View Full Version : 12" PowerBook G4 stoped working. Won't even turn on.

Jan 17, 2007, 09:34 PM
I have a 12" PowerBook G4 Rev A (867mhz, 80GB, 640mb DVDR, Wireless) that suddenly stopped working today. I had recently serviced the computer and upgraded it's 40GB hard drive to an 80GB hard drive. That was last week, and everything has been working fine.

I was using the PowerBook at a friends house where I shut it down. Later I drove home with the PowerBook in it's bag. When I came home to turn on the PowerBook the computer chimed up and the hard drive spun-up. The computer started up except one thing was wrong. The backlight on the display was off. This has happened about a month ago with the backlight not being on, after a restart or two the problem was fixed. So I restarted the machine to see if it would help.

Now the computer will not turn on at all. I took out the additional Memory stick, the battery, and tried to boot it up with just the AC adapter. If I press the power button I hear the speaker pop (which should be followed by the chime, but it's not) and the high-pitch noise goes away. The hard drive doesn't spin up, it just sits there. If I hold down the PowerBook I hear a high-pitched squeal. If I remove the AC adapter the noise stops, I've tried two AC adapters and this happens with both of them. The machine is just sitting here not booting up. If I have to open it up again I will but, I'm curious what happened to it.

Also, I plugged in the video adapter to the TV but, I get no video. Also, when plugged in (or when on battery) when I press the power button, after it pops, I can press the Caps Lock key, which lights up the LED. That's the only sign of life I can get from the machine.

Any ideas? Thanks :o :(

mad jew
Jan 18, 2007, 01:00 AM
Hmm... Is it any different if you try starting in Safe or Verbose Mode? :)

Jan 18, 2007, 01:44 AM
Hmm... Is it any different if you try starting in Safe or Verbose Mode? :)

Unfortunately no. It doesn't make a difference since I don't think the machine is actually booting up. I guess I'll be sending it out to MacResQ.com, it's only $49 for them to check it out. I took it apart and unplugged basically everything one at a time and I got nowhere. Even with the speakers unplugged (which I thought was making the high-pitched buzz) it still makes a noise. I'm guessing maybe some metal is touching something but, I can't find out what.

Oh well :) I guess I'll go fix my Lime iBook's Hard Drive and I'll use that for now I guess. :o

Jan 18, 2007, 06:45 AM
My G4 died in a remarkably similar manner a couple of months ago. Turned out to be a dead logic board.

Jan 18, 2007, 01:00 PM
I just took it apart again. I found out the sound was actually coming from the battery board (next to where the trackpad is). I removed it and I no longer get the high-pitched squeal. The machine still won't boot however, hmm.:confused:

Jun 18, 2009, 03:07 PM
Sorry to revive such an old thread. But the exact same thing (high pitched squeal coming from the DC-DC board) just happened to my 12". Any chance you ever figured this out?

Jun 22, 2009, 12:32 AM
Sorry, but no I never found out what the problem was. :(

I remember the night it stopped working it was in my car which was very cold. Then I brought it inside. Maybe there was some condensation? I'm not sure. But it still doesn't work, but I still have the parts. I suppose a new logic board should do the trick. Unfortunately those are also costly. :(