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View Full Version : PowerBook G4 PBG4 1.5 No Video, No Chime, Fan On, KB Lights On


nj_computer_repair
02-08-2010, 03:32 PM
Hello all, have not been here for a while, hope you all are doing well.

Got a PowerBook G4 12 inch 1.5 that will not chime in unless you reset the PRAM. When you reset PRAM, you get a chime, NO video, NO fan, NO hard drive spinning, nothing. You can not even tell the computer is on unless you hit the CAPS lock key which will light up the key.

If you do not reset the PRAM, there is no chime but the fan spins and the kb lights work. Still no video.

External video does not work either way. I tried isolating the issue to a piece of hardware but did not really get anywhere.

Any ideas what this could be? Thanks!

anonymous Mac Tech
02-08-2010, 05:25 PM
First off try to reset the PMU (http://support.apple.com/kb/HT1431?locale=en_US&viewlocale=en_US#faq10). Next remove any added on RAM and see if it makes a difference. Still no joy I'd pull the top case and start looking for signs of a spill. Also while you are taking it apart, if you know the screw locations pretty well on those try looking for places where they may have put a long screw where a short screw belongs. Those 12" PBs use all different lengths of screws and I've seen cases where folks have gotten brave and tried to take them apart and put a screw through the board reassembling.

nj_computer_repair
02-08-2010, 05:58 PM
I had the thing apart, did not see any signs of spills. I tried every combo of starting the thing with either the video cable unplugged, or the ram or the cd drive and still no joy. The screws seemed to be in the right places and they were all there. Tried resetting the PMU and nothing. The board looked in good shape.

anonymous Mac Tech
02-08-2010, 08:00 PM
You wouldn't happen to have a different top case to try? Its a long shot but I've had at least one ibook with those symptoms and it turned out to be a top case causing it. Also if you haven't already try AC power and battery power alone to see if there is a difference.

nj_computer_repair
02-08-2010, 08:29 PM
When the thing was apart, I had the kb and the trackpad detached - all that was plugged in was the power button from the top case to power it up. I do have an ibook top case that I can try hooking it up to.

One thing I noticed was the power button connector on the motherboard was loose. Not the actual connector but it seemed the plug on the motherboard was loose almost like someone pulled too hard on the power button cable and damaged the plug. Could this possibly be causing this issue? I wouldn't rule anything out at this point.

I tried powering on with and without the battery but that did not work.

anonymous Mac Tech
02-09-2010, 03:52 AM
One thing I noticed was the power button connector on the motherboard was loose. Not the actual connector but it seemed the plug on the motherboard was loose almost like someone pulled too hard on the power button cable and damaged the plug. Could this possibly be causing this issue?

I wouldn't doubt if that is what might be causing it. I've seen those connections get loose on the ibooks after the wire being yanked out, but that usually kills power altogether. Too bad these things aren't like the new unibodies where you can short jumper pads on the logic board to fire it up. But at the same time if you are getting chimes when trying to zap PRAM that means will POST. Most likely a bad logic board.