Can someone tell me what size fuse is used in the 1930U's amp gauge?
I am not sure what the recommended rating was but my 29U had a 15 Amp when I purchased it. Keep in mind that the Fuse only protects the Lights and Horn ckt. See diagram below. The generator, ignition, and starter motor are fuse less.
Item 31 is the fuse. Generator Max output = 16 Amps. In order to keep the battery charged total electrical consumption needs to be less then 16 Amps. Probably a 10 Amp Fuse would work OK.
(http://www.chetscoins.com/1929/images/1929%20Wiring%20Dig-01.jpg)
Chet...
I have an old Plymouth mechanics manual that says for the Model U and 30 U the fuse is 20 Amps capacity