ibook g4 won't run on ac or charge battery

Discussion in 'PowerPC Macs' started by NickApizza, Jun 5, 2010.

  1. NickApizza macrumors newbie

    Jun 5, 2010
    New England
    My ibook g4 (1.42ghz) will not run on ac power nor will it charge the battery.

    It runs fine on battery power alone. Plugging the ac adapter in has no effect. It doesn't recognize it or stop draining the battery.

    Here's what I have done:

    Replaced the ac adapter. No change.
    Installed a new battery. Runs fine on battery, but doesn't recharge it.
    Reset PMU.
    Reset PRAM.
    Installed a NEW DC-IN Board. No change.
    Above resets again. No change.

    I've purchased an external battery charger, so at least I can continue to use the computer for as long as the battery remains charged.

    Is there a way to hardwire the ac adapter to where the power needs to go, so it will run on ac, but won't be "managed" for charging, etc?

    Any other possible fixes short of replacing the logic board, which I believe costs over $250?

    Thanks very much.

  2. NickApizza thread starter macrumors newbie

    Jun 5, 2010
    New England
    Runs better than ever on the battery!

    Well, the overwhelming response to this problem tells me something. I did find a thread that suggested shorting out the capacitor to shock the pmu chip back to life.

    I think I'll hold off on that, though. The computer is working better than ever on battery power. I think the pmu and pram resets did some good in that department. When I installed the original battery that came with the machine, after charging it in an external charger, it said it had 4+ hours of life in it! Wow!

    So I think it's time to leave well enough alone and not push my luck or my computer repair prowess any further!

    BTW, I've owned 7 Macs and this is the first one that "broke."
  3. max¥¥ macrumors 6502a

    Aug 7, 2008
    Over there....
    you probably have a break in the cable, at either the plug end or the adapter end
  4. drewdle macrumors regular

    Apr 26, 2010
    Nanaimo, BC
    I never would have thought of the external charger.

    On the original issue, I don't think you'll be able to fix it without a logic board. The DC in board doesn't handle control for switching between battery and AC, and charging, it just breaks down the DC and funnels it where it needs to go, if I understand correctly. I've seen this issue before at work.

    Do you have the original Apple power adapter? Does it light up red? That typically points to a charging hardware/control issue.
  5. NickApizza thread starter macrumors newbie

    Jun 5, 2010
    New England

    Thanks for your suggestions. I think there were definitely issues in the original power cord, though it never glowed red. I patched together the plug from another ibook with the adapter unit from mine and there was no glowing at all, in any color! I also purchased a new power adapter and cord. No effect.

    It's still working well with the externally charged batteries, though noticeably slower because the power management is more aggressive now.

    Truth be told, I've gotten my money's worth out of this machine. When I'm as old in people years as it is in computer years, I'll probably need external charging, too.
  6. Agincourt macrumors newbie

    Oct 21, 2009
    I've got the exact same problem as you do. I've just recently replaced the DC component and it appears to work alright, although I won't feel safe until I've had a few days with no incidents.

    Before this, it has always been the AC/DC and power adapter that was the problem. Works fine on battery, and the AC cord only occasionally causes the computer to malfunction and be shut down.

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