Digitrax Decoder DN136 Loco Slow Running Issue

[Jaggzuk]

I have slowly been adding some decoders to my fleet of locos and have a bit of an issue with apparent slow running of locos that I have installed with a Digitrax DN136PS and DN136D decoder.

 

The slow running is across the range of loco manufacturers and is a very apparent drop in the max speed compared to that when using them on DC.

 

The setup:

 

Contoller NCE Powercab

Locos with DN136 installed:

Hornby Railroad Class 66 DCC ready

Bachmann Class 25 DCC ready

Lima Class 37 hard wired

Hornby Railroad Class 37 swaped TTS deocder as a test

Decoder CVs all as factory defult and then I tried various CV2, CV5 and CV6 settings

Track layout, no change from when run as a DC layout

 

All locos ran much slower than when used on the layout before I switched to DCC. Although the loco speed is now much more realsitic and to a better scale, the max speed is now too slow. Eg the Class 25 max scale speed was 56mph and the Lima Class 37 was 73mph.

 

I did a test by swapping the Class 37 TTS chip with the Digitrax one and the max speed capable plumited.

 

I then tried various CV settings which made slower runing much better and smoother but I could not increase the max speed.

 

I also found on 28 speed steps, the max speed was reached by about step 14-17 with the subsequent 17 to 28 steps making no difference to the speed for the Digitrax decoder. I have the throttle set to Main Line running and not Yard.

 

I have one loco with a bought Bachmann decoder and that runs fine, and a Bachmann DMU with a factory fitted decoder and that too runs to a good max scale speed.

 

So my to question, is this a fault with something, a specific feature of the DN136, something that can be corrected by other CVs, or something else?

 

Will I find other decoders makes better offer better max scale speed? I am happy to spend up to about £20 per chip.

[bgman]

I use the DN136PS and DZ126PS where there is very little room for a more conventional one ( is there such a decoder?).

My system is Digitrax which I'm completely happy with, and the default settings are at 128 with each decoder through the system.

Whilst each setting/CV can obviously be altered to suit each loco into which it is installed, I haven't encountered any problems with these.

 

The decoders have been fitted in a wide range of locomotives/diesels from all major UK and European manufacturers in my possession and all run without fault, which includes both 8 pin fittings and cutting the loom for hard wiring into older stock.

 

Whilst the above may not be the answer you are seeking I thought I'd post it to give you an insight into another Digitrax decoder user.

Hopefully another, more knowledgable DCC user/members on here, will point you in the right direction to find a solution for you.

[Jaggzuk]

Cheers for the insight bgman.  Hopefully I will get some help soon.

 

One question based upon your experience/system, would you say that your locos fitted with the DN136 can run faster than what would be considered a good scale max speed?

[bgman]

Cheers for the insight bgman.  Hopefully I will get some help soon.

 

One question based upon your experience/system, would you say that your locos fitted with the DN136 can run faster than what would be considered a good scale max speed?

 

Sorry I've not answered sooner. There are ways which the more experienced dcc experts could answer this better than me, that said I use the free JMRI programme linked to my laptop and use it to alter the decoder CV's. There are several videos on YouTube which you may find helpful should you decide to go down this route e.g. https://youtu.be/Yc8OzTUk4uQ 

I've found the programme really useful once you've set it up and it saves a great deal of time rather than using the handheld to alter any CV's.

Hope this is of some help ?

As ever...... Happy modelling !