Help with a soldering / micro-soldering

Electronics
#1

Hey guys,

I have a little soldering/electronic project. I believe I have a capacitor that blew on a logic board for an iMac (it fell off). The computer works just fine, but the display doesn’t turn on (I have checked the computer by connecting it to an external display and everything is great). I have done a little research and it is apparently a 250 Ohm ferrite bead that is part of the 12v power to the LCD burned and fell off. I was told that I need to replace it. I bought the chip and need to learn / get help soldering it on there. I was hoping someone knowledgable would be around DMS this weekend that could help me. You would be amazing!

I would appreciate the help immensely!! :slight_smile: :slight_smile:

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#2

If it burned you have a short circuit somewhere in the LCD display. That will need to be fixed first or it will just burn again.

2 Likes
#3

Ah yeah, I wanted to see if for now that is the main issue and if there are other things that might be issues as well. I will definitely want to learn to check for a short circuit as well, if that is something someone can teach me

#4

It’s hard to see what’s going on there. Any chance of getting a closer photo? The microscope in the elab has an adapter you can fit your cell phone camera to.

I don’t see a burned ferrite bead or the empty pads. If anything it looks a little like the discoloration is centered around a via. The repairability depends a lot on what’s left of the pads so that’s why I bring it up.

But it’s still true that the ferrite bead seems to have acted as a fuse in this situation and you should expect to find the real problem elsewhere. I might start by replacing the ferrite bead with a resistor in order to measure the current going through it. But you have to be careful doing this because if you let too much current through and you’ve replaced the ferrite bead with something less fusible then something new is likely to pop instead.