Strange Bachmann N 2-6-0 Decoder Behaviour

[Jamesn320]

Hi All,

I have a decoder from a new Bachmann N 2-6-0.  The loco ran perfectly, out of the box.  The decoder was then removed and replaced with a sound decoder.  Not wanting to waste the normal decoder I fitted it into an old Con-Cor PB1 shell to power the lead PA1.  This PA1 runs like a Swiss watch however with this decoder fitted everything starts fine but after about 30 seconded it gradually slows to a crawl.  It doesn't stop, but keeps creeping along.  If I turn off the throttle, wait a few seconds and then turn it on again the loco starts off, then does it all again.  The lights respond at all times and I this repeats on the Digitrax layout and on the Sprog via my laptop.  I can find no settings in the decoder itself to explain this.  I originally thought the motor might be expanding with heat and binding but under DC it still runs fine and with a Digitrax chip it runs fine as well?

I put a volt meter across the motor and and the voltage does drop when this happens.

Anybody got any ideas?

Cheers,

James

[peteski]

That is very strange and the only explanation I find is that the problem is the decoder itself. Best thest would be to temporarily reinstall it in the original loco and see how it behaves.

Also, Bachmann seems to include an overcurrent protection on their decoders for very small motors. Maybe the loco you installed it in consumes much more current than the original loco. The overcurrent protector is a sort of a solid-state circuit breaker (I believe it works by heating up which trips it) and it resets when cools down. Maybe that is what is causing the problem?  Assuming that this decoder has one of these.

[Jamesn320]

Hi Peteski,

I think you have confirmed my suspicion.  The 4-6-0 (not 2-6-0) it came form has the new style coreless motors which consume next to nothing.  Ware as the Con-Cor PA, let’s face it, is a tank!

If it does have a overcurrent protection that works as you say then that is exactly what it’s doing.

I’ll stick the Digitrax decoder back in and use the Backmann one somewhere else.

Cheers,

James