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power mac G4 wont power on

by vicsrc / March 5, 2009 10:08 AM PST

My power mac G4 wont power on
No lights no noise
No nuttin!
The battery voltage is 3.71
Ive disconnected everything and no luck
Tried the PMU? reset no luck
Any Ideas?

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by jedirock / March 5, 2009 2:46 PM PST

Does the power cord work?

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Reset the logic board
by mrmacfixit Forum moderator / March 5, 2009 8:59 PM PST

Remove battery and power cord
Press power on button on front
Press CUDA button, next to battery holder
Leave for 20 minutes
Replace battery
Replace powercord
Press power on button on front.

Any result?
If NO, suspect the power supply.

It would have been handy if you had mentioned what flavor PMG4 you had. There were a few, all different


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G4 10
by vicsrc / March 5, 2009 11:54 PM PST
In reply to: Reset the logic board

I think this is a G4 10 Its my wifes computer.
I am a ex IBM service tech I have done all the things you mentioned.
Yes there is power in the cord
do you know the pin layout for the power supply?

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mac G4
by vicsrc / March 6, 2009 12:37 AM PST
In reply to: G4 10

I just metered the power supply connector P1 and have no voltage on any pins.
Bad supply?
Does mac supplys go bad from just sitting?
It worked a week ago just fine and she tried last night to turn on and nothing!

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Things go bad,
by mrmacfixit Forum moderator / March 6, 2009 9:57 PM PST
In reply to: mac G4

The light in my bathroom was working yesterday morning, now it's not. It happens.

Your PSU did not go bad from sitting, it was just its time. It would have failed anyway, it probably failed this time when it was turned on.

Check out the link. There are a lot of Pinouts for Mac power supplies around the net. Not all Mac PSU's are the same. This is why it is important to get the correct G4 model.

Here is a place to get you started. Click here

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Just a link.
by R. Proffitt Forum moderator / March 6, 2009 12:43 AM PST

I like STEP 2. Can you do that?

Also, I apologize if that's not your exact PSU but it's all I could gather from above.

PS. Stuff does fail. I see you asking why. The reason is costly to find out. Is it worth it to find out?
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