Hornby Flyingscotsman power shorting

[Mapadi]

Inexperienced newbie here, have been running my TTS Flyingscotsman for a few months,using Railmaster through elink controller, with no problems but now it short circuits as soon as motor starts. It sits on the track with power on OK, sound starts up and carriage lights are on but as soon as motor starts I get "controller error short circuit" have tried it on a different track and always same problem. All other trains work OK and have reset to factory default but with no success.Do I need a motor replacement or any other ideas please?

[poliss]

First thing to do is turn the loco upside down and check that nothing metal has been picked up.

[WilliamDavid]

I must give up on mine.

After replacing the TTS decoder with a standard Hattons one because of its jerky movement, and fixing its desire to leave the track by fitting washers to the front bogie, it decided to do a runaway and then burn out the decoder after seeming ok for a month or so. A replacement decoder suffered the same fate ( dc running was disabled on both decoders)

This thing is jinxed.

[walkingthedog]

Mapadi as poliss suggested check that nothing has been picked up causing a short. If all looks OK can you try the loco running on DC?

[Fishmanoz]

Mapadi, that is certainly a strange one.  The only other faint possibility I can think of is if it has connections on the tender post, is one of the fingers on them bent?  Otherwise return it under warranty is my suggestion.

 

PS.  WD, don't you think it might be better to start your own thread instead of trying to hijack this one after only one reply and no solution confirmed?  Then, you might just do a forum search on your (different to Mapadi) problems as they are well documented with known solutions in other threads.

[WilliamDavid]

No Fishmanoz. My post is related to issues with this model, and so is relevant.

Please go policing somewhere else.

Walkingthedog, thank you for a positive and helpful reply

[Fishmanoz]

Sorry WD, didn't realise that your TTS FS shorts out on motor start too, as described by the OP.  You only seem to have mentioned:

 

-  Jerky starting - the most common TTS problem from Day 1 and more threads on here than any other TTS problem.  Usually fixed or at least minimized by changing the motor algorithm but sometimes by motor replacement under warranty.

 

-  Front bogie derailing - again very common across many models, some more so than others, with weights, or springs, or back-to-back adjustment, or a combination  being the solution, as you already seem to have done.

 

-  Runaway with DC Running turned off in a Hatton's decoder (only Hatton's? And not CV29 reset on ID change as you have described previously?) followed by decoder burnout - don't think I've heard that one before, so a good topic for a new thread with an appropriate title to see if anyone using Hatton's decoders has found anything similar (might be TTS FS socket wiring issue but unlikely, more likely faulty decoders to discuss with Hatton's).

 

But I digress, apologies Mapadi.  Any progress with your motor shorting problem?

[Mapadi]

Thanks for replies. Have checked everything suggested but cannot see anything that would cause problem. have no DC track to check it on so I think a return to Hornby is probably best. Thanks for help will post if Hornby advise of fault.

[WilliamDavid]

Fishmanoz. My apologies for my response to your post.

I appreciate the mechanics of using the forum to obtain advice, but felt in this case that the behaviour of the PO's loco and my loco may be  linked in some way.

As this loco is the only one I have had trouble with burning out the two types of DCC Concepts decoders I use on a number of locos, I wondered if there might be some common factor.

[Fishmanoz]

Always a possibility WD but I'm not convinced on this occasion.  Leaving aside the front bogie, your original problem is common across all TTS locos from the posts on here, not something specific to FS.  You can check your leaflet with the loco to try the other algorithm (CV150?), but if that doesn't work return it.  With the Hatton's decoders, they shouldn't blow with a new loco (they are 1Amp I believe and max current draw of the loco shouldn't be more than 250mA).  And I'd also be checking that CV29 isn't resetting to default so that DC Runaway becomes a possibility.

 

For the motor short, it will be interesting to hear what Hornby have to say.  If it's a motor problem, won't be the first one on TTS locos.  Also won't be the first if it's a weird decoder thing.  The low cost sound objective is a good one, it's unfortunate the implementation has been problematic so far.

[WilliamDavid]

Please ignore my comments about poor running, bogie issues, etc. They were all sorted.

My point was the loco has burnt out two decoders, and my view was that only a short across the motor wires would do this. 

What is the result of the motor 'stalling' . Would it overload the decoder and possibly burn it out, or, if you are lucky, trip the controller? Can I and the OP both have a motor issue?

 

[2e0dtoeric]

If a motor stalls, it draws more and more power in the attempt to get it spinning again. This will eventually cause the decoder to go pop. (How long - depends!)

No, it will not trip the controller, unless the decoder itself goes short-circuit on the track pickup wires. In DCC there is NO direct connection between the motor and the controller (via the track).

[Fozzy Bear]

I had exactly the same problem with my Scotsman also after about 2months and took it back to the shop (450kms away!). They sent it off somewhere and it was repaired somehow , but at least it worked. Until now as the front bogie has seemingly gotten very loose and derails very easily.

[Fishmanoz]

Rather than narrowing down problems, we seem to be getting more variables in this thread, so very difficult to reach conclusions.  Let me try to summarize to make it clearer where we are at.  And remember, we are talking about a TTS FS, though WD has swapped to another decoder for now.  As the two are quite different, Fozzy saying his is the same doesn't help - same as the OP or same as WD Fozzy ( tell us more)?

 

First Mapadi - weird problem, only happens when power applied to the motor, sounds work until then.  New loco, return it under warranty. Let the supplier worry about whether it's decoder or motor.

 

Very different symptoms for WD, problem likely to be different.  With the TTS decoder, problem may be fixed by swapping motor algorithm in the decoder.  Or it may be the motor, not the first report of such.  So if the algorithm doesn't fix it, return under warranty.  With Hatton's decoders, no mention of it being stalled, so probably not a stall current issue (stall current doesn't keep increasing, it reaches the stall current value and stays there.  And, stall current on a modern motor should be less than the 1 Amp the decoder can handle).  Also, it can only run away as WD describes if the decoder supplies full power, not because the motor is faulty.  Assuming the throttle hasn't been turned up to full and left there, then the decoder must be faulty to supply full power.  Again sounds like DC runaway, which, as WD says he's turned DC Running off in CV29, could only have occurred if CV29 has been reset, a known problem at times when ID is changed (using RM WD?).

 

Back to Fozzy, for a start is yours a TTS FS with the original decoder still fitted or something different?  Tell us more.

[Fozzy Bear]

Hi Fishy. My FS is the TTS version. It started shorting about once a week but deteriorated to the point where any power to the motor would create the short. It came back from the shop with a Hornby TTS steam decoder and runs fine though I had to alter CV29 (I think) to make it run with a linear speed curve. 

[Fishmanoz]

Not CV29 for motor algorithm, CV150 if I remember rightly. 

 

You say it came back with a TTS, what did the shop say was wrong?

[2e0dtoeric]

Fishy put - probably not a stall current issue (stall current doesn't keep increasing, it reaches the stall current value and stays there.  And, stall current on a modern motor should be less than the 1 Amp the decoder can handle).

Sorry, but I'll argue that. If your controller can deliver 1 amp, and assuming the speed is set to max,  then all the stalled motor can draw is 1 amp.

But if the controller can deliver 4 amps (or more) then the stall current will go up until it reaches the available current max - or the decoder goes pop - or the motor winding glows like an electric fire, and melts etc.

An electric motor will continue to pull more and more amps until it reaches it's designed speed, if it is loaded up, and a motor with no load at all will not go any faster than it's designed rpm's per volt, no matter how many amps are available to it.

-

Hopefully, though, a good decoder will have a current-limiting circuit in it, so if the draw rises to anywhere near max, the decoder shuts down before any harm is done.

[96RAF]

I cant agree 2erics.

A motor will obey Ohms Law and the current draw (to the limit of the power supply)will be a function of voltage and resistance of the windings. The resistance may change with heat as the motor is held in stall, but unless it has a dead short somewhere it should not glow.

[Fishmanoz]

The impedance (combination of resistance and inductance) of a stalled motor is lower than the impedance of a running motor, hence it draws more current.  Further, the impedance changes, in fact increases, as the motor windings heat up due to the higher current and the lesser cooling of the stationary armature.  So given the power supply can provide the stall current and more, the current rises in a very short time until it reaches stall value, then stays there until the power supply is removed.

 

Motors must be designed such that they can survive their own stall current, otherwise they would have very short lives.  The problem is the supply, in this case the decoder, being able to deliver it without shutting down or burning out.

 

That's the long way of saying, I'm with you Rob, not with 2e0.

[Fozzy Bear]

Not CV29 for motor algorithm, CV150 if I remember rightly. 

 

You say it came back with a TTS, what did the shop say was wrong?

Ahh yes, 150. The shop didn't know as they sent it back to the distributor.

[WilliamDavid]

After testing all was ok with dc running on a dc controller with the blanking plug refitted, I fitted a new decoder.       I put it on the programming track and all worked ok with the reading and setting of the cvs.

I put it on the main track and set it to run. After half a lap, it failed.

I did some tests with the dc plug in place, and the Railmaster registered a short circuit. This only went away when I removed the loco/tender plug, pointing the short to be in the loco. The motor is free to turn.

That's three decoders blown and one loco in the bin.

However I have just received the B17 Barnsley to make up for it. What a beauty.

[96RAF]

The fact that it worked on DC with the plug fitted would suggest the loco and the tender are wired correctly as far as the outer four pin of the socket are concerned.

 

there has been report of another TTS loco having its front bogie wired into the inner four pins of the socket so that when a decoder is installed you get a short and a dead decoder.

 

I would be checking that the inner four pins are not connected on your model, but if so to what, then I would be reporting that to HCC for repair action..

 

.

[WilliamDavid]

Thanks RAF96.

The wiring seems in order here, even if it is a very messy affair with wires trapped and squashed.

I stripped it all down, and checked everything. I connected it up to my dc controller, which made the motor rotate.

However, should the inside of the motor light up like a furnace? It is quite bright under the white translucent body.

I also measured the dc resistance of the motor. Is was mostly about 10 ohms, but drop to 1.5 ohms when it is rotated.

Bearing in mind it ran ok until recently, I feel that tthe motor is the issue.

Never mind, those B17s run a treat.

[96RAF]

That illuminated motor sounds like a short indoors, maybe a dodgy commutator or bad windings.

 

A motor change should fix it but who pays and who is required to fit it TBD Per any warranty.

[WilliamDavid]

May I just add that a comment was made earlier about me hijacking this thread. Seems my problem and the OP's post were indeed related.