We have a couple here at the shop. An external +/-16VDC PSU can be used and works just fine, I think mine is a Power One .5amp (I think). These things are pretty sweet to have, save time and saves the possibility of blowing up the rest of a console with a suspected bad module. There is also another box that is used for modules with VCA cards for Ultimation Faders, the SL654/613. Finding one for sale is going to be a task for sure. Not many out there and most are considered gold to the people that have them. Best bet to finding one for sale is finding a studio that is liquidating their studio. I have opened them up for a peek, not too much going on with them and you could probably fabricate your own fairly easily. If your just testing audio paths you could cut out a lot of the circuitry and "dumb it down". Lots of Rotary Switches though which could be costly. We have a huge stock of 4K and 9K parts, if you need anything as far as that goes shoot me a PM.