Class 31 TTS decoder - fast-slow-fast-slow

[Birthwaite]

Purchased a class 31 TTS decoder and put it in a Hornby EWS class 92. Everything seemed fine - the sounds were good BUT the loco at low and mid range speeds goes - fast-slow-fast-slow and so on. Not until full speed does it run smoothly. New to this so and ideas please? Thanks.

[2e0dtoeric]

Is the model new? It might need running in.

What controller are you using?

Have you cleaned the track, loco wheels and pickups?

How are you connecting the controller to the track? One of those flimsy plug-in things, or proper soldered connections.

If one of those plug- in things or a clip-on power track, have you removed the dc capacitor?

(edit for a typo)

[Chrissaf]

Have you tried any of the other motor control algorithms included on the TTS decoder range.....documented on the TTS leaflet datasheet.....look for references to CVs 150-154 in the datasheet text.

[jane1707819582]

alter the back emf setting the two loco's motors may have different characteristics,

[Sultan]

As Chissaf has suggested you may need to adjust some of the CVs as this is a common problem with the 31 decoder normally fitted in a class 31.  Plenty of advice on this Forum.

I am rather bemused why you have fitted a diesel sound decoder in an electric loco though?

[Sultan]

@Birthwaite

Some simple CV settings that may assist in stabilisng the movement of your class 31.

Set CV for DCC/DC to DCC only ie discbale operation on DC

CV 151 set to 225

CV 152 set to 1

'Cravensdmufan' on YouTube https://www.youtube.com/channel/UC90_QEPr-tXjG-frGb_2uUQ/videos  has some good videos of locos fitted with TTS decoder and there are some CV values in teh comments.

Hope this helps.