Re: 39 Packard Generator and Regulator

Posted by HH56 On 2019/4/1 12:40:42

I don't have any schematics other than what is on this site and the AEA diagrams at the PAC site. None are of spectacular quality but the one on this site is the factory diagram for 6, 8 and 12 cars. Since it relies on tracing numbers instead of wires and being of poor quality it is hard to read.

There is a good description of the Autolite voltage regulator and 3 brush generator on page 65 of the 38-39 shop manual which you can download from this site if you don't have one. It has service cautions and adjustment procedures.

From the description the third brush adjustment and not the regulator controls current output. From the schematic it appears to do this by limiting the amount of voltage available to the field coils thus controlling their maximum strength. The regulator controls the voltage out by rapidly cutting in and out extra resistance to the field to weaken it when voltage starts climbing. With the burned points and other issues I would wonder if that third brush is adjusted properly or could possibly be intermittently shorting to the output brush or wire and giving the field a jolt so the generator produces a burst of max current. Less likely but still need to be checked would be if the field wire between the regulator and generator was somehow intermittently shorting to ground.