I'd like to hear someone's explanation why you
would want to do this. It you're concerned about thermally shocking an old
circuit, simply unplug the power supply circuitry from the load. If
some component on the power supply board can't handle the inrush of an
unloaded system, you would want to know anyway and want that part fail
without being plugged into the system.
A better idea would be to put a power
rheostat across the load and slowly load up the power supply circuitry
after it's powered up.
As for the incoming AC mains, I can't see the
benefit. If you're
concerned about the age of the parts, just make sure they're a nice room
temperature then put the poop to it. Anything else is snake oil IMO. I sure wouldn't variac anything. It's
designed for 110 or 220, (depending). Run it there.
All an isolation transformer does is get rid of
minor line noise or spikes. Unless you live in a really crappy power area, it's
not really going to do anything. It certainly
can't hurt of course, but I'd say the money would be better invested in a solder
vacuum system (Hakko) or cheap o-scope.
Scott
----- Original Message -----From: Tom ButcherSent: Friday, September 13, 2013 12:21 PMSubject: [vintagesynthrepair] Isolation transformer / variac during restoration
Hi list,I'm getting my feet wet with restoration and repair. I mistakenly bought a broken Oberheim DMX from Ebay and wound up accumulating some more parts that should give me enough to get it going.I've read in various places that it's a good idea to use a variac or isolation transformer with voltage control to gradually bring up the device after cleaning and drying etc. Is this a good practice? I found an isolation transformer with voltage regular for about $200 I'm considering buying. From what I can tell, this would give me the ability to gradually increase the AC voltage to the power supply as well as circuit isolation from the AC mains.So if I have that thing there's no need for the variac, right? Seems like the advantage to the variac is just more current capacity.t