<For PSU's without switches and with a label that doesn't state 
<110V-220V as the input range there are three options:
<
<One:
<Take the 'easy' way out and put a 220->110 transformer in front of 
<the PSU. Does use some extra juice and can get kinda 'heavy'

The 3100 has a under 200w power supply so the transformer is not immense.

<Two:
<Open up the PSU and take out the PCB and other stuff. Look at the input 
<on the PCB. A lot of PSU's were actually designed (and built) to run on 
<both voltages, but were delivered in a 'preset' mode. 

most of them have a switch or a board level jumper to get to 220.

<Re-wiring the 110V to the 220V input and then testing it with a 'safe'
<load (I often use a car headlight bulb of 50 or so watts) and a 
<voltage-meter to see if everyting checks out.

The 3100 series use a switchmode powersupply, no transofrmer.


Allison