Hornby DCC Terrier problem please help

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Alexander Court
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Hornby DCC Terrier problem please help

Postby Alexander Court » Thu Sep 30, 2021 12:08 pm

My Centenary terrier 'Merton' which I have fitted with a 6 pin decoder since I got it and has been one of, if not my best, performing locomotives has stopped working. It was just running normally and then suddenly stopped, the controller (the most recent Hornby Select) started flashing the layout lights on and off and going into emergency mode.

I assumed it had blown the chip or something but I cannot find any trace of a short on the layout and my tts fitted Duck seemed to be fine on it until I placed the terrier on and tried to move it forward. Then the controller got upset again.

I took the body off and replaced the blanking chip and tried it on an analogue line and it started to smoke. I quickly turned off the power and removed the blanking chip. I put my motor contact test wires from the hm200 to the motor contacts and they just sparked and no life from the motor.

Is the motor dead? Is this because of something relating to the chip or controller?
I don't know what I can do about it, I can't afford a new terrier right now, I don't know if I can get a spare motor (my next google search I think).
As if this month hadn't been bad enough.
FML.

Any help would be much appreciated,
Thanks,
Alex.

"I love the way you call it Art, When you never even use your Heart, and I just wanna tear you Apart"

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Roger (RJ)
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Re: Hornby DCC Terrier problem please help

Postby Roger (RJ) » Thu Sep 30, 2021 12:45 pm

Not familiar with this loco. Can you turn the motor by hand? If not, look for something stopping the motor from turning or burnt out motor windings.

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Mountain
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Re: Hornby DCC Terrier problem please help

Postby Mountain » Thu Sep 30, 2021 1:00 pm

This is the proceedure I used with a loco on DC. (With DCC one needs to isolate the DCC side to do this as one can't apply 12v to the motor direct where there is a decoder fitted as it can fry the decoder.I write this so that anyone reading this will see it and take note. (Alexander has removed the decoder)).

I tend to remove the motor from the chassis and test the chassis for both free running ad for short circuits. I then look to the motor and give its commutators a clean and the brushes and go from there. Some fully enclosed motors can be difficult to open up so I only open if they are showing signs of not working. One can test the motors by themselves on DC to check how they run.

An oiled up motor will smoke. It will run for a few seconds until it cuts out. Weak magnets will also do this as in they run for a while and start to slow as they overheat, and they then trip the overload on the controller. I prefer a DC controller where one can hear the overload tripping in and preferably gives a visual indication of an overload. Annoyingly todays Hornby (And some other makes) do not give any visual or audiable indication of their overload protection cutting in, so one can be puzzled as to what is going on! Old controllers used to provide a visual overload light, but at least with Gaugemaster one can hear the audiable "Click" of when the overload clicks in and the power light goes off (If one has the control knob turned high enough so the power light is illuminated).

Check chassis first for free running though, as if the chassis is not free running the motor will have a hard time and end up overheating, hence the smoke.
Then if chassis is ok begin looking at the motor and don't forget the gears. (Gears can jam if broken or worn or not set up right).

I hope this helps. I may have repeated a few things as I explain.

If theloco then runs well on DC, then one looks towards the DCC side of thinngs and examines the decoder.

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Bufferstop
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Re: Hornby DCC Terrier problem please help

Postby Bufferstop » Thu Sep 30, 2021 3:17 pm

If this is the Hornby version of the Ex Airfix, Ex Dapol Terrier then it's a type 7 motor, the one for which they put it's lifetime down to 100Hrs. Removing the motor from the chassis would be a good start, the motor commonly fails with an open circuit coil, giving a resistance across the terminal of 30 - 40ohms, or either 0 or open circuit as the shaft is turned. If it stops with the intact coils between the brushes it will pass current but not turn, so there's no back EMF generated so no real resistance to the incoming power' hence the smoke on DC. Some decoders will sense the problem and protect themselves. Less well designed ones will start leaking blue smoke! Of which they have a limited supply, once it's gone they die. With the motor out and turning freely by hand try a 9V battery across its terminals if it makes no attempt to turn it's dead.
The Hornby spares seem to be in short supply, the version for the Jinty 0-6-0 and others including the Terrier seem to be out of production. The usual far east sources on Ebay don't appear to have any either. If it turns out you need one and they are still not available PM me.
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Alexander Court
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Re: Hornby DCC Terrier problem please help

Postby Alexander Court » Thu Sep 30, 2021 5:38 pm

The model is the brand new version, in the edition released for Hornbys centenary year,it has a small closed can motor thing inside a black housing. I put the blanking plate in and managed to get it moving, so reassembled with chip back in and now it is working again.
Very strange and I don't understand what the issue is. Google was unhelpful. I'm going to have to see if it behaves itself tomorrow.

Alex.

"I love the way you call it Art, When you never even use your Heart, and I just wanna tear you Apart"

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Mountain
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Re: Hornby DCC Terrier problem please help

Postby Mountain » Thu Sep 30, 2021 8:48 pm

Question. Could the gears be the issue? The reason why I ask is early signs of mazak rot are the expansion or distortion of the metal, and some locos have had the metal motor mounts suffer with mazak rot which caused the motor to have meshing issues with the gears due to the altered angles. I am not saying that this is the issue here or that that individual model could be effected. It is more of a possibility as it is sometimes not so easy to see.

I am glad it works again. :) Sometimes a strip down, clean and rebuild sorts out any issues because any part that wasn't quite seated in the right place will be corrected when one re-assembles it which can sometimes be a complete mystery as to what the issue origionally was!


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