[ARC5] Cap Test

[Robert Nickels]

On 2/8/2011 1:10 PM, J. Forster wrote:
> 3. With the filaments OFF, slowly crank up the voltage to normal operating
> voltage. If a cap is bad, the light bulbs will light.
I do a similar technique but using substitute solid state rectifiers and 
a mA meter, where possible to reform the electrolytics in-situ.  Either 
way, the secret is to have an indication of the current being drawn from 
the B+ supply.   All the folklore floating around the internet about 
"bringing it up slowly on a variac" is apt to create just as many 
problems as it solves if done blindly.

Another tip an old radio-TV repairman told me about can be done at the 
same time, and is a time-saver when working on receivers, audio amps, 
modulators, etc.   Pull all the tubes (perhaps running them past your 
favorite tester) and once you have the B+ safely  cranked up, use a 
voltmeter to verify the absence of DC voltage at the grid end of the 
coupling capacitors.    If the cap is leaky, voltage will be present, 
and if not you can generally assume the cap is OK.

73, Bob W9RAN