DCC running/decoder issue

[GVS]

Hi All,

I;ve just signed up so i'm new to all this so I hope this first posting is in the right place.

A little while ago I bought a Schools Class loco, R2845X, as a non-runner with decoder issues. It's seen better times but it was very cheap!! so I took a gamble.

In case there are some who don't know, the decoder is fitted in the tender and connected to the loco with a small plug. All wheels, tender and loco, appear to have pick-ups.

I removed the tender body to reveal a Hatton's decoder (8 pin) not the original Hornby. I understand that there might be issues with Hatton/Hornby compatibility, so swapped this for a spare (new) Hornby unit I had in my bits box. 

The situation is this: With the loco on my test track, the second I turn on the power, the loco moves forward at what I guess to be about half speed. There is absolutely no response from the controller (Hornby Select). I swapped the decoder back to the Hatton's unit and got the same response. I then replaced the decoder with a blanking plug and went back to analogue control which worked OK if a bit jittery which I put down to the loco needing a good clean and service.  

My thoughts on this are that if it's OK on analogue then the motor and basic wiring must be OK. If it misbehaves on two different decoders then it has to be somthing in that department except it's the same result even using a new decoder which should also be OK. 

I need somebody with a bit more knowledge to throw some light on this problem please. Has anyone else had similar issues with a Schools or other loco??

Thanks for reading and sorry for rambling - I'll try harder next time.

Graeme

[96RAF]

You will probably find DC running is enabled in CV29 and what you are seeing is DC runaway due to the DCC signal being misinterpreted by the decoder.

Whether you can do anything about that depends upon the revision state of your Select’s firmware.

 

Note the first double digit number as you power it up. This will be immediately followed by 30 then 03 meaning it is ready to operte loco 03. To be able to write to CVs you need this number to be 16 or 20.

 

If it is less than 16 then you can have it updated by return to works at Hornby after you ring them for a returns number and pay the modest £18 charge. You pay postage to them and they send it back within the cost.

[Chrissaf]

Yes your post is in the right place and as a first post, plenty of detail [something we usually see too little of].

 

Just a little bit more detail needed to fill in some gaps.

 

1) Do you have other DCC locos that operate absolutely fine on the track with your Select?

 

2) What firmware version does your Select have installed?

[The very first number to appear briefly when the Select is powered up. Expect to see a number between 10 and 20]

 

3) Assuming Hornby track what track power connector are you using?

[Choices R602, R8206, R8241, R8242 or direct wires soldered to rails.]

 

EDIT: Rob got in just ahead of me as I was preparing my reply.

 

TIP: As a newbie poster on the forum, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

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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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[ColinB]

I have got 4 of these, I bought one secondhand and basically rebuilt it as it had so much wrong with it. The DC runaway, is probably more to do with the Schools loco losing the DCC signal, I have never noticed it much with a Hornby or Hattons decoder, but that is more due to the fact that I only have fitted these to locos that have decent pickups. With the LaisDCC decoder I have even had them going backwards when they lose the DCC signal. The issue with the Schools loco is that it can "rock" on its traction tyres if you have the slightest uneven track or points, meaning that it relies on the front bogie or the tender to get power so check that these pickups are working properly. I don't know if you have the older Schools loco with the really bad pickups on the front bogie, or the newer one where they improved the pickups. Unfortunately, Hornby don't sell either as spares, so having seen the later type I modified mine using bodged parts.If you want more information see Sam's Trains on YouTube he explains the issue with front pickups exactly. Hattons Decoders work just well as Hornby's, I think there was an issue with the earlier Select software. I shouldn't be saying this on this site, but I have found that the Zimo £20.00 decoders handle a bad dcc signal much better than the rest. TTS decoders have a big issue with "DCC runaway" but they seem incredibly sensitive to anything, I have never noticed it on Hornby decoders but there again, I tend to always use Zimos as they are tons more reliable (sorry Hornby) and the people at a certain firm that sells them are so helpful.

[GVS]

Thanks for the replies and comments - very speedy too!

Just to fill in a few blanks. My Select is old - Version 10 - but I use it on my test track only so not intending to update it. I have e-link and Railmaster software on my main layout, but that is partly dismantled at present. I'll transfer that to the test track and see if anything changes. The e-link works fine with my other locos.

As regards the age of the loco I think it was produced around 2009, so not the oldest version nor the newest. To help isolate the model type it has an 8 pin socket and was available DCC Ready or Fitted, Mine is a fitted example although as mentioned previously does not now have the original decoder. 5 pole motor and no traction tyres. The track is all Hornby and power supply is via direct soldered connections to the track, not a power connector or track.

RAF96, I'm a bit confused by your CV29 and DC runaway comment. Are you saying I need to reprogramme CV29, if so what value? It's a new decoder so should have the factory default setting anyway. Also what can cause the DCC signal to be misinterpreted?

Thanks,

Graeme 

[Howbi]

@GVS.............have a look here at the CV29 calculator......... http://www.2mm.org.uk/articles/cv29%20calculator.htm ......all of my decoders are set to a value of 2 in CV29.......the default for most decoders is 6 which includes DC operation, it is this that causes "DC runaway".........HB

[Chrissaf]

Also, what can cause the DCC signal to be misinterpreted?

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1) Dirt and or grime on anything (rails / wheels etc) that is part of the metallic path that transports the DCC data signal.

 

2) Poor or loose electrical connections such as wire connections that are not soldered or poorly aligned / fitted / dirty / intermittent wheel pickups. These loose wires could be part of the track wiring or within the loco itself prior to the decoder.

 

3) Using DC Analogue power connectors instead of DCC friendly ones (not your issue as you have soldered track feeds).

 

4) Basically any thing that allows bits and bytes of DCC digital data to be lost, distorted or corrupted. When the decoder looses synchronisation with the DCC data packet stream coming from the controller, the decoder thinks that the DCC signal is not present and switches into DC Analogue support mode and all DCC control is lost.

 

Regarding CV29 .... the normally accepted factory default of CV29 is a value of 6

 

This equates to 'Speed Steps' set as 128 and 'DC Operation' is enabled and that the 'DCC Loco Decoder Address' is stored in CV1 and is a value between 001 and 127. If your DCC address for this loco is higher than 127, then the value of CV29 will not be 6.

 

As you have eLink / RailMaster then you can read the value of CV29. If it is 6 then write a value of 2 to CV29 to disable 'DC Operation'. If CV29 reads a value of 38 you have a DCC Address configured that is higher than 127, and you then need to write a value of 34 to CV29 to disable 'DC Operation'.

 

If you have any value of CV29 other than 2, 6, 34 or 38 then the web link page below will decode your current CV29 value and tell you what you have configured [use the 'BackCalc' tool on the page].

 

CV29 and how it functions is explained on this web link page.

http://www.2mm.org.uk/articles/cv29%20calculator.htm

 

When testing this loco use your eLink / RailMaster combination. Because your Select is Version 1.0 ... using the Select for testing is likely to give inconclusive results. Some decoders have issues with version 1.0 Select firmware. If you are going to continue to use the Select for any purpose, even testing. Then it is highly recommended that you get it upgraded as version 1.0 firmware is likely to give you false results. You should be taking the view that as a 'testing controller' you want a controller that is totally dependable. In my view, version 1.0 Selects do not meet this criteria, whereas version 1.6 [2.0] Selects do.

 

The current installed firmware is displayed as the very first number to briefly appear on the Select screen as it is being powered up. Expect to see a number between 10 and 20. At the time of writing, the latest version is 1.6 [16] or 2.0 [20] - both the same. These latest versions completely transform the user experience of the Select controller and add the ability to write (not read) all CVs up to CV255. As well as access to the full F0 - F28 range of functions.

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The upgrade charge is typically £15 plus VAT [£18] plus your sending postage costs. You need to get a 'returns number' from Hornby Customer Services - see 'Contact Us' link at the very bottom of the page.

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If you do arrange to get your Select firmware upgraded, then you will need both the Select version 1.5 full manual and the version 1.6 addendum manual. As the operation of your Select (how to use it) will be completely different in certain areas of operation compared to your current firmware version.

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You can download these two manual PDFs from here:

https://www.hornby.com/uk-en/downloads/view/index/cat/12/

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If nothing appears to happen, check your nominated browser download folder for the files as they can download silently in the background.

 

[96RAF]

V1.0 Select can address a loco, change accel and decell values as well as operate F0-F4 only. It is also unlikely to support many newer decoder types and has other issues. Getting it updated whilst not absolutely necessary is a definite upgrade in capability for the Select making it a very capable basic controller.

 

Other folk have kindly answered your other questions for me.

[Fishmanoz]

I'm wondering if maybe there is a socket wiring problem. This is not unknown on even new locos and can be such that DC operation is ok but not DCC.

[GVS]

Thanks to all for the replies and suggestions.

I accept your comment regarding the upgrade for my Select - especially at the low cost of it. It's basic nature makes it a good tool, I think, as a 'test' unit but an upgrade certainly won't harm.

As regards the problem itself, it's still present. Taking heed of Chrissafs comments about dodgy connections of one sort or another, I took a while to dismantle and clean the loco and tender. Oil everywhere which must have upset the wipers on the wheels which were as dirty as I've ever seen! A few were also bent and suspect for that reason. I really thought I'd found the solution but No.

I also checked connections using a multi-meter at the 8 pin socket, both off track so no returns form wheel to wheel through the track - all seemed OK, and then on the track, live, to check for voltage, again seemed OK. The onl thing I haven't been able to check is the connections at the motor itself, and there is no way to check for any voltage drop when under load. I am now starting to think that maybe oil has got into the motor itself (can motor), there was a lot of oil about, and is spoiling contact at the commutator. Only solution there is a new motor I think.

Have I missed anything? Even DC running hasn't improved and is still a bit chuggy even after a careful clean up.