Replacing Capacitors in tube PS

Thread Starter

snav

Joined Aug 1, 2011
115
I was checking on a hard to turn potentiometer and noticed two old electrolytics that needed replacing. When I looked at the schematic I noticed that the rectifier was a triode creating a dual supply. The original owner left a note that resistance was measured using 60hz so measuring choke resistance was not possible.
I am uncertain how critical the values used are considering the trick being used here. I have 22uf/500v on hand and can easily find 10uf 450v.



https://forum.allaboutcircuits.com/...7/?temp_hash=3ff7611ebc398f7c2baccfe197623056
 

AlbertHall

Joined Jun 4, 2014
12,345
I would think that replacing 8uF with 10uF would be OK, but 22uF would increase the peak current through the rectifier and might cause problems.

450V seems rather close to the 410V marked across one of those capacitors given that it is an unregulated supply. What is the voltage rating of the original?
 

Thread Starter

snav

Joined Aug 1, 2011
115
I would think that replacing 8uF with 10uF would be OK, but 22uF would increase the peak current through the rectifier and might cause problems.

450V seems rather close to the 410V marked across one of those capacitors given that it is an unregulated supply. What is the voltage rating of the original?
Originals are 475 and 350 so yeah, not a great margin. I will look for some 500 or 600v.
 

Thread Starter

snav

Joined Aug 1, 2011
115
While waiting for replacements I started checking other items, The 47k resistor that helps form the voltage divider was 89.7k. Interestingly the unit seemed to be working before the shaft of the Power factor pot got too stiff.
 
Top