envwpk@epb2.lbl.gov (Werner P. Keilholz) (03/20/91)
I'm almost sure this is a stupid question, but what the heck... Recently I brought a (switching) power-supply from the US to Germany. On the box it said, "110/220 V switching Power-supply". Since I could not find any means of adjusting the Voltage (i.e. changing the input voltage from 110 V (US) to 220V (Germany), I just plugged it into an outlet, hoping for the best. Happily I put a small load at the output side and measured 5V DC - everything worked fine... for about 30 seconds. After that I could hear a capacitor boiling... Of course I have in the meantime replaced the power supply, but I still would like to know what I did wrong ? I obviously proofed that the power supply does *NOT* automatically adjust to a different voltage... but how does one change it ? I even opened the case (ignoring the label "no servicable parts inside"), but there's no trace of any kind of switch etc. I understand that "switching power supply" referes to the fact that it adjusts to its load and that this has nothing to do with the input voltage, but still it said "110 V / 220 V" and there was no hint that this might refere to two different versions or something ! P.S.: broken power supply for sale... cheap ! :-) Werner