Posts: 933
Threads: 140
Joined: Mar 2015
City: Lansdale
State, Province, Country: PA
All, I have a bad Silicon rectifier.. will replace with a 1N5408.. Question is do I need any additional resistance after the diode?
Here is schematic
[Image:
https://live.staticflickr.com/65535/5072...5bf7_c.jpg]
Thanks
Skip
Posts: 2,118
Threads: 112
Joined: Jun 2010
City: Medford OR (OR what?)
I take it that you were replacing a selenium rectifier? ( I see that you stated silicon, which is what your replacement will be?). I would see what the voltage is after the last filter, then add resistance if necessary.
"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
(This post was last modified: 12-16-2020, 05:46 PM by
Phlogiston.)
Posts: 693
Threads: 8
Joined: Apr 2018
City: S. Dartmouth
State, Province, Country: MA
There is 27 ohms in place now to limit the charging rate of the first filter cap.
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
Posts: 987
Threads: 40
Joined: Feb 2015
City: Roseville, MN
The original rectifier is a selenium. If you replace it with a silicon rectifier you should increase R33 by about 100 ohms or add a resistor. You will want to check the voltage chart for the 12AT7 plate voltage and adjust the resistor value accordingly. If someone already replaced the rectifier with a silicon then put your new one in and check if a resistor was added. FM front end amps are usually sensitive to variations in B+.
(This post was last modified: 12-16-2020, 06:00 PM by
RodB.)