Hi:

Am working on replacing the caps (29) 8mfd and 4 mfd on the philco 84 ( Rider (4-34). The original philco can capacitor was disconected years ago and replaced with two smaller electrolytics both rated at 20mfd. 450 volts. HOWEVER I noticed that one of the caps (8mfd in Riders) was placed in with a reveral in it's polarity. No mention of this in the schematic or any footnote No explosion. Was this placed in correctly?? The radio plays but low in volumn I also plan to change the 4 meg resistor (16) to a 2 meg to see if that helps the volumn issue. But I am at a loss about the reveral in polarity Can anyone explain??? Thanks

The two electrolytic caps (4/8 uF) must have their negative leads connected together and then connected to the CT of the B+ winding on the power transformer. Anything else is incorrect.

Low volume is probably caused by (1) weak tube; (2) leaky RF bypass cap from audio signal path to ground; or (3) open (low capacity) coupling cap in the audio signal path between the 2nd detector tube and the audio output tube.

Philco 84 only has 4 tubes. To get more volume there are adjustments in back. One causes regeneration of the IF stage. For decent volume controls in back need adjustment.

http://www.nostalgiaair.org/Resources/875/M0013875.htm

Norm

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:The two electrolytic caps (4/8 uF) must have their negative leads connected together and then connected to the CT of the B+ winding on the power transformer. Anything else is incorrect.
:
:Low volume is probably caused by (1) weak tube; (2) leaky RF bypass cap from audio signal path to ground; or (3) open (low capacity) coupling cap in the audio signal path between the 2nd detector tube and the audio output tube.
: