UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Boater Sam · 8th Dec 2017, 11:57 pm

I would have expected the red terminal to be the reservoir cap, 32uF, connected to the rectifier cathode, being the "outer" layer in the can, and the other, usually yellow terminal, 16uF, to be the smoothing cap.

If you study the circuit diagram you should find the order to be, rectifier cathode, reservoir cap (red 32uF), 12k ohm resistor, smoothing cap (yellow 16uF)
[ C20, R5, C21 on the Trader sheet. ]

So another 32uF across the existing one is a no-no as it is then 64uF which exceeds the 50uF limit for a UY41 rectifier valve.

8th Dec 2017, 11:57 pm	#36
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: DAC 90A Smoothing Capacitor replacement I would have expected the red terminal to be the reservoir cap, 32uF, connected to the rectifier cathode, being the "outer" layer in the can, and the other, usually yellow terminal, 16uF, to be the smoothing cap. If you study the circuit diagram you should find the order to be, rectifier cathode, reservoir cap (red 32uF), 12k ohm resistor, smoothing cap (yellow 16uF) [ C20, R5, C21 on the Trader sheet. ] So another 32uF across the existing one is a no-no as it is then 64uF which exceeds the 50uF limit for a UY41 rectifier valve.