Quote from: BestSnowman on February 21, 2010, 09:35:59 AM
... I would guess that the light board in the first one is at issue, you could try wiring up the slow one directly from pickups to the motor to see if it speeds up. That way you would know for sure if its the lightboard or something else.
That's a great plan. On the slow loco picture I see two groups of four diodes. Before DCC days one would make constant lighting in a locomotive by wiring four diodes in a "bridge" (I forget the name), and the bridge in series with the motor. There would be a constant voltage drop of 1.5 volts across the bridge which would power 1.5v gow/gor bulbs full brightness at anything above 1.5v on the track. Further circuit connections would yield directional lights as well as constant intensity. I have several Athearns set up this way, i.e. a GP-9 with constant light in the cab and directional headlights. Only thing is these locos take a significantly higher voltage per unit speed vs unmodified locos. Wasn't a problem for me as I always ran one powered loco with additional ones being dummies.
When I saw those groups of four diodes, I thought that might be what's going on with your slow loco. I believe this circuit is still being used today in some way with LED's. However... there is a jumper wire in the middle of your slow loco board which is labeled "CUT FOR DC". I wonder what that indicates?
Robert