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View Full Version : MDD G4 won't turn on after replacing Pram battery




chet.d
Feb 1, 2010, 06:15 PM
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.



wickerman1893
Feb 1, 2010, 08:26 PM
faulty battery?

chet.d
Feb 1, 2010, 09:12 PM
That's all I can come up with.

OrangeSVTguy
Feb 1, 2010, 09:14 PM
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.

chet.d
Feb 1, 2010, 09:43 PM
No, I'm certain I didn't put in backwards. I was very careful about that.

Sinan
Feb 2, 2010, 06:22 PM
Did you try booting it without the battery? Unplugging mine for a while usually does the trick.

666sheep
Feb 3, 2010, 04:07 AM
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.

BellyUpMac
Apr 13, 2010, 05:03 PM
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.

OrangeSVTguy
Apr 13, 2010, 11:12 PM
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.

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.

BellyUpMac
Apr 14, 2010, 09:59 AM
See the fans don't even rev up.

666sheep
Apr 14, 2010, 10:45 AM
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

BellyUpMac
Apr 16, 2010, 09:20 AM
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

No red led light up on logic board, the power buttons light up when pressed.

raysfan81
Apr 20, 2010, 08:42 PM
No red led light up on logic board, the power buttons light up when pressed.

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.

dante damore
Mar 15, 2011, 12:15 PM
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