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Thread: Mobo Swap on my G3

  1. #1
    Join Date
    Oct 2004
    Posts
    20

    Default Mobo Swap on my G3

    Hey all,

    I finally got fed up with my G3 B&W rev1. I bought a used rev2 mobo to replace it with. My question to those who know is this.

    Besides the motherboard are there any other replacement parts I need to make the swap?

    Also can I put a Sawtooth G4 cpu in the rev 2 ? If so what are the ultimate speeds for this machine? I don't want it to burn out.

    I've never done anything this extensive before. Are there any precautions that I need to takee before proceeding with this?

    Any help is appreciated.
    Thanks

    BB57

  2. #2
    Join Date
    May 2001
    Location
    1hr N/W of LA LA Land
    Posts
    3,317

    Default

    The logic board should be a pretty straightforward swap.

    The usual precautions for working on sensitive electronics apply. Ground yourself, and the Mac's chassis. Avoid walking around on carpet with sneakers while working on a windy day.

    As long as you keep the components cool you should be able to clock it up a bit. How much varies by the individual components. 10-15% is not unreasonable IMHO, but as always YMMV. G4 chips run hotter, and are less tolerant of mismatched or low-spec RAM so keep that in mind. An AGP G4 daughtercard won't work in the B&W/Yikes!. It has to be a ZIF chip.

    There are others here with more first-hand experience on B&W. They may have some more specific suggestions.

  3. #3
    Join Date
    Oct 2004
    Posts
    20

    Default

    Okay,
    I pulled the old mobo, put the new one in. Hooked up all the components pushed the on button an NOTHING. No chime , the light came on and it sounded like it was whirring up but that was it. So I ask again, are there any specific steps to be followed that I don't know about?

    Do I reset the cuda?
    Replace the battery?
    Unplug all the cards,(ATA, USB/Firewire)
    Unhook the hard drives?

    I need some serious help with this.
    How do I know if the motherboard I just put in is good / bad?
    Any suggestions?

    BB57
    G3 B&W 400 GHz 512 RAM Rev2 MOBO 10g Quantum Fireball 8g Quantum Fireball

    iMac G4 15" 800 GHz 40G hd

    G4 MDD 1.25GHz Superdrive 512 ram 40g / 250 G hd

  4. #4
    Join Date
    May 2001
    Location
    1hr N/W of LA LA Land
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    3,317

    Default

    A new battery is always a good idea. They can test good with a voltmeter, but not have enough current available for booting. A bad battery usually doesn't prevent booting though.

    When troubleshooting something like this it's also best to start out with a bare-bones hardware config. No extra cards/devices.

    Open Firmware reset on boot would be a good idea too. Boot from CD, and run Disk First Aid (OS9) or Disk Utility (OSX).

    Are you sure your PSU is OK?

  5. #5
    Join Date
    Jun 2002
    Location
    Lawrenceville, New Jersey, USA
    Posts
    220

    Default

    May sound strange but the three finger salute sometimes forces macs that won't boot to boot. Command control and the on key. After putting a Sonnet G3 zif into my beige I couldn't get it to boot same symptoms you posted. Out of desperation I tried the 3 finger salute and the sucker booted right up. Ya never know...

  6. #6
    Join Date
    Oct 2004
    Posts
    20

    Default

    Thanks for the replies. I have been searching for some deliberate information on-line. Seems a cuda reset to bare bones is the best bet.
    Otherwise it's back to the rev1 board and send the rev2 back.

    I will keep you posted on my progress.
    G3 B&W 400 GHz 512 RAM Rev2 MOBO 10g Quantum Fireball 8g Quantum Fireball

    iMac G4 15" 800 GHz 40G hd

    G4 MDD 1.25GHz Superdrive 512 ram 40g / 250 G hd

  7. #7
    tachyon Guest

    Default

    Tell us about the LEDs on the logicboard!

  8. #8
    Join Date
    Oct 2004
    Posts
    20

    Default

    Okay,

    I found one problem the jumpers where set wrong,so I put the proper jumper on. Reset the cuda, replaced the battery,powered up and got a CHIME! However it didn't come all the way back up.
    So I attempted to re-boot with PRAM reset and nothing..
    Now I get no chime just hear it power up and the HD kick on. But it stays in that mode never getting past the whirring.

    My next step is to pull everything, reset the cuda and see if I can get a bare bones restart. I know one HD is bad and I need to yank that, but I am still perplexed as to what the @#$% is wrong with this machine.

    Again any suggestions or info to guide me through this quagmire would be most appreciated.

    BB57
    G3 B&W 400 GHz 512 RAM Rev2 MOBO 10g Quantum Fireball 8g Quantum Fireball

    iMac G4 15" 800 GHz 40G hd

    G4 MDD 1.25GHz Superdrive 512 ram 40g / 250 G hd

  9. #9
    Join Date
    Aug 2000
    Location
    Concord, CA
    Posts
    7,056

    Default

    One thing you said about a bad hard drive reminded me of a similar situation I had with my QS G4. Had a Deathstar in it relegated only to storage files, not a boot drive. Eventually I could not boot. I tried everything until it dawned on me to pull the 4-pin Molex power cable to the drive. That solved the boot problem. k

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