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Replace power supply in G4?

3714 Views 7 Replies Latest reply: Jul 18, 2008 5:49 PM by Grant Bennet-Alder RSS
Tina Siegenthaler Calculating status...
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Jul 16, 2008 8:18 AM
Hi all

I have 2 G4s (a 450MHz AGP and a 733MHZ Quicksilver) with dead power supplies. Since these are no longer available as spare parts from Apple, I thought I'd just buy a standard PC power supply to replace them.
However, all the PC power supplies I found so far have a 20 or 24 pin connector that goes to the motherboard, whereas the G4s have a connector with 22 pins. I don't think they will fit, or do they? Don't tell me they did this on purpose...

Thanks for your advice,

Tina
G5 Dual 1.8, 23'' Cinema Display, Mac OS X (10.4.5), iMac G4/800, iBook G3/700, G4/400, iBook G3/366, iMac G3/233, PM 7200, Mac SE
  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)
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    Jul 16, 2008 9:46 AM (in response to Tina Siegenthaler)
    It seems very unlikely that you have two of these Macs with dead power supplies, unless you bought them that way, and have evidence of sparks, smoke, or burned stuff.

    Many Macs will misbehave and may not start at all if their PRAM Backup battery is low. For debugging, remove the PRAM battery if it is under 3.2 Volts and reset the PRAM/PMU using the tiny button nearest the battery. Hold for about a quarter minute, then wait at least five seconds before attempting to restart.

    Those power supplies also have an internal fuse on the AC input, but the supplies must be opened to access it. It should only blow when the supplies have had way too much current drawn, such as from a short-circuit on one of the outputs.

    Power supplies are routinely harvested from otherwise-dead Macs and resold on eBay for cheap.
    Beige G3,G3 B+W,G4/867,G4/MDD, Mac OS 8.6 or Earlier, and 9.2, 10.4 and Server - LW IIg, LW 4/600, ATalk ImageWriter LQ
  • Texas Mac Man Level 8 Level 8 (44,220 points)
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    Jul 16, 2008 12:02 PM (in response to Tina Siegenthaler)
    The AGP has a 20 pin power supply, but requires mod of the ATX supply. See:

    Power Macintosh G3 (Blue and White) and Power Mac G4: Power Supply Voltage Test
    http://docs.info.apple.com/article.html?artnum=58561

    G4 (AGP/Sawtooth) to ATX case Conversion
    http://www.xlr8yourmac.com/systems/ATXG4_AGP_conversion/G4_AGP_to_ATX_casepg2.htm

    Don't know if these are available, but check this out.
    Power Supply Adapters
    http://groups.google.com/group/lemswap/browse_frm/thread/1b2c5f07358e809c/a96b79 e1d5048047#a96b79e1d5048047

    I believe that the Quicksilver has the 22 pin supply like the G4 Gigabit Ethernet. See http://docs.info.apple.com/article.html?artnum=95064

     Cheers, Tom
     G4 AGP 400, G3 400 FW Pismo, OS X (10.4 + 10.3), OS 9.2.2, DSL, Zip, Canon LiDE30 Scanner, CD-RW, Canon i960 Printer, Belkin UPS
  • Cnz Calculating status...
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    Jul 17, 2008 1:53 PM (in response to Tina Siegenthaler)
    I'm also looking for a new power supply unit for a Mac G4.

    My dad's G4 has a 237 W box, and I'm looking for something with a little more kick. I was referred to http://atxg4.com by the same folks that I bought processors and hard disks from, for three computers.

    This site sells prefabricated adapters for various ATX power supplies.

    I also went by the local computer shop and asked about PSUs there and was told that Apple uses proprietary power boxes, as does Dell, so finding one that will work and give a fair amount of juice will be hard.

    On the other hand, if you're looking for a part out of a mac to put into another, then ebay would be a good place to look.

    Message was edited by: Cnz
    G4 (DA), generously modified., Mac OS X (10.4.11), 1.733 GHz G4 Single Core, 1.25 GB SDRAM, GeForce 7800GS OC, 80 GB + 500 GB HDD.
  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)
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    Jul 17, 2008 8:30 PM (in response to Cnz)
    This article may add a little insight. Read Carefully the notes at the top regarding the 28 Volt supply -- especially if you intend to use an ADC display!

    http://www.xlr8yourmac.com/systems/ATXG4_AGP_conversion/G4_AGP_to_ATXcase.htm
    Beige G3,G3 B+W,G4/867,G4/MDD, Mac OS 8.6 or Earlier, and 9.2, 10.4 and Server - LW IIg, LW 4/600, ATalk ImageWriter LQ
  • Cnz Level 1 Level 1 (5 points)
    Currently Being Moderated
    Jul 18, 2008 2:39 PM (in response to Grant Bennet-Alder)
    Well, thing is that my dad's G4 AGP, which I'm trying to find a PSU for, isn't using an Apple Display.

    What I really would like to do is find a PSU that will physically fit, as well as work correctly with it with out frying it. What's more, can I pick just about any 20 pin PSU, plug in the adapter for it, and let her rip, or is there anywhere I need to go in particular for a G4 AGP PSU that puts out more than 300 W?
    G4 (DA), generously modified., Mac OS X (10.4.11), 1.733 GHz G4 Single Core, 1.25 GB SDRAM, GeForce 7800GS OC, 80 GB + 500 GB HDD.
  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)
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    Jul 18, 2008 5:49 PM (in response to Cnz)
    Page 2 of the article above shows exactly what wires to modify to turn an off-the-shelf ATX supply into a supply for any G4 up to Gigabit Ethernet G4. Includes wiring diagrams and photographs:

    http://www.xlr8yourmac.com/systems/ATXG4_AGP_conversion/G4_AGP_to_ATX_casepg2.htm#next
    Beige G3,G3 B+W,G4/867,G4/MDD, Mac OS 8.6 or Earlier, and 9.2, 10.4 and Server - LW IIg, LW 4/600, ATalk ImageWriter LQ

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