Britannia Class TTS Decoder R7143

[ifair365]

While not exactly correct I thought I'd fit this decoder to my Class 6 'Clan Macleod' (R2847). It ran correctly for a short time and then failed to respond to the controller - no sounds, other than the chuffing; no speed control and no response to the Stop button. Once reset the sounds play when static and it responds normally to the controller for about 20 seconds. My supplier exchanged it but I hesitate to try again. Was the chip faulty or is it not compatible with my Lenz LH100? The loco current is 150mA so well under the maximum 500mA permitted. I've tested other sound locos and all perform normally. Any ideas?

Thanks,

Iain

[Fishmanoz]

Hi Iain, welcome to the forums.  You seem to have hit a blank wall in terms of members’ knowledge to help you given no replies after a day.  So let me see if I can.

 

One obvious conclusion from your problem as described is that the decoder may be faulty, and you’ve covered that.  So let me first ask if the loco was previously running well on DC or perhaps non-sound DCC?  Given you’ve done a current test, chances are it is but still worth asking.  And that current seems to be consistent with the 5-pole skew wound motor in the model, so well within TTS load capability, even if that rises somewhat on stall.  You could always do a stall test to confirm.

 

Another question - have you fitted a socket as part of your conversion?  If so, do you have a non-sound decoder you could try (much easier with a socket)?

 

Barring all of that, you may just have to fit the new TTS and see how it goes.  From what you’ve said, there’s nothing obvious that might be wrong with the loco.

[ifair365]

Thanks for the reply. It was a DDC ready loco so no issues with fitting a socket. It ran perfectly on DC and I've just fitted a non sound chip - and that also runs fine. So, took a chance and fitted the new TTS chip and have pretty much the same problem. It gets up to a certain speed and won't respond further - and no sounds when moving except the chuffing. All sounds play when reset and stationary. Stop worked a couple of times but no longer. Obviously there's something not right. Might be a case of waiting to see if any others have issues with this new chip.

[Phil_Spiegel.]

In common with many other sound decoders ... Without the addition of 'stay alive' energy storage, sound decoders are more sensitive to momentary power interruption ...

 

Such as caused by intermittent pickup .. Which may not show up with a silent decoder. .. Even though the current draw is the same or similar.

 

So it may still be worth checking for the QUALITY of the pickup as the wheels turn.

 

The other check is to test the TTS decoder either in another loco or on its own ( eg with the ESU decoder tester.

 

In Zero-1 days, Hornby supplied dealers with Yellow-cased Master Controllers complete with an attached Ring field Motor Chassis for testing decoders.

[Fishmanoz]

Hi Iain, trap for new players - using the blue button to reply.  All that does is repeat my reply to you which is immediately above anyway.  Go down to the bottom of the page and use the text box and green button.

 

Phil makes a good point but if it still happens after track and wheel cleaning, pickup tensioning etc, just one more thing to check that I can think of - do you happen to be using a DC power connector or power track rather than DCC?  Easy to check and fix - flip open the black plastic cover (between the rails on the track) and see if there is a capacitor soldered between the rail connections.  If so, remove it by clipping off the legs.  It will now work for DCC or DC and will most likely solve your problem.  Some decoders will work with the capacitor, then you will always come across one that won’t some time.  Best to remove all such capacitors from all tracks and connectors Now so you don’t get caught in future.

[irf365]

Thanks Fishmanoz. Realised I'd used the wrong button as soon as I posted. Thanks to Phil as well for his observations. 

As suggested, I've just tried the TTS chip in another loco - and it works perfectly. Strange that the non-sound chip works OK. Maybe there's a wiring issue with the socket so will double-check. I've previously hard-wired a TTS chip into an old non-DCC ready loco and that works fine. 

[Julesdad]

I have exactly the same problem fitting the TTS to a clan. Did you manage to solve the problem

[96RAF]

I can only suggest tracing the loco wiring with a multi-meter to determine all pins on the socket are wired OK and there is no solder tracking between socket paths.

 

Julesdad - which TTS decoder are you installing (R number?) and which Clan (R number?). also which controller and at what firmware revision - usually seen at controller startup.

 

All this information will help us provide valid advice.

[Julesdad]

The loco is R2846 Clan Buchanan 

The TTS decoder is Britannia Class R7143

The equipment Bachmann Dynamis Ultima

The loco ran fine on a standard DCC decoder, I fitted the new TTS decoder.

It responded to all the different sound functions whilst static once it started moving it would not responded to the controller and the only way to stop it was with the emergency stop. Refitted the old decoder and it ran ok again 

Sent the decoder back to Hornby, great service and replacement by return.

Fitted the replacement decoder and exactly the same problem.

Tried replacement decoder in another loco and it works fine.

Connected the clan to the TTS tender of another loco and the system trips stating a short on the system, refit standard decoder and it works fine.

Any ideas what I should be looking for? 

[96RAF]

Uncontrollable runaway usually means DC running is enabled in CV29. Having said that more recent Hornby decoders have this set to off as default, but it pays to check. 

 

The only way to prove the loco and tender are OK is by methodical fault finding. Check continuity between loco and tender wheels on each side. Check the loco to tender connection. If it is the springy fingers and clamp type on the tender post, these are prone to shorting. The plug and socket arrangement is much better but prone to wires breaking off.

 

The fact the decoder seems OK in another loco and other decoders work in this loco suggests maybe the pins on the dodgy decoder are linger and causing problems.

 

As I say methodical checks from track up to motor.. a word of caution unplug the decoder whilst doing motor check as if you apply a voltage to the motor brushes with the decoder plugged in you will kill it.

[Howbi]

Suggestions.........

1)  Check power track connector for capacitor inside the case, if there snip it out.

2)  Change CV29 to turn off DC running. If on deduct 4 from total....  http://www.2mm.org.uk/articles/cv29%20calculator.htm

3) Change CV150 to a value of 1 (default is 0)

[ColinB]

If I remember I had issues with one Britannia TTS decoder, eventually I got it changed. I had also had a lot of issues with the Britannia itself, mainly pickups. It is funny I have 3 of them, two caused me lots of issues, the third one a limited edition black one, was no problem at all. I keep saying this but that is where I found the tester I bought really useful, you can test the decoder on its own.without worrying about loco pickups etc.

[Julesdad]

Thanks for all your advice

[Julesdad]

Tried everything nothing worked until I removed the supressor ( I think that what it is called) now it great.

Thank you all.

[96RAF]

Thanks for the feedback. It will help convince others to remove the capacitors.

[ColinB]

It might be the suppressor was damaged anyway, the one om my class 66 from Hornby failed after 6 months. Looking at them they are really cheap disc ceramics, which I stopped using in Electronic design years ago as there was an issue with reliabilty, funny Lima used decent ones. They are very cheap though, hence why people use them.

[Howbi]

I had assumed Julesdad was saying he had removed the capacitor in the power track to solve the erratic running.........HB

[Julesdad]

I had assumed Julesdad was saying he had removed the capacitor in the power track to solve the erratic running.........HB

The external capacitors (suppressors or condensers different names for the same things)

[Fishmanoz]

I'm not sure what external means in this context, so still unclear whether you've removed the suppressor capacitor between the rails in a connector (like HB, I'd assumed that) or a suppressor capacitor wired across the motor terminals in the loco.

 

Let us know which please.

[Simmo009]

I have exactly the same issue on a Brit (Anzac). Starts off ok, then ignores every command after a short while. Perfectly fine with a non-sound chip and a blanking plug.

[Simmo009]

I have exactly the same issue on a Brit (Anzac). Starts off ok, then ignores every command after a short while. Perfectly fine with a non-sound chip and a blanking plug.

[96RAF]

Have you checked your power connector is not a DC one. If so clip out the capacitor.

[Simmo009]

Not a possibility,  DCC only circuit with bus and multiple droppers direct to the rails.

[ColinB]

Thae capacitor we are talking about is the one across the locomotive motor. If the loco has bad pickups you may well get the the ssame issue with a normal DCC chip but probably never notice, with TTS it becomes very clear when the loco loses power as you get the sound for the loco pulling away. Also the TTS will require more current that a normal DCC decoder, so the pickups on the loco are more critical, so this may explain why the issue only occurs with TTS. It also depends on which DCC decoder you use, I have found that they differ in what they do when they get a weak signal, one of the really cheap ones I used, even decided to drive the loco backwards when it hit a bad piece of track. So are you comparing the TTS with a normal Hornby DCC decoder, but even then we don't know if the software implimentation is the same in both. As I said in a previous post, I have had no end of issues with pickups on the Hornby Britannia, more so than with the Hornby West Country which seem pretty reliable.

[Chrissaf]

Julesdad posted the text below at 16:16. Due to incorrect use of the 'blue button' the whole post was contained within the quote box. The text has been replicated below and reformatted. Plus the original incorrectly formatted reply has been removed.

------------------------------------------------------------------------------------------------------------------------

@Fishmanoz

 

I'm not sure what external means in this context, so still unclear whether you've removed the suppressor capacitor between the rails in a connector (like HB, I'd assumed that) or a suppressor capacitor wired across the motor terminals in the loco.

Let us know which please.

.

I removed the suppressor capacitor wired across the motor terminals in the loco.

.

Julesdad, please review TIPs 1 - 3 in my 'How to use this Forum' post.