Replacement inductor for Aluminum Powerbook G4 1GHz?

s_pupp

Well-known member
I have a Powerbook G4 that won't boot with the RAM cover installed. The Superdrive makes noise and the shift lock key turns on and off when pressed, but there's no other sign of life. PRAM won't zap - nothing. After some experimentation, I have become suspicious that the problem is what I presume to be an inductor, labelled "3R8 N33." When pressed on while the computer is running, the screen becomes distorted, and the computer either becomes unresponsive or has a kernel panic. When the RAM cover is in place, the cover presses down on this inductor.

An attempt to resolder the connection resulted in no change whatsoever.

I guess the next step would be to replace this inductor (if that's what it is), but I can't find any information on "3R8 N33" components.

Any ideas?
 

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mdeverhart

Well-known member
That’s definitely an inductor. Before you replace it, try covering it with some Kapton tape (or paper, if you don’t have any Kapton. I’m wondering if the cover is pressing down on the exposed leads on top of the inductor and shorting it out. It’s probably part of a switching regulator circuit, and shorting the inductor would definitely cause problems - the voltage would be really choppy/noisy instead of smoothed out and stable.
 

s_pupp

Well-known member
What happens if you play around with those RAM sockets/modules?
Good thought. I'll try that now.

OK - I tried one stick of RAM in each socket, then the other stick of RAM in each socket. No change in behavior - no-go with the RAM door closed, normal booting with it open. I tried pressing on the RAM and wiggling the RAM socket back/forth and side to side - no problems elicited.



That’s definitely an inductor. Before you replace it, try covering it with some Kapton tape (or paper, if you don’t have any Kapton. I’m wondering if the cover is pressing down on the exposed leads on top of the inductor and shorting it out. It’s probably part of a switching regulator circuit, and shorting the inductor would definitely cause problems - the voltage would be really choppy/noisy instead of smoothed out and stable.
Good suggestion. I tried Kapton tape, with no change in behavior.

After replacing the inductor with one scavenged from a dead A1013 in my e-waste bin, there was no change in behavior - distorted picture when the inductor is pressed upon, non-booting when RAM cover is closed.

Further experimentation reveals that pressing on any component on that part of the board (inductor, capacitors, IC's) causes these symptoms. The opposite side of the board is where the video cable is located - so that would explain the video issues when that part of the board is pressed, but would a bad connection of the video cable prevent booting?
 
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