Cursitor Doom wrote:

I don't think any of us here would take some semi-ancient item of
electronic equipment of unknown provenance and just plug it in the mains
socket and switch on. We know from experience or elsewhere that is not an
advisable thing to do. So we typically gently wind up the voltage via a
variac over an extended period of time. But is that enough? I read
somewhere one should also monitor the current drawn by the equipment as
one does this. I admit I've never been quite that fussy, but would be
interested in hearing what others think about this rather more cautious
approach and if it actually achieves anything worthwhile.


** I've been using a variac plus RMS current meter for 30 years and also see a lot of gear that has been out of use for over a decade, mostly tube amplifiers.

Providing you have a good idea what the AC draw should be under idle and standby conditions, you can apply full supply voltage in a short time if the draw seen rises smoothly towards the expected value.

Of course you need a decent current meter to do this, a 10amp moving iron type is not adequate. I use a dedicated 3.5 digit LED meter with internal RMS converter.



..... Phil