Intermountain SD40-2 decoder issue

[CPR9009]

I figured I would check here first and see if any of you have encountered this one yet.

I pulled the body off one of my SD40-2s (non sound DCC with ESU LokPilot decoder) to add underframe detail, and it now will only move in reverse.  If I change direction the headlight switches to the front, but no power goes to the motor.

I have reset the decoder 3 times and still the same thing happens.  Am I missing something? 


Scott

[peteski]

If you did a decoder reset with no improvement, you might have somehow blown one or two transistors for the forward direction in the motor output circuit.    We have just been discussing a similar problem in a Walthers Mallet with a QSI decoder.

https://www.therailwire.net/forum/index.php?topic=42198.0

[CNR5529]

I have just witnessed the same problem on a sound equipped IM SD40-2 at a local hobby shop. The unit was pulled new out of the box, the road number was programmed, and upon testing poof went the one time exhaust feature. We opened it up to find a burnt transistor. Back to IM it goes!

[peteski]

I have just witnessed the same problem on a sound equipped IM SD40-2 at a local hobby shop. The unit was pulled new out of the box, the road number was programmed, and upon testing poof went the one time exhaust feature. We opened it up to find a burnt transistor. Back to IM it goes!

The cause of this is usually either a short in the motor circuit or one of the motor outputs shorting to the track voltage.  It could be intermittent short - it only takes a fraction of a second to let the magic smoke out.

[CPR9009]

Thanks guys.  You are probably correct about the issue.  Looks like it's going back to Intermountain.   

On another note, when I pulled it apart there was so much grease in it all the cavities were packed full.   

Scott

[peteski]

On another note, when I pulled it apart there was so much grease in it all the cavities were packed full.   

Scott

That is nothing new. I expect all the Chines-made models to be severely over-lubricated.  They seem to thin that more is better.  I documented something similar in my review of the Arnold/Hornby SW1.

[CPR9009]

I just received my locomotive back from Intermountain.  They replaced the decoder.  Looks like the issue was in the forward transistors.

I've got it on the layout consisted with an SD40 w/sound and its working fine now.

Scott

[peteski]

Good to know - thanks for update. Going by what I read in online forums IM does have very good customer service.