0-4-0 convert to digital

[Ghutchi1]

Hi,

I just purchased 2 0-4-0 trains, the Rothery Industries loco, and the GWR train pack, I also purchased 2 decoders, a DCCConcepts decoder, and a Hornby r8249 decoder. I fitted the first loco with the Hornby decoder and changed its id to 1, tried to run it on the track and it moved about 3 inches and stopped, after about 15 seconds it moved another 3 inches and again stopped. I replaced this with the DCC decoder and the loco ran perfectly. I then fitted the Hornby decoder into the other 0-4-0 loco and the same thing happened.

Thinking it was a faulty decoder I replaced the decoder, but the same thing happens, (it goes around the whole track in this fashion), is this a settings problem for these locos, and where can I get a list of CV's for all the Hornby locos.

I am using the elink and Railmaster software.

I followed the instructions for fitting the decoders from the Hornby DCC help section of the web site.

Thanks for any assistance you can provide.

Geoff

[96RAF]

Welcome to the forums Geoff.

 

First of all the CVs listing is particular to a decoder not a loco. whilst there is a generic list on the NMRA website there are many CVs that the manufacturer can change to their own configuration. Hornby used to post a full list of all the CVs on this web site but its no longer there that I can find.

 

The fact that swapping to the DCC Concepts decoder in the first loco fixed the problem points to a dodgy Hornby decoder. Their early decoders as often included in 'train sets' were prone to problems such as runaway and memory,loss, but the R8249 is fairly robust and is not prone to those problems. Try resetting the decoder by writing value 8 to CV8 which will also put its address back to 3 which is the default. If as you say you have tried two decoders in the second loco then I would check your wiring is OK per the instructions.

[Ghutchi1]

Hi RAF,

 

I have reset the decoder, and also rechecked the wiring to make sure it is the same as the other loco, and they are both the same. I suppose I should try another decoder, will purchase another one and see if that resolves the problem.

 

Thanks for your suggestions.

Geoff.

[Rog RJ]

If the meshing of the gears is too tight the motor could be drawing too much current for the Hornby decoder and causing it to shut down to prevent damage through overheating. The other make of decoder probably has a higher current rating so it doesn't shut down.

 

Check that the gears can be turned fairly easily by hand.  If the body is pressing down on the motor it can cause tightness, especially when a decoder is fitted.  Even the wires from the decoder can be a cause.  Have you tried the model with the body off?  Does it work OK then?

 

[RDS]

Hi Geoff

After reading the first paragragh of your post, I was convinced it was a faulty Hornby Decoder but your second para (which starts Thinking it was a faulty decoder I replaced the decoder, but the same thing happens) seems to go against that logic.

Are you saying that both Loco's exhibit the same problem, with either the Hornby or DCC Concepts Decoder?

[Ghutchi1]

Hi RDS,

 

No, the first loco with the DCC Concepts decoder is working correctly, but I have tried 2 decoders in the second loco and it runs as stated with either of them installed. This is also while the body is off, (thanks for that ROG), at first I thought it might be a setting issue since the DCC Concepts decoder worked correctly.

This is my first foray into digital control and I love the control it provides, read everything on the Hornby site before installing the decoder, and followed the instructions on screen in front of me while performing the installs.

The only reason I had the DCC Concepts decoder is that the shop was out of stock of the Hornby ones, which was what I asked for. I bought the locos at different stores, the second store had a Hornby decoder.

It is frustrating, but at least I have one working 0-4-0 loco on track which pleases me. I also don't want to unsolder the decoder out of the working one to try it in the problem one.

It just seems very strange, like the decoder turns off then on again, and it is very regular, it does not affect any other trains running at the same time so I am sure it is not the elink or railmaster software.

It does the same thing either forwards or reverse.

 

Geoff.

[poliss]

Take the faulty decoders back to the shop for replacements.

[Howbi]

@Ghutchi1...........Geoff, before soldering the decoder into your 0-4-0 loco did you remove the small capacitor from the motor..........it is not necessary when a decoder is fitted.........some say it can affect the performance on DCC..........you may consider fitting the Hornby X9659 4pin decoder rather than the R8249.........it is same spec & cheaper but fitted with short leads and a small socket which I find very convenient for attaching  breadboard link wires to, the solid pin ends just push securely into the socket as per photo attached......this is easiest solution for decoder fitting into these small locos..........HB

/media/tinymce_upload/6b3e4ffc79e78b8f2b09e354ada8a4a0.JPG

[RDS]

Hi Geoff

Thanks for the more detailed explanation.  Seeing as both of your Loco's display the same fault with either of your Hornby decoders it does seem that they are either both faulty (maybe unlikely) or that the Loco's are drawing more current than they can supply, as suggested by Rog (RJ).  Also as howbiman has mentioned, the Capacitors can cause problems and can (and should) be removed when fitting decoders.  Poliss has suggested returning the decoders for replacement and of course this may be the best solution but in that case I would try to exchange them for DCC decoders that you know do work with your Loco.

Incidentally, I have quite a few of the R8249 decoders in quite a range of Loco's and although I had problems with them a few years ago, with them forgetting their addresses, I never suffered the type of problem you describe.  I have not had any problems with the replacement R8249 decoders I have bought, so maybe you have some older stock ones.

Let us know how you get on.

[poliss]

Presumably Hornby have actually tested the installation shown in their guide, so it should work with the capacitors left in. Could be a faulty batch of decoders if bought at the same time.

[Ghutchi1]

Thanks for the replies everyone much appreciated, HB I think I will try your suggestion of the smaller decoder, (didn't know about that one),  and see about returning the other decoders.

Geoff.

[Woody52]

Hi Geoff, If the problem is that for some reason the loco is drawing too much power for the R8249 decoder to handle, then replacing it with the X9659 recommended by HB will not help, as it has the same power rating. I would be trying a 1amp decoder although it shouldn't really be necesary

. The symtems you describe are the type you would get with a system overload, but in that case all locos on the system would be doing the same thing. You haven't got any accesories drawing power from anywhere in your system have you?

Above all remember "Model Trains are Fun" although it doesn't always seem to be.

Good Luck, Peter

 

[96RAF]

Proof of the pudding re current draw would be to lash in a hefty decoder (forget about getting it inside the body for now) and see if it works then, if so we are on the road to proper fault finding.

The next step - and would already have been done if you have followed conventional advice -  is to do a stall current check on the loco. The problem with this is you need a multimeter that can handle the expected current around 2A, and most DIY meters only cope with 200mA on DC.

There is a way of measuring stall current using a shunt resistor and converting the voltage reading to amps using ohms law but I will leave it to the cognisant chaps on this forum to detail that method (then I can check mine

[poliss]

Ghutchi has already said it works with the DCC Concepts decoder.

I plug one of the multimeter leads into the 10A socket for DC stall current testing.

My DCC system tells me the current consumption of a loco.

[RDS]

... already said it works with the DCC Concepts decoder ...

 

So, surely the answer is to install one of those.  It is known that the DCC Concepts Decoder works, why try anything else?

[poliss]

The motor is probably drawing too much current and needs servicing.

[Ghutchi1]

Hi All,

 

I have an update on this, I decided to resolder the plug back onto the decoder and test it in another working dcc fitted loco, and it worked perfectly. So I resoldered it back into the problem loco and was reading the manual for the decoder and found the last part about the decoder cutting out on overload. I eased the mnotor from the chassis and rested it on the chassis so it was not meshed with the running gear, the motor turned over for about 3 seconds and then cut off. This may be a case of the motor drawing too much current and causing the decoder to do an overload cutout, the max continuous current is 500mA, the max continuous current of the DCC Concepts decoder is 750mA, it looks like the  little 0-4-0 loco motors draw just a little bit too much current for the Hornby decoder.

At least now I know what is going on and that the decoders are ok. This also maybe help someone else in the future.

 

Thanks to everyone who provided suggestions for me to complet my diagnosis of the problem.

Geoff.

[RDS]

@Ghutchi1

Thank you for keeping us informed.

[96RAF]

All my (oldish) 0-4-0 have R8249s installed, although mine are plugged into bespoke sockets rather than hard wired

 

My little diesel even has a head and tail light as well as a rotating beacon.

 

Never had an overload problem, even when they had the earlier dodgy R8215s.

 

@Geoff - you can get new motors for these blighters from New Railway Modellers shop for about a fiver, as well as other suppliers.

[96RAF]

This is the socket I use In locos that would otherwise have to be hard wired.

[Ghutchi1]

Thanks RAF good to know.