A4 TTS Decoder Problem

[thirdline]

Hi all,

i purchased a new A4 TTS decoder and fitted it to my Hornby Railroad Mallard. At first I replaced the existing decoder with the TTS one and tested it with speaker laying alongside the loco, it worked fine. Next I cut the speaker wires and fitted a sugar lump speaker ( no room for the standard speaker as the tender has the frame for the ringfield tender drive) all worked fine, refitted the body and the tender top and everything worked ok. Next I altered the loco's address to 010 using my elite controller, that's when the trouble began, I got no response from the loco, put it back on the programme track and read CV1, it returned 255!!!  I then wrote 8 to CV8 to do a reset but CV1 still returns 255, and funnily enough so do CV3 & CV4!

im not sure what to do next if indeed anything can be done, oh dear.

Any suggestions would be gratefully received,

Mick.

[Chrissaf]

When multiple CVs read back as 255 this has a special meaning. It does NOT mean that the CVs are actually 255. It means that the controller cannot communicate with the decoder. As far as the controller is concerned, multiple 255 readings mean that there is no decoder present that it can detect the presence of.

.

This may be due to many reasons, but usually there is a poor electrical contact between the 'programming' output of the controller and the input to the decoder. This could be a poor electrical connection on the wires connecting to the programming track, poor contact (dirt) between the loco wheels and the programming track. Poor electrical contact between the wheels and the wheel pickups.

.

Check every connection in the electrical path, clean the wheels, clean the programming track, check the pickup connectivity. Sometimes the wheels just (by bad luck) stop on a wheel position where pickup connection connectivity is lost, giving the loco a nudge on the working powered main track can sometimes get the loco running again. The programming output is extremely low power and the slightest bit of dirt or grime in the programming circuit can prevent the controller from being able to communicate with the decoder.

.

Some members resort to applying a gentle weight on top of the loco to press it harder onto the programming track to ensure good electrical contact of the wheels.

.

TIP....on the Elite and the eLink. The 'Prog Output' terminals are via spring loaded "speaker type" connectors. These connectors are not gold plated and tarnish easily. The very low power of the 'Prog' output means that there is very little scope for the contacts to be kept in good electrical contact using electrical current as a cleaning mechanism (sparks for example). I had exactly the same issue with my Elite / RailMaster combo (all read CVs returning 255). I went through all the processes I have suggested above and saw no real improvement. I then cleaned the bare wires that were being trapped by the spring terminals with a small piece of 'wet n dry' and manipulated the bare wires back and forth under the connector terminal spring to try and clean the contacts of the connector. Total success, all my CV reading errors were completely fixed. Moral of the story, just don't rely on a visual inspection, treat every connection as being tarnished and dirty even if it looks perfectly OK to the eye.

[thirdline]

Thank you Chrissaf for taking the time to send another logical and informative reply.

I removed the decoder and put the blank back in to convert it to DC so I could get it on my wheel cleaner, checked all the wiring, whilst still in DC mode I checked continuity between the track and the relevant points on the decoder socket, also the motor to the decoder and all was ok. I refitted the TTS decoder and read CV1 which returned XXX as did CV's 3 & 4. This doesn't look very promising to me.

Thanks again,

Mick.

[Chrissaf]

In those circumstances it is perhaps tending to look like a TTS fault. There are so many posts with TTS issues, it does perhaps seem more likely.

[Howbi]

@thirdline.........did you remember to change the connecting leads to the program output on the Elite........an xxx reading would indicate the leads were in the track output..........HB