Packard Forum Index » V-8 (1955-56)

I assume this has been covered before but I'm not finding it.

My "new" '55 400 has undoubtedly had the battery connected backwards in the past by people not realizing it's a positive ground system. I repolarized the generator to correct the charging issue but find that the radio is dead. I seem to recall reading somewhere that is a common casualty of reversed polarization. If so, what specifically is damaged? Is it typically the vibrator (which is not vibrating)? The fuse is okay.

Any other damage that may have been caused?

Normally the stock Packard radios are not damaged with a reversal because anything polarity sensitive in the radio is fed by the internal voltage supply. That supply is generated by the secondary coil of a transformer and is isolated from the external supply. The external power is only on the primary coil side of the transformer which is energized by the vibrator. The internal supply has its own rectifier tube and will always stay the same polarity to feed the rest of the radio.

If the radio has been repaired, possibly the original vibrator was changed to a solid state version and those will be damaged or just not work. If the stock vibrator is still in the radio possibly it or another component just chose to fail at an inconvenient time.

I've confirmed voltage is at the radio but no vibrator hum. It's a stock looking vibrator. Guess I'll be pulling the radio. I see there are two separate chassis.

When I got my '55 Caribbean the ground was backwards (see post). It ran fine with a neg. ground and everything worked great except the amp meter. When the lights went on it showed "Charge" and when it was rev'd up it showed "Discharge". At the time I assumed the meter was wired backwards until I read "Positive Ground".

When I discovered it, I switched back to a pos. ground and there were no issues. The amp meter now worked as it should. Then I wanted to update the radio while keeping the original look. I opt'd for radio from Aurora Designs which required a neg. ground to avoid additional cost(see post).

I have not switched the polarity on the amp meter because I don't want to take any changes with messing the wiring up by digging around in a tight space.