Cutout confusion

29spcoupe

29spcoupe

Well-known member
I have found in my stash of parts what is either a cutout or voltage regulator or possibly a diode cutout. Is it positive or negative ground. The reason I am asking is do I keep it for my Model A Ford or sell it because I no longer own T's?
 

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You should be able to use voltmeter on the output terminal and case, with test leads from your battery to see what polarity it is.
 
The diode case is negative in the forward direction. So if wired for a positive grounded battery, the terminal on top of the diode would go to the pole on the generator and the case would go to the battery. The diode is low leakage.

As Bruce said, you can use your multimeter to test how it is hooked up. Set up the meter in the ohm measuring mode. Put the positive (red) lead on the the terminal that would normally go to the generator and the negative (black) lead on the terminal that would go to the battery. You would measure low resistance if it is for a positive grounded battery. Now reverse the leads and you should find high resistance. If the reverse is true then it is for a negative grounded battery.

Data sheet is here: https://datasheetspdf.com/pdf-file/1312403/Motorola/1N3491/1
 
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