My first BookPC was aquired because it was dead. Nobody knew what was wrong with it. I wanted the project, so it became mine. I've since fixed it up, and use it daily. Turns out the power supply had some dead components. There was a dead capacitor and a burnt power resistor.

You can see the replaced capacitor, upper left corner, just below the blue capacitor sort of obscured by the negative wires. The power resistor is soldered to a heatsink immediately to that caps left.

After I got the PSU working, the original fan was noisy, and dying. I attempted to replace it with an externally mounted 60mm fan from an early Xeon retail box HSF. Great idea, but even running it at 5v it made too much wind noise.

So I opted for a quieter 60mm fan from a noname P4 HSF. In the second picture, you will also see that I've wired up a 5v voltage regulator to give the fan 5v instead of using the 12v header on the board. The fan still moves enough air to keep the system running at a good temperature, and dramatically cuts down on wind noise. I also opened up the vents on the PSU to allow the air to flow with less restriction into the PSU case.

I've now been using the machine for over 8 months without problem. It is currently running Debian Linux with a 2.6.5 kernel. Using the onboard NIC, S-Video and sound, the machine runs Mythfrontend as part of my MythTV setup.

But now, I have purchased another BookPC!

Because I've had soo much success with the first unit, using it on our main television in the livingroom, I wanted another machine to run Mythfrontend in the bedroom. The BookPC is pefect for the job. Sure it seems silly to run a network cable into the bedroom, but we're already running a television cable in there, and a telephone cable, whats one more cable? I'll just tidy everything up and nobody will be the wiser.

And ofcourse, about 6 hours after I fire this new BookPC up for the first time after I received it from a friendly guy in Florida, the PSU craps out. These power supplys were seriously underbuilt.

It appears that a 2000uf 10V cap on the PSU died. I just happen to have two of the same rating, but slightly different physical size on hand. I was getting a little carried away while trying to trim away the old white glue, and ended up trimming a chunk of the plastic casing away. oops. I did put a piece of electrical tape on the inside of the housing to prevent the cap from accidentailly touching it. There is enough space where it wouldn't be a problem anyways.

update: even tho this capacitor was working perfectly, it's ugly as hell. I dug up another proper, nice looking cap. You can sort of see it in the pictures below.

Sadly, after replacing both of those caps, the unit was still dead. I double checked, and it's actually the PSU that isn't working right now. After some more investigation there didn't appear to be any burn marks on the board. That would make it far too easy for me to discover and repair.

It turns out that R3, a 120k ohm resistor had failed open. R3 takes power from the bridge rectifier when you plug the PSU into the mains. It is part of a circuit that provides power (can't remember what voltage) to the Vcc pin on the PWM (pulse width modulator). The PWM provides the signal to the power transistor which inturn feeds into the actual transformer which lowers the incoming mains voltage to something usable (~12v DC and some other stuff).

So the problem was that R3 was open, but not physically damaged. It looked just fine. I didn't take any pictures of the dead one because it's nothing special. It looks like a 120k ohm resistor, but it's dead.

I went to pickup a replacement flameproof 1 watt 120k ohm resistor from Main Electronics. Unfortunately they were out of stock. So I picked up 2 x 240k orm of the same ratings.

I had to do some creative wiring/soldering and it's worked out great. Running the two 240k ohm resistors in parallel provides 120k ohm. The bending was done to make the legs line up with the holes in the circuit board. The slant is to clear the rectifier bridge.

The BookPC is now working properly again.

The next modifications to be made are the 5v voltage regulator for the fan. And to open up the grille holes to allow for better ventilation and less wind noise.