Class P" decoder with no sound.

[ColinB]

I bought a Class P2 DCC sound decoder. Fitted it to the Hornby loco, changing the speaker to a "YouChoos" sugar cube, because the DCC socket is in the loco. Ran the loco, but no sound. So I disconnected the "YouChoos" speaker and replaced it with the one supplied in the kit resting on the loco without its body with some tape, to avoid shorting it out, still no sound. I have checked the circuit from the PCB to the speaker and it is all connected with the speaker measuring 8 ohms. Is there anything else I can do? Unfortunately, I bought it from a Dealer in Malta (I know, I should have stuck to one nearer, but unbelievably it gets here quicker from there and is cheaper), so do I return it to Hornby? I do not know who makes these, but from the posts on this forum and my experiences they seem incredibly unreliable, and this is from a person that spent their whole career in the electronics industry (hardware and software design).

[Chrissaf]

One has to ask this basic question, because you haven't said yah or nay. But have you switched the sound on?

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You have to send (typically) an F1 command from your DCC control station to turn on the sound in decoders. It is not a case of 'teaching grandmother to suck eggs' we have genuinely seen posts on this forum where users did not realise that the F1 command was needed to turn on the sound and there is nothing in your post to indicate if you have done this or not.

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Also, what controller are you using. Some controllers (RailMaster for example) need to be configured differently to lock a sound on, else the sound command is sent then disabled a few seconds later.

[ColinB]

One has to ask this basic question, because you haven't said yah or nay. But have you switched the sound on?

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That has to be the most incredible question yet. The short answer is yes, I even tried another one of my locos just to check the settings on my controller. I have since reset the chip both with the global command and the sound command. I have doubly checked all the connections from PC to speaker. To me it looks like an issue with the sound not being connected, funny though the DCC decoder works OK, a bit sluggesh but that could just be the settings. I have even tried it on a separate piece of track and no joy.

I have two controllers a Hornby Elite and Fleishmann Twin Centre ( I bought them broken and cheap and fixed them). I have about 10 locos with these chips in, so it is pretty easy for me to check whether the controller is sending the right commands.

[2e0dtoeric]

Why incredible question? You'd be surprised/horrified how many readers don't think of the obvious first!

It's no more incredible than an experienced poster NOT using the green reply button, but hiding his comment in the trimmed repeated post. 😛

[westernwill]

Quite agree with you, Eric.

 

I once had an electrician fitting some new ceiling lights in a bathroom. Went along to offer a cup of tea and asked how he was doing. Ha said he could not get them to work, had checked all the wiring and was on the point of taking them back to his supplier. I mentioned have you tried a different bulb. He looked at me as though I was an idiot, but then thought and tried another bulb. Lo and behold it all worked. 

 

[ColinB]

Look I don't want to get into throwing insults, I used the quote button for my reply, which I assume is what it is meant for, I was quoting the previous message, if that is not what it is meant for then remove the mouse hover function. I know there are some inexperienced users on this site, but there are some that think that are a bit above it all. Generally most people, me included go down a "check list" before they start asking questions, so in my case the check list is a) have I switched sound on, b) is the speaker connected, c) have I done anything to blow up the circuit. Just in case we have this arguement in the future I am a qualified Electronics Engineer with a degree in said subject, spent 40 years working on hardware and software design mainly designing microprocessor circuits and associated software from the ground upwards mostly on embedded engine control but also associated test equipment (no, I didn't write the specs I actually did it). So basically I was wondering if there was inherant issue with these devices. if I had a circuit diagram I could probably figure out why the stupid device is not working, but I haven't. 

[Chrissaf]

I really can't comprehend why you got so upset with my reply. I read the bit about your electronics experience and thus purposely added the bit about 'grandmother egg sucking' so as not to cause any offence with it. In the absence of your writing a full description of the tasks you performed, then sending F1 was a perfectly valid point to raise and was written with appropriate politeness.

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I was quoting the previous message, if that is not what it is meant for then remove the mouse hover function.

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The blue quote button would not have been so much of an issue, if you had not included your response within the buff quote text box. Follow up readers now have to compare your post to the original to then see what is different......this is more time consuming for readers than if you had not used the blue button at all. Particularly as your reply directly followed mine, thus it is pretty obvious to readers what post you are replying to. This reply includes clear space between the quoted extract and the new text as an example.

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You are obviously frustrated that the Hornby decoder? (I assume TTS....again you never confirmed this) does not work. But is there any need to take out your frustration on others who are only trying to offer some assistance.

[ColinB]

Yes, I was a bit upset. My controller remembers previous settings, so F1 is always set. My fault I did not see two boxes appear, some packages you have to remove the text which I assumed in this case, which was obviously wrong. Yes it is TTS, unfortunately these seem to be a constant issue, I have bought other types admittedly more expensive, but these always seem to work straight out the box. The TTS although very cheap, seem to be very suspect in their design, I get the opinion Hornby don't even test them and not having the function outputs protected must be a serious issue to them. I know from my previous job, that blowing up an output is not obvious, it is not as it the chip is going to have a corner missing, so Hornby must get numerous "no fault found" returns. In my case, the only thing I did was to connect a different speaker and insulate the circuit board in loose fitting "heat shrink". From my experience of audio, if the speaker was suspect it would have blown up the chip and anyway it measures 8 ohms, and there was no difference when I connected the original speaker. Generally when an audio stage blows it is pretty obvious and on these it seems to take out the regulated supply. I suspect that probably one of the surface mount devices is not connected properly, I was just trying to see if this was a regular issue. There was a guy on this site yesterday complaining that the heat was making them fail, which is really concerning, normal electronics is usually good up to above 40 deg C if adequately designed. 

[Ruffnut Thorston]

I always test any decoder before fitting it to the final location.

 

I have used a known good controller and DCC socket fitted loco, and also a dedicated DCC testing board.

 

Before I had the board, I made up a basic test rig with a 12volt DC can motor, wires, and a DCC 8 pin socket.

[ColinB]

Yep, done all that, removed all the filter circuit on the motor. Works perfectly in DCC, but no sound, it is a return job, even used a different DCC controller. @Sarahagain sorry to point this out, but there is an issue with your testing. Before you fit the 8 pin plug into the socket on the loco, you need to check that there are no shorts between adjacent pins on the 8 pin socket on the loco. On one of my Locos (I hate keep saying this) Hornby had wired it incorrectly, there was a short between the motor feed and the feed from the track(you would never notice this on DC). I had never used the Loco on DCC before, so I come along with my new Zimo Sound module, plug it in, and of course blows one of the drivers so the loco only goes one way, your test would not have found this. So I always check for shorts, also on some models Hornby use a very cheap PCB (why, a decent one is pennies from China), so it is really easy to get solder splashes across tracks during their production process, hence the need to do the checks. The only line you should read a value, is across the motor pins., assuming the loco is not on the track. The thing I cannot understand saving a penny in my line of work, on a million cars is worth doing, for Hornby it is a waste of time as they spend it on the warranty process. These modules you breathe on them and they blow up, the function outputs are not short circuit protected, whereas most microprocessors have that as standard, so the poor Dealer gets unnecessary returns, costing Hornby even more money.

[The son of Triangman]

On the teaching granny etc., and please don't feel insulted as no matter how experienced you are we all miss things at times.  Did you observe ESD handling precautions with decoders being ESD sensitive devices?  Have you continuity and resistance tested the wires from the decoder, it could be a broken wire to the speaker.  Failing that it's most likely a dud decoder.

 

As even the most experience electronics people here will testify,  it's very easy to miss the blindingly obvious.

[ColinB]

Yes, checked all that pcb to speaker, and pcb speaker feed and return. Even checked the AC voltage on the speaker with it running, but nothing. Yes, initially I thought it might be a broken wire or a "dry" solder joint.  Even reflowed the solder on the two joints on the pcb as they looked a bit crystalline.  I even checked it with 3 different speakers and two different DCC controllers. Before I changed the original speaker, checked the new one was 8 ohm (used suger cube as Hornby one doesn't fit).  Yes, did observe ESD handling, although I must admit the only time I have ever seen one blow up from ESD was in the mid seveties when all this stuff was new, FET analogue switches were a favorite, although we did use TI micros in a car audio design in about 2005, that were very sensitive. Even my soldering iron is a Weller Temperature controlled iron, just in case I blew it when I soldered the wires on, but I handled it no different to any of the others I have fitted. I have sent it back to Hornby for them to test. It came from a model shop in Malta, could the Xray scan have killed it, I am pretty sure it was in an electrostatic covering, so I doubt it. Anyway, I will find out soon.

[96RAF]

Invoke the Hornby no-quibble warranty.

[ColinB]

Yes, actually it took about a week, but Hornby sent me a returns number, so I sent if off yesterday. I will wait and see.

[morairamike]

One simple question.

When you removed the speaker did you unsolder it at the PCB or the speaker terminals. Reason I ask is that I read somewhere that unsoldering at the PCB could damage the output stage.

I have figured three TTS units, two A4s and a Castle class. All are running sugar cube speakers. In my case one of the A4 speakers supplied with the TTS failed and was replaced by Hornby.

Like you I have been in electronics for many years, now retired. Only ever saw one item destroyed by static. 

[Ashbourne Junction]

Had exactly the same experience with a p2 decoder last week. Changed speaker twice, no joy. Bought a replacement... works fine. It is no doubt a faulty batch. Your experience mirrors mine to the letter. I understand your frustration - poor quality control. Added to which, fitting the decoder and a mini sugar cube speaker in my dcc ready p2 (in the loco not tender) was an exercise in patience and tedium. Since they did not leave any room to comfortably fit the decoder and speaker. I absolutely love the brand and most products, but this was a pain from start to finish. And for what it’s worth Hornby, please start supplying sugar cube speakers by default instead of the huge round frisbees which no doubt most people cut off and discard since they fit very few locos. Rant over. 

[Fishmanoz]

Two things AJ - have you contact HCC for possible warranty replacement, or your supplier?

 

And no point whatsoever ranting at Hornby here, they will never see it.

[Ashbourne Junction]

Yes. I have contacted them. I realise they will never see a rant on here, and have expressed my opinion directly. It does suggest a problem with a batch if more than one person has the same issue and that was my actual reason for posting. It is odd that no one from Hornby touches base with this forum from time to time. 

[96RAF]

This is not aimed at any particular individual before anyone jumps down my throat.

 

All TTS ready locos have a mount suitable for the speaker provided with that locos retro fit TTS decoder. If Hornby supplied sugar cube speakers folk would still moan that they didn’t fit their particular loco, although the odd tender weight has both round and oblong holes, see recent forum posts forman example.

 

I  have suggested to Hornby that they supply TTS without a speaker but they say the effect on retail cost is negligible and folk would then moan they didn’t get a speaker so it is not fit for purpose.

 

Given that other make sound decoders come with/without a speaker I don’t see folk on this or other forums whinging about them not fitting a loco. Is that because the people who buy them expect to use modelling skills to fit them, but many Hornby buyers are still of the train set mentality where they need simple plug-n-play levels of modelling.

 

Rock and a hard place Hornby, you will never win with some folk.

[ColinB]

It does sound like a faulty batch, but I must admit that must be quite difficult with electronics, they are supposed to test them end of line with a bed of nails. I suppose Hornby probably "outsources" it and is probably at the "beck and call" to their supplier. The good thing about Hornby supplying the speaker is you can check the decoder works before changing the speaker. So I have no issue with them supplying the speaker, although I do have a lot of spare ones now. The thing I do have an issue with was on my West Country where they had  designed a space for the speaker, but forgot that the hole where all the DCC socket wires ran, was now covered by the speaker (see my earlier post), I cut a slot in this case. I used to work for Ford as an Electronics Engineer and one of the things that hit me early on, was how bad Mechanical Engineers were are understanding electronics, there were a few that did, but the majority thought it was a black art. When it comes to software, well that was just something for the geeks. So I suppose Hornby suffers from the same, they probably have the odd one that knows what is going on, but probably get overridden by the rest. I feel sorry for the Dealers, I bought my one off EBay, I could have given them bad feedback for suppying a faulty part, but they shipped it efficiently and it was brand new, so it wasn't their fault. The Dealer could test every one but if they did the packing would be broken.