Electronics guru's need help identifying something again.

[harrkev]

Since the cap goes to a pad that has a nut, I agree that it is most likely a decoupling cap. I would just throw a 1.0 uF ceramic on there and be done with it.

What is the item, and is it working right now? Since there is already a cap there, my guess is that the device still works as-is if you remove the dead one.

 

[Demon-Xanth]

Just a guess, but most likely one of those two caps is something like 0.1uf and the other 0.001uf or 100pf. They do that because of frequency response.

 

[Kaervak]

Originally posted by: harrkev
Since the cap goes to a pad that has a nut, I agree that it is most likely a decoupling cap. I would just throw a 1.0 uF ceramic on there and be done with it.

What is the item, and is it working right now? Since there is already a cap there, my guess is that the device still works as-is if you remove the dead one.

G4 iBook motherboard. It's mostly working. It's in the batch of iBooks that has the logic board problem where the GPU's soldering is poorly done so after it warms up the chip looses contact and freezez the system. After I found that cracked cap I thought that might have been causing it, but from what everyone is saying it doesn't seem to be all that important.

 

[GalvanizedYankee]

Bad soldering joints on Dell/BenQ LCD monitors are common.

Good luck on this project.

 

[harrkev]

Originally posted by: Kaervak
G4 iBook motherboard. It's mostly working. It's in the batch of iBooks that has the logic board problem where the GPU's soldering is poorly done so after it warms up the chip looses contact and freezez the system. After I found that cracked cap I thought that might have been causing it, but from what everyone is saying it doesn't seem to be all that important.

Well, in that case, toss it. Seriously. If you have a soldering problem on a large BGA (ball grid array) part, you are pretty much hosed. Yes, you can re-work them, but the equipment, time, and training needed all cost MUCH more than just buying a new iBook.

Once I designed a board that had a 144-pin BGA on it (rather small as BGAs go). At manufacturing, they were trying out a robot to do the underfill operation (inject thermal goop under BGA to aid in head conduction). The robot went crazy and ripped the chip off of the board. Even though they were able to replace the chip, I never could get that board to work.