Restoration Idea 2

Restoring Transistor Radios

1957-58 Sylvania 3203GR Six Transistor Radio- A Near "Basket Case" Restored winter 2012-2013

I found this at an antique mall in the city of Orange in California. Pre 1960's transistor radios are not common and I like the look + Sylvania is not really known for radios but for electronic components. This radio like many battery radios suffered from battery leakage and this in turn damages the contacts and components. Usually the damage is so bad that the radio is not worth fixing. Since this radio has a large chassis there was a chance that it can be repaired. What I found was worth writing about.



TOP: Front Face with all the gold lettering repainted BOTTOM: Nice Back showing Sylvania LOGO and identification as a Six Transistor Radio and "Unbreakable Case"!


1. How corrosion destroyed components:

A. The Sylvania 2N194 Converter Transistor leads rotted away. I found a 1950's replacement and used a "top hat"

GE 2N169 I had cannibalized from a real basket case radio.

B. The Sylvania 2N233 IF Amplifier Transistor also lost half its lead. I was able to fix that one. Some resistors were way out of tolerance so as you can see I replaced them.

C. The battery corrosion destroyed the speaker and I wound up replacing it. However the output transformer was riveted into the speaker so I had to remove it and mounted it on the hardboard as shown. The hardboard was also damaged by corrosion and I had to make a substitute and painted it to original color. In addition the tuning capacitor was corroded, I removed the corrosion and repainted it (not shown).2. Turned the radio on and checked transistors and electrolytic capacitors. The radio made a sound but it was weak and sounded terrible. I put my hand near the antenna and the sound got stronger and can tune stations. I ran a signal test through it and I lost most of the signal past the audio amplifier stage. Usually there is a detector diode and filter circuit that changes the radio signal into sounds the human ear can hear. I looked all over and can't find one. Sometimes radio designers use a transistor as a detector but this was not the case with this radio. I had to find a schematic for this radio and wound up buying one online.

A. After looking at the schematic I found the detector diode was built into one of the IF transformer cans as shown below. After carefully taking it out of the circuit board and opening the can I checked the transformer and it checked good, but the detector diode (Raytheon 1N60 in plastic molded body) had a much higher than normal forward voltage, which is probably due to moisture contamination as the plastic started to shrink and the seal gave way. I replaced it with a modern 1N34A glass sealed diode. Put everything back in and turned it on and now I got a LOT more speaker volume but not clear.

LEFT: The aluminum can on the left has the diode and filter circuit built inside. The brown tubes are electrolytic capacitors that are stuffed inside with more modern capacitors.
RIGHT: shows the red diode found defective and the new glass diode it replaced.

B. Finally one of the transistor was leaded improperly in the audio output stage. I installed the transistor backwards and it works with a loud clear sound. I electronically aligned the radio for maximum sensitivity and line up the dial with the station. Finally removed all the corroded parts from the battery holder and filled in and repainted the missing corner on the front top left side of the "unbreakable plastic case" it tauts and it's now part of my collection!

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