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Restoring a Philco 71 Code 121-No sound
#17

Try using another meter, a VOM is recommended. The readings, now, are not really out of line. Re-solder the terminals of the observed offending coil.

Check the capacitors in the circuit. Schematic seems to indicate four variable condensers. At least two are the main tuning condenser and its (mounted) compression trimmer. Any leakage from damage, corrosion or dust can kill the oscillator.

NOT associated with any particular radio is that the insulators for the stator of tuning variable condensers have been known to leak. Poor electro-mechanical connections to the rotor can also be troublesome.

I see no copper corrosion but, the decaying celluloid can be a source of low resistance by shorting turns of the tickler, unseen on the inside of the winding.

The tickler is at cathode potential, any leakage to the other windings which reference ground, will carry some of the total plate current.

GL

Chas

Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”


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RE: Restoring a Philco 71 Code 121-No sound - by Chas - 07-07-2024, 12:22 PM



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