OK, Worked very carefully on a LL FA-1 install. Wired the bulb with white and blue wires, careully insulated. Put it on the programming track. Great! Put it on the track, and it ran great in forward. Hit reverse--pzzzt! Now it won't read on the programming track. What did I do wrong?
There are clearance problems, which I thought I took care of with a bit of grinding. The other three identical installs went well. I'm guessing when I reinstalled the shell on this one, I pinched something. Why it blew in reverse, I just don't know. Perhaps yellow wire touching something?
I have done the exact thing in one of my Z loco's 2 times already. Both times while in reverse. I'm stumped, because when I buzz the wiring, there is no short. Decoders blow when the Gray or Orange wires are shorted to anything else. I was able to fix the last one by replacing the 7509 Hexfet chip (the one where the Orange wire is soldered to) on my TCS M2 decoder, but I have not looked at the Digitrax decoder yet. It's probably a transistor too. The reason they blow is because of a switching circuit called an H Bridge which is usually made of 4 transistors or FET's which are wired in a bridge arrangement that looks like an "H" in the circuit. Transistors are fired in an order required to drive our motors forward or reverse, but you can only fire in a certian order or Pffft! you blow a FET. It was the hardest soldering I have ever done to date, but I mamages to fix the first decoder, and I will be extra careful to look for shorts before popping another one. Bottom line... Orange or Gray wires must never short to anything. -Robert
Pete: The decoder blew because of the "stall factor". The gear mechanism caused the the decoder to blow when it was put in reverse. I had this happen on a LL 2-8-8-2 when it was put in reverse. You need a decoder with a higher amp rating in that loco. Stay cool and run steam....
