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  • Electrical: Radio

    I have a rebuilt Philco radio that goes with a '51 Champion. A note on the radio says "for negative ground." The car is positive ground. What would be the proper way to make the connections?

  • #2
    If it was rebuilt with a solid state vibrator, they may have used a negative ground one. If so, it MUST be connected for negative ground OR changed out the vibrator for a positive ground one. The mechanical vibrators were not polarity sensitive and the tubes don't care but the solid state ones will blow if connected wrong.

    If your car is positive ground, the easiest approach is to swap out the vibrator if its the negative ground version. Otherwise, you will have to somehow insulate the radio chassis from the dash and the chassis gets connected to your power feed and the power feed gets connected to ground. That would be extremely difficult.

    As an electrical engineer, I don't know why the makers of these solid state replacements can't add polarity protection so, yes, it won't work but it also won't be damaged in the attempt. We have such circuits on ALL the electronics modules my group at work designs that go on Ag, construction, and truck applications. Its was too common for someone to install a battery backwards and they would NOT be happy to blow out many $$$$$ of controllers and displays.

    Jeff in ND

    Comment


    • #3
      The new vibrator designs made by Aurora Designs protect themselves from reversed polarity and short circuits in the outputs. The engineer of that company is really savvy to real world situations.

      http://www.tech-retro.com/Aurora_Design/Home.html

      The old vibrators made by AAR in Florida will eat themselves if reversed polarity is applied.

      Do what Jeff says and replace the vibrator. Don't try to jury rig the radio the way it is. Take the back off, unplug the vibrator and see what it says on it. It should say the manufacturer and what polarity it is designed for.
      Last edited by RadioRoy; 02-04-2020, 04:22 PM.
      RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

      17A-S2 - 50 Commander convertible
      10G-C1 - 51 Champion starlight coupe
      10G-Q4 - 51 Champion business coupe
      4H-K5 - 53 Commander starliner hardtop
      5H-D5 - 54 Commander Conestoga wagon
      56B-D4 - 56 Commander station wagon
      60V-L6 - 60 Lark convertible

      Comment


      • #4
        Thank you for your responses. For the uninitiated, it is confusing. It has been in a box for 15 years. Rebuilt by Dan Skidmore.

        Comment


        • #5
          With any radio that was rebuilt that long ago, you should fire it up on the workbench before installing it in the car. That way, if it does not work, you will not have to remove it again.
          This is in addition to our previous suggestions.
          RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

          17A-S2 - 50 Commander convertible
          10G-C1 - 51 Champion starlight coupe
          10G-Q4 - 51 Champion business coupe
          4H-K5 - 53 Commander starliner hardtop
          5H-D5 - 54 Commander Conestoga wagon
          56B-D4 - 56 Commander station wagon
          60V-L6 - 60 Lark convertible

          Comment


          • #6
            Maybe it was a radio I restored. I use Aurora Design vibrators. BTW, they make them for positive and negative ground and are polarity protected. Has it been converted to 12 volts? Usually when someone wants a negative ground radio they also want 12 volts. To convert to 12 volts I rewind the primary of the power transformer for 12 volts.

            Here are some of those radios I restored: https://mseriesradio.blogspot.com/

            **UPDATE*** Just saw the post about who restored it...
            1948 M15A-20 Flatbed Truck Rescue
            See rescue progress here on this blog:
            http://studem15a-20.blogspot.com/

            Comment


            • #7
              You rewind the primary of the transformer? You have more talent/energy than I do, that's for sure. Good work!
              RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

              17A-S2 - 50 Commander convertible
              10G-C1 - 51 Champion starlight coupe
              10G-Q4 - 51 Champion business coupe
              4H-K5 - 53 Commander starliner hardtop
              5H-D5 - 54 Commander Conestoga wagon
              56B-D4 - 56 Commander station wagon
              60V-L6 - 60 Lark convertible

              Comment


              • #8
                Actually, the process is fairly simple, go here to see how I did it:
                Tried the Zener diode approach, it did work but the Zener diodes got to hot. I knew there would be a power issue but didn't know how big of ...
                1948 M15A-20 Flatbed Truck Rescue
                See rescue progress here on this blog:
                http://studem15a-20.blogspot.com/

                Comment


                • #9
                  I don't know how to tell if it has been converted to 12 volts. The notice on it said "for negative ground." I did order a positive ground vibrator.

                  Comment


                  • #10
                    I am not familiar with that series of radios (only ever worked on '53-'55). So, I don't know if any of the tubes are visible w/o taking a cover off the chassis. If its been converted to 12v, the tubes should have numbers printed on that glass starting the 12 like 12BE6 or something where if its still 6V, then that same tube would be 6BE6.

                    The solid state vibrator can should also have the voltage on its label or markings.

                    Jeff in ND

                    Comment


                    • #11
                      When you test the radio on the bench (which you should do before installing it) do not use a battery charger by itself. They are not good at regulation - holding the 6 volts constant. If you do use a battery charger, make sure it is connected to a battery at the same time.

                      When you install the radio into the car, make sure you have the J-hook that goes to the firewall. The radio is attached to the car at three points: two special bolts coming up through the bezel into the bottom of the dash, and the J-hook that goes through a hole in the upper firewall to the U-shaped device on the bottom/rear of the radio.

                      If you do not have the J-hook, the radio will flop around and bend up the chrome bezel. You can make a J-hook from all thread.

                      If you need a picture, send me an email and I will send you the installation drawing for that radio.

                      If someone can show me how, I can post that picture in the forum.
                      Last edited by RadioRoy; 02-07-2020, 05:37 PM.
                      RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

                      17A-S2 - 50 Commander convertible
                      10G-C1 - 51 Champion starlight coupe
                      10G-Q4 - 51 Champion business coupe
                      4H-K5 - 53 Commander starliner hardtop
                      5H-D5 - 54 Commander Conestoga wagon
                      56B-D4 - 56 Commander station wagon
                      60V-L6 - 60 Lark convertible

                      Comment


                      • #12
                        It would be interesting to know what is written on the vibrator.

                        Was it a 1015-N? Did you then order a 1015-P?
                        RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

                        17A-S2 - 50 Commander convertible
                        10G-C1 - 51 Champion starlight coupe
                        10G-Q4 - 51 Champion business coupe
                        4H-K5 - 53 Commander starliner hardtop
                        5H-D5 - 54 Commander Conestoga wagon
                        56B-D4 - 56 Commander station wagon
                        60V-L6 - 60 Lark convertible

                        Comment


                        • #13
                          If the radio came from Dan Skidmore, it will be a 6 volt positive ground radio as I have done most of the electronic restorations for him for many years and I know for sure I never converted any of the 51 series radios to 12 volts. I did convert a few of the 53 to 55 series radios to 12 volts though. Like Jeff-H says, remove the rear cover on the radio and look at the tube numbers, that will tell you for sure whether the radio is 6 or 12 volts. Bud

                          Comment


                          • #14
                            Yes, the old one is 1015N. I just received a 1015P.

                            Comment


                            • #15
                              Bud, this radio was serviced by you Aug. 28 2005. It has been in a box since then.

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