TTS decoder speaker meltdowns

[Robert Downie JR]

Hello, Recently installed a TTS deccoder into a J36 at first it was alright then when i later selected the J36 ,the decoder made a pulsing sound and indicater lights started to flash on the select controller after investigating I found the speaker had melted not sure if it was a dead short on the speaker or a fault with the decoder, the decoder can still control the movement though I'm not sure if it would perform the sound function, has anyone experienced any similar faults

Many Thanks

[Chrissaf]

I think your particular observation is probably the most extreme failure I have seen reported. Most TTS sound faults reported seem to be either the speaker going 'open circuit' or the TTS decoder audio output failing usually accompanied by very distorted sound or no sound at all.

 

However, wait to see what others that actually use the TTS decoder have to say .... all my sound is ESU Loksound based.

 

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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[96RAF]

Not a factory fit TTS so which retro-kit R-number.

 

R-number of the J36.

 

Standard speaker or a replacement other make speaker. If replacement what make/model and what impedance 4/8/16/100 ohm?

 

Which PSU was the Select using 1-amp or 4-amp.

 

Select firmware revision state e.g. 10 to 20.

 

You say ‘...when the loco was selected...’ by this I take it the loco was OK on track until you called up its address, then what else did you select or did it fail immediately upon address selection.

[ColinB]

I have a number of these and have had many faults, I must admit I have never seen this fault. I think it might just be the speaker, generally if it was a short circuit on the speaker it probably would have taken the decoder with it, that is my experience. Buy another speaker and see if it still works. I very rarely use the supplied speaker, so perhaps that is why I have never seen this issue, I either use ex iphone speakers or sugar cube ones when there is very little space, they also sound tons better. The one big advantage of iphone speakers is they are very easy to electrically insulate, they are also very thin. If it is damaged and is under a year old, return it to Hornby, it is guaranteed(see the documentation that came with it). Unless your controller has something internally wrong with it, which I seriously doubt, as it would have blown everything, the only thing that could have happen is there was a short internally on the decoder, but again if that happened it would take out the decoder. It is a lot of current to melt a speaker, if the decoder tried to source that it itself would probably melt. Believe me you can smell it.

[ColinB]

I suppose the only thing to add to my original post, is are you sure the decoder still works. I have had them when I have had a major failure, work for about a couple of minutes, then you get the familar burning smell as it smokes and blows up the rest of the circuit. Then off course your controller trips out because the decoder has put a short across the inputs  (usually caused by the input diodes going short circuit). So as I say check it still works as a decoder over a reasonable time. As Rob says you did make sure you used an 8 ohm loudspeaker, the Loksound 4 ohm ones look exactly the same as the Hornby ones.

[Robert Downie JR]

Hello All , I am very new to all this so please excuse   my lack of technical knowledge regarding these decoders and things in general. The TTS decoder which I fitted was Hornbys and that locomotive was the only one on a small section of track I had started to use ,I had disconnected the speaker which had melted and I could see the cone had disintegrated to expose a coil of wire beneath it which looked charred  however I was surprised to see that  the motion functions of the decoder were still working after the speaker had been removed.I did notice that there is a resin type material which covers a component on one side of the pc board and it was quite warm to touch I guess I'm lucky in so far as the basic functions are still working. I will as suggested replace the speaker with one which has the same impedance, e-bay has the sugar cube version and hopefully it might work.

Many Thanks for your help 

Robert

[ColinB]

I think I might have figured what might have happened. I suspect you might have had a short on the speaker, but because you are using a Select rather than an Elite, it couldn't source enough current to completely damage the decoder. What might have happened, which happened to me is if you didn't adequately insulate the speaker, it might have moved slightly and touched something, which would cause exactly what you are decribing. It happened to me with a LokSound decoder, worked perfectly ok, ran it along the track, went to program the address. It suddenly buzzed and was no more, but in my case I have an Elite that can source a lot more current than the Select, so it can do more damage. Do all the checks I said, but I suspect it is a return to Hornby. As I say, it is only a calculated quess.

[96RAF]

Hello All , I am very new to all this so please excuse   my lack of technical knowledge regarding these decoders and things in general. The TTS decoder which I fitted was Hornbys and that locomotive was the only one on a small section of track I had started to use ,I had disconnected the speaker which had melted and I could see the cone had disintegrated to expose a coil of wire beneath it which looked charred  however I was surprised to see that  the motion functions of the decoder were still working after the speaker had been removed.I did notice that there is a resin type material which covers a component on one side of the pc board and it was quite warm to touch I guess I'm lucky in so far as the basic functions are still working. I will as suggested replace the speaker with one which has the same impedance, e-bay has the sugar cube version and hopefully it might work.

Many Thanks for your help 

Robert

 

 

From that we can assume it was a standard round speaker supplied with the TTS decoder retro kit.

 

The decoder will work without a speaker attached as the amplifier will be open circuit without a speaker and cannot therefore load up.

 

You did not not answer the majority of the questions asked but please report back once you have attached a new speaker.

[ColinB]

From reading the text, I have a horrible feeling that the module was not insulated. I must admit where ever possible I try to just insulate the bottom of the decoder, the top has the components that are going to get warm if something goes wrong, I suspect this is the reason for failures on hot days.. You have to be so careful nothing touches the tender chassis. I assume the decoder must have a cooling issue otherwise it would come in a heatshrink jacket as do Zimo and Loksound decoders. Not a criticism of Hornby just an observation.