"Rambo" wrote in message
...
On Wed, 30 Apr 2014 21:24:41 -0700, "coffelt2"
wrote:
Garth, I'm no expert, by any means, but have dabbled in old stuff for
quite a few years. I am always concerned that even at the first
application of voltage, something might be actually shorted, and not just
needing "reforming". Good idea if one can devise some way to measure,
even roughly, how much current is being drawn from the Variac.
Some (me included) have inserted a low wattage incandescent lamp in
series with the applied voltage. Better, probably would be an AC ammeter.
Of course one never knows just what current is normal, but a nearly dead
short should be reasonably easy to detect.
Start off very slowly, feeling (without touching) around for warmer
than normal parts, keeping nose carefully tuned for any odors not present
when the stinking thing was still cold and unpowered.
Keep fire extinguisher and telephone handy. Good Luck!
Old Chief Lynn, W7LTQ
"gareth" wrote in message
...
Having now borrowed my friend's Variac, what is seen as
good practice for ramping up old valve radios to reform the
capacitors?

Start off at, say, 50VAC and then increase by 50VAC every
1/2 hour until 240V is reached?
Gareth,

Ive done this in the past and its not for the fainthearted! Check
Check and check again that the chassis is not live!

Already done that in respect of checking the mains plug and earth
connections.

Then if you have
an ESR meter check for very low resistance capacitors. An Esr meter is
quite essential when dealing with vintage gear. Most electrolytics
will be leaky as hell.
The pp is quite right in suggesting a current indicator/ limiter in
the form of a bulb in series use one about the same or higher than the
rating of the set.

Thanks to both, but it seems that it might be acadaemic for the moment,
because initial safety checks before applying any power suggest that the
transformer primary is O/C.

(But the loaned variac does have an integral ammeter)