03-15-2012, 05:56 PM
OK, I finally found a little time to scan the 38-5 schematic.
Click the thumbnail to see a larger version:
[Image: http://i326.photobucket.com/albums/k420/...schema.jpg]
There are four wires going to the original electrodynamic speaker in the 38-5. These are used to connect the primary of the audio output transformer, and the speaker field coil.
One of those four wires serves a dual purpose - it is connected to the center tap of the audio output transformer plus to one lead of the speaker field. This is why there are four wires, and not five.
The partial schematic below is intended to make things clearer:
[Image: http://i326.photobucket.com/albums/k420/...5_part.jpg]
In this partial schematic, I have labeled the leads going to the speaker in larger type.
The GREEN and WHITE leads run from the plates of each 6F6G output tube to the primary of the audio output transformer.
The GREEN-WHITE TR. (green with white tracer) lead is connected to both the center tap of the audio output transformer, and to one end of the speaker field coil.
The BLUE-WHITE TR. (blue with white tracer) lead connects to the other end of the speaker field coil.
If you use a PM speaker to replace the original, you will need to connect your resistor inside the chassis to the same points where the BLUE-WHITE TR. and GREEN-WHITE TR. leads connect inside the radio.
The replacement speaker should have the audio output transformer mounted on it, as the original did. Now you will only need three wires running to the speaker, and connected to the primary of the audio output transformer. Those wires are GREEN, WHITE, and GREEN-WHITE TR.
I hope this clears things up.
Click the thumbnail to see a larger version:
[Image: http://i326.photobucket.com/albums/k420/...schema.jpg]
There are four wires going to the original electrodynamic speaker in the 38-5. These are used to connect the primary of the audio output transformer, and the speaker field coil.
One of those four wires serves a dual purpose - it is connected to the center tap of the audio output transformer plus to one lead of the speaker field. This is why there are four wires, and not five.
The partial schematic below is intended to make things clearer:
[Image: http://i326.photobucket.com/albums/k420/...5_part.jpg]
In this partial schematic, I have labeled the leads going to the speaker in larger type.
The GREEN and WHITE leads run from the plates of each 6F6G output tube to the primary of the audio output transformer.
The GREEN-WHITE TR. (green with white tracer) lead is connected to both the center tap of the audio output transformer, and to one end of the speaker field coil.
The BLUE-WHITE TR. (blue with white tracer) lead connects to the other end of the speaker field coil.
If you use a PM speaker to replace the original, you will need to connect your resistor inside the chassis to the same points where the BLUE-WHITE TR. and GREEN-WHITE TR. leads connect inside the radio.
The replacement speaker should have the audio output transformer mounted on it, as the original did. Now you will only need three wires running to the speaker, and connected to the primary of the audio output transformer. Those wires are GREEN, WHITE, and GREEN-WHITE TR.
I hope this clears things up.
--
Ron Ramirez
Ferdinand IN
