7mm Problems with my Heljan 31

[richard carr]

Steph

You could well be right that it is a layout problem, but I do find it confusing that all my other locos run fine both Heljan and none Heljan all with Loksound decoders (V3.5 and V4s) and yet these 2 don't want to. I did wonder if there was short on the loco but if there is I cannot find any evidence of it. If it were a voltage drop would it not effect all locos ?

Richard

 

[richard carr]

Interesting problem. I don't know much about DCC, but does the chip think you have a bigger load than you actually do and is trying to represent that strain by slowing down?

I would guess in that situation the chip would apply a heavier exhaust note? As I said, I don't know much about DCC!

Steve

Not sure about that Steve but that is why I am keen to see other peoples CV settings.

Richard

 

[Steph Dale]

Richard,
I'm just thinking around that myself. Might have to try and replicate the problem myself. As a thought though, if the loco sound fades out as the model slows down, then it might indicate a power drop. If the sound stays at normal volume is almost certainly something else, in which case I'm interested in whether you get idling sounds or running sounds. The former might indicate there's some DC power on the track which is triggering the automatic braking. (By way of an example)
As a further thought, are your locos (these and others) set to run only on DCC, or can they run on analogue?
At the very least, with Cliff's help you should get a pair of better-running locos and that must be a good thing.
In truth I'm still unclear as to why you have the problem you describe, but still have a feeling it's not (just) the loco decoder.
Steph

 

[Cliff Williams]

Richard I have emailed my settings to you to see how you get on.
Worth noting the motors on the Heljan locos do show up power drop on any circuit.
Let me know how you get on with them.

 

[Sug@rP@lm]

Richard

Could be a drive problem, the same as I had on my '31.
Check that the gears are meshing OK, and that these clamps are tight and not allowing the motor to "ride-up"::

My Heljan Class 20 also exhibited similar symptoms, but I couldn't find the cause. I came to the conclusion there was a problem somewhere in the drive-train of one bogie. and ended-up removing one of the motors! Runs fine now, but I'm not suggesting you do that!

Cheers

Tim

Hi

More than one of my 7mm Heljan diesels has come out of the box with insufficiently tight motor clamp bolts and with not all the wire pickups contacting the axles, or making intermittent contact. And then there are the broken gears, which has happened twice; all of which showed as more or less loss of performance. At the moment my Class 37 has become a slug again, but I haven't had time to investigate.
I'm a simple person, and it is a pain, but I might be tempted to run one of your 31s on DC (with the decoder completely disconnected) if Cliff's settings don't do the trick.

BFN

Bill

 

[Cliff Williams]

I have had to remove a few motors in my time and wrap a ring of black insulatiion tape round the case, then refit and tighten it up.
This was due to the clamp being screwed tight and the motor still slid up.

Off topic in term of speed I will have to throttle back the Loveless Deltic as it is very fast!!

 

[TheSnapper]

Phew Richard!

Hope were not bombarding you with too many possible scenarios & ideas, bu further to my post above, if Cliff's settings don't fix the problem, I suspect it could be a drive train problem, as I had with my '20.

It may be worth disconnecting one motor at a time from the chip, and loosening the strap to lift it from the gear-train ie: so the loco is only using one motor.

Another thing to try is switching off Back-EMF (Bit zero in CV49 = zero) - it may be that the chip is getting conflicting signals from the dual motors, which would indicate a mismatched pair.

HTH

Tim

PS Just realised this is my 200th post!

 

[richard carr]

I spent all yesterday evening playing with the settings and testing the layout.

I connected up a dc controller and tested the voltage round the layout, it was a steady 13.5 volts except in one section where I had 13.7, so that rules out a voltage drop.
Analog is turned off on the locos.
I loaded up Cliff's settings and the locos run fine a high speed but slow speed is a little disappointing.

At slow speed the loco stutters and stalls and the sound goes even though the stay alive is set to the maximum of 4 seconds. It appears as if the stay alive is not working or the motor is demanding so much current it drains the stay alive in a very short time.


Richard

 

[JimG]

I connected up a dc controller and tested the voltage round the layout, it was a steady 13.5 volts except in one section where I had 13.7, so that rules out a voltage drop.
Analog is turned off on the locos.

At slow speed the loco stutters and stalls and the sound goes even though the stay alive is set to the maximum of 4 seconds. It appears as if the stay alive is not working or the motor is demanding so much current it drains the stay alive in a very short time.

Richard,

Butting in here but I've been keeping an eye on this thread. Did you do the voltage test with a load across the supply? If you suspect that the loco is drawing a heavy current, the voltages you read with a voltmeter only could be very different with a load - like a locomotive drawing heavier than expected current.

Jim.

 

[Steph Dale]

Richard,

What Jim says; you'll only get a true measure of voltage in parallel with a load. A traditional incandescent filament lightbulb will probably work well as such a load. What you've actually measured is the controller no-load output, which is something quite different.
The stuttering you're describing with the loco could just be pick-up related, but I suspect it's probably the decoder drive. Now might be a good time to check the motor fixings and other loco-specific issues identified in this thread.
Although we've failed to characterise the problem thus far, everything you can eliminate by the 'blunderbuss'* method of fault identification will help get you closer to the solution.
I have one more idea of a potential layout-borne gremlin, but I'd like to eliminate what we've currently got in play before we head off in that direction.
Steph

*like 'scattergun', only further-reaching, noisier, more chaotic and typically involving more opinions. Basically it involves trying everything until you happen across something which works.

 

[richard carr]

Steph

I will re do the voltage check this evening.

As for the loco its fine mechanically I have stripped it down tightened up everything and checked everywhere for a possible short, its just fine. To me it appears to be drawing too much current when I run it on my test track with a load you can feel the power cab getting warm. On the layout its a 10 amp nce supply.

Richard

 

[Cliff Williams]

My 31 has started to splutter on the sound on load too after giving it a good thrash yesterday.
I have a feeling that the pick ups are not up to the load carrying capabilities demanded of the chip once run.
I think I will do some testing when I get a chance with some extra pick ups but that will be a few weeks down the road.

Dropping CV 54 down 2 to 10 will help the slow running, although my running is smooth, it is just not super fast compared to others.

I am using NCE 5 amp.

The Western is quicker, I believe they have changed the gearing on them!

 

[richard carr]

Yesterday evening I managed to test the layout under load and found only a 0.4 volt drop nothing that should make any significant difference.

A couple of friends were round and observed the 31 and we all agreed that it appears to start running then it is as if something on the decoder says I don't like that and it shuts down and then starts again.

I think it requires a call to SWD but that wil have to wait until I get back from a business trip in a weeks time.

Richard

 

[Brian Daniels]

If you are having pick-up problems on the 31's it could be because the pick-ups are made of a too smaller gauge phospher bronze wire and they might not be making contact with the screw tab which the wire is connected to. Howes has a supply of the correct gauge pick-ups for these models,

 

[richard carr]

Brian

Mine are too thin 0.25mm when they should be 0.7mm
Ordering more from Howes now.


Richard

 

[Osgood]

That is very helpful, thanks. Is this in effect a DIY recall, i.e. all locos would be affected?

 

[Steph Dale]

Yesterday evening I managed to test the layout under load and found only a 0.4 volt drop nothing that should make any significant difference.

Great stuff, that must be very reassuring

If you are having pick-up problems on the 31's it could be because the pick-ups are made of a too smaller gauge phospher bronze wire.

I hadn't thought to check that, but that sounds like the sort of thing we're looking for! I will have to check my model.

Mine are too thin 0.25mm when they should be 0.7mm

I'll be very interested to know whether it fixes the fault, can you get back to us when you've got them installed, please?

Steph





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[Cliff Williams]

Thanks Brian Daniels I have asked for three sets for locos here, that may help.

 

[richard carr]

Steph

The new pickups are ordered and should be with me for when I get back home next Friday (in Sydney and Sinagapore this week). I have found some setting that work well enough though even with the pickups as they are, its prone to stalling on dirty track at very low speeds when it shouldn't so hopefully the new pickups will fix this.

The good thing from all this is that I now have a good understanding of how to setup a chip and know exactly the effect of each of CV 51 -56. I have to agree with Cliff though that the auto setup by setting CV 54 to 0 doesn't work that well. I am going back to redo all my Loksound 4 locos when I get back


Richard

 

[Cliff Williams]

I got five new pick ups from Howes next day which was good.
They are significantly stiffer than the ones on the three Heljan 31s here, but I think they need to send me more than just five to sort the problem. I have asked them for more, maybe they are running out now!