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Post-War Other Herald 1200 Polarity

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Herald63nut

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I own a 1963 Herald, commission number GA 100920 LCV. When I purchased the car, the battery was grounded negative and it did run. However, the workshop manual indicates that negative earth was not used in the Herald until March 1968, commission GA 238107 onward. The car once had a radio, but it was missing when I purchased the car. Is is possible that the car could be grounded negative earth even though the workshop manual indicates that it should not be or is it an "option" to do so under the circumstance that no transistorized components are used? I am at a loss to figure this out. Any insights will be greatly appreciated.
 
As you say, it's an "option". The various motors (wipers, starter, heater) don't care about polarity, so with the radio removed, that leaves only the coil and generator. The coil can have the leads swapped (or actually will work well enough with the wrong polarity, just not quite as well as otherwise). And the generator only needs to be repolarized.

Conversions to negative ground are quite common, as virtually all car electronic devices today assume negative ground. It's even possible that your original radio had a switch to select ground polarity (tho maybe not in 63).
 
It's the latter scenario: so long as no polarity sensitive components are involved, polarity doesn't matter. Most dealer-installed radios back then were switchable polarity as well.

It's quite possible that someone long ago simply replaced the battery and put it in presuming the car was negative ground (which just might have fried that original radio). The slight difference sometimes found in the size of the battery terminals should have been a tip-off, but....

Also, one usually repolarized the generator when switching polarity, but some cars seem to have been able to do that on their own!

[Ha! As is so often the case, Randall and I seem to have been composing answers at the same time; this time he beat me by a minute and a half! :wink: ]
 
Andy,
Not to sound stupid, but how does one go about repolarizing the generator? Okay, if not stupid, not experience.:smile:
Thanks
Bob
 
Those directions will certainly work, though perhaps with a bit more sparks than strictly necessary.

But you may find it easier to simply disconnect the wire from the 'F' terminal at the regulator (aka control box) and brush it against the 'A' or 'A1' terminal. You should see a bit of a spark, and possibly a tiny 'nip' if you are touching the bare wire (not enough to hurt). Then reconnect the wire to the F terminal, you're done.

When you first start the engine, the residual magnetism in the generator housing and pole pieces is what allows it to start generating a fairly small current/voltage (less than 1 volt/amp). This low current gets fed back into the field winding (through the regulator contacts), causing the magnetic field to grow stronger, which in turn increases the output; and within just a fraction of a second, the output has reached battery voltage and the cutout contacts close to connect the battery to the generator output. "Polarizing" the generator is the process of making sure it has a residual magnetic field of the proper polarity to begin this process.
 
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