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So, I recently saw the schematics for this radio at a library, placed the radio on the bench and started probing it.
First thing I found was that a 100 ohm power resistor opened up. This is literally the first component to see direct current.
Further work showed that it could play fine on AC by jumping the resistor. The selenium rectifier and the lyrics seem to be fine after all these years.
Disappointment came when I jumped the bad resistor with a new one 100 ohm resistor instead of a near-zero ohm jumper. Silence. I then determined that the oscillator will oscillate using the jumper but not using the 100 ohm resistor. A further test showed that briefly jumping the resistor will start the oscillator and it will continue to run for some time after the jumper is removed, but is prone to suddenly stopping. I've tried different tubes in all stages of the circuit with different results (using 1L6 as well as 1R5), but none are delivering reliable results.
This is weird, Where could I go from here?
Last edited by Robert Grant; 04-09-2017 at 08:40 PM.
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