Thought that perhaps a post indicating the stay-alive connection options with the Hornby TTS decoders might be useful.

There are two ways of adding the wires, one of which I feel is rather easier than the other due to the small sizes involved.

I have used a fine Antex Tip to help illustrate where to solder and how small the parts are. This is a new/un-used one ( which is why it looks so clean!), and has a 1mm point.

The first is how they can be added to a plain Hornby R8249 decoder on which the TTS version is based, the sound part being basically added onto it. This involves adding the wires to the diode rectifying part.

The Positive connection

And the Negative one.

As I hope you can see it's really tight to get a soldering iron tip in there. Okay if like me you use a small iron with a fine tip, a 15watt Antex with those 1mm tips, but if you have a larger iron, 25-40watt with a bigger tip... well.

So, this is the other way with the TTS decoders. The connections are on the opposite side.

The negative connection is to where the sound part is added, and is on the edge. So much easier to get to

.

And the Positive just uses the Blue wire tab. Again on an edge.  I am afraid I used a spare TTS decoder I had for these shots, and the wires not needed had been removed. Both these connections are easy to remember though in that they are both the fourth one along/down.

IZZY

Don't ask me how I did it (because I don't actually know!!) a Zimo MX623R chip lost ALL settings - everything was showing 0 (zero) even CV 7 and 8. I tried resetting with CV8=8 several times and always it failed.

Luckily I found this page https://www.1001-digital.de/pages/programmierung/zimo-decoder/hard-reset.php which is for a HARD RESET with this sequence on entries 

CV 7 = 0
CV 31 = 0
CV 32 = 0
CV 8 = 8
CV 15 = 0
CV 16 = 0
CV 8 = 8
CV 144 = 0

and blow me down with a feather - this worked and decoder is recovered

A quick blast of the old settings from DecoderPro now has the setting all back, custom curves and all - phew.

I hope this saves someone else later as well.