Bondi Blue G3 Won't Power Up

Discussion in 'PowerPC Macs' started by bunnspecial, Jul 30, 2014.

  1. bunnspecial macrumors 603

    bunnspecial

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    #1
    I mentioned in another thread that I was given a pair of iMacs today.

    The two I was given essentially "book end" the G3 production-one is a 600mhz Indigo "summer 2001" variant. I just ran the restore disks on this one, and it's running perfectly on OS 9.2 and OX 10.0.

    The other is a Bondi Blue slot tray loading 233mhz(not sure with logic board revision yet). This one, as best as I can tell, is completely dead. When I plug it in, it does nothing. I haven't had a chance yet to investigate it too much, but am wondering if anyone can provide suggestions about where to potentially look for a problem in it.
     
  2. Intell macrumors P6

    Intell

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    #2
    An easy to check if it's a revision A board is to look for the IRDA port on the front next to one of the speakers. If it doesn't have the black/purple part about the size of your thumbnail, then it isn't a revision A model. It's possible that the power supply is dead.
     
  3. bunnspecial thread starter macrumors 603

    bunnspecial

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    #3
    I do have the IRDA port, so it sounds like it is indeed a Rev. A logic board.
     
  4. Intell macrumors P6

    Intell

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    #4
    Correct, unless a previous owner switched out the board for a B-D board, you should still have the A board.
     
  5. drnebulous macrumors regular

    drnebulous

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  6. bunnspecial thread starter macrumors 603

    bunnspecial

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    #6
    I pulled the logic board tray and gave everything a good dusting out and cleaning...still a no-go(not that I had a lot of hope).

    I do hear a faint "hiss" when I plug the computer into AC power...that's the only sign of life that I'm getting from it.
     
  7. bunnspecial thread starter macrumors 603

    bunnspecial

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    #7
    I found some suggestions on the internet that a bad PRAM battery could cause a seemingly dead iMac G3.

    I changed the battery, and it's still a no go(my Quicksilver needs a new battery, so at least it's not wasted).

    Incidentally, Radio Shack sells a Radio Shack 1/2AA battery that looks identical to the old ones I've removed for $19.99. They also sell an Ultralast brand Saft LS14250 that has the exact same specs(1200mAH Lithium) and as best as I can tell is the same battery in a different outer wrapper for $9.99. At least both list the same country of origin on the side. Needless to say, I bought the less expensive one!
     
  8. bunnspecial thread starter macrumors 603

    bunnspecial

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    #8
    I spent some more time with this one, and am getting +5V at pin 12 from the power supply, but this is the only real sign of life I'm getting. I also have been struggling to find a pinout for the first generation iMacs.

    Does anyone know if there's a way to jumper the PSU on these to check all the voltages?
     
  9. bunnspecial thread starter macrumors 603

    bunnspecial

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    #9
    Okay, so I've been playing around with this some more and had the whole logic board and associated parts spread out on the floor and connected trying to trace power through the system.

    I found two pins I could short that would power up the flyback transformer and make the fans spin. So, with that in mind, I hooked up the logic board, HDD, and everything else(except for the optical drive.).

    Much to my surprise, I shorted the pins and was treated to the startup chime along with the hardrive spinning up(I couldn't see if anything poped up on the screen). Then, the computer shut off and I couldn't get anywhere else.
     
  10. bunnspecial thread starter macrumors 603

    bunnspecial

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    #10
    Okay, I think I might be getting somewhere(or maybe nowhere-I don't know).

    I now have the computer to the point where I can do the following:

    1. Press the power button, which will then light up orange.

    2. I then hear the startup chime, accompanied by the sound of the hard drive spinning up

    3. I will then hear a "click"(much like a flyback transformer powering up sounds like), the power button will turn green momentarily, and then the computer will shut off.

    Once it goes through this sequence, it will be "dead" again for a few minutes, and then I can go through this sequence again.

    So, at least I'm getting some signs of life, but I'm not sure if they're good signs.
     
  11. DeltaMac macrumors 604

    DeltaMac

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    #11
    Sounds like you have a new hobby!

    I think your initial fix will be replacing the analog board/video board.
    The power-on flow pretty much can work, until it's time to turn the CRT on - and too much power draw, and it all shuts down. I suspect that you never see any brightness at all. So, Analog/video board.
    Back in the day, when I used to work on those old iMacs a lot, and they were still in warranty - both the analog/video, and power supply boards had to be replaced together. The flyback would fail, for example, taking the power supply out with it (or just weaken it enough to fail when the OTHER board was replaced), or the power supply would fail taking some of the video/analog components - so, replacing just one was often an exercise in futility. Your power supply board MIGHT be OK at this time, so replacing the analog/video would be a next step, I think.
     
  12. Altemose macrumors G3

    Altemose

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    #12
    Sounds like the PAV board is toast. Does there appear to be any blown capacitors on the PAV board?
     
  13. cjmillsnun macrumors 68020

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    #13
    I'd bet on faulty capacitors on the power supply.
     
  14. DZ/015 macrumors 6502a

    DZ/015

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  15. bunnspecial thread starter macrumors 603

    bunnspecial

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    #15
    I removed the PSU board(right board with the back of the CRT facing toward me) but not the PAV board. As a general rule, CRTs scare the crap out of me, and it hadn't been unplugged long enough at that point for me to feel safe poking around on that side of the case. I have the right side board a good looking over and didn't see any obvious distress. The fuse also tested good.

    I'll pull the other board when I work up the courage to do it(and have had the computer unplugged for a few days) and see if I can see anything obvious.

    With the abundance of "imacquariums" and other iMac related projects, I'd think that parts for these would be plentiful. Hopefully the people re-purposing the cases are at least saving the parts to keep other computers running.
     
  16. Altemose macrumors G3

    Altemose

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    #16
    Well... The reason why I said it is the PAV board is because that is the most common failing part on these machines, aside from worn out hard drives of course!
     
  17. Intell macrumors P6

    Intell

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    #17
    Tray loading iMac's don't have a PAV board like the slot loading iMacs do.
     
  18. Altemose macrumors G3

    Altemose

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    #18
    Doh! Sorry for the misinformation. My mind is elsewhere...
     
  19. mgguy macrumors 6502

    mgguy

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    #19
    It sounds implausible, but you may be able to start it up by using a hair blow dryer to warm it up through the air vents on the top of the machine. It is the only way I have been able to get my G3 to start up. There are plenty of web links on this. Just search under g3start up using a blow dryer. It works.
     
  20. bunnspecial thread starter macrumors 603

    bunnspecial

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    #20
    I have tried numerous variants of the "hair dryer" trick, all with the same result.

    I realize that all of the service documentation explicitly states that the iMac is not to be used with an external monitor, however it seems to power up fine with no monitor plugged in. I have a 14" Apple CRT(with a DB-15 plug) that's currently serving my G3 desktop, and am wondering what would happen if I plug this into the monitor port on the iMac logic board. Any thoughts on this?

    In any case, it looks like I'm going to be in need of a power supply. I really hate to dump that money into this computer(unless I can find one really cheap), so it will likely end up either being parted out or just stuck back in the closet.

    Fortunately, the later model(slot loading) Blueberry that the same person gave me is chugging along quite happily. In fact, just this afternoon I hooked it up to my Quicksilver via Target Disk mode and installed Tiger. I had to do it this way, since my only Tiger install disks are on DVD and the iMac can't read DVDs. Once I max out the ram from the 320 currently in it(64+256) and possibly install an Airport card(I need to track down one of the adapters) I think that the slot loader will be a very useable machine.
     
  21. Intell macrumors P6

    Intell

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    #21
    You can use external DB-15/VGA monitors with the tray loading G3 iMac.
     
  22. DeltaMac, Aug 15, 2014
    Last edited: Aug 15, 2014

    DeltaMac macrumors 604

    DeltaMac

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    #22
    The video out on your iMac G3 is not DB-15, but is the standard DE-15 connector for VGA. Your 14-inch Apple CRT would need a DB-15 to VGA adapter, something like this: http://www.amazon.com/DB-15-HD-15-Female-monitor-Adapter/dp/B001I22L9C/ref=pd_cp_e_1
    I think that example is the reverse of what you would really need. It does show the difference in the connectors….

    I totally missed that you were asking about connecting your old display to a bondi-blue iMac internal video connector, so the above is really incorrect = sorry :)
    That is certainly a DB-15, and I (think) that connector should output to an old Apple display - but, I honestly don't remember now, been a few years since I had a tray-loader iMac.
     
  23. bunnspecial thread starter macrumors 603

    bunnspecial

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    #23
    Thanks for your clarification. Your first response had me really confused :)
     
  24. Dandu macrumors regular

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    Jan 23, 2009
    #24
    Have you try to reset the CUDA chip ?

    There is a little button on the motherboard, near the CPU card.

    With my iMac G3, if i change a component, i must disconnect the iMac, press this button many seconds (5) and he boot after that.

    And you can use a LCD with the iMac and an adapter (i have tested last week), but attention, try to use à 60 Hz refresh rate, many LCD don't like other value (and the iMac use weird value with is internal display)
     

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