R100RT generator light stays on dimly as revs go up

[Kurt in S.A.]

Where on this diagram is the diode you're talking about?

http://www.buchanan1.net/charge.shtml

Kurt in S.A.

[Ken in Oklahoma]

it's easy enough to get the tension too loose

I like that Chas. I'll use it as my new mantra.

I understand that the brush tension must be much higher than a person might think. And also that, properly tensioned, the brush wear will be much less than you would think. The idea is that, if tensioned too loosly, the brush will chatter against the slip ring, causing the premature wear.

Ken

[Jean]

Kurt, it's NOT shown on most schematics which only show the diode board as a "block". You've got to find a schematic of how the alternator works and a picture of the diode bridge circuit and all the associated parts to see it in schematic.
I think the last time I saw it was on Snowbum's site. I'll go there and check...
HOWEVER that one is not the problem here. If the alternator is not putting out the 13.5-14 volts to the battery, it's one (or 2) of the BIG diodes that's shot...if not the brushes.

[Jean]

YEP.
Snowbum Technical Article #15B.
Scroll down to nearly the bottom of the text and you'll find such a picture.
The single diode called "small diode" in the bottom of the drawing is the one ME109 is showing in his photo.
NOT in the Motorrad Elektrik book....