Stop start during slow running with Hattons decoder in Hornby Mallard

[Jaggzuk]

A bit of an odd one this.  One of my boy’s Christmas presents was a “like new” second hand Hornby Railroad Mallard, which I got from Hattons.  Without a DCC decoder it ran fine on DC.  Most of our locos are equipped with the bargain Hattons DCR-8PIN decoders, as it is a balance between decoder cost and what do I really need for a 8x4 DCC play layout. I have never had any issue with any I have so far bought (15+), they all work fine.

 

I plugged a new decoders in to the Mallard and it ran OK.  But then I began to realise that at slow speed it was not so good.  It would randomly stop and then do a slow start without any intervention.  Initially I thought it was the loco pick-up contacts. So I cleaned the track, check the loco and tender pickups.  Still no joy.  It ran at speed OK and anything was fine over about step 8.

 

I then thought it was shorting out, but the NCE controller did not show that this was the case.  But I still checked the sprung pickups between the tender and the loco coupling, as I had read this can be a problem.  I also stripped of the blacking from the metal coupling pin contact on the tender.  But still the same issue.

 

The poor running was starting to be noticed during play time too and the Mallard kept being put in the engine shed and not being played with, which was disappointing.

 

I was left with the concept that I had a doggy decoder.  So one final check was to try another make of decoder.  I had one which I had taken out of a Bachmann Class 108 (TCS I think) and suddenly everything is fine, the loco runs great at slow speed and no more stop starts! I then put Hattons chip into a Bachmann Class 25 and oddly the stop start problem did not occur?  So I am not sure what the issue was with the Mallard and the Hatton decoder.

 

Any ideas, as I am now unsure if it is a doggy chip or if there is some other odd interaction between the type of decoder and the Hornby Mallard.

 

[amdaley]

I can only suggest that the taking out of the decoder had something to do with it. Could have been a dirty pin or socket in the decoder socket of the loco.

Try the first decoder in the Mallard again & see if the problem returns ?

Sometimes particular decoders don't work well with some locos for some reason ?

[Free At Last]

Be careful the doggy decoder does not go WOOF!

[Trip]

This is a guess but it would explain it.

 

Hattons chips are (or at least were) actually rebranded DCC Concepts. At least one DCC Concepts decoder type has recently been updated and its behaviour when seeing very short duration loss of power has changed. When power comes back instead of continuing at the existing speed it goes back to zero, suddenly, and then starts to accelerate again using the momentum settings.

 

So my guess is your new chip has this new characteristic and the Mallard fails to deliver power to it for a split second and it halts, then starts again with no prompting. Putting that chip into another loco which doesn't have intermitten power delivery issues means you don't see the problem any more. Similarly putting a 'normal' chip into the Mallard masks the tiny outages because it doesn't suddenly decide to stop.

[brossard]

I was looking for the part where you removed the capacitors from the loco.  Some decoders work fine I think, but others have a problem - cap removal is something I always do.  Another thing to try is to turn off DC running capability at CV29 (subtract 4 from whatever value is there but do note the original value).

 

John

[Jaggzuk]

Cheers Guys, some informative answers there.  I will check that the Cap has been removed John, I normally do, but as it was DCC ready I might have forgotten.

 

Trip, your reply sound absolutely spot on to what I have been experiencing of the stop star issue.  The Mallard once stopped will then stat up again with moment style speed increase.  The chip was a new one for Hattons in their new style of packaging so may well be a newer version of the chip,  My question here is then, is this a fault or a feature?  If a feature can it be turned off and on?  Or is this just the effect on this particular Loco?

 

I am not sure on the intermittent power delivery aspect, as it happen on plain straight track, when I would expect very good pick up on more than one set of wheels.

[RAF96]

Does Mallard have the post and springy prongs type,of,drawbar. If so they are notoriously unreliable an dliable to cause shorts. This would,account for your dodgy behaviour.

 

Unhook the tender and see of it will go Ok then, but I doubt it as the loco pickups are also unreliable and rely upon the extra tender pickups to make enough collection for it to go well.

 

Rob

Edited February 10, 2018 by RAFHAAA96

[Trip]

 

Trip, your reply sound absolutely spot on to what I have been experiencing of the stop star issue.  The Mallard once stopped will then stat up again with moment style speed increase.  The chip was a new one for Hattons in their new style of packaging so may well be a newer version of the chip,  My question here is then, is this a fault or a feature?  If a feature can it be turned off and on?  Or is this just the effect on this particular Loco?

 

 

In my opinion it's a design fault. I spoke to DCC Concepts about it and they claimed it was the intended behaviour on the new version of the decoder. I have not bought any DCC Concepts decoders since, and sent three decoders back.  I have not found anyone else who thinks this behaviour is a good idea. I dare say this bug feature will be ironed out designed away in future versions but until then I'm steering clear of DCC Concepts decoders. Which is a shame because they do a lot of things right, including the price.

[Jaggzuk]

Hmm not sure what to think now as I bought a multi five pack from Hattons, so they will all be the new type.  

 

So did DCC Concepts offer any advice on weather this can be CVed on and off?  What also concerns me is that it was happen on plain line and not just on places like dead frogs where you might expect power loss.

 

The bad design of this feature is that when it stops the loco dead and then starts up again I have been finding that the conservation of momentum rule results in derailed rakes of coaches or wagons.

 

I have started to wonder if it can be solved using some capacitors to create stay alive setup.  But not sure if you can do this with these decoders. 

 

Otherwise I may try sending them back to Hattons and got for another make.  I do not like the feature, to me too it is a fault.

[34theletterbetweenB&D]

...I am not sure on the intermittent power delivery aspect, as it happen on plain straight track, when I would expect very good pick up on more than one set of wheels.

 I don't know how these models are wired in more recent production, but as originally produced the pacific mechanism used in A3s and A4s was marginal for DCC in my opinion, because the whole chassis block is live to one rail (applies to all the Hornby introductions until the Britannia). If there is a lead with a tag under the screw that holds on the combined worm cover and motor clamp, then the chassis block is live. This is a fruitful source of momentary short circuits in my experience, best corrected by isolating the chassis block from the track. It can happen anywhere on the layout, and the worst of it is that there is nothing to diagnose, because the mechanism will have run on a little from where the short occurred!

 

Decoder sensitivity to these momentary shorts is variable, some more sensitive than others; but short circuits on the loco will eventually stop most decoders at some point. Applying an elastoplast in the form of stay alive is one way, but my preference is always to fix the cause of the trouble by rewiring.

 

How to know if this is the problem? Operate in the dark to aid seeing the momentary spark on the mechanism. If you see a spark and the loco stops, there's the trouble...

[Trip]

Hmm not sure what to think now as I bought a multi five pack from Hattons, so they will all be the new type.  

 

So did DCC Concepts offer any advice on weather this can be CVed on and off?  What also concerns me is that it was happen on plain line and not just on places like dead frogs where you might expect power loss.

 

 

DCC concepts claimed it was the intended behaviour and there is no way to modify it with CV changes. DCC Concepts decoders (but not the ones they make for Hattons)  usually come with a small keepalive capacitor which can mask the problem.

 

Hattons will refund you for those decoders without question, or at least they've always done so for me. I've found Bachmann decoders (which are currently rebadged ESU) to be much better, and the same price or actually slightly cheaper.

[Jaggzuk]

Cheers for that Trip, I will make some enquires.  Not start another debate, but for my Boys locos I might consider the TTS sound range as they are such a good price at Hattons.

[trainfan101]

Hello all,

I also have had problems with the latest Hattons decoders.  I recently bought some 6-pins to fit to DJ Models' J94s and have had exactly the same symptoms described by Jaggzuk.  The locos run fine(ish) on DC, right down to a crawl, but stop-start-have a rest-start-stop-have a longer rest-etc when the chip is fitted.  If the loco manages to get to maybe half speed, then it runs fine, but half speed is of no use if slow speed can't be relied on.  To try and identify the problem I have:

* tried different chips

* tried different locos(I have two of the J94s)

* cleaned the track

* played with CV settings by turning BEMF off and on, ditto with momentum settings

all to no effect.

 

I thought the issue was with the coreless motors, but in the last week I've also had the same problem with an 8-pin in a Heljan Garratt, an 8-pin in a Hornby J15 R3230, and a 6-pin in a Bachmann 31-166 L&Y Class 5 .

 

I have previously fitted a dozen or so Hattons chips to Hornby & Bachmann locos and all have been quite OK, so this latest batch of issues was unexpected. I emailed Hattons who replied that they had sent some samples to DCC Concepts for testing.  That was 2 weeks ago.

 

I've just ordered some DCC Concepts 6-pins with Stay Alive to see if that eliminates the problem. I suspect I shall soon be returning a number of decoders to Hattons as either faulty or not fit for purpose.

[Trip]

 

I've just ordered some DCC Concepts 6-pins with Stay Alive to see if that eliminates the problem. I suspect I shall soon be returning a number of decoders to Hattons as either faulty or not fit for purpose.

 

It might do but to be honest you're better off using another brand of decoder until they get that issue fixed. If you've got room for a keepalive you got room for several other options.

[lambretta]

i have just fitted one to a b17 and have the same problem also if i hit stop it still moves  again a bit later as if it had a stored up instruction