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Fried Märklin Decoder of 37589 Loco- What is this component & how can I get it?
 Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hello Marklin fans Yesterday I had the sad surprise of my Märklin BR 58 ref 37589 to have its decoder in short circuit while moving slowly and alone. Here is the picture of the culprit  The culprit is circled in red. I tested the motor and its ohmic resistance is very low ( 2 to 3 Ohms) but when connected to a DC transfo it turns without a noise and no smell My questions: - do you know this component ? - how can I get a replacement? Thanks for any advice Cheers Jean |
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 Joined: 15/12/2005(UTC) Posts: 3,590 Location: Spain
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Originally Posted by: JohnjeanB 
I tested the motor and its ohmic resistance is very low ( 2 to 3 Ohms) but when connected to a DC transfo it turns without a noise and no smell
Yes; Only when a higher voltage is applied and the thing starts to turn, will it induce a magnetic field which offers resistance to the electricity. For a motor, that is normal. |
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 1 user liked this useful post by hxmiesa
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 Joined: 04/08/2018(UTC) Posts: 1,156
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Originally Posted by: JohnjeanB Hello Marklin fans
Yesterday I had the sad surprise of my Märklin BR 58 ref 37589 to have its decoder in short circuit while moving slowly and alone.
My questions:
- do you know this component ?
- how can I get a replacement?
Thanks for any advice
Cheers
Jean
Sorry to hear do want to replace only the fried chip or the whole decoder ? in theory you should be able to get a new mSD3 decoder and load the decoder project from https://www.maerklin.de/en/products/details/article/37587 (I have 37589, and I believe they are quite similar.)
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 Joined: 01/03/2008(UTC) Posts: 2,883 Location: South Western France
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Originally Posted by: hxmiesa Originally Posted by: JohnjeanB
I tested the motor and its ohmic resistance is very low ( 2 to 3 Ohms) but when connected to a DC transfo it turns without a noise and no smell
Yes; Only when a higher voltage is applied and the thing starts to turn, will it induce a magnetic field which offers resistance to the electricity. For a motor, that is normal. 2 to 3 ohms seems a bit low if you ask me ...  Besides , this is a permanent magnet motor, and, stictly speaking the magnetic field is always present  What offer "resistance " is the opposite tension generated by the rotation of the motor in that field ( in French force contre électro-motrice ou réaction d'induit) Back to your BR 58: the main failure mechanism of these can motors is carbon residue from the brushes shorting the blades of the commutator, and thus also shorting the decoder output. Yours looks like the typical outcome The motor part number is E189104, and it sells for € 25.00 , available from Märklin . Personally I would try to take the brushes out and try to check how the commutator's surface looks, but I cannot offer any advice on how to get to them as I never worked on this type of loco/motor in the past. Cheers Jacques |
Jacques Vuye aka Dr.Eisenbahn
Once a vandal, learned to be better and had great success! |
2 users liked this useful post by jvuye
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Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hi Thank for all your answers and questions. Originally Posted by: hxmiesa
Yes; Only when a higher voltage is applied and the thing starts to turn, will it induce a magnetic field which offers resistance to the electricity.
For a motor, that is normal.
I hope you are correct but frankly the value seems very low to me. Only one way to verify if you are correct: measure the motor's current when running with 8 volts (a medium/high speed). IMO current should not be more than 100 mA . Originally Posted by: bph Hi BPH, I am checking if by replacing a cheap MOSfet component I can save the decoder. I have done this already on my coal system (Grossbekohlungsanlage) Otherwise I have a project to program a mSD3 and provided by Märklin. Originally Posted by: jvuye 2 to 3 ohms seems a bit low if you ask me ... Besides , this is a permanent magnet motor, and, stictly speaking the magnetic field is always present What offer "resistance " is the opposite tension generated by the rotation of the motor in that field ( in French force contre électro-motrice ou réaction d'induit) Back to your BR 58: the main failure mechanism of these can motors is carbon residue from the brushes shorting the blades of the commutator, and thus also shorting the decoder output. Yours looks like the typical outcome The motor part number is E189104, and it sells for € 25.00 , available from Märklin . Personally I would try to take the brushes out and try to check how the commutator's surface looks, but I cannot offer any advice on how to get to them as I never worked on this type of loco/motor in the past. Hi Jacques I quite agree with you and I will compare with a similar Märklin motor. On the other hand the motor runs so smoothly and quietly. Anyway I have to check. Otherwise it is additional 25€ plus shipment to add to a 74€ mSD3. I must measure the current absorbed on DC 8 Volts. It must be in the range of 100 mA My dream wish: the motor is OK and I can find an SMD component to replace the one with a "beer muscle"  On the other hand I don't want to risk burning a new mSD3 because of motor overcurrent Thanks again for your help. It is great Jean |
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 Joined: 15/02/2008(UTC) Posts: 693 Location: Bournemouth, Dorset
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As you have said, the melted component on your sound decoder is a Mosfet. If you can source one and have the soldering skills then that should restore your decoder.
However, there are two Mosfets on your decoder, one for forward and one for reverse. I have had this problem on an LGB decoder, the symptom being that the loco would only run in reverse.
Have you tried reversing the direction of the loco? It might prove the motor is OK and the decoder repairable by the replacement of the melted Mosfet.
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Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hi Ashley
This is a very interesting information. Thanks
I have not tried yet because the decoder is shorting the power, so I need first to remove the suspected IC and then test what you say.
I noticed there are 2 identical components: the fried one and its immediate neighbor which seem to confirm what you write.
Thanks again
Jean
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Joined: 15/12/2005(UTC) Posts: 3,590 Location: Spain
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Originally Posted by: JohnjeanB I tested the motor and its ohmic resistance is very low ( 2 to 3 Ohms) but when connected to a DC transfo it turns without a noise and no smell By all means if you suspect the resistance to be too low; As you are able to run the motor from another DC source AND you have a tester, then you can easily measure the amps going through it when running. That would tell you directly if it is consuming too much energy. |
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Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hi Ashley
Yes and today I removed the fried component UP 3A3 ( from LG I guess) now the decoder provides sound OK but the
Motor is not driven
At least it means the mother board is OK
Cheers
Jean |
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Joined: 15/02/2008(UTC) Posts: 693 Location: Bournemouth, Dorset
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I think that is mostly good news Jean, the sound part is the expensive part!
I think there is a good chance that, if you cannot find the two Mosfets as components, you may be able to use them from a standard non sound decoder, if you can find one with the same components.
Of course, I think it is going to very hard to find any of this now in the current situation across the world.
Take care and keep well.
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Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hi Ashley
Thank for your kind wishes. Keep away from harm.
The bad {technical} side is I measured the motor resistance and found 2.3 Ohm while on a similar motor on a Märklin larger engine (the 39241) it was 46 Ohms so the motor even if it runs is to be changed.
Take care
Jean |
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1 user liked this useful post by JohnjeanB
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Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hi Here is the last picture of the needed component  I need help to find these 8 pin SMD components marked UP 3A3 in red circle. Any information would be much appreciated Thanks Jran |
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 Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Hi
My opinion is that the best think is to buy a new decoder....
Costas
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Joined: 23/07/2014(UTC) Posts: 8,470 Location: ENGLAND, Didcot
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Originally Posted by: JohnjeanB
I need help to find these 8 pin SMD components marked UP 3A3 in red circle.
Any information would be much appreciated
Thanks
Jran
Hmm, as it appears (from your thread) that it drives the motor, my bet is that they are power MOSFETs, two to a chip, with the two chips making a full bridge configuration. As it appears there are two identical chips, then the two FETs inside will be opposite polarities. A quick search doesn't show any obvious candidates, and I suspect it may require a more investigative approach to the schematic to get a replacement.
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Joined: 15/02/2008(UTC) Posts: 693 Location: Bournemouth, Dorset
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Another option, if the Mosfets prove difficult or impossible to source, would be to leave the existing decoder in place for the sound effects, but fit a second basic decoder for motor control only. The wiring would need some thought, so that the motor is only connected to the motor outputs on the basic decoder, but both decoders need the track input. Probably best to get a simple wired 8 pin decoder, as there is no second socket.
The arrangement would be similar to using a non-sound loco with one of Marklin’s sound coaches that they produced a few years back. I have one, so I need to read up on how to get the two on the same address. Not easy with MFX. But everything is solvable with a little ingenuity.
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 Joined: 08/11/2005(UTC) Posts: 3,528 Location: Mullerup, 4200 Slagelse
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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. In case this is not legally possible: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.  |
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Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hi Costas, Alan, Ashley & forum friends
Thank you for your ideas:
@Costas: yes probably getting a new sound decoder and a new motor would be the safe way forward (not the cheapest nor a daring solution though
@Alan: finding a replacement for this component would be my preferred solution because I would learn 2 things: get a replacement for those power components that are likely to burn (also the rectifier bridge) and the other thing would be to get myself a SMD soldering system (SMD Lötstation) and learn how to use it. But so far no indication of the missing component.
@Ashley: yes it would be a great idea but there is no much room in my BR 58 to have an additional decoder (mLD3). Driving both in parallel would be made by creating a traction on my CS2 and Rocrail so there would be no problem there.
Stay away from harm & take care
Jean |
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Joined: 23/07/2014(UTC) Posts: 8,470 Location: ENGLAND, Didcot
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Originally Posted by: JohnjeanB ...and the other thing would be to get myself a SMD soldering system (SMD Lötstation) and learn how to use it. But so far no indication of the missing component.
One way to do this is to use a halogen lamp to heat all the pins at once, which is almost a necessity when removing components. There is a video on Youtube on doing this. You could then do the same to fit the new component.
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1 user liked this useful post by kiwiAlan
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 Joined: 11/07/2018(UTC) Posts: 217 Location: Aruba (general), Oranjestad
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Hello Jean Although this is an old post, i am curious to know if you were able to find the mosfet and repair this decoder? I bought myself one of those SMD rework soldering stations, and as i have a decoder where the same part shorted out, i want to try to repair it. I removed the old chip already (was easy to do with the heat gun), but was not able to identify the chip yet with the codes that are printed on it (UP2M3 in my case) so i can source a replacement....  Best regards Jean-Pierre
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Joined: 04/02/2011(UTC) Posts: 3,559 Location: Paris, France
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Hi Jean Pierre
The solution was found by Märklin: the loco 37589 being an insider model, it has a 5 years warranty and I used it, returning the loco to Göppingen thanks to my dealer in Paris (Au Pullman). They replaced the decoder, lubricate the loco and return it to me.
Replacing the SMD (Surface Mounted Devices) is feasible but require:
- to identify the component for a replacement
- to have an SMD soldering system with regulated (temperature and flow) air blower and a fine-tip, regulated temperature device
- a large magnifying lens with illumination
- a soldering paste for SMDs
- to take a picture before doing anything (orientation of circuits, etc).
Since, I don't have such a soldering system and being offered a repair for free I didn't hesitate one bit. Sorry.
Jean |
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1 user liked this useful post by JohnjeanB
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Joined: 11/07/2018(UTC) Posts: 217 Location: Aruba (general), Oranjestad
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For the tinkerers among us:
Well, i was able to resurrect the decoder with the blown chip on it!
I contacted M* for the spec's of the Mosfet, but they could or would not be of any help, the internet was of no use either in trying to determine the translation for code "UP 3A3"...
So the next best thing was to remove a good chip from another problem decoder and transplant it.... and with success! Decoder is as new again!
Regards
Jean-Pierre
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1 user liked this useful post by cintrans
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Fried Märklin Decoder of 37589 Loco- What is this component & how can I get it?
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