That sounds like the varnish on the copper wires on the rotor might of melted first causing a short in a pole on the rotor, that causes a weak field which then requires more power. Causing more heat which causes more melting.
It is possible that after running for 11 years that the wire on the magnetic field coils were near the point of shorting. even if the locos weren't run that much the varnish could of just broken down over time.

I have had good luck using original 3 pole rotors used with ESU permanent magnet and a lok-pilot decoder. Although not as smooth as a 5 pole they run very well. so you should be able to find some 3 pole rotors for relatively cheep on the used market.
And if you want it to run fast the lok-pilot CV's are factory set for a 5 pole motor, so if you leave that setting in with the 3 pole rotor, the decoder thinks it is running at 3/5 speed so the thing will fly around the track.

Even with 5 pole motors I still have to take them apart and clean then at the first sign of slowing down. just the other day I tore down my V210 after it lost speed.

Sorry Zarko that you have had problems.

Well I wonder if the high frequency information signal on the track really gets to the rotor of an engine. I expect the rotor is really fed with a DC signal.
Maybe the problems in the collector are caused by semi-short-circuit caused by dirt accumulating between the collectors?

The rotor is fed with DC current at the maximum voltage. to obtain anything else than top speed, the motor is pulses of current, with the same net. effect on the motor speed(the more time between the pulses, the slower the rotor goes)

The neat thing about the pulses is that the decoders with "cruise control" measure the back-EMF in the time between the pulses to figure out how fast it is going.
On some decoders, you can alter the frequency of those pulses, in order to reduce motor noisget better runing characteristics.

I suspect that the damage is done to the rotor when a pulse of current has just switched off. because of the coils in the rotor, a voltage builds up which then creates sparks which do the damage to the rotor

When you've changed the reversing unit with a decoder, did you change the brushes ?
Make sure your wire connections from track to Central unit 6021 is correct.
Make sure all wires have been re-connected to the brushplate.
I have had locos for almost 60 years and never experienced anything like this before.
Yes there can be dirt accumulated between the gaps of the rotor, yes, you could of damaged one of the wire connections going from the armature coil to the armature plate, but having the same problem with another loco is also very unlikely unless it is a fluke you've damaged both armatures when converting the locos.

At one stage, brushes came onto the market for the drum collector (soft compound) but I've never heard a motor being fed with brushes from the front (1 copper, 1 graphit) caused a problem.

another problem could arise by over oiling the front of the armature, causing it to make contact between the isolated plates.

John

Hi Zarko,

Your last post is rather gloomy and pessimistic. Fortunately, old Marklin motors are easy to repair and new armatures are cheap and easy to obtain. Don't let this small problem spoil your enjoyment of a great hobby.

Zarko,

Sometimes, oil gets to the armature but it is rather small amount so it vaporized very fast and I am trying to avoid that every time when I put some oil to the side where the brushes are and copper plates of the armature.

If I read your 2nd last reply correctly, you add oil to the side of the brushes ?
This is a no-no.
You don't need oil unless the loco runs erratic or makes an unusual noise.


To your question regarding converting analog locos into digtal with 6080 decodrers.
I have done over 200 conversions and have never experienced anything like you describe.

Yes all the original parts and a thorough cleaning and all of my locos are still running (cogwheels)

regards.,
John

Zarko,

I can confirm you that this collector problem shown by you also occurs/red on purely analog driven models which did not contain any digital parts/decoder.

Hello, Hemmerich, Robert, all!


I just want to say thanks to Mr. Hemmerich whose statement calmed me down a little bit. Thank You!

Here I want to add something. I have replaced the rotor on my E41 and she ran like never before (so fast that I can hardly recall when she was running like that) still, I noticed one problem: motor's temperature is high!

I put new brushes, cleaned the motor, remove oil from the places where it should not be, no oil on brushes (I have never put the oil on brushes directly nor indirectly, but some amount got to the rotor sometimes but it is rather small amount of oil so, it should not be a problem), cleaned transmission mechanism and put additional capacitor directly to the brushes.

Still, the motor is heating and to be honest to the end, the motor always heating even 36 years ago as far as I remember. Now, with the completely new rotor and brushes, motor is heating again. Temperature comes from the brushes - sparks and the rotor is new so there was no dirt nor oil between collector's sectors at all. Brushes are not filled with a single atom of oil and I still have sparks that heats the motor and the rest of the story is well known.

But, I hope that this new rotor will last. Now, the only problem is the brushes. They are worning out just too quickly and I noticed it on my BR103 which runs perfectly and no overheating whatsoever, but she "consumes" carbon brush just too quickly...I am not running my trains above the prototypical speeds and I shall run my E41 at maximum speeds between 100 and 120 km/h. I hope that this will not cause collector to be worned out in a couple of years and I also hope that the brushes will last a little bit longer (smaller sparks, longer life of the brushes as well).

Robert, You are probably right because when the model is unable to reach the maximum speed at lower voltage, the voltage is increased by me in a try to reach maximum speed (for example, for my BR216 it is between 100 and 120 km/h) and then, the problems came. As You said, brushes started to worning out just too quickly and motor is warm as the direct consequence of the sparks, again, caused by the higher voltage...

I have my own data base and I can see how many kilometers each model ran and when. According to my own data, I can clearly see that the brushes life got just too short, specially after I have converted the model into digital. I was suspected at the high frequency of the digital current so I came to the conclusion that LFCM/SFCM motors are not made to be used on higher voltages then 16 V nor on higher frequencies. They should be replaced with 5 star rotors...But, in order to save the "spirit" of the old motors, I have decided to leave some of them as they are and replace them on places or better, in models that runs faster then 120 km/h such as E10, Rc 1010, BR103 and such...If I use one model more often then the others, I should replace the motor in it so I shall not be in position to loose the money for brushes as I really do not want to open/shut/open motors every time when I use them. That does not make any sense.

I am fully aware that rotors are small and that revolutions are rather high per minute and that I must give them proper maintenance on time. But, I just can not do that after each usage when the model ran for 300 or 400 kilometers only which means that she was on tracks maximum for 4 hours.

I shall do my best to avoid high voltages and high speeds as much as I can, but, some models must be fast on request. Well, I really hope that I shall avoid total collapse of my older models and I shall do my best to replace the motors only in the models which are critical or in frequent use.

Once again, thank You Robert and thank You Mr. Hemmerich on your answers and help!

Oh, yes, by the way, I found one interesting discussion about, almost the same topic on John's Oxlade web page and the question is almost the same but considers Faulhaber motors. Now, if anyone knows what kind of warranty Faulhaber gives for their motors and how many hours they can stand running on tracks?

Once again, thank You all on your time and attention!

With best regards,
Zarko

Zarko,

One factor not much mentioned in this thread is, of course, total number of hours run. I was actually quite surprised when you said how many hours you got out of your locos. Four hours of continuous running is a long time for a tiny motor. Doing this once or twice a week at high speed is definitely going to cause a lot more wear than I'm used to seeing in my locos.

Hi Zarko,

I'm afraid it won't work with a 1/4W resistor, you will blow it to pieces. Your transformer (if you use the grey 52 VA Märklin one) delivers 52VA which depending on the load factor while feeding the Control unit is close to 52 Watts!! Generally, using a (series) resistor to reduce the voltage on a transformer is not a good idea. It is better to use another transformer with a lower output voltage rating. Just as an experiment, you can use for instance the Märklin 6646 transformer and feed the Central Unit from the red and brown rail connections. By turning the knob you can adjust the input voltage any way you like without risking overvoltage so long as YOU DON'T USE THE REVERSE COMMAND. You will only be able to run 1 maybe 2 trains at the same time that way but you will see the effect of the reduced voltage immediately.

Secondly, you put an extra capacitor parallel to the existing one. That doubles the capacity. Usually and as far as I know Märklin puts in a 270 pF ceramic capacitor, You have now doubled the capacity, which for spark suppression shouldn't make all that much difference but it may interfere with the speed control. If it doesn't you can leave it like that or (better I think) replace the old capacitor with the new one.

Good luck, Robert

Ps: You won't notice an immediate difference with the capacitor, at least not in terms of running characteristics or warming up of the motor. If you want to see the difference in spark suppression run the loc without the body (motor visible) in a completely darkened room.

Hello, Robert, all!


Well, I was just thinking on the resistors that I currently have and I have just written down what was on my mind at that moment without any thinking.

No, 15 Ohms 1/4 W will be burnt out in a second if I connect it directly to the motor (decoder outputs) or to the tracks...So, no experiment in that way was not done.

On the other hand, DIP switch 4 on the Control Unit 6021 is not recommended to use and I tried it already but my 6021 was getting hotter and hotter in a matter of seconds, so I turned it off and returned everything on the previous settings and everything was just fine...It looked like that 6021 is in a short circuit but, no visible shorts are noticed...

Using analogue transformer is acceptable, but, my personal opinion is that I must go to 5 star motors and replace all critical motors which are in certain models with it. Brush consumption is rather unbearable and it will take my money out of the pockets and nothing will be solved.

Also, old rotors are not cheap at all and I do not want nor I have any intention to experiment with them how long will they stand undamaged spending bunch of brushes just to prove something that is more than obvious...They are not for digital operation. At least, they can not stand the way I am using my trains...With analogue, I have not that kind of problems and all analog models (except ones with DCM motors) will not be changed.

Little by little, I must replace my old motors sooner or later...

Thank You all on your useful informations and suggestions!

With best regards to all,
Zarko Kristic

Hi Zarko,

I suggest you to use capacitors with higher voltage (I think 16V is too low...).

Bye

Renato

Hello, Robert, Renato all!


I have just installed four capacitors in two of my models E41 and E94. The capacitors are 270pF at 16V.

I did test runs and the results are more than obvious: motor is not overheating at all! I can say that it is slightly warm but not even close to the temperature that I had previously on the same models. That clearly shows that capacitors are extremely important in this case and You were right about this! I just want to say thank You very much on your help! Now, I shall see how it will behaves in the future with current capacitors...

Regarding capacitors of 50V and higher (same capacity) I can try and see what will happen then...

When I get those capacitors, I shall try them and let You know (and to all members of this list as well)!

Until then,
With kindest regards,
Zarko Kristic

Thanks for the update Zarko,

I may try this capacitor on my v200 as it tends to ware out the brushes faster and the drum gets dirty faster than my other locos.

Hi Juhan,
In principle of course you're right about capacity and high-freq. absorption. However, the goal here is spark absorption. The low PWM frequency already being reduced to a ripple by the relatively high (series) induction of both rotor and field coils in Zarko's case (series motor with 6080).

The 6090 uses a much higher frequency on a smaller induction (only the rotor, field coil being replaced by a PM). So they upped the capacitance.

in Zarko's case the sole purpose is spark suppression, and since sparks have an extremely high frequency anyway, the 270 or so pF is quite sufficient for that purpose. Obviously Zarko has already doubled it in some experiments and didn't see any effects on the control characteristics. Doubling (or more) the capacity will have very little or no effect on spark suppression however it will give the decoder an added capacitive load, which the 6080 decoder output stages will not necessarily take kindly. That of course depends on the design of the 6080 which I am not familiar with but based on my knowledge of medium to high freq. power semiconductors of that design era, I tend to be careful with capacitive loads when the circuits are not designed to handle them.

Best regards, Robert

Zarko,

It still surprises that you have such a negative experience, considering that no-one else seems to have this problem to the degree that you quote!

All first generation digital models from Marklin were fitted with the 6080 decoder, and a large percentage of them had unmodified SFCM and LFCM motors, so that to say that these models "could not answer the new challenge called digital operation" is quite false. As well as the 6080 decoders there are a large number of Delta decoders out there, factory fitted into SFCM and LFCM motored locos. The Delta decoder is based on the 6080, and would behave the same way.

In my collection I have 14 locos with SFCM or LFCM motors and either 6080 or 6603 decoders. None of them show abnormal commutator wear, shortened brush life, or overheating.

Do you have any 36xx models which come factory fitted with a 6080? Are any of these a problem?

Well, good luck, Zarko.

I don't know what the answer is to your problem, but I can certainly say that I don't accept your conclusion that these motors and digital don't go together, as I have plenty of them and have no problems at all. And no, I don't keep them in a glass case, I run them regularly on my layout.

Maybe you should just accept that you run them too hard and too long and accept the consequences!

I hope you can come up with some way of running them which gives you less problems, but I don't see that the problem is with the motors.

Hi Zarko,

point taken - agree, Sir!
That's why I built two levels on my layout - an analog one for my classic beauties, and a digital level for nowadays' stuff. Works perfectly nice

And congratulations on your most interesting topic
John

It may be interesting to see what the conditions of the train room and affected locos are: is it airconditioned? dusty or not? are there any direct connections to the outside?. On the affected locos, you might want to check rolling resistance(push the loco, without rotor, over a glass pane. the wheels should turn)
For example, high humidity may encourage arcing across the brushes and a heavy running gear train may overload the motor.
It may just be that it is a combination of factors that are at the root of the cause

Hello kariosls37, Robert, Ray, Juhan!


I want to give some answers here to some questions. I do not think that is something wrong with the motors themselves as well, so I agree with You Ray in this, but I think that it is something wrong with the digital power or better, old motors can not stand it for longer period of time or even better, their lives are shortened. I am saying this because my BR216 is "only" 15 years old and it was brand new locomotive when I bought her and I have installed c80 decoder instantly, which means from the day 1. That period of time is just too small for the model to last in comparing with all other models. Also, I did not use her every day and she was running on usual distances nothing special and not too much. But those symptoms started to appear very fast and in the end, she is standing in the display waiting for the new rotor or, which is better solution (if I want to use her on digital system) 5* motor.

The only difference between You and me might be the difference in using models and that is why You did not have or had such experience and I wish You to never have!

kariosls37...There is no humidity in the room and the room is not air-conditioned. I am not using my trains during Summer because of the high temperatures that affect to the models as well. When I was working on those tests on my BR216, outside temperature was more then acceptable, 24 degrees C. Yesterday, I let my trains to run for a while and I have noticed that motors heated unusually on analogue locomotive (nice Austrian OBB green locomotive) and on E40 equipped with 5* motor (on digital system), so I stopped the trains after very short period of time.

So far, I did not notice any kind of resistance (mechanical) on the "problematic" models, but it is good tip to test the mechanic characteristics on the glass! Thank You very much on this tip!

Hello, Robert! Unfortunately, I do not have such decoders as a spare parts so I can replace current ones with them and reduce the voltage on the motor that way. Now, can You tell me what kind of booster/transformer do You use for voltage supply of your tracks?

I must add here that I noticed this damages when I noticed that I had to change brushes on the locomotives that I use, almost every time when I took them out of the display and then, I took a look at my data base which shows how many km did the model ran, when the brushes was changed (the date) and when I used particular model last time. So, I noticed that it was just too often, almost every time when I took it out of the display...That started all this and I noticed damages on the rotors. Also, changing in speed was very suspicious so, I found what I found on the collectors surfaces on four of my models and that, really, horrified me...

As I have replaced the rotor on my E41 and E94 with the new ones, I shall see how they will behave. I must add here that E94 was something more then 8 hours on the tracks already without any changings in brush conditions as well as E41. I shall see how they will behave in the future...

...and, thank You John on your support to this topic!

With best regards to all,
Zarko

I would like to jump in on this topic but like Ray, I have no problems. Of course, I don't run my Loks 6 to 8 hours straight.
Why would you do that? Anyway, this topic seems to only be driven by the originator. No one else seems to have a supporting issue.
Anyway, brushes are cheap and rotors are $25. on a much more expensive Lok.
Now, I do seem to remember that Scott Houseman, of Helmutshobbies.com warned on his web site that digital Loks had to be cleaned more often to avoid decoder failure. Check out his web site.

Eric

Hello to all!


First, I want to answer on few questions and comments...

Thank You Robert on your help and advise! I shall see what can I do regarding transformer with desired characteristics!...and thank You on the information about Tams decoders!

Eric, I have never ever ran my trains for 6 to 8 hours straight. I was talking about total running time, nothing else. My models can run (per one or two days per week) between 2 up to 3 hours maximum and not 2 up to 3 hours straight! In total, including stops, they could run 2 up to 3 hours...sometimes, and that is rather rare, they are running something above 3 hours and that all depends on what kind of train is on the tracks: cargo or passenger or both. Passenger trains run less, cargo more because of their maximum speed which is from 60km/h up to 100km/h (but rarely). So, no straight runs of 6 or more hours! Thank You on the information about spare parts! Yes, not so long ago, I have to clean the motor of my E40 (5* DCM)because I noticed that the motor heated a little bit more than it used to. So, I opened it and found out that motor (collector) and other parts must be cleaned. I shall check the site that You gave the address of!

Thomas, I have pretty much steady voltage of 230-240 V which is today's European standard. I have only one extended power cord and that is all. No voltage drops from that side. No, I did not change the transformer but I measured the output voltage and it is 21-22 volts which is normal for digital operation. No voltage fluctuations of any kind...and, no, I do not have any problems with electric appliances in the house.

Now, I have some interesting data regarding the voltage that came to the motor or to be precise, from the decoder (in this case it is c80 and c81) to the brushes. I have measured the voltage that comes to the brushes directly from the decoder (c80 and c81 in this case). The universal ampermeter shows clearly changing of the voltage values as you turn the speed knob from lower to higher speeds! The ampermeter was attached to the motor brushes, connections was going over the coil field magnet and to the right brush and the second wire from the decoder goes to the left brush over the choke.

So, here are the results of measuring (6021 control unit):

Speed knob position Voltage on the brushes (V) comments
50 8 acceptable
100 12 acceptable
150 14 acceptable
200 16
Warning! Voltage reaches its maximum value for LFCM/SFCM motors
250 21
Danger! Voltage crossed safety level! Damages of the rotor and brushes are possible to happen quickly!

So, as You can see, voltage on the brushes is not constant! It is pulse but the voltage itself does not go over the given level! So, there is no "constant" voltage whatsoever! At least, it is like that using c80 or c81 decoders! How does the DC pulses looks like, only oscilloscope can show and nothing else or other much more serious instruments.

Here are the values of the intermediate position of the speed knob on 6021:

Speed knob position between Voltage on the brushes (V) comments
0-50 6 acceptable
50-100 10 acceptable
100-150 13 acceptable
150-200 15 acceptable
200-250 18
Danger! Voltage lever cross the safety level! Damages of the rotor and brushes can be appeared quickly!

The results show that the voltage limits for LFCM/SFCM motors is when the speed knob is, at maximum, 200 (16 V on brushes). These are, if I can say like that, laboratory measures as there is no resistant of the rotor, transmission, load and resistant between brushes and rotor, but, this data is very valuable in case that you are using LFCM/SFCM motors.

So, I do not know what kind of instruments they used to measure constant voltage on the brushes (motor), but the ampermeter shows more then clearly that the voltage is not the same (constant) and that the voltage is directly regulated by the decoder itself. If You do not believe me, or if You do not believe me 100%, make your own measurements and use decoder(s) in the same way I did and that can be achieved by removing the brushes from their places if the motor is in the locomotive.

From this table, it is visible that possible damages of the rotor and abnormal brush consumption can appeared when the speed knob is turned to the maximum (21V) or between 200-250 position (18V).

Now, load and all other resistance was not included and that means that the voltage can cross the safety level earlier, but this shows the value of the voltage that decoder gives to the motor (brushes) directly.

So, what can damage the rotors and brushes so badly? If we add frequency and higher voltage (speed knob over 200), that could be the reason. Also, I admit, time can do its part as well...

So, dear Marklin collectors, this will be all for the moment.

I wish You all the best,
Zarko

Hello, Ray!

The peak voltage will be constant at 20 - 22 V, and will look like square wave pulses on the oscilloscope. When the speed dial is at a low setting, the pulses will have short duration, and at a high speed setting the pulses will be longer. This variation of pulse width is what drives your motor slower or faster, and your ammeter reacts in the same way.

Well, I saw the look of the digital power in Marklin book called "Getting Started with Marklin Digital" and that, as You said too, is true. The thing that I did not know is that, model is actually, constantly running on those peaks. If the peaks are only "the peaks" then the digital operation with LFCM/SFCM motors would not be a problem as the "maximum" voltage for those motors is reached at 200. But, as the peaks seems to be constant, then it does not matter at all at what speed the train (locomotive) is running and those peaks are directly connected with the frequency of the digital power.

ou seem to have set your own limit to what is a safe voltage for a flat commuator motor. Marklin have never said that the voltage on a motor has to be less than 16V. In fact, it is quite common to exceed it when you activate the reversing pulse, if your relay is not properly aligned. Obviously at this kind of voltage the locomotive will be screaming off down the track at great speed! This might give you an indication that all is not right!

Yes, I know how analogue locomotives behaves when the reversing unit is not adjusted properly. And You are right: the locomotive starts to run like a rocket instantly (pulse of 24V). And, yes, Marklin did not say anything regarding that at all. Still, the locomotive does not run all the time at 24V as she stops and change direction of travel after a second or two. It is questionable how would it behave if the voltage can reach of 24V of constant power directly to the motor all the time (speed knob at maximum)?! This belongs to the sphere of speculations only, of course...

Your own measurements show that the average voltage on the motor is only around 16V at the top end of the speed dial.

Well, no. See the table...Speed knob turned to the maximum (250) gives 21V on the brushes not 16V! 16V is given to the brushes when the speed knob is at the position of 200. I suppose that You just missed the adequate data because it is not shown clearly and I noticed it too late and did not notice formatting text on time. Sorry for that!

Is this how you run your trains, at maximum speed? Maybe we have a clue here about your problem?

No. I am running my trains only at prototypical speeds. That means that, for example, E94 as a cargo locomotive, has its maximum speed of 90 km/h as the prototype so she is running at 90 km/h maximum in exact scale on my tracks. When the problem appeared, she, just, could not reach that speed on the tracks and I had to turn the speed knob to the end (at maximum) and, I must add, that I do not want to speak about motor overheating and such...

So, if those peaks are just like they are, then, nothing can change the current situation and only time will have last word regarding how long new rotor will last (and brushes)...and that, may take years. If new rotor lasts for 10 years or so or something more, then, I shall leave them inside the locomotives, but I want to be ready on every possible situation and therefore, I shall try to get two or three 5* motors and replace the old ones in critical models (high speeds ones and frequently used ones) just in case. As I do not have, almost, any spare brushes more for my LFCM/SFCM locomotives, and I do have for 5* DCM motors, it is recommended for me...

Well, we shall see what will happen. Just to add that I do not have any room for more experiments any more just because I must choose to have the model as it is or to "play" around and push the limits of it and see how long will rotor or brushes stand such treatment...

If You have any suggestions or possible solutions, they are more then welcome!

Thank You Ray for the explanations!

Best wishes,
Zarko

Hello, Thomas!


Thank You very much! All changings will be reported instantly on this forum and all answers no matter are they positive or negative!

To see how new rotors behave, it will take some time, but, the answers will be given!

Thank You on your support and comments!

Best regards,
Zarko