TTS Loco start up on their own.

[Chrissaf]

HI all after oprating my railway for a long time the TTS locomotive start up on there own but not all. an one know. what happing thank Ron 47.

[Chrissaf]

You asked this question before in this previous existing thread:

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https://www.hornby.com/uk-en/forum/locomotives-starting-up/?p=1/#post-324378

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The most likely reason is because your DCC track signal is being corrupted in some way, such that the TTS decoders think that they are getting commands that they are not. You were asked in your other thread to provide more detail with regard how you are wiring your layout.

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In the other thread you said that you were wiring direct to rails thereby eliminating the Hornby power clip. But there must be something about your wiring that is causing signal corruption. A bad joint for example. or something else electrically wired across your track or DCC feed. Have you for example wired any LEDs or other components to your track power.

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Are you for example using Hornby's R8201 Link Wires .... these are not recommended for use with DCC.

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TTS Decoders seem to be particularly sensitive to these signal corruptions, far more so than other decoders.

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There are other possible causes, but the one above is AFAIK the most common.

[96RAF]

It has been reported before on the forum some time ago. I can’t remember the outcome.

 

We would need to know which controller you are using and its revision state as well as the decoder ID of those locos going off the reservation, especially if they are the same ones every time.

 

By decoder ID I mean the R-number if it is a TTS retro kit or the loco R-number if factory fitted TTS and the readback value from CV7 if your controller supports readback of CVs.

[ron 47]

Thank you yep as it a garden railway and lot of train tech signals and a hornby powe boster in line it no a problem and yes it is only the TTS Sound chip that start up but no all at the same time. using E Link Railmaster. i do not get a lot of problem. and there is a Bus running all the way around the Layout. thank for the help regards Ron.

[Chrissaf]

As a Garden Railway. Atmospheric conditions will affect the electrical characteristics of the rails and exposed wiring / soldered joints. There might very well maybe moisture and/or other atmospheric residues on the rails and joints, allowing a capacitance leakance across the rails. If there is electrical capacitance leakance across the rails, then that will affect the digital DCC signals.

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The DCC Waveform is a sophisticated and complicated waveform carrying a digital signal that is in the form of a Bi-polar square wave. The base frequency is 7khz (7,000 cycles per second), but a Bi-polar square wave has very many 'odd harmonics' to maintain wave shape accuracy. This requires the DCC signal distribution to support a frequency bandwidth many hundreds of Khz. If there is any capacitance leakage across the rails, then these higher frequencies can be shunted, this will affect the shape of the DCC waveform, which in turn affects the ability of the TTS decoder to read the DCC commands. As I said before, the TTS decoder does seem to be more sensitive to DCC signal corruption compared to other DCC decoders and products.

[96RAF]

The only real way to find out is to run a ‘scope trace across the rails at various points around the track to look at the signal waveform.

Unfortunately few folk have such kit.