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Offline Danlake  
#1 Posted : 09 June 2018 13:55:28(UTC)
Danlake

New Zealand   
Joined: 03/08/2011(UTC)
Posts: 1,571
Hi all,

Need some advice regarding faultfinding on a Danish railcar fitted with ESU M4 decoder and a standard DC can motor (Heljan Y-tog).

The railcar had been working flawless for about 6 months when suddenly it would not move anymore (only brief very short jerks). All lights function would still work normally with no flickering.

Initially I did the usual faulting checking adequate connection to slider and ground for wheels etc. Reset the decoder to factory setting. Also removed the can motor and checked with a 9 V battery and it seemed to run very smoothly. I had a spare Mfx decoder (for 21MTC) and removed the ESU one and installed the Marklin, but same result.

I contacted the vendor (Heljan) and very kindly they sent me all the wiring drawing schematic. They suggested it may be a faulty can motor. However as the motor seems ok when applying voltage directly I suspected some faults with wiring/PCB board.

As I had a spare ESU adapter board (for 21MTC) I completely rewired the railcar (I used existing wires from slider, wheels and the micro LED for lights).

And now I end up with these peculiar results....:

Railcar making same short jerks and then won’t move anymore.
All lights function working properly

In desperation I then cut the wires for the can motor and instead connected them to my multi meter which (regardless) of speed setting gave a constant reading 14.8V?

Hmmm – then I thought it must be the decoder? So again swop it with my spare MfX decoder (has been configured for a standard 5 pole high efficiency motor) and now I get constant reading of 10.8V?

In further desperation I then cut the wire for the centre slider and connected straight from adapter board to third rail, but that gave same result.

Normally I would expect to see a low voltage (3-4V) with slow speed step and then gradually increasing. But this somehow is not happening and I can’t figure out why?

The only thing I can think of is some of the existing wiring for the LED is grounding with the chassis? But could that play trick on the adapter board and constantly give a high voltage on the motor output?

The last test I did was to remove the can motor (unknown Chinese brand) and wire up to my regulated DC 0-20V power supply for testing. It started running smoothly around 2V. When I reached 12V the amperage flew up to 1.5A and it stated smelling burned...

I am still planing to get an replacement can motor, so not to concerned if this one is for rubbish. But still no point in installing if I can’t solve the first problemConfused

Any guidance appreciated?

Thanks!

Lasse








Digital 11m2 layout / C (M&K) tracks / Era IV / CS3 60226 / Train Controller Gold 9 with 4D sound. Mainly Danish and German Locomotives.
Offline skeeterbuck  
#2 Posted : 10 June 2018 03:48:56(UTC)
skeeterbuck

United States   
Joined: 15/12/2015(UTC)
Posts: 523
Location: Maryland, Baltimore
Lasse, maybe check the gears? Is it possible that the gears are somehow binding that's causing the jerking. From you description it seems like you eliminated any electrical issue. You could try wiring it up and bypassing the lights completely with just the decoder and motor. That way you could eliminate the possibility of it being a light issue. Good luck!

Chuck
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Offline Danlake  
#3 Posted : 11 June 2018 12:02:43(UTC)
Danlake

New Zealand   
Joined: 03/08/2011(UTC)
Posts: 1,571
Hi all,

Did some more faultfinding this evening.

I removed one of the bogies and checked the gears and seems to run very smoothly with no issues.

I then completely removed the adaptor board (ESU 51698) with ESU decoder and instead connected directly to my program track. Still measuring 14.8V on the motor output (grey/orange wires).

As the decoder is working fine in one of my other loco I can only conclude there must be a fault on the adaptor board...

And based on feedback from danish forum - if the DC can motor suddenly draws 1.5A at 12V its faulty and needs replacing.

Fortunately the danish supplier had spare stock of motors - now I can only hope it will last a bit longer than 6 months...

But it looks like it will be awhile before this rail car will carry passengers on my provincial line again.

Best Regards

Lasse
Digital 11m2 layout / C (M&K) tracks / Era IV / CS3 60226 / Train Controller Gold 9 with 4D sound. Mainly Danish and German Locomotives.
Offline jvuye  
#4 Posted : 11 June 2018 15:42:07(UTC)
jvuye

Belgium   
Joined: 01/03/2008(UTC)
Posts: 2,881
Location: South Western France
Originally Posted by: Danlake Go to Quoted Post
Hi all,

Did some more faultfinding this evening.

I removed one of the bogies and checked the gears and seems to run very smoothly with no issues.

I then completely removed the adaptor board (ESU 51698) with ESU decoder and instead connected directly to my program track. Still measuring 14.8V on the motor output (grey/orange wires).

As the decoder is working fine in one of my other loco I can only conclude there must be a fault on the adaptor board...

And based on feedback from danish forum - if the DC can motor suddenly draws 1.5A at 12V its faulty and needs replacing.

Fortunately the danish supplier had spare stock of motors - now I can only hope it will last a bit longer than 6 months...

But it looks like it will be awhile before this rail car will carry passengers on my provincial line again.

Best Regards

Lasse


Sounds a bit like the can motor has one or two pole windings shorted, these type of faults can destroy most decoders (by thermal breakdown) even though their output are "protected" against shorts (peak current protection)

Check the commutator gaps for carbon deposits to start with.

My two cents

Jacques
Jacques Vuye aka Dr.Eisenbahn
Once a vandal, learned to be better and had great success!
thanks 1 user liked this useful post by jvuye
Offline Purellum  
#5 Posted : 11 June 2018 19:57:27(UTC)
Purellum

Denmark   
Joined: 08/11/2005(UTC)
Posts: 3,498
Location: Mullerup, 4200 Slagelse
Cool

Originally Posted by: Danlake Go to Quoted Post
Still measuring 14.8V on the motor output (grey/orange wires).


The motor is PWM-regulated, which means that you will always measure full voltage, unless the speed is set to zero.

https://en.wikipedia.org...i/Pulse-width_modulation

You need to find an oscilloscope or similar to measure the motor output.

Per.

Cool
If you can dream it, you can do it!

I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide.

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Offline Minok  
#6 Posted : 11 June 2018 20:22:03(UTC)
Minok

United States   
Joined: 15/10/2006(UTC)
Posts: 2,310
Location: Washington, Pacific Northwest
My first guess was also, check that the drive train mechanical gearing and wheels are free to move and not seized up. With the motor removed can the gears run smoothly all the way back to the4 motor? Is the motor to gears connection clean and good? If the decoder is outputting a proper voltage (regardless of the pulse width), I'd expect the locomotive to move at some speed and not just sit there. The motor spinning on a 9v may not be the same test as the motor moving under decoder output power AND with the load of pushing the loco on its output shaft... so there may still be a motor problem.
Toys of tin and wood rule!
---
My Layout Thread on marklin-users.net: InterCity 1-3-4
My YouTube Channel:
https://youtube.com/@intercity134
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Offline Danlake  
#7 Posted : 11 June 2018 22:00:57(UTC)
Danlake

New Zealand   
Joined: 03/08/2011(UTC)
Posts: 1,571
Originally Posted by: Purellum Go to Quoted Post
Cool

Originally Posted by: Danlake Go to Quoted Post
Still measuring 14.8V on the motor output (grey/orange wires).


The motor is PWM-regulated, which means that you will always measure full voltage, unless the speed is set to zero.

https://en.wikipedia.org...i/Pulse-width_modulation

You need to find an oscilloscope or similar to measure the motor output.

Per.

Cool


Hi Per,

This is where I am getting a bit confused, because when I measure with my multi meter on a Marklin loco with a standard 5 pole engine I get 2-3V for speed step 1 and then gradually it increases as I go up in speed step?

Maybe it's because the PWM is different from ESU and Marklin and with my type of multi meter I can measure on a Marklin setup but not on a ESU setup?

The reason I am concerned is that when I apply 12V to the can motor it seems to be burning out. If my decoder/adapter board is constantly giving 15V on output (as measured) will it just not burn another motor I may purchase (I am not sure either what the specs are for DC can motor but thought it used to be 0-12V range?

Best Regards
Lasse
Digital 11m2 layout / C (M&K) tracks / Era IV / CS3 60226 / Train Controller Gold 9 with 4D sound. Mainly Danish and German Locomotives.
Offline Minok  
#8 Posted : 11 June 2018 22:19:21(UTC)
Minok

United States   
Joined: 15/10/2006(UTC)
Posts: 2,310
Location: Washington, Pacific Northwest
If the motor output is PWM (pulse width modulated) then what you are likely measuring on your multi-meter is the average DC voltage over some timeframe. The signal though is a square wave between the positive voltage max output by the decoder, and the minimum voltage (often ground or 0V for DC motors). The more of the time period the signal spends at 0V, vs the top voltage, the lower the average is.

UserPostedImage - from arduino.cc

The 0% duty cycle has an average of 0, the 100% duty cycle has an average of the full voltage of 5v, the 50% duty cycle spends half its time at either end, so the average voltage you wold read is 2.5vDC even though its actually (practically) never at 2.5v.
Toys of tin and wood rule!
---
My Layout Thread on marklin-users.net: InterCity 1-3-4
My YouTube Channel:
https://youtube.com/@intercity134
thanks 2 users liked this useful post by Minok
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