ColinB

I have never tried this but X6171 looks very similar. I am not building any A1/A3s at the moment, otherwise I would order one to see. It is on EBay at the moment for £3.49 plus £1.99.

Do you require both gears or just the top gear, the one with the double gears. If it is the double gears I am pretty sure it is the same one used in the Duchess and the old Merchant Navy (not the new one).

It may be a plus point having the 8 pin. It depends what decoder you are going to use. I recently put a 21 pin Zimo sound decoder into my Coronation and I couldn't get the "Keep Alive/ Stay Alive" capacitor to fit whereas with the 8 pin I could have gone for the smaller PCB which would have fitted better. Surprisingly I always thought the 21 pin would be a better fit.

Now that is serious, sorry I didn't realise. I know the Coronation is 21 pin and it says 21 pin, Queen Elizabeth II and Evening Star are the same. Sir Nigel Gresley is 8 pin. I suppose they could have printed the boxes but issued the wrong PCB I think connection wise, the 21 pin and 8 pin PCBs are the same. As you say, you need to find someone with one.

I noticed on my Hornby Coronation that it actually says 21 pin decoder. So does the A1 not do the same? All my Hornby locos that have 21 pin decoders (three in total) have it printed on the box. It took a little while for Hornby to get there but it appears they are now doing the right thing. If it says 21 pin that is what it is, if it says nothing then 8 pin or 4 pin, which you can probably figure by the size of the loco.

I couldn't find which loco this is anywhere in the text but it is probably me missing it. I have no end of issues with decoders not doing what they are supposed to, I read the specification mainly the current limit, but still quite often I get issues. That is why I mainly standardised on Zimo ones, because they do what they say on the packet. Surprisingly Hornby ones work ok as long as you don't exceed the current limit. I don't know if this loco has a capacitor across its motor, but these can give issues. On one Duchess the TTS decoder kept dropping sound, in the end replaced the decoder with a Zimo sound and it solved the issue. The only thing I could think is that there is an interaction between the pulse width modulation used by the decoder and the motor. I cannot explain why, I spent a whole day with smoothing capacitors and doing tests. Do you use that same brand in any other locos? I don't know if they sell them in the US but try a LaisDCC only for the fact that they are very cheap so if they blow up you haven't lost a lot and surprisingly given their bad press, work a lot better than many of the known brands I have tried.

If you haven't done this yet I found with mine that if you take the coach apart there is extra room between the socket and the seating on the driver cars. I am surprised nobody else has noticed this. The real annoying thing is with a little more thought when they designed it, they could have created a slot or something to allow easy access, rather than taking the whole driver car apart. The LaisDCC decoder would fit, if you shortened the leads. I just carefully took the driver car apart.

There isn't that much wrong with the design other than you have to be careful with lubrication. When I was doing mine about 6 A4s and 4 Scot/Patriots you could still get the insulators from Bachmann. I think if I remember correctly there was an issue with the valve gear, the locating piece of plastic snaps off as you try to remove it. Bachmann still had those but it was about 2 years ago.

I have done many of these converting them to DCC, I live in Essex near the Dartford Crossing.

What I normally try to do if I think the decoder is broken, is put it on a programming track and see if I can read a manufacturer id. I can't remember which CV number it is but I am sure you can find out (I have an Elite which just reads it without knowing the CV number). Sometimes if the decoder has Keep Alive/Stay Alive fitted then this does not work. I suppose the other thing to check is that there are no broken wires or pins on the decoder header. Yes it is a sound card with an iphone speaker, probably a TTS one as it has black heatshrink over it, LokSound and Zimo tend to use clear heatshrink but I could be wrong. Carefully snip off the heatshrink and you will see more and possibly if any wires have fell off.

The decoder manual may state the voltage limit is 27 volts but there must be something wrong somewhere. I measured the unregulated output from my really old H & M duo when it blew up one of my Zimo modules I was running in DC, it was about 21 volts and if you think about it peak is 1.414 of rms, so 27 means an rms voltage of 19 volts. Now 19 volts would cook a loco on DC. I suppose you could get an inductive effect that might give above 27 volts but I am not so sure. I suspect the maximum voltage is actually between 18 and 20 volts, which seems to be the maximum a Zimo module seems to run at. I don't know enough about their exact module design but that is just a calculated guess. Anyway Sam uses a modern HM supply to run his trains, so I doubt his controller will be throwing out the same sort of DC an old H & M one would, so not the same issues. When I studied my HM7000 a lot of those components looked extremely small, now sure they work, but being so small there is not much surface area to dissipate heat. So if something goes wrong these devices fail. In fact the decoder manual also has a very high motor current limit which also looks a bit optimistic. Seeing as this was a very rushed design, highlighted by the Android app not working, I would be very dubious of a lot of the figures stated.

Well Fishmanoz as I only have one HM7000 the list would be very short. I have many TTS decoders and generally I usually bin the Hornby speaker and replace it with either one from Road and Rails or if it is a fitment inside the loco itself rather than the tender, an Ice Block speaker from YouChoos. I don't use Sugar Cube speakers as their wires are too exposed and more difficult to insulate.

Lenz and LokSound have a higher current rating. The motor can't draw more than its "stall current" so if the stall current of the motor is under 0.5 of an amp then no issues. I think the TTS has a current limit anyway so if it goes slightly over then I suspect the sound will stop first.

When I do this sort of thing I just buy a later chassis and fit it to the earlier body. If 9F design is similar to other Hornby locos, it should fit.

To be quite honest Fishmanoz the list would have more relevance if it listed whether each loco needed modifying to fit the HM7000. Jenny did cover this quite well in her video, identifying what locos it would fit and the one she modified. I have seen locos where someone has machined away the highly detailed tender interior, covered it with a false top with coal on to get a sound decoder to fit. Sure it fits, but not everyone including myself wants to do that. Quite often with a lot of 8 pin DCC decoders I have often shorted the wiring harness by resoldering it and in other cases taken a Zimo 6 pin decoder, because it is small, and added the necessary 8 pin header. Sure it fits in the loco but not everyone has the ability to do that. The HM7000 is a DCC decoder so it should work in any loco as long as the current limit is not exceeded. The bigger issues are with size and whether in the case of the 21 pin option the lower connector doesn't interfere with anything. I do wonder if it would work inside a metal bodied loco like a Wrenn because of the Faraday cage effect, the new Hornby HDs get away with it because their tenders where the decoder is fitted, are plastic.

Well SteveM6 we tend to differ in our views there but that is no surprise. As to 96RAF, have you not heard of fast forwarding a video, there are some people that probably find that interesting. Some people get really concerned about what the packing is like. I must admit I am not generally interested in the packing unless it is extremely bad, I am more how easy it is to get apart for a DCC decoder and its mechanism, which Sam does a really good job of doing. There is another reviewer I watch that tends to waffle a lot, but hidden in there are some hidden gems of information, so I will put up with the waffle to collect that data. As with all YouTube videos it is entirely up to the viewer whether they watch them or not. Perhaps we should get back to the original subject.

In response to 96RAF. Have you never watched any of Jenny Kirk's videos? A common phase is "Hornby kindly lent me this loco". I have no gripe against Jenny, in fact I like her reviews. In relation to the original post I would assume the HM7000 will work with any loco, it is after all a DCC decoder, the big issue is whether it will fit. It would be interesting to see if it works in a Wrenn with the decoder in the loco body. Post edited to remove defamatory remarks. R-

Yes LaisDCC decoders for lights and Hornby R8249 will work fine. As Barry-350851 said the LaisDCC decoders will even be ok for motor control. The only issues I have had with them is that they are a bit sensitive to a bad DCC signal you get with dirty track, but then I am comparing them to a Zimo decoder. They are no worse than a lot of makes and a lot better than some.

I do have one loco fitted with HM7000, it is the rebuilt purple West Country Queen Elizabeth it still has the default sound loaded as I use Android products, so least said about that the better. The other issue I had was that the 21 pin HM7000 that the loco uses didn't sit correctly on the socket as Hornby had placed a small connector on the bottom of the PCB. Funny on the 8 pin variant both sockets are on the top. I had to replace the mounting screws for the PCB for it to sit nearly properly and work reliably. So not what I would call a perfect experience. I must admit I am used to buying products that fit without any modification. It is interesting that you got it to fit in a Duchess class loco, even with a TTS decoder and a super thin speaker it is a squeeze, especially tenders fitted with the inner sloping coal hopper.

Here we go again. I have watched both videos from the two contributors that you mention. Now Jenny Kirk was quite honest and pointed out the very many locos that they won't fit. Sam, who I assume you are talking about, pointed out that a certain configuration didn't fit any of his non Hornby locos, which is true. It is also of great use to Hornby, I nearly bought one of the HM7000 series Plux18 ones to fit into my EFE class 143 which would have been really bad news, it is about twice the size of the available slot. Similarly he raised the issue of using any DC power supply to power said module. Hornby should have realised that there are many DC controllers out there that generate unfiltered DC with peak voltages well in excess of 20 volts, I pointed this out many posts ago. The solution is easy, just put a large capacitor across the outputs and this issue should disappear. Finally, some of us don't use "Apple" products, so the current HM7000 doesn't work for us and I am really surprised nobody has laid into Hornby over the delay, least of all Sam. As a final point I have bought a very many locos off Hornby this past two years, ones that I would never have bought because Sam did an extremely honest review of them. If he says they are good then they generally are, sadly the same can't be said of the other reviewer. So you may hate him, but he probably makes Hornby a lot of sales in the more obscure locos they make. As to the device fitting my locos I could get my Dremel out and machine a slot, I prefer not to, generally I can buy a Zimo decoder that does. Try fitting one into the APT.

Well they did have a change of management at the New Year so who knows. Perhaps the new guy is trying to run it as a business. Anyway I wish Simon a happy retirement but from what I can gather he will still be involved in the model railway industry.

I just bought some LaisDCC ones off EBay they are plenty good enough as function decoders although they are full decoders. They were £11.99 each plus postage.

I watched Jenny Kirk fit the three in her APT, the big issue was with the function decoders, she used 6 pin ones for the function decoders in the two driver units as the make she advertises and uses, only makes them in 6 pin. She used a 6 pin to 8 pin adapter which doubled the amount of wire and caused issues. The Hornby normal decoders are pretty small anyway, so I assume you shouldn't have the same problem. I assume you bought the bargain one off TMC, as I did, so I will be doing the same thing soon.

I did find on a Duchess that the wheel gear was the same as one of the transfer gears. So that is probably why Hornby sent you the pack.

I bought the Dublo Sir Nigel Gresley and I must admit I was impressed. It has the new coupling and connection to the tender. Generally though all the A4's from Hornby seem to be well built.