[GreenKeys] CV-89A parts & advice needed

[Jeffrey D Angus]

I will attempt to NOT fumble it this time

boatanchor at martasystems.com wrote:
> Kevin -
>
> Use the variac - with a fuse. Start with 50% power for at least 4 hours (I
> always leave it overnight at this level), then increase 10% every two hours
> until full power. That should re-form the electrolytics. 
>
> Kevin wrote:
>
>> My first question is, after replacing the frayed power cord, can I safely
>> power it up immediately or should I bring it up slowly with a Variac?
This might not be a popular opinion as it goes against all the common
urban legends that have been passed down over the years, but I am
not in favor of re-forming electrolytics. They are either good, or they
are bad. If they're bad, re-forming them isn't going to magically make
them good again. And considering the price of new components it
makes no sense to waste the time fiddling around with reforming.

I work on 30-70 year old radios for a living. Anything over 50 years
old automatically gets all the filter caps replaced. Occasionally, I will
grab some NOS twist lock electrolytics made by Sprague and test
them for leakage on Tel-Ohmic before using them. But for the most
part I just install brand new electrolytics under the chassis and that
solves the problems with thing failing at a later date. Hours or days.

Secondly, if the rectifier is a vacuum tube type, using a variac is some
what of a moot point, as the line voltage has to be at least 80% or
the tube won't conduct to begin with.

Jeff-1.0
wa6fwi