I am hobby auto-restorer and recently aquired a circa 1937-1941 six volt auto radio that I planned to install in a truck of the same era. Major problem is vibrator is bad and in order to purchase new solid state vibrator I need to know the ground polarity of the radio. Unfortunately I don't know what make of vehicle it was installed in originally and haven't a clue on how to establish polarity. Radio is GE model M-58 (manufactured in Canada) and has standard 4 pin vibrator. I perhaps should not have done this, but when power applied the tubes light up irrespective of polarity used. Please help if you can! Any and all comments will be greatly appreciated. This is my first visit here.

:I am hobby auto-restorer and recently aquired a circa 1937-1941 six volt auto radio that I planned to install in a truck of the same era. Major problem is vibrator is bad and in order to purchase new solid state vibrator I need to know the ground polarity of the radio. Unfortunately I don't know what make of vehicle it was installed in originally and haven't a clue on how to establish polarity. Radio is GE model M-58 (manufactured in Canada) and has standard 4 pin vibrator. I perhaps should not have done this, but when power applied the tubes light up irrespective of polarity used. Please help if you can! Any and all comments will be greatly appreciated. This is my first visit here.

Polarity does not matter for tube heaters. And for a four-pin vibrator, purchase and use what the corrent vehicle is; that is if the vehicle is negative ground, ground the radio chassis, and use a negative ground vibrator. If the vehicle is positive ground, ground the radio chassis, and use a positive ground vibrator. Check the rectifier tube, and replace the vibrator capacitor (across the tube plates) before proceding.

::I am hobby auto-restorer and recently aquired a circa 1937-1941 six volt auto radio that I planned to install in a truck of the same era. Major problem is vibrator is bad and in order to purchase new solid state vibrator I need to know the ground polarity of the radio. Unfortunately I don't know what make of vehicle it was installed in originally and haven't a clue on how to establish polarity. Radio is GE model M-58 (manufactured in Canada) and has standard 4 pin vibrator. I perhaps should not have done this, but when power applied the tubes light up irrespective of polarity used. Please help if you can! Any and all comments will be greatly appreciated. This is my first visit here.
:
:Polarity does not matter for tube heaters. And for a four-pin vibrator, purchase and use what the corrent vehicle is; that is if the vehicle is negative ground, ground the radio chassis, and use a negative ground vibrator. If the vehicle is positive ground, ground the radio chassis, and use a positive ground vibrator. Check the rectifier tube, and replace the vibrator capacitor (across the tube plates) before proceding.

Hi Ed,
If the radio was positive ground and the -6 volts was used to bias the audio output tube, the radio won't work. If that wasn't done then Bert should be OK either way, as you mentioned.

Best Regards,

Bill Grimm

::I am hobby auto-restorer and recently aquired a circa 1937-1941 six volt auto radio that I planned to install in a truck of the same era. Major problem is vibrator is bad and in order to purchase new solid state vibrator I need to know the ground polarity of the radio. Unfortunately I don't know what make of vehicle it was installed in originally and haven't a clue on how to establish polarity. Radio is GE model M-58 (manufactured in Canada) and has standard 4 pin vibrator. I perhaps should not have done this, but when power applied the tubes light up irrespective of polarity used. Please help if you can! Any and all comments will be greatly appreciated. This is my first visit here.
:
:Polarity does not matter for tube heaters. And for a four-pin vibrator, purchase and use what the corrent vehicle is; that is if the vehicle is negative ground, ground the radio chassis, and use a negative ground vibrator. If the vehicle is positive ground, ground the radio chassis, and use a positive ground vibrator. Check the rectifier tube, and replace the vibrator capacitor (across the tube plates) before proceding.

In addition to the above, some capacitors age over time, and may be defective - and may damage the rectifier, another tube, or even the new vibrator. If there is an antique radio club in your area, perhaps if you took the radio to a meeting, a member would be willing to give free advice.

Hi Bert,
I tried to locate the schematic for your radio, but couldn't find it.
The polarity can be found in the biasing of the audio output tube. Its grid needs a negative bias, and the engineers that designed these radios usually took advantage of an available -6 volt supply to bias the output tube grid.
If you know where a schematic is, I woulg gladly look it over and tell the polarity of ground.

I have managed to repair vibrators by operating them with AC going through their points and manual adjustment. These can be opened.
I found the process by entering 'Radio Vibrator' in Google. In among the links to sex toy vendors was an article from someone in Austrialia on this. He even was using a vibrator identical to the one I was trying to repair.
If there is a chance yours is salvagable, you may want to look at it.

Best Regards,

Bill Grimm

:Hi Bert,
: I tried to locate the schematic for your radio, but couldn't find it.
: The polarity can be found in the biasing of the audio output tube. Its grid needs a negative bias, and the engineers that designed these radios usually took advantage of an available -6 volt supply to bias the output tube grid.
: If you know where a schematic is, I woulg gladly look it over and tell the polarity of ground.
:
: I have managed to repair vibrators by operating them with AC going through their points and manual adjustment. These can be opened.
: I found the process by entering 'Radio Vibrator' in Google. In among the links to sex toy vendors was an article from someone in Austrialia on this. He even was using a vibrator identical to the one I was trying to repair.
: If there is a chance yours is salvagable, you may want to look at it.
:
:Best Regards,
:
:Bill Grimm

E::Hi Bert,
:: I tried to locate the schematic for your radio, but couldn't find it.
:: The polarity can be found in the biasing of the audio output tube. Its grid needs a negative bias, and the engineers that designed these radios usually took advantage of an available -6 volt supply to bias the output tube grid.
:: If you know where a schematic is, I would gladly . look it over and tell the polarity of ground.
::
:: I have managed to repair vibrators by operating them with AC going through their points and manual adjustment. These can be opened.
:: I found the process by entering 'Radio Vibrator' in Google. In among the links to sex toy vendors was an article from someone in Austrialia on this. He even was using a vibrator identical to the one I was trying to repair.
:: If there is a chance yours is salvagable, you may want to look at it.
::
::Best Regards,
::
::Bill Grimm

Sorry about the double post, I'm new here, just wanted to express my thanks to Bill G and Ed M for their quick and informative responses, to tell you the truth I was absolutely astounded! I have a brother who has a long technical background in radio and television matters and will rely on him to do the checks and repairs that have been so graciously suggested here and also have him explore this marvellous site. He will be able to more adequately comprehend the information you have presented. We did in fact open the vibrator can and dress the points with the result that the vibrator is once again functional but who knows for how long. AS for the schematic, I think I may have found a source for it in Ontario, Canada from a fellow named Dave Cantelon of Just Radios (justradios@yahoo.com) I will order it tonight. After a slow and discouraging start I am now feeling quite upbeat about the possibility of actually listening to some tunes on this relic. I certainly intend to keep you posted on my progress. Again sincere thanks and best wishes to all who post on this site.

:Hi Bert,
: I tried to locate the schematic for your radio, but couldn't find it.
: The polarity can be found in the biasing of the audio output tube. Its grid needs a negative bias, and the engineers that designed these radios usually took advantage of an available -6 volt supply to bias the output tube grid.
: If you know where a schematic is, I woulg gladly look it over and tell the polarity of ground.
:
: I have managed to repair vibrators by operating them with AC going through their points and manual adjustment. These can be opened.
: I found the process by entering 'Radio Vibrator' in Google. In among the links to sex toy vendors was an article from someone in Austrialia on this. He even was using a vibrator identical to the one I was trying to repair.
: If there is a chance yours is salvagable, you may want to look at it.
:
:Best Regards,
:
:Bill Grimm

Greetings Bill- Could you please direct me to the Google radio vibrator repair link using AC,
as mentioned in the above post.

Best,

Bert