[jan-jaap]

I recently did some work on the PSU of my Professional IRIS 4D/70. On the bench with a couple of power resistors attached it worked fine. I spent 4 hours assembling the wiring inside the Twin Tower chassis, only to find out the PSU has an oscillation of ~ 0.6V TT @ 2500Hz on the +5VDC output under load. Lesson learned: need better tools to test PSU before assembling everything. An electronic load for 200A is very expensive, and the wiring is troublesome, so I settled for this 40A specimen from China. The cables are custom made, 16 mm2 to attach to the 8mm bolts where normally the bus bar attach.

The rotary selector know is the cheapest ever, but it seems to do what it's supposed to do otherwise.