AB's Useful Box - Toshiba Satellite Pro 480CDT - Back Lighting broken

Were recently given a Toshiba Satellite Pro 480CDT laptop pc in excellent condition other than one small problem, the back lighting of the LCD was gone.

It had already made a trip to the local Toshiba service agent who unfortunately reported that spares for the circuit that drives the back lighting were no longer available, so basically the laptop was a write off. Which was a shame as it had a 2Gig HD and 160Meg RAM and the display was other wise in excellent condition.

Well if it was only going into the bin, may as well pull it apart and see how it all works. Found inside the display was a small printed circuit board(PCB) that provides an inverter circuit for driving the LCD's back lighting. A closer examination of the PCB revealed there were two fuses, one was a 0.6Amp fuse protected the main power line into the PCB, the second was a 2Amp 102degree C thermo fuse. Quick test with the aid of a multimeter revealed the main fuse was still intact and the problem being the thermo fuse was open circuit, thus no power to the back lighting. Just as a simple test the thermo fuse was by-passed, and hey presto the back lighting came to life.

One small problem with some thermo fuses is that they appear to age, and as such their tolerance level slowly decreases. So if the component was very close to the normal operational temperature, after a couple of years of constant use they expire and in most cases render the equipment generally unrepairable.

Next was to locate a replacement part, found one very similar through Farnell In One.
Part details: #262-511 WTF105:Fuse, Thermal 108C (tollerance +0/-6) @ $2.05 each.

To install the new thermo fuse required some very good soldering experience.

Below is some pictures of the said machine.

There are lots of screws, but these are the only two that
need to be removed to disassemle the screen. All the rest
is just clipped together.

After the front has been removed, this shows the location
of the printed circuit baord(PCB).

And this is the offending component, a 2amp 102degree
thermal fuse. Replace it and you're back in business!