[Johnson] VIKING VALIANT II

[Roy Morgan]

Ed and others,

This old capacitor problem has been around for a long time. Yes, just applying full B+ to old electrolytics can lead to trouble.  The trick is to reform them, (oil filled caps are likely to be JUST FNE).

I have a “diatribe” on reforming electrolytics that I’ll send to Ed and AA8K73, and others who may be interested.

In brief: with a variable B+ supply and limiting resistor, limit the reforming current to FIVE milliamps and WATCH the voltage on the capacitor as you increase the B+ supply.  You may need to unhook the cap it there is drain on the B+ or the system is complicated with dropping resistors (as is common in audio amplifiers).

I wil also send my diatribe on variacs to hopefully help hapless restorers some troubles.

(Note: I did not refresh my memory of the Valiant system, but I seem to remember that the plate B+ filter cap is an oil unit.)

Roy



> On Oct 29, 2018, at 5:25 PM, AA8K73 GMail <aa8k73 at gmail.com> wrote:
> 
> Please consider using some form of current-limiting, like the "dim bulb" circuit.  A shorted capacitor can open your transformer winding faster than you can get it turned off.
> 
> On 10/29/18 10:55, Ed - K9EW wrote:
>> I inherited a Valiant II from my friend ….- I don't see how I can avoid instantly
>> applying the HV to the electrolytics, running the risk of a small
>> catastrophe.   

Roy Morgan
K1LKY since 1958
k1lky68 at gmail.com