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Thread: Powermac G3 - Power up question

  1. #1

    Default Powermac G3 - Power up question

    Hi all,

    I recently picked up a cheap, incomplete G3 powermac (desktop model) and I have a question about it's power up/initialisation.

    The unit is missing its personality card (the sound card thingy). Would this prevent it from booting?

    At the moment the computer powers up; screen turns on (but black), then screen turns off. It has RAM (tried a few different sticks of PC133 SDRAM); and I tried both an IDE hard drive and a SCSI hard drive. I also did the usual PRAM reset and CUDA reset which made zero difference. PRAM battery is new and I confirmed it has 3.6V on the terminals. Obviously I can't listen out for chimes as it doesn't have a sound card; so no help there.

    I CAN however boot the machine into open firmware just fine. I can type away and it responds; so at least the logic board is partially good.

    A personality card is reasonably cheap so I am happy to buy one; however there is little point if something else is dead. Any suggestions welcome!
    System 80 Expansion Interface located! Thanks to all who helped out and the good people in the NZ vintage computer forums!

  2. #2

    Default

    Mac OS is probably not going to like booting without a personality card, so that would be the first thing to do. I wouldn't think a Whisper card would be that expensive. The fact it comes up in OF implies that most of the machine is probably functional.
    I use my C128 because I am an ornery, stubborn, retro grouch. -- Bob Masse
    Machine room: http://www.floodgap.com/etc/machines.html

  3. #3
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    749

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    Remove the heatsink from the CPU and check the die for discoloration.

    I bought a beige G3 desktop years ago and it had a similar issue where it wouldn't boot properly. In my case, it turned out the heatsink had been dislodged and was only covering half the die, resulting in the CPU being damaged.

    It would still boot, but you had to start it up, wait a few minutes and then soft reboot it for it to start.

    Both G3s and the early G4s with that style of CPU package were notoriously easy to damage because the entire heatsink rested precariously on the tiny square of the exposed CPU die. It was a really dumb design decision to not include some sort of extra support like the pads on AMD Socket 462 CPUs, or shims.

  4. #4

    Default

    Quote Originally Posted by GiGaBiTe View Post
    It would still boot, but you had to start it up, wait a few minutes and then soft reboot it for it to start.
    That's more the typical behaviour when the PRAM battery is empty.

  5. #5
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    749

    Default

    Naah, in my case it was a burned CPU. You could see a distinct line where a bit more than half the die wasn't cooled and turned a dark purple color and lost its sheen. I replaced it with a faster G3 and the machine started working fine.

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