Hornby TTS Class 08

[rossco72]

Evening all,

 

I am in the process of fitting my third or forth Hornby 08 TTS to a model and have encountered a strange issue this time whereby the F0 white wire always appears to be on, irrespective of the Controller selecting the headlight on or off. The yellow wire will only become active if the headlight is switched on and the loco is put in reverse, as it should be. However the white wire is always live (I know its the negative polarity but you know what I mean).

 

Is there a CV setting likely to be causing this?

 

I have checked for shorts in the wires and 8 pin socket and on the chip itself with nothing showing up.

 

Any suggestions or ideas welcome on how to solve this or if anyone has encountered this before.

 

Cheers

Stuart

[RAF96]

You have checked the obvious things like solder tracks twixt pins on the socket. It could be a wiring fault in the loco. Can you swap another decoder into it and does the problem stick with the loco or follow the decoder.

It may well be a duff decoder,  but have you tried a general decoder reset CV8 value 8, as often this can correct an odd behaviour problem. It is possible  but less likely that a controller reset (you don’t say which controller nor its firmware revision state if known) would sort it out.

Edited May 13, 2020 by RAF96
More speculation...

[RAF96]

On 17/05/2020 at 06:29, Richard Croft said:

I had a similar issue with a class 20 when fitting a lighting kit, I assumed it was a faulty decoder because it caused the same issue in other locos so I sent it back and ordered a new one but it did the same. I spoke to Simon and ken at Hornby and they didn’t seem sure what was happening either. In the end I had to fit a laisdcc to control the lights and get the job finished, the Hornby decoder just did the sound and motor.

 

Sounds like the lighting kit was overloading the TTS decoder function output of 100mA. An additional 1k resistor in the blue wire would likely have fixed that. My TTS Class 20 with DIY leds is fine.