iBook: faulty DC-In board or something more serious?

G4 iBook runs and charges via the mains power cable intermittently. When it does connect, the laptop runs fine and the battery is charged. At times the connection is lost and the laptop then switches to battery power but the battery does not recharge even though the mains power cable seems to be working.

On a couple of occasions it initially connects ok only for the laptop to then suddenly shut down after a while when the connection is lost: (not a full shut down: the screen goes black but I can still see what I was looking at faintly along with the message 'do you want to shut down or restart'?

I've tried the mains cable and battery in another iBook and they appear to be working correctly. I've run the Apple Hardware Test via the original install disc twice and the laptop has passed all stages.

I'm a bit concerned that when the connection is lost sometimes I can hear a feint buzzing sound from either where the plug goes in to the laptop or from under the casing, near the left hand side of the trackpad (presumably where the DC-In cable attaches to logic board?). The buzzing stops when the cable decides to connect properly again.

Before I go to the trouble of sourcing a new DC-In board and cable and dismantling the iBook, could the symptoms described above be due to something more serious such as the logic board being on it's way out?

I had the DC-in board go on my iBook. My only issue was I couldn't charge the battery, had to use a different iBook to charge it. But based on the fact that you are getting kernel panics, makes me thing it is something more than just the DC-in board.

''based on the fact that you are getting kernel panics''

Am I!? Do you mean the darkening screen and shutdown or restart messages?

Yeah, when the screen goes dark and tells you to restart, thats a Kernel Panic.

Thanks.

Would the Apple Hardware tests I performed not have flagged any problems?