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Old 10-26-2009, 12:55 AM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,829
I started working on the electronics last night and ran into a few issues. First, someone has replaced the original field coil speaker with a PM one.
Now instead of a 500 ohm coil, there's a 220 ohm resistor feeding the audio output tube and output transformer and a 1.2 K resistor feeding the other tubes.

Wouldn't a single 500 ohm resistor be more appropriate? Were they trying to boost the output power?



The other issue is with what is labeled C14 and L1 on the schematic connecting the chassis ground to earth.
The existing parts are a 0.02 uF cap with a few turns of plastic insulated wire. Does anyone know the purpose of this? Maybe a noise filter ?

My modern 0.022 uF caps are a lot smaller and a rewound coil won't have the same inductance.
Any thoughts on how to replace it?
Here's the old one behind that big yellow cap.

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