K-Line Alco S-2 Wiring Question

TomP posted:

...The black wires go to the center rail and the red wires go to the outer rails. Is this correct?

It doesn't matter with AC, especially on this diesel, as the first components on the reverse board are 4 diodes arranged in a full wave bridge so the entire loco actually runs on DC.

Yes, that makes sense, Thanks for the reminder. I'm just trying to figure out why the reverse unit is acting up after installing the sound board.

The sound works fine, but the bell and horn buttons are reversed. The instructions for the sound board said to check the transformer wiring to make sure they weren't backwards. They're not, so that's what brought the question to my mind. 

Which transformer are you using? Are the headlamps still connected to the hot/ground?

What is this sound board you mentioned?

It's an ERR Railsounds Commander module I bought from DCC Hobby Supply. The board and speaker just barely fit the low hood of the S-2, but it sounds great. Its too bad its affected the reverse unit, I don't want to take it out! Hopefully, someone can help me figure it out.

Any Ideas?

Originally, I had the idea the battery back-up might be back-feeding into the reverse unit and preventing it from operating correctly. I began by trying to install a Schottky Diode to see if that would prevent the feed back, that's when I found the wires looked to be reversed.

Sorry Rob, I didn't see your reply before now. I'm using an older CW-80 that has the separate transformer brick (literally, it's the size and weight of a brick!) I Know there are issues with the CW-80s and some MTH PS1 or 2 engines (take a wild guess how I know this!)

In order to make room for the speaker I removed some of the weights and replaced the headlamp/cab lights with LEDs. They are still  wired to the original configuration, so the red goes to common and black power.

TomP posted:

In order to make room for the speaker I removed some of the weights and replaced the headlamp/cab lights with LEDs

There's your problem... hence the question about the bulbs.  Your BW-80 transformer, like the CW, doesn't go to zero volts entirely because of their architecture.  You need a current draw sufficient to effect a zeroing to get the K-Line reverse unit to cycle - they are very sensitive about this - and the bulbs performed that function.

Great, that makes total sense! I have measured that voltage and thought it was unusual. Plus the LEDs do stay dimly lit after power has been cut to the tracks.

Do think putting a resistor (maybe a 1/4 watt) into the circuit would provide enough of a load?

Thanks for helping!

Tom 

A 2 or 3 watt 14v bulb would be better as you want to draw about .2 amps to get the voltage down to zero.

Ok, thanks Rob! I will look into putting the bulb back into the cab. There's no way to reinstall it the way it was. I think I'll wire it first just to make sure everything (sound board, lights and reverse unit) works the wat it is supposed to.

Thank You so much for all the help!

Tom 

The bulb does not have to be visible... you can paint it black and stick it anywhere it'll fit. If you use a 24 volt bulb that would make it easier & cooler.

Rob,

A quick question, should the bulb be in the engine itself to be most effective?  I was just wondering if a track-side structure could be lit with the bulb and still work.

Thanks ,

Tom 

Trackside is fine... even a caboose with an incandescent bulb.

Great, thanks so much for all the help! Hopefully I won't have anymore questions/problems to bug you about!

Just wanted to thank Rob for the help! I finally got everything back together and rewired and it works great!

It turned out the wires were in fact backwards. The bell and horn/whistle buttons now operate the correct sounds when pressed.

I wired the original bulb back to the controller output. I actual have the bulb attached directly to the controller terminals at the moment, but will place it into a speeder shed I'm building when I'm done. This restored the function of electronic reverse unit .

I also found another thread about rewiring the motors in series to reduce the speed of the engine. It was a speed demon before, now it operates much more realistically.

Thanks again for the help.

Tom