Good point, so the antenna case has to be insulated from the vehicle as
well (or find one with a plastic case). The speaker leads could also
become a hazard as could short circuits from metal knobs and bezels to
ground. It only requires one potential path to be overlooked.
Trevor Jordan
74 TR6 CF29281U
At 1:00 PM +1100 3/3/99, Randall Young wrote:
>Most car radios also have the antenna grounded both at the antenna mount
>and at the radio.
>I once saw an MGA catch fire because it had the "cross-wired" solution
>suggested by Trevor ! (no fuse in the hot wire, ala British tradition <g>)
>
>The internal conversion should be possible, but difficult. You will need
>to provide DC block in the antenna connections and from the circuit board
>ground to chassis ground. Probably also a high resistance DC bleed to
>remove any static buildup from the antenna.
>
>Converting the car to negative ground is much easier !
>
>Randall
>
>On Tuesday, March 02, 1999 5:26 PM, Trevor Jordan
>[SMTP:tjordan@vic.bigpond.net.au] wrote:
>>
>> At 10:56 AM +1100 3/3/99, Zempel, David W wrote:
>> >Does anybody have any notes on converting a negative ground TR radio to
>> >positive ground? My '63 TR4 came with a POC aftermarket radio which I
>> >removed when I started my restoration 18 years ago. I've since obtained
>a
>> >real Triumph radio (negative ground) that I hope to convert.
>>
>> It would be very dificult to convert a radio internally. One solution is
>> to completely insulate the frame of the radio so that the polarity of the
>> radio is no longer important. The ground wire can then be connected to
>the
>> battery and the battery wire to the ground. However, it is not easy to
>> insulate a large lump of metal like a radio; particularly when it has to
>be
>> solidly mounted to the dash. The frame would still be positive and it
>> becomes a potential source of short circuits in a negative ground
>> environment.
>>
>> I would suggest that it is simpler to convert the car to negative ground.
>> This has the added benefit of eliminating the problem forever.
>>
>> As far as originality is concerned, if you have a real Triumph radio with
>> negative ground, it probably came from a later model. If you want to
>keep
>> the car original, try to find an earlier positive ground radio (or
>> reproduction).
>>
>> Trevor Jordan
>> 74 TR6 CF29281U
|