passes the smell test...you may be right about the spare part. What all was with this spare part system..enough stuff to build one out of two.

  6. #6
    G5 Power Mac No Boot
    dtravis7's Avatar
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    Like Mac SK and others are saying, the replacement Power Supply out of that other G5 might also be bad or the wrong supply. I have not worked on any G5 towers but I know Apple did change even the pinouts on newer G4 systems.

    Does that old G5 you were given have the same specs? Did you try the supply in the parts G5 first to see if that machine does anything?

    I am almost 100% sure like Chscag that the BANG was a Electrolytic Capacitor exploding in your original power supply. I just HOPE that when it blew it did not cause a spike and hurt the logic board.

    I had 3 PC's here all with the same brand power supply. All 3 Power Supplies died with a BANG (One also poured out smoke). ALL 3 when they blew took out the Motherboard and some PCI cards and the controller on one hard drive! Expensive lesson for me! Don't get Cheap power supplies.

    Does that parts G5 have all the parts in it? If so try the power supply back in that machine. Does it boot? Post?

  7. #7
    G5 Power Mac No Boot

    Member Since
    Aug 27, 2010
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    Sorry it has been a while. This is a work computer so I haven't done anything to it over the weekend. The power supplies are the same.

    Here is the information on them.
    They both have the same ID on them

    ID 291G
    Apple P/N : 614-0373

    Update: So I put the (original system) old motherboard and the (from spare system) new power supply back in the machine. I plugged in the AC cord into the machine and immediately heard a buzz sounds from the power supply. I unplugged it right away, and can smell smoke coming from it. It isn't over bearing because I removed it right away, and it still buzzes when I hook it back up.

  8. #8
    G5 Power Mac No Boot
    dtravis7's Avatar
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    So the G5 you got for parts does the above with the power supply that came with the Parts G5? If so, it's in the same shape as your original G5.

    What I am asking also, you did not put the blown supply from YOUR G5 in the parts machine I hope? Just woke up and half asleep so being sure!

    It's starting to look like there were a lot of Power Supply issues with some of the Power Mac G5's.

  9. #9
    G5 Power Mac No Boot

    Member Since
    Aug 27, 2010
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    Quote Originally Posted by dtravis7 View Post
    So the G5 you got for parts does the above with the power supply that came with the Parts G5? If so, it's in the same shape as your original G5.
    It seems so. I never tested the spare part system. The coworker of mine told me that it wasn't working, but he wasn't sure why.


    I tested voltages coming from the pinouts from the power supply (from the spare). I am getting 24.7 volts out of one of the pins with the system off, and with the power supply unhooked from the motherboard. I am not sure what this means, but I thought that only the 5v pins were supposed to deliver electricity with the system off.

    P2 Connector (excuse the crappy diagram)
    nob
    1 2 3 4 5
    6 7 8 9 10

    From 9(blue wire) I am getting 24.7v, and from the 4 & 5 pins(green) I am getting 5v. This is while I am putting the black end to a grounded pin (black). Am I doing this right? I am not too experienced with using a DVM.



    Edit:
    Hrmm, perhaps that doesn't mean much. The original PS does this too.

  10. #10
    G5 Power Mac No Boot

    Member Since
    Aug 27, 2010
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    Also I only get the buzz from the PS with the P2 connector plugged into the board.

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