Hi Boxwood,
I presume you have already checked with
www.power-one.com for info? You might have to contact them to get the info.
http://www.power-one.com/resources/p...asheet/lin.pdf
However, having said that, usually the main transformer on the power supply has multiple taps on the output side that permit the changing of the voltage by unsoldering the connection and moving it.
You need to have a respect for electricity before you fool around with these things with the power applied, because you need a volt meter to measure the voltage at the output taps on the transformer. Use your volt meter's AC functions to measure transformer voltages, since transformers are AC devices.
You should be able to determine that it is outputting 24 volts now, if that is how it is wired. One tap will be common, so you can check the other voltages between that one and each other tap on the output side of the transformer.
There may also be multi-taps on the input side of the transformer, but you should be able to easily trace which side of the transformer is the high voltage input by where it connects to the input terminals. Don't mess around with your probes in this area.
Since the power supply has a constant watt output rating, the allowable amperage drops from 12 amp @ 24v to 10 amp @28v. There is no direct adjustment to make for amperage, except to protect the output circuit with proper fusing to make sure the applied load cannot draw more than the manufacturer's rated amperage recommendation.