Hi, my name is Paul from the UK, I've been browsing here for a while - great forum.

At the moment I have a temporary layout using M track and I am considering switching to digital before building a more permanent layout.

I converted a couple of my locos using the ESU lokpilot v4 and the permanent magnet. These were small flat commutator motors and the locos work fine in digital mode.
However I also converted a 3072 V100 using the appropriate Lokpilot 4 kit. This loco has a drum commutator motor.
The conversion worked fine until I increased the speed to about half. After a few seconds at this speed the loco slowed then stuttered and I could smell burning!

I removed the motor and the commutator was a bit scorched but cleaned up ok. I reassembled and tried a different Decoder (of the same type) with the same result. The motor seemed to run ok with the decoder disconnected and a DC voltage applied to the brushes but as soon as it is powered from the decoder the burning returns.
I had checked the armature (anker) with a meter and there was around 8 ohms resistance between the segments on the commutator.

Lastly I reverted the loco back to AC Analogue with the original parts and it runs on analogue as it did before at high or low speed.

This has me puzzled. I am reluctant to continue with my conversions to digital until I can find out what happened here.
I was wondering if the drum commutator motors are more 'delicate' but figured that ESU wouldn't produce the kit if the motors weren't suitable.

The controller that I used is a CS1 (non updated).

Sorry for my first post being a long one and thanks in advance for any help or advice.
Paul

Hi Ray, thanks for the quick reply.

Yes, I included the chokes that came with the ESU kit - one on each brush terminal.
I also set the motor parameter CVs to those recommended in the ESU instructions for Marklin DCM motors. I also tried the factory set defaults.

Ive just had the loco running (as AC analogue) for the last half hour with about ten wagons at a reasonable speed on a track that includes gradients so it appears the motor survived the experience.

I forgot to add that before I did the last try with the decoder I skimmed and trued the commutator on a small lathe and then cleaned out the slots - just in case the commutator was uneven causing the brushes to skip. I also checked the solder joints to it.

I suppose I could try a new armature but in the UK everything has to be ordered so takes time.

This is a bit of a pain as I don't know whether to carry on converting locos if I'm going to run into these sort of problems.

Paul

Hi Ray,
Thanks for the reply. It sounds as though my loco just has some bad bits in it.
I've ordered the Marklin 60760 kit that you recommended. As you say it's a bit cheaper and should replace all the bits that could have caused the problem.
I'm new to Digital (and Marklin in fact) but I'm enjoying the learning experience so far.
Paul

I think you're probably right Chris, there must have been something in the motor although I did clean it out during the conversion including the grooves in the commutator. I cleaned it again after skimming it too.
Ah well, we'll see how the new marklin motor in the 60760 kit works.

What I find strange is that the motor is now working nicely back in analogue AC mode.

I've decided not to let it put me off digital though.

I must get around to starting the new layout - my temporary one seems to be growing but I can't make it permanent as the boards are too wide to get good access to the back for scenery building.

Paul

Hello Paul,

Have you removed the 2 condensators on the "motorschield" ? The one's that goes from each pole to ground ?

I am not really sure but this could be the problem,,, The condensator on the top of the "motorschield" should be there.

Hi Paul,

I left the one between the brush terminals at the top of the shield. There weren't any between the poles and ground.

Thanks, Paul

Good point. I thoroughly tested the armature for shorts but not anything else.
Next time I'm going over everything with a meter at every step of the process
Thanks

Thanks for the info River,
Mine definitely had a drum armature in it. I did get it secondhand so maybe it had been altered previously.
I haven't been collecting Marklin very long so unfortunately I'm not too familiar with all the numbers yet.

It's a bit of a learning curve.

Paul

Thanks John,
I looked at the soldering around the commutator and one of the joints was pretty bad and dry looking. I think this may have been parting under the high centrifugal forces when the speed increased. This would have caused local heating and hence damage to the commutator.

Anyway, today the postman delivered a Marklin 60760 kit which has a new armature, motor and motor brush plate along with the permanent magnet and decoder.
I have to say the magnet fitted far more precisely than the ESU one did (which may also have caused a problem if it wasn't sitting square).

The loco now performs very nicely in both digital and analogue mode.

Thanks to everyone for your help and advice.
Paul

Nice to hear Paul