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Uhlenbrock 76200 and Marklin universal motor
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Offline fje  
#1 Posted : 29 January 2015 20:26:06(UTC)
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fje

Spain   
Joined: 14/02/2011(UTC)
Posts: 125
Location: Madrid
Hello,

I have installed decoders in several "old" Märklin loks, changing the stator for a permament stator and using ESU lokpilot decoders.

But, for different reasons this time I wanted to maintain the original SFCM motor of a BR89 old Märklin lok and use a Uhlenbrock 76200 decoder.

I have seriously read some discussions about the problems of this decoder when used directly with a SFCM motor and problems of overheating that seem to be solved when the correct filter is used.

So, without any further tests what I did was to directly put the inductance/capacitor filter directly between the decoder and the motor. The question was where to connect them, either in the field coil or in the motor shield.

Finally, my interpretation of the english manual was to put them connected between the green/blue cables and the motor shield and so I did.

Result:

1.- Lok works, it moves, but I feel the chasis is very heat, not so much the decoder as the motor itself.

2.- Trying to program the 76200 with my Intellibox in DCC, paging mode, as suggested in the manual, when I try to read CV 1 (and later on, any CV) the result is "shortcircuit"... But the lok works and moves.... and lights switch on.

Is the filter connection OK? Values are: inductancies: 10microH capacitor: 470nF

Or... should I connect those same components in the white cables that connect to the field coil and, so, the blue and green cables will be directly connected to the motor shield?

Additionally, if I put the lok in an analog circuit, it works, moves, BUT it doesn't recognizes the overvoltage for changing direction, it accelerates, but doesn't change direction of circulation...

Any idea of help?

Thanks and regards

Javier
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Offline H0  
#2 Posted : 29 January 2015 21:06:56(UTC)
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H0


Joined: 16/02/2004(UTC)
Posts: 15,446
Location: DE-NW
Hi!

The chokes (inductors) have to filter the effects of the sparks generated at the collector, so they have to be at the blue/green wires. They'd have no effect in the white wires.

The decoder feeds DC through the white wires, thus the field coil substitutes a HAMO magnet. This leads to higher power consumption (overload on IntelliBox programming track) and more heat.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
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Offline fje  
#3 Posted : 29 January 2015 21:34:40(UTC)
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fje

Spain   
Joined: 14/02/2011(UTC)
Posts: 125
Location: Madrid
Ok, thanks.

So, I can understand the "shortcircuit" detection of the Intellibox, but in this case, how can I program the decoder CV's? Should I disconnect the white cables for the programming?

And... thus this imply that I cannot use it in an analog circuit?

Thanks again.

Javier
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Offline H0  
#4 Posted : 29 January 2015 21:45:05(UTC)
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H0


Joined: 16/02/2004(UTC)
Posts: 15,446
Location: DE-NW
Originally Posted by: fje Go to Quoted Post
Should I disconnect the white cables for the programming?
That won't do any good.
A resistor between Intellibox and programming track might do. I'm not sure where I saw this. I think someone recommended about 47 ohm.

Originally Posted by: fje Go to Quoted Post
And... thus this imply that I cannot use it in an analog circuit?
No. According to the manual it should work with analogue AC operation.

Maybe something is wired incorrectly.

I don't have any 76200, but at least one member here uses them and might share first-hand experience.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
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Offline fje  
#5 Posted : 29 January 2015 22:29:16(UTC)
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fje

Spain   
Joined: 14/02/2011(UTC)
Posts: 125
Location: Madrid
OK, thanks for such quick replies...

I will test the resistor solution tomorrow and will come here with result.

And hopefully the other guy using 76200 will read this topic and will post his knowledge...

Regards.

Javier
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Offline fje  
#6 Posted : 30 January 2015 16:00:46(UTC)
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fje

Spain   
Joined: 14/02/2011(UTC)
Posts: 125
Location: Madrid
Hi, no way, finally, no way. :(

I tried with different resistors, even with several of them in parallel (to lower the final value) and also with a lamp bulb... No way.

Then I disconnected the field coil and everything seemed to work OK in program mode. So I presume the problem is related to the impedance of the coils. I read somewhere that they should be more than 11 ohms to be OK for this decoder.

They are 10,3ohms... so, just under limit. This can explain the high heat and the "shortcircuit" Intellibox detects...

I will have to replace the coils by a permanent magnet. I tried to save in work and I will have to expend more money than planned :( :(

Regards.

Javier
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Offline jvuye  
#7 Posted : 30 January 2015 17:18:36(UTC)
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jvuye

Belgium   
Joined: 01/03/2008(UTC)
Posts: 2,883
Location: South Western France
Originally Posted by: fje Go to Quoted Post
Hi, no way, finally, no way. :(

I tried with different resistors, even with several of them in parallel (to lower the final value) and also with a lamp bulb... No way.

Then I disconnected the field coil and everything seemed to work OK in program mode. So I presume the problem is related to the impedance of the coils. I read somewhere that they should be more than 11 ohms to be OK for this decoder.

They are 10,3ohms... so, just under limit. This can explain the high heat and the "shortcircuit" Intellibox detects...

I will have to replace the coils by a permanent magnet. I tried to save in work and I will have to expend more money than planned :( :(

Regards.

Javier

Well, the results will be better anyway.
I have tried the 76200 in several ways, but always failed to have proper traction and smooth running performance comparable with what you get out of a well tuned decoder driving a permanent magnet motor.
When I say "tuned" I mean adjusted load regulation parameters.
The ESU Lokpilot has an autotune feature (read the manual!!) that brings you very close to perfection from the start.
Good luck with your conversions.
<Cheers
jacques

Jacques Vuye aka Dr.Eisenbahn
Once a vandal, learned to be better and had great success!
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Offline fje  
#8 Posted : 30 January 2015 20:29:42(UTC)
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fje

Spain   
Joined: 14/02/2011(UTC)
Posts: 125
Location: Madrid
Hi, Jacques, you are totally right.

I usually use lokpilot, all my loks have lokpilot V4.

BUT this time I was trying to digitalize an old BR89 lok and I remember that when I did similar with a Märklin 3005 time ago I had many troubles due to the motor shield. That 3005 had a mixed bakelite/metalic (brass) motor shield and I remember that everything worked OK till I put the shield, as soon as I put it, the rotor blocked.... I finally had to change the shield with a plastic only one that a colleague very gently gave to me as gift....

And this BR89 one, had the SAME shield, so I tried not to go to the same problem.... But, at the end of the day (never better said) I came to the same problem... As soon as I put the shield, the rotor blocked and no way to have it working.

Finally I remembered that my colleague gave to me TWO plastic shields, I looked on my drawers... and found it ... without the needed springs for the brushes... It took more than one hour to take them out of the old shield and put them in the new one...

And finally it works....

So, finally, to be written in my experience book for posible future digitalizations:

1.- First of all have a look to the motor shield. If it is very old and thus mix of metal (brass) and bakelite, try to avoid digitalization. If it is 100% plastic, go to your preferred decoder and permanent magnet
2.- If the digitalization has to be done anyway, then find out the impedance of the coils.
3.- If the impedance is higher than 11ohms, go ahead and try Uhlenbrock 76200 using the universal motor as it is and provided the lok has ventilation enough (coil will become heat any way)
4.- If the impedance is lower than 11ohms, again try to avoid digitalization.
5.- If, again, the digitalization has to be done, first thing is to find a 100% plastic compatible shield. If not, again, try to avoid the digitalization.
6.- If the plastic shield is found, go ahead with a permanent magnet and the decoder of your preference....

Regards.

Javier

Edited by user 30 January 2015 23:51:31(UTC)  | Reason: Not specified
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Offline amartinezv  
#9 Posted : 31 January 2015 12:57:47(UTC)
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amartinezv

Spain   
Joined: 25/08/2004(UTC)
Posts: 332
Location: Madrid,
Hello

respect to temperature problem is solved by setting CV (61) = 125

Then the decoder doesn't shut off.

A spanish marklinist "jamarcos" has investigated about this decoder and also has reported problems with the mixed (bakelite and iron ) motor cover have a look to www.lctm.info (el taller de märkos), and so..

Best regards
Antonio Martínez
marklin, IB, era 3, Train controller
www.raildigital.es/davidruso
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Offline fje  
#10 Posted : 31 January 2015 15:31:41(UTC)
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fje

Spain   
Joined: 14/02/2011(UTC)
Posts: 125
Location: Madrid
Hi, Antonio.

I know Jose Antonio (Märkos) and his works. In fact I have been discussing with him about this new try I was doing.

Main problem is not the heat, I knew the possibility to change CV61, BUT I was not able to do it, because the real and main problem was the unability of programming because the Intellibox detected "shortcircuit", I presume due to the low impedance of the coils. In fact, when I disconnected the white cables from the coils, I was able of programming the decoder.

But it was not question of every time I wanted to re-program to open the lok, cut one of the white cables, program and then re-sold the cable... So I took the other way and put a permanent magnet.

And then, the motor cover came. I also discussed it with Jose Antonio. He has been able to work with them I was not, and two times, so, change for plastic.

Regards. Un saludo

Javier
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Offline Graham HO  
#11 Posted : 04 February 2015 07:56:10(UTC)
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Graham HO

New Zealand   
Joined: 03/07/2008(UTC)
Posts: 126
I may be the person amongst others - that has been referred to in this thread as having had some experience with Uhl.76200 Lok decoders. I had 3 Loks converted - BR120, BR152 and a BR052. I now only have the BR120 which in continuing to run well after 4 years - these decoders must to be treated with the utmost respect when installing into any Lok with a metal body and/or chassis - full insulation [shrink tubing] is required around the decoder at the expense of permanent fixing to the chassis.

The 2 white wires providing current to the Field Coil terminals need protecting at their solder points - and some considerable time must be allowed to program and fine tune the decoder for optimum performance in any Lok given the variation in current draw and loading on the motor. They have great potential to provide all or most of the functions that might be required including the addition of sound modules that are plugged directly into the main decoder board - sounds like many other retrofit decoders that are available - and they can be much cheaper.
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