Hornby TTS sound in Bachmann 8 pin 37 lights issue

[Nick G]

Help, I am stumped!

 

Having around 40 locos all fitted with Loksound decoders by myself I like to think I know what I am doing but clearly not?

 

I offered to fit a Hornby class 37 TTS sound decoder in a 8 pin Bachmann Class 37 for a friend, easy I thought but I have a strange problem. The 37 is an early one without working tail lights just has working markers and headlight. On installing the TTS decoder the loco runs and the sound works however the head/markers come on at the wrong end. The loco moves forward but the lights are on at the opposite end?

If I put a Lenz decoder in all works as it should with lights on in direction of travel. Plug the TTS in and the problem comes back, any ideas?

 

Thanks. 

[Nick G]

Hi Richard,

 

Was the TTS decoder bought brand new? There was an early batch that were made for Hornby models without lights) that had a problem with the light outputs, I thought that caused the lights to flash though

 

 

 

Yes brand new. I have two TTS decoders here and they both throw up the same problem.

[pauliebanger]

Unsolder the yellow and the white wires from the 8 pin plug and resolder them to the opposite pins, i.e. fix the white where the yellow was and vice versa.

[Nick G]

Unsolder the yellow and the white wires from the 8 pin plug and resolder them to the opposite pins, i.e. fix the white where the yellow was and vice versa.

 

 

 

Cheers Paul, I will give that a go tomorrow.

[RAF96]

I can confirm early Class 37s had reversed lighting logic, since fixed by Hornby on later production runs.

You may find early steam decoders had the same fault but probably never spotted by many folk as few steamers have lights installed.

I swapped my white and yellow wires at the decoder as I found it easier to do there than at the plug end and this left the loco socket correctly wired for any future decoder change.

Rob

[pauliebanger]

I can confirm early Class 37s had reversed lighting logic, since fixed by Hornby on later production runs.

You may find early steam decoders had the same fault but probably never spotted by many folk as few steamers have lights installed.

I swapped my white and yellow wires at the decoder as I found it easier to do there than at the plug end and this left the loco socket correctly wired for any future decoder change.

Rob

 

Soldering to a decoder is not easy for everyone.

 

Changing the wires at the plug as I suggested keeps the heat away from the decoder yet still leaves the 8 pin socket correctly wired for when users swap out TTS for ZIMOs, LOL.

 

Best regards,

 

Paul

[letterspider]

Hi Richard,

 

 

 

Yes brand new. I have two TTS decoders here and they both throw up the same problem.

 

Can't remember if this can be done as easily on the Bachmann but with Vitrains 37 I desolder the motor conections and swop them around to deal with the polarity problem on the early Hornby chips.

The later 37 TTS chips don't have this problem

[Nick G]

Unsolder the yellow and the white wires from the 8 pin plug and resolder them to the opposite pins, i.e. fix the white where the yellow was and vice versa.

 

 

Worked a treat, all as it should be now, thanks again.

[KDG]

Sorry to resurrect this thread again.

 

Is it possible to change the end that illuminates by altering cv's, or is it best to swap the wires over?

 

Thanks

[KDG]

Apologies, just googled it and found the answer here on RM Web.