Computer supplys for charger power question

[BrianG]

There are a few ways you can boost the output, with different levels of complexity:

1) Use a resistor to load the 5v and/or 3.3v line with ~1A. This usually just makes the 12v line more stable rather than boosting it though. Whether to load the 5v or 3.3v line depends on the design, a simple experiment on each quickly shows which one though.

2) Some supplies have an internal PCB mount pot you can tweak the output. Most don't. If there is one, note the current position, then adjust it while monitoring the output. If the output doesn't change, then the pot is used for something else, so put it back where it was.

3) Some supplies have a smaller wire that senses the voltage, like a feedback line. This wire usually is attached to the rail it is monitoring at the motherboard connector. You can use a couple resistors to trick this wire into seeing less voltage than there is, which causes the output to increase to compensate.

4) If you are really good, you could reverse engineer the PWM circuit and figure out how to trick the feedback pin on the main IC to output a higher voltage.

In any of these cases, you can usually get a solid 12-13v out of the supply, but anything higher tends to cause the supply to shut down. Your mileage may vary.