Depends what the variac is rated at, unplug radio switch on and measure the resistance across mains lead with an analogue meter, if it's an AC/DC set it should measure approx the sum of the heater resistances + the dropper, if that reads ok then make sure a correctly rated fuse is fitted and monitor the expected current consumption with an analogue meter while slowly advancing the variac.
My own personal way is to publish and be damned ie: plug it in and switch it on at full bore, if anything smokes it will take you straight to the area of the problem.
Lawrence. (Edit) Whoops Mark beat me to it..
My own personal way is to publish and be damned ie: plug it in and switch it on at full bore, if anything smokes it will take you straight to the area of the problem.
Lawrence. (Edit) Whoops Mark beat me to it..
