TTS loco runaway after short

[TTS runaway after short]

So I've got 2 hornby TTS sound locos there both a4 classes and everytime my layout gets a short they go joy riding up the mainline so can some one tell me if this is normal or not thanks 

[Howbi]

You will need to change a value in the decoder's CV29 but needs a suitable controller........which controller are you using?.........HB

[Chrissaf]

By now you will have noticed that your displayed name is showing the same text as your post title. I assume that this is an error. We can't change your displayed name for you, but you can do it yourself (but only once). I strongly advise that you login to your 'Forum Account' page and change your user name (nickname) to something more appropriate. If you don't do this now, every post and every reply you make from now on will display the same "TTS runaway after short" name.

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The image below shows where in your account pages you can find the "Nickname" field to edit. Note that changing this name does not change the details you use to log in with:

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TIP: As this is your very first post, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

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Particularly as my reply includes an image. If you use the blue button, any reply you write, may be held back for image approval. Even though it is already a previously published image.

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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[Chrissaf]

In answer to your question.

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Transient 'short circuits' disrupt the DCC data signal synchronisation with the TTS decoder. If the decoder (any decoder) cannot detect a valid DCC timing signal. It thinks that the loco is sitting on a DC Analogue track and switches the decoder into DC Analogue mode. The full DCC pseudo AC track voltage is then rectified into DC by the decoder and treated as being a DC Analogue full speed voltage.

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By changing the value of CV29 to disable 'DC Operation' this unwanted behaviour is eliminated.

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You need a DCC Controller that can write to CV29 to do this. Elite is OK, eLink is OK, but only Select with revision 1.6 firmware can do this. Selects with firmware 1.5 or below can not.

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This web site provides a 'calculator' to help you to work out what value you need for CV29 to disable Bit 2 (DC Operation).

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