iBook G4 - logic board repair

[marcosfisica]

Hi everyone!
My first post here in the TinkerDifferent. My name is Marcos, I'm from Brazil, and I have a small collection of powerpc Macs.
I have an iBook G4 14" late 2004, that doesn't boot up. I bought it as a "not working" condition and I'm trying to restore it.

However, I couldn't find the schematics of the logic board (820 1646 A). So I'm doing some tests and going by trial and error. When I plug the charger in nothing happens, but, this component of the picture heats up. It gets really hot! I believe that could be some short here. Is this a resistor or a capacitor? I think it's a resistor but I'm not sure.
I'm a physicist, I have a basic knowledge of electronics and what each component should do, but I'm not a technician. I just like to tinker around with my old Macs (well, maybe as everyone else in this forum ). Should I try to replace this component? I know that maybe there are other problems with this iBook, but I think this could be a good start.

 

[Kai Robinson]

The silkscreen marking indicates that it's a resistor, with a value of 390ohms.

Get a multimeter and measure the resistance across it when powered off. If the reading doesn't tally with the rating, replace it. It might be shorted, but equally something it's connected to is shorted and that resistor is funnelling the load through itself.

 

[GiGaBiTe]

I would suspect a nearby shorted tantalum or MLC capacitor. You might try looking for shorts to ground on nearby capacitors, or shorts across the capacitors. While other components could be at fault, SMD tantalums and MLC capacitors are the ones that cause trouble more often.