Using a Variac to revive power supplies

[dwight elvey]

>> From: toby at pdp11.co.uk
 
> I've recently acquired a Variac (220V 10A) and was wondering what the
> collectives views are on using them to revive long dormant power supplies.
> 
> Previously I have removed the electrolytics and reformed them with a bench
> power supply setup, slowly ramping up the voltage (as per
> http://www.vcomp.co.uk/tech_tips/reform_caps/reform_caps.htm). Am I right in
> thinking I can use the Variac to effectively reform the capacitors in
> circuit?
> 
> I'm currently rebuilding one of my PDP-8/E's which has a linear PSU which I
> believe is ok, but will it also work with later DEC switchmode PSUs?
> 
> All the best,
> Toby

Hi
 Don't use it on switchers. It is sure to either cause a failure
or for those that have brown-out feathers to not work
as expected.
 If you want to bring up capacitors for switchers, remove
them from supply and use bench supply with a limiting resistor.
 This is the better way, even for a linear supply.
Tinker Dwight