[OwossoBorn]

Last night my 800Mhz Ti Powerbook lost its trackpad. It was sitting for half the day on a pile of papers that obstructed the natural flow of air underneath as well as accumulation of heat in the paper. I thought it would be fine, but I started smelling something like burning electronics and noticed the trackpad wasn't responding. I did a force shutdown and immediately opened her up. I put on my magnifyer goggle headstrap and started looking around the logic board. What I found was a lonely little surface mount item that had performed a suicide bombing of itself, leaving a black mark all around it. One of the trace pads came off in the mico-mini explosion, but the other is fine. Also, the tiny device living next door took some heat as well and may also need to be replaced. They look like capacitors or resistors but the silk-screening on the circuit board is labeled "L63." Not sure I know what the L stands for.

Ok, enough setup and explanation. Does anyone know how I can find out what these dead surface mount parts are so I can replace them? Sending to apple for repair, buying a new or used logic board are all out of the question. I had my 17" PB stolen back in January and this one was given to me to use while I try to scrape up the money to buy a new MBP. I have to give it back at some point, so I have to fix it. I have no issue with soldering tiny things and have the right equipment, I just don't know where to find the correct values of the components in question.

Here's a nice shot of the carnage:


Anyone?

[gse1woody]

OUCH !

L stands for inductor.

It doesn't look like there is much pad left to solder a new one to. Is it on the mainboard or a subassembly ?

[OwossoBorn]

It's on the mainboard, between the airport card connector on the left and the trackpad connector on the right.

Ok, so it's an inductor. How do I find out the values of the dead one(s)? I have seen internal Apple service manuals for the powerbook before, but they basically are glorified take apart manuals. I'm guessing I need a schematic to get the real values, but that doesn't seem too likely. Maybe I could look for a dead logic board that probably still has those little guys intact? I can follow the trace pads to their next connection and solder there if I have to. Not sure if it would work, but I have to try.

[OwossoBorn]

gse1woody, you got me thinking when you asked if it was on the mainboard or subassembly! I had replaced a PMU from my old 500Mhz Ti Powerbook a year ago and kept the dead PMU. I just found it and looked at where the trackpad connector is and look what I found!

It would seem this is possibly a common issue with trackpads on the older Ti powerbooks? You can clearly see L4 is lifted up and separated slightly from the circuit board. The surrounding area looks a little different than the rest of the board, ie.too much heat. L5 & L6 look unaffected. I'm going to try and remove those and put them on the 800Mhz logic board from the first photo above. This would totally ROCK if it allowed the trackpad to be recognizeable again!!

[OwossoBorn]

IT'S ALIVE!

I cleaned up the exposed traces/pads, put a smidgen of epoxy over the thin traces that go under the exploded part, tinned the pads, desoldered one of the inductors off the PMU board and two slight taps of the soldering iron later I had a working trackpad. I left it running for about 10 minutes with the back off to see if the newly soldered part was heating up or not. I didn't know if the exploded part was a casualty of some other part failing, causing millions of volts (ok, a few too many milliamps) to surge through it. All seems well so far.

This shot shows the 500Mhz PMU board sitting on top of the 800Mhz logic board to show the inductors are at least of similar size/shape/color etc.. There are no markings on these babies, so I was trusting that they were all the same.


Here is the final inductor replacement.


Thank you again gse1woody for triggering the thought of part hunting on the PMU board!

[gse1woody]

No problem...glad I could help.

[macgyvr64]

Nice recovery, dude!