MDD G4 won't turn on after replacing Pram battery

Discussion in 'PowerPC Macs' started by chet.d, Feb 1, 2010.

  1. macrumors member

    Joined:
    Dec 6, 2009
    #1
    I replaced the battery with correct one...

    http://eshop.macsales.com/item/Newer...gy/BAA36VPRAM/

    ...The G4 will not turn on?

    ...I then put the prior/old battery back in to check and it does fire up though with the whole 1969 date set back thing.

    ??

    Getting an 08 MP very soon but wanted to do this replacement thing for now.
    Appreciate any insights.
     
  2. macrumors 6502

    wickerman1893

    Joined:
    Dec 16, 2008
    #2
    faulty battery?
     
  3. thread starter macrumors member

    Joined:
    Dec 6, 2009
    #3
    That's all I can come up with.
     
  4. macrumors 601

    OrangeSVTguy

    Joined:
    Sep 16, 2007
    Location:
    Northeastern Ohio
    #4
    The G4 should still start up even without a PRAM battery in there so even if it's dead it will still start up. You didn't put the new battery in backwards did you? A faulty battery could also be the culprit as already mentioned.
     
  5. thread starter macrumors member

    Joined:
    Dec 6, 2009
    #5
    No, I'm certain I didn't put in backwards. I was very careful about that.
     
  6. macrumors newbie

    Joined:
    Feb 2, 2010
    Location:
    United Kingdom
    #6
    Did you try booting it without the battery? Unplugging mine for a while usually does the trick.
     
  7. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #7
    Reset PMU (small button on logic board - press once without battery and with power plug disconnected), wait 2 mins and try to boot with new battery.
     
  8. macrumors newbie

    Joined:
    Apr 13, 2010
    #8
    My powermac g4 MDD won't power up

    My powermac g4 mdd stopped working but the power buttons on the display and tower light up when pressed. I unplugged it, reset the pmu, took out the battery- no luck. I bought a new battery and installed it, and it turned on. I tested it again by turning it off and on and it went well. I left it turned off a few days and turned it on again, then after I was done I turned it off. When I went to turn it on again it would not power up, other than the buttons lighting up when pressed. So once again I removed the battery after unplugging it and reset the pmu again but no luck. I can't figure out what's wrong with it. I've even switched power cords, moved to different wall outlets, and I dusted everything inside the case with a new paintbrush. Can anyone tell me what to do? I'm familiar with electronics as I was an avionics technician in the navy so I can comprehend, but I have no multimeter.
     
  9. macrumors 601

    OrangeSVTguy

    Joined:
    Sep 16, 2007
    Location:
    Northeastern Ohio
    #9
    As long as it doesn't boot up with the fans running full rev after 15 seconds, it's probably just the power supply. Those are known to go bad and are still quite expensive to replace. People have went the other path with replacing and modding a regular ATX PSU to work in the MDD.
     
  10. macrumors newbie

    Joined:
    Apr 13, 2010
    #10
    Fans don't even rev up

    See the fans don't even rev up.
     
  11. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #11
    It looks like PSU is dead (exactly like OrangeSVTguy wrote).
    You need to examine it for visual damages (burnt paths on PCB, bad caps etc) and "burnt electronics" smell.
    It will be hard to check much more without multimeter or working spare parts.
    Except PSU, only dead motherboard could be cause of such issue. See, is red LED on motherboard lights up while pressing Power btn.

    Some links about ATX PSU conversion:
    http://jimmykirk.com/?p=34
    http://www.applefritter.com/node/23857
     
  12. macrumors newbie

    Joined:
    Apr 13, 2010
    #12
    No red led light up on logic board, the power buttons light up when pressed.
     
  13. macrumors 6502a

    raysfan81

    Joined:
    Oct 6, 2009
    Location:
    North Carolina
    #13
    Sounds like a bad PSU to me. If I were you I would try to make an ATX PSU replacement because it would be fun.
     
  14. macrumors newbie

    Joined:
    Mar 15, 2011
    #14
    MDD G4 won't turn on after replacing Pram battery

    I had the exact same problem.I had to constantly unplug from the wall then plug back in for the power button to work.So replaced the battery,disconnected the HD,video card and drives,NOTHING. I then purchased a refurbished PS with a year warranty and installed it,same thing,power button light was on when pressed then went right off again.The fan started spinning faster and LOUDER .

    Then after getting ready to trash it I decided to take out the dual processor board and reseat it.Guess what.... IT'S WORKING AGAIN !!!!!

    Every once in a while it will crash,guess when that happens,whenever I CLOSE THE SIDE PANEL of the case.

    I think this is a design flaw.Every time we close the case back up it needs to "Click " to lock.I've found that the logic board is jarred loose enough to make the system crash.

    When it crashes,I take a bamboo chop stick ( because it's softer than a screwdriver ) and press 4 times on the two exposed sides( all four corners ) of the logic board into the mother board.Once it reseats it starts right up with zero problems.If I close it hard it crashes but once logic board is reseated it starts right up again.

    I hope this helps
     
  15. macrumors newbie

    Joined:
    Sep 12, 2014
    #15
    Replaced Battery, Still Dead, But Got it Working Finally

    This is a late post, but thought it might be helpful to someone.

    I have been down a similar path as the OP: dead iMac after disconnect from power, replace battery then nothing still, re-open and fiddle with cables.

    Thought my iMac was dead. But found others on the 'net talking about letting computer sit (with power cord plugged in) for 24 hours (or more) and then their computer booted.

    Well, after my failure with the new battery, etc., I let my computer sit for approx 24 hrs (with new battery), power cord plugged in, and viola. First some low level internal sounds, then a loud odd chime (not the standard), and within 15 - 20 seconds, that beautiful boot chime and computer back to normal.

    I have yet to try unplugging power, so cannot report on that.

    I'm actually an EE, but not in the electronics field, yet my gut tells me many of the mac computer products have some funky power management stuff. I'm guessing a long dead battery does something weird that requires another weird kind of "charging", hence the fix with the 24 hour sit period. Just a relatively wild guess.

    The reason for my post is to say, if you replace the battery, do not give up (I almost did). Try the 24+ sit with power plugged in.
     

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