Capacitors for Radio Frequency Amlifier and Converter Oscillator Tubes

[dscottguitars]

I have two capacitors in this Stromberg Carlson, 1946 console amplifier that I cannot get to. They are on the Radio Frequency Amplifier tube, #1 on the schematic and the Converter Oscillator tube, #2 on the schematic. See link for schematic: http://audiophool.com/Schem_R/Stromberg_1121-schem.gif

Attached is a picture of them, the are in the center and light blue colored. As you can see they are buried and I cannot get to them without taking it completely apart and that's more than my expertise will allow. I've replaced all the other caps in the unit.

They are Solar brand and have 'sealedtite' on them. How crucial are these two caps in these two stages? Any suggestions for changing them?

Thanks...

 

[DUG]

"How crucial are these two caps in these two stages?"

I would say that if they are there then they are required to be there.

If you could determine which caps they are in the schematic I could offer an opinion of how critical their values and type are.

If they need to be changed then you will have to find a way...or find someone that can do it for you.

Sorry I could not be more help.

 

[dscottguitars]

I believe they are #34 and #31. With my question, I meant more of how crucial are they that they should be changed. They are a different type than the others and thought-hoped-they didn't need to be replaced. Hope that helps...

 

[gootee]

Usually you only need to replace the electrolytics and any that are paper-based.

Here is some good info: Replacing Capacitors in Old Radios and TVs

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So, is that photo from before you started? Or are you one of the people who puts the new caps inside the bodies of the old ones?

 

[dscottguitars]

That's before I started. I'm not sure if those Solar brand caps are paper based or not. I'll research that more, thanks...

 

[DUG]

#31 is to bypass supply and to offer low Z point for A6 and A12 IF coils to do their bandpassing. It also keeps any IF from higher amplitude stages from feeding back to a more sensitive amplifier stage. This one needs to be low Z @ 455KHz. Without it bandwidth may suffer and IF gain will be reduced or oscillation may occur.

I think it is kind of important.

#34 It keeps the RF out of the supply line. Less critical than #31.

IMHO of course.

Hope that helps.

 

[dscottguitars]

Here is a link to a discussion about the Solar Sealdtite Capacitors. I think I am just going to trust they're okay and put it back together and fire it up...

Antique Radio Forums • View topic - A general education question about capacitor brands.

Thanks for all the input.

 

[Tom Bavis]

Both have a current-limiting resistor if they should fail - so at least they won't take out a difficult-to replace part if they do.