I'm working on someone's iBook G4 and it has a blank screen. The backlight comes on and sometimes lines flicker on the screen.

It will boot into target disk mode so I know that the CPU, RAM, Hard disk work just fine.

The owner says that the sceen originaly went all green for a while then he had someone work on it. The technician opened the screen and wiggled the cable and closed it back up. This has been done 3-4 times on sepperate occasions.

I opened the screen and it was clear that the cable had been removed and re-connected several times. The wires look to be in good condition but i believe that the cable might have been strained or the connector. I also oppened the bottom of the ibook and found the other end of the cable. The connector is slightly cracked but it does not appear that it is the source of the problem.

The owner told me that an apple technician in Hong Kong told him to replace the Logic board. I've never seen an onboard video card go out on a laptop so I don't believe it's the logic board.

Please advize.

I have a similar problem, backlight but nothing on screen, it will work on a monitor or TV, I have swapped the LCD, the inverter, tested all the cables and the reed switch, none of this has helped so I am thinking it must be a logic board problem?

Any help would be very welcome!! Scott.

The place to start with this issue is the Display cable, and next the LCD to rule out these two possibilities. The fact that playing with the cable seems to fix the issue seems to suggest a problem with the cable itself.

Worst case you'll be looking at a logic board failure of th eonboard video. It is actually quite common. More common in the iBook G3 line then the G4, but we've still seen several iBook G4s with onboard video issues that require a logic board replacement.

-Bradley
Powerbook Medic