class 66 tts issue

[Railking]

i have a hornby class 66 dcc ready i was given a 66 tts decoder worked well for the first month now 1 minte into running the loco the sound stops but the loco will keep running i checked the decoder just after and the decoder was hot in one corner this happons each time i run the loco now???

[ff2nd]

Sounds like a decoder failure. Best to contact Customer Care at Hornby to get it resolved.

[ColinB]

That is funny, I have just put a post on the same subject. Mine was perfectly OK, then just stopped, opened up the class 66 and the module was very warm, not  hot. When I powered off then on, the module sort of made a bit of a noise then nothing happened. I am waiting for Hornby to come back on this. I like the TTS decoders as they are cheap (no much more than a decent decoder), but from my experience their reliabilty is a bit suspect. I wonder who makes them for them? I have had ones that suddenly lose their sound, then recover, one that went quiet then recovered, it does not give you a feeling of confidence in their product. I wonder if they under spec their components and if they get a bit hot they just fail.

[96RAF]

Can I just repeat the advice given above by ff2nd - that if you are having problems with your TTS decoders then your first port of call is to Hornby Customer Care on the number at bottom of every page on this site. Their TTS decoder warranty is no quibble even if you have destroyed the decoder by ham fisted installation, mishandling or plain stupidity. That is not a cover up for a poor product, just Hornby playing very fair and reasonable to their customers.

 

There may be information on the forums that could help you identify if there is a real problem or not with your TTS decoder or its installation, so please do look for such discussion, but its no good ranting about it on the forum if you haven’t taken your issue back to the manufacturer.

 

Thinking about the relatively small number of failures reported on the forums to date. There was trouble with a few TTS models a long time ago (uni-directional programming, etc) but that was quickly sorted by Hornby and free updates provided. There are around 30 different TTS variants out there now and given the suggested minimum order of quantity for a production batch was say 2,000 units, that is an awfull lot of TTS decoders that are obviously still working as advertised. Compare that with the reported failures and you can see the reliability stats are well within the norm for any similar kit.

 

[ColinB]

Actually I wasn't ranting, each of the decoders that have failed I have returned and yes they eventually get replaced (the last one about 4 weeks, I am still waiting for the one from Rails, but I am sure it will come). The one that failed yesterday, I immediately contacted Hornby for return. I was trying to work out if anyone else was having issues. From my experience and I worked in the stuff for a great number of years electronics is very reliable, so it seems unusual that so far I have had three bad units. Electronics normally fails because of excessive current, over voltage or excessive heat. They were fitted correctly, the only issue that does concern me, is cooling, where these are mounted there is not a free flow of air. If I had shorted something out, I would have instantly admitted to it, in fact in this case that was the first thing I did, check for stray wires.  As for the 30 different variants out there, I assume that is the the same hardware all they are doing is replacing the memory map, for individual locos, that is how most people do it. There is still the possibility of a bad batch of components, and they don't make enough to really notice. I was actually asking for advice, so please don't assume I was ranting.

I didn't realise they replaced modules if you blew them up.

[96RAF]

Colin my remarks were not directed at you personally, but folk in general. We have quite a few rants on here about all sorts of problems, yet often it pans out that folk have neither approached the retailer nor the manufacturer, which should be the first port of call in any dispute within warranty. Forum advice is given freely, but taking it on board is down to an individual.

 

The Hornby decoder warranty is as plain as it can be and a copy is provided with each decoder. The Vent Van decoder warranty is less definitive against user abuse as the decoder is factory installed and they do not expect you to remove it.

Standard Warranty including TTS

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Vent Van warranty

/media/tinymce_upload/3a039b5851d0cafe8094fc57c31c3d76.jpg

 

To answer your question about the TTS decoders. Yes they are essentially blanks of the same manufacture, which are initially loaded with operating firmware (which is changeable by rewriting, else rogue decoders like the uni-directional problem one could not be repaired). Then the sound files are loaded in a write once read many (WORM) condition. This is why you cannot reblow TTS decoders with another sound file once they are initially produced. What the Hornby QA arrangements are in place at production facilities I have no idea, but would expect an industry standard of percentage checks of batch once a new facility is brought into production.

 

I would agree with your remark that heat is a potential problem and many installations are almost airtight so heat failure could be a definite factor. That is why advice about decoder insulation has changed over the years from the early days when layers of electrical insulation tape was recommended, then shrink wrap sleeving was provided with DCC Ready locos and now a single layer of sellotape is recommended. Good engineering practice would go for insulation of the loco against metal to decoder contact, thus allowing the decoder to breath as best as possible.

[2e0dtoeric]

If you follow Jenny Kirk's You-tube channel, she said she had some 'duff' chips - but found out by accident that if you force-reset them to manufacturer's settings, they often spring to life again.

[96RAF]

If you follow Jenny Kirk's You-tube channel, she said she had some 'duff' chips - but found out by accident that if you force-reset them to manufacturer's settings, they often spring to life again.

How does one accomplish a force reset Eric

[ColinB]

I eventually found the issue only after I had tried and damaged another TTS decoder. Amazingly it was the 9 month old loco that caused it. The capacitor across the motor had gone short circuit, I only noticed as I reverted it to DC and found the controller was being short circuited. The annoying part about all this is I normally remove the capacitors as recommended for DCC operation, but it was buried right next to the motor on the bogie so I never noticed it. TTS decoders are protected for stall currents but obviously not short circuits across the motor. When I first add a DCC decoder I normally check the resistance across the motor, but as it had been working I never thought to check it. Do you know in all my years of electronics I have never known a ceramic capacitor to go short circuit.

[96RAF]

Is this a case of where use of a low energy programming track may have saved the day by flagging up an error. i.e. It would see the failed cap as a wiring fault.

 

The TTS blurb I posted in the other thread specifically says overload or short circuit protection.

 

Certainly it adds weight to the argument that all caps should be removed not just trackside ones in a loco or track connector.

[ColinB]

I think the big issue in this case was the cap failing. I naturally assumed I had a duff TTS module as generally locos are usually OK if they are not abused and it was only 6 months old and only been used a couple of times. I doubt it will ever happen again especially as I will be removing all the capacitors in future. In this case to get to that capacitor I had to virtually dismantle the whole of the front bogie, which I don't usually want to do on a new model. Once I figured it was the loco, it was easy to find it on DC, joke of it is before I put the decoder in I normally check for shorts between pins on the DCC connector and resistance across the motor, but as it was ok when I fitted it, I never bothered testing it again.

[96RAF]

Good to you for finally tracking down the root cause Colin. I am sure other folk will be looking for the same thing if they are seeing similar problems, although if it were me I would be stripping out any and all associated gubbins just to be sure.

[Glenn_RhB]

I have a Hornby Class 66, fitted with a Hornby TTS chip and have nothing but problems with it.

Firstly, it runs in the opposite direcion to all my other vehicles, and changing CV29 or selecting 'reverse polarity' (I use MRCDCC software, or the JMRI interface) makes no difference.

Second problem is that the acceleration curve is very rapid after speed step 3 of 28. Amendments to the relevant CV's are either ignored, deleted or the loco refuses point blank to move.

I initially solved the problem of no/little movement by changing CV150 to '1' (why doesn't that come already set?)

Does anyone have a set of CV settings for the min/mid/max speed CV's that work (along with any other CV settings that might help) in order to get this loco to play nicely?

The chip works fine in my ESU test bed, other chips in the loco have the same problem. So I'm looking at the motor as being the problem currently.

Thanks in advance for any help

[ColinB]

I assume you have the DCC decoder in the right way round. The easiest and most secure way to get the motor working in the right direction is to reverse the wires on the motor. If you do it using CV values if you ever reset the decoder you will have to do it again. The bigger question to me is if it is a standard class 66 why is the motor wired up wrong. I convert a lot of my old locos to DCC so quite often they go the wrong way, but it never bothers me, I just turn the controller in the opposite direction. As to the othe CVs I haven't got a clue. I have a Hornby Evening Star with a TTS decoder and other than the documented issues with motor capacitors, I find it works perfectly ok. Do a double check on whether the decoder is in correctly, on this loco it doesn't have lights so you would never really notice if it was in wrong.

[Rog RJ]

Second problem is that the acceleration curve is very rapid after speed step 3 of 28. Amendments to the relevant CV's are either ignored, deleted or the loco refuses point blank to move.

TTS decoders need to be used in 128 step mode to get the best results.