High pitch humming noise.

[TezzaG]

I have fitted a brand new 21 pin decoder in an R3997 City of London loco, it was a brand new loco from Jadlams last week, and a brand new R7322 21TXS decoder from Hornby last week. 

Loco did approx 3 loops and was running absolutely fine, and with sound. Then it just stopped and all I get now is a high pitched humming noise when I increase speed on the app, and the loco won't move. It will still do sounds in its stationary position, but wont move.

Has anyone else had this, or have any ideas what might be causing this please?

Or, any ideas how to cure it, is there some kind of reset I can do for example?

Many thanks in advance.

[Paul K]

If you pull the decoder and replace the loco blanking plug, will it run on DC, or has the mechanism jammed? First thing I would try, to rule out a physical problem with the loco drive.

If you have another loco w/ a 21-pin plug you could also move the decoder over to test it at the same time...

[TezzaG]

Thanks Paul, I'll give that a go, not back home until over the weekend but will report back.

[P-Henny]

I concur with the other Paul.

I would suspect a physical jamming of the drive mechanism before considering a decoder configuration issue.

The decoder is obviously trying to turn the motor (hence the humming) but physically can't.

Drive mechanism jamming due to connecting rod & wheel slippage on the axle stubs is an all too common problem.

Another possibility for a source of jamming, is motor mounts becoming lose and the drive gears going out of alignment.

Paul H.

[TezzaG]

Morning guys. Update on this. I have checked for anything jamming the wheels, there's nothing, so then I removed the decoder and replaced the original blanking plug, it still doesn't move on DC and the motor sounds like its labouring. Pics show underneath of loco.

I think that given how new this loco is, I'm gonna contact Jadlams next week to see what to do with it.