Locos start too quickly

[Cwmiss]

I have a couple of locos, a Hornby HST in particular that takes a lot of turns of the controller to get it going but then it takes off very quickly. If I then dial back the controller, it runs quite well. Are there any adjustments that I should make to the CV's to adjust this start up. This is an older locomotive.

[Chrissaf]

Which controller?

 

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[96RAF]

If supported by the decoder there is CV2 which is kick start voltage. This sends a higher throttle setting to get the loco going and is handy if you have a sticky motor. Raising the value of CV2 until the loco starts as you just move the throttle is what you are aiming for. Start with value 5 and if it moves then try 4, and 3 util you have the minimum value that lets the loco move on immediate throttle. It may take a higher value if the motor is particularly awkward, which would suggest the motor itself needs maintenance. Essentially what you are doing is making speed step whatever you set into speed step one, or vice-versa depending upon how you view it.

[Flashbang]

In addition to the excellent reply posted above by RAF96 re CV2 value (I was writing all that and he beat me to it!  😀 )

I would start by resetting the decoder to its default settings including address number to 3. This is usually via CV8 entering a value of 8, but do check with the decoder manufacturers leaflet to ensure its CV8/8.

Then set the address number to whatever is required, then carry out the CV2 value settings.  Use speed steps 28 or 128 and set CV2 value so as the loco just moves at speed step 1.

Once you have CV2 set up, set CV5 for the top speed needed, then set CV6 to approx. half of the value set in CV5. i.e. CV6 is at 110 so set CV5 value between 55 to 60.

 

All the above assumes your DCC system allows CV alterations and the loco decoder supports these CV settings. Not all do!  😮

[ColinB]

Are you sure it is the controller, some DCC decoders especially the TTS ones wait a while before they move off. So you instintively increase the speed because you think it is not working, so when the loco decides to moves it goes to the requested speed. Have you tried dialing up a slow speed and just waiting. Similarly, some also take a while to slow down, it is meant to simulate the dynamics of a real loco.

[Fishmanoz]

Colin is referring to CVs 3 and 4 for acceleration and deceleration rates.  I believe the usual default value is 5 but for TTS it's 15 to allow time for startup sounds.