Reply to "Reverse board won't go forward, bad transistor or some thing else?"

quote:

Originally posted by stan2004:
What are you using to determine continuity?

Fluke set on Diode test.

quote:

Something's off here. If both your NPNs are shorted, I can't imagine how it can work even in one direction.

I'm assuming the motor is disconnected when you made these measurements.

Yes

quote:

Confirm there IS continuity between the emitters of the two NPN devices.

There is continuity between the two NPN emitters, likewise on the PNPs. I rechecked everything and I have continuity between pins 2-3 on both the NPNs. The PNPs check out fine, no continuity on pins 2-3.

quote:

gunrunnerjohn's idea to just be done with it and replace them all has merit. But if you want to tinker more, tolerate 20 questions, and explore the wonders of E-units along the way I'll try to help you. A photo of the bottom of the board would be handy. Is there a separate bridge rectifier off the board?

I don't think there's a separate rectifier off the board. The motors plug in directly to this board. Considering how cheap the transistors are I'll probably order one extra set of all of them, just in case. However, I like fooling around with my trains (chronic tinkerer) and learning how it works, or doesn't, which is simply another chapter in life on how to fix stuff. When I was a kid, I remember being fascinated by taking apart the open wound motor in my steam engine, cleaning and reassembling it. I suppose not much has changed.