Arfa Daily wrote:

Jacking these PSUs up a couple of volts is not usually that hard. There's
often an 'adjustable zener' IC on the primary side, which is fed from the
secondary side via an opto coupler. This zener serves as the reference to
set the PWM for the desired output voltage. Altering that voltage is just a
case of changing one resistor to alter the reference voltage.


Another resource.

http://www.pavouk.org/hw/en_atxps.html

The above schematic could be frigged about with by selecting a new value
for R25.

Typical 13.8v project.

http://www.webx.dk/oz2cpu/radios/psu-pc1.htm

--
Adrian C