View Full Version : iBook 12" G4 black screen

Apr 18, 2011, 07:35 PM
The black screen issue seems pretty prevalent on these G4 ibooks. I have two old G3s and they still work great.

Here's my problem on the G4:

Black screen, no trace or flicker of anything.
Have reset both PRAM and PMU. Still black.
I removed extra RAM and the Airport Extreme card. No change.
Computer works in target mode. I can read and write to the drive from another computer via Firewire.
No image on an external monitor so it doesn't appear to be an inverter or backlight problem. I suspect the video subsystem on the motherboard but I hope that's not it and I don't know the wiring for these, so I can't judge.
Squeezing the area left of the keypad where some are known to have a badly seated chip made no difference, even when I put varying amounts of pressure on it.

Any ideas? It's such a great little machine. I wish it had the same reliability and longevity as my G3s. I'd like to get it working.

Apr 18, 2011, 08:27 PM
If there is no output from the external then it could be that video card is failing. You will know that the inverter is faulty if the apple logo on the lid is not turning on.

If the screen is black and there is output on the external port then it might be that you have a poor LVDS connection or the cable is faulty.

Apr 18, 2011, 10:35 PM
The G3s are also notorious for their GPUs separating from the logic board.

On the G4s it's a different chip but still basically the same concept. There is a little chip that had developed micro fractures causing the same symptoms.

Read here. (http://macintoshhowto.com/hardware/how-do-i-get-my-broken-g4-ibook-fixed.html)

Apr 19, 2011, 09:49 AM
The GPU on the iBook G4 is not to the left of the trackpad like it is on the G3. It's below the keyboard, almost directly below the S and X keys.

The G4 Vreg Chip failure (the little chip that develops micro-fractures, which is to the left of the trackpad) usually causes a no boot/black screen situation, but it completely disables the computer. You would not get a chime, you wouldn't be able to get into Target Disk Mode and usually the fan will ramp up to full speed on boot. If you can still get into Target Disk Mode, I doubt the chip solder fractures are the problem.