Forward but not backward

[tstage]

Hi Gang!

A quick question: Is there a component on a decoder that can blow that would prevent a locomotive from going in one direction but not the other.  The reason for asking is that a friend of mine brought over one of his locomotives this afternoon and asked me if I could help him troubleshoot it.

It's an NCE decoder.  (I believe a "14" series?)  The lights work but the locomotive will only travel in reverse, not forward.  Also, I can neither read any CVs nor the make and model of the decoder in Programming mode.

Should my friend just set this decoder aside and look at getting a new one?  Thanks for the help...

Tom

[tstage]

Thanks, David.  I did try a reset (CV30 = 2) and it was a no-go.

So, is there a particular component on the decoder that reverses the polarity whenever you press "Forward" or "Reverse"?

Tom

[rrinker]

tstage

Thanks, David.  I did try a reset (CV30 = 2) and it was a no-go.

So, is there a particular component on the decoder that reverses the polarity whenever you press "Forward" or "Reverse"?

Tom

 Yes, there are 4 transistors in the motor drive (look up an H Bridge Circuit), Typically, two turn on for forward and two others turn on for reverse. So theoretically it is possible for one or two to be damaged and prevent operation in one direction while everything works fine going the other way.

                                    --Randy

 

[tstage]

Thanks for the explanation and education, Randy.

Tom