I have replaced all capacitors on under chassis. I still had a hum from speaker. I took out large electolytic capactitor and removed alum. can. The cap is 20-20-20mfd 450 volts. Schematic calls for 40-40. the cap had 20mfd in parallel and one separate at 20mfd.When I took can apart there was paper and foil, one ground and one line still attached-20mfd line. The 40 mfd lines were rotted/not connected. Smell was like a short. So I have 3 new 20mfd caps, how do i wire them in? the cap can was grounded. Do i run two in parallel to ground, and one to ground? Or will my work blow up!

Hi

Be sure all old electrolytic caps are removed when connecting new ones. Is polarity of new capacitors correct? Electrolytic caps have positive and negative terminals. Voltage rating needs to equal or exceed originals.

Negative terminals connect to chassis if original can was that way..

Since the schematic calls for dual 40 mf caps use 47 mf, modern standard value. Using a lower capacity may allow hum.

Norm

:I have replaced all capacitors on under chassis. I still had a hum from speaker. I took out large electolytic capactitor and removed alum. can. The cap is 20-20-20mfd 450 volts. Schematic calls for 40-40. the cap had 20mfd in parallel and one separate at 20mfd.When I took can apart there was paper and foil, one ground and one line still attached-20mfd line. The 40 mfd lines were rotted/not connected. Smell was like a short. So I have 3 new 20mfd caps, how do i wire them in? the cap can was grounded. Do i run two in parallel to ground, and one to ground? Or will my work blow up!

All non polar caps are replaced, they used 40mfd of the 20-20-20 on two lines coming in. They were polarized and grounded. Can looks original, yet they ganged up on 40 mfd and left second line with only 20 mfd. Radio worked on AM only at time of rebuild. I'll put caps in the same way and see what I get.Still have resistor checks to do. Thanks for the info.
:Hi
:
: Be sure all old electrolytic caps are removed when connecting new ones. Is polarity of new capacitors correct? Electrolytic caps have positive and negative terminals. Voltage rating needs to equal or exceed originals.
:
: Negative terminals connect to chassis if original can was that way..
:
: Since the schematic calls for dual 40 mf caps use 47 mf, modern standard value. Using a lower capacity may allow hum.
:
:
:Norm
:
:
::I have replaced all capacitors on under chassis. I still had a hum from speaker. I took out large electolytic capactitor and removed alum. can. The cap is 20-20-20mfd 450 volts. Schematic calls for 40-40. the cap had 20mfd in parallel and one separate at 20mfd.When I took can apart there was paper and foil, one ground and one line still attached-20mfd line. The 40 mfd lines were rotted/not connected. Smell was like a short. So I have 3 new 20mfd caps, how do i wire them in? the cap can was grounded. Do i run two in parallel to ground, and one to ground? Or will my work blow up!