Good day,
As I'm still trying to salvage this loco form the scrap yard I have asked Marklin support if I can replace the ESU 21 pin decoder with one of theirs, specifically I asked about 60972 DCC

Marklin replied that I can use it but, there are a few things to keep in mind:
1) you have to define this motor type in the programing of the motor.
2) that aux 3 and aux 4 has to be defined as a logical function.
3) that for Aux 3 you need a steady function for the direction forward and for Aux 4 a steady function for the direction backward.

The first request seems easy, find the correct CV and set the parameter for SDS. You have to do the same on ESU's
2) and 3) are weird. How can I define the AUX as logical functions and then set a steady function for both AUXs ? Maybe the translation from German is not the most appropriate.

I don't understand it, a bit too complex. Is it clear for you Marklinists ?

I know you can't have variable motor steps with SDS because it 'destroys' the motor or PCB. That is why you can only set Vmin and Vmax but not Vmid, so I have understood.

At the same time I'm in talks with SB-Modelbau to rip out the SDS motor and PCB and install a decent motor with a proper DCC decoder.

Obviously the price difference is huge.
Cheers
Marco

It was 39120 Marco talked about before.

Previous threads for that loco are at

https://www.marklin-user...3---39120---motor-issues

https://www.marklin-user...COS-station---loco-39120

well apart from involving a conversation on the same crap motor and electronic delivered by Marklin

kiwi you are right, let me explain. C-Sine motors + mfx decoders by ESU are a bad combination if you have an Ecos control unit. mainly when I tried changing decoder settings the loco driving characteristics went down the toilet and I had to reset the decoder. Same as with 39120 that you remembered.
I thought about using a ‘modern’ decoder by Marklin, hence this thread since I don't understand Marklin’s explanation.

I’m trying to sell this loco, it is spoiling the little fun I have left for trains, but nobody’s interested and if I can’t sell it I will have SB-Modellbau rip out the entrails and install something more decent to drive the loco.

What does logic function output mean? I've downloaded the decoder's manual but it still isn't clear. I will be using DCC and nothing else. The decoder already has Aux3 and 4 as logical outputs so what do they mean?
Thank you

Leif good afternoon,
I have an Ecos control Station. I will have to check the other DCC dedoders I have with Aux 3 and Aux 4 and see how they are setup prior to put them backwrds and forwards.
Thank you
Marco