Hi to all
I bought recently a Märklin 3111 Class 59 Of the SNCB. Production year 1982.
The loco is in excellent condition

Inside there is a LFCM motor. These motors in the S 3/6 variants and others like 3089 etc can be converted with the 60944 set, but after that the body does not fit, and needed special modification.
Märklin manuals don't include these locos to the list that can be converted with Märklin kits.
The other solution is the use of a permanent magnet and LokPilot decoder (ESU kits) but again the motor remains a 3pole with variant results and a lot of calibration needed for acceptable performance.
This solution requires knowledge of the decoders and access to a control station that can change CV values etc.

Two months ago Märklin put in the market a new decoder that is for conversion of old locos with Alstrom motors, either SFCM, LFCM or DCM.
The decoder is the 60906, and of course I have receive a couple them, but I haven't try so far.
So I decided to give the 60906 a try....
The target is mfx decoder, LED lights, front and cabin, smoke generator. (I din't put any lights on the tender because I like the tender as it is with the red imitation of lights.
Inside the box there is the decoder the base and a screw:

The decoder itself is quite large with the various cables soldered on the decoder PCB with Märklin color code

Is a 2 side PCB but with components only on the one side.

The manual gives all the informations that you need for the conversion.
First step is to strip down the loco.
Everything is OK except that the previous owner used liters of oil, and generally the transmission was a bit stiff, something normal for a 37 years old loco without any service.

I clean everything with isopropyl alcohol, and after careful oiling everything was smooth an nice

The motor had work very little and after a good cleaning is like new.

Then the motor parts put together, I removed all the capacitors except the one between the two brush plates.

Decoder base in place the space is enough.

I removed all the cables witch I don't need (violet, yellow) and put the decoder on the base and did the soldering work.

The two SMD resistors for the LED's on a small vero glued behind the decoder

The loco after the installation of the decoder

The cabin light is a 805 size WW led on a small vero glued on the roof of the cabin, and the wires pass through a 1,5 mm hole drilled in the side of the cabin and is no vissible at all.

The final look with the cabin light cables soldered, smoke generator No 20 in place

Close the loco and test track....
The CS3 recognized the new mfx decoder
The lights working nice.
Start: In 1 on the speedometer, the motor does noise ( the well known one of the Alstrom motors) but the loco starts to move!!!
With the speed up about to 10 the noise disappears and the loco runs very smooth (runs smooth from the start). In higher speeds no any problem!!!
I did a small video and I will post it later.
The decoder is very good.
Is NOT just an mfx version of the 6080!!!
Of course the motor has a lot of limitations.
For most of the users the most importad is: mfx with all the controllers that support the protocol. (works fine with MS2)
No need for calibration.
Easy installation (if you don't put LED's the installation is half an Hour job)
Of course no control of the motor, noise.
I have to look in the configuration to see if can do any better but needs a lot of time.
Conclusion: An easy cheap way to convert old locos in mfx digital with 2 functions plus the lights
I think that I will use it in locos if the conversion to 5 pole motors is not easy.
No need to use it in DCM motors or SFCM and LFCM if the conversion with the other kits is possible.
There is no any comparison.
Except if the cost is the reason.
So now the good news are: MäRKLIN HAS SOLUTIONS TO CONVERT ALL THE LOCOMOTIVES IN mfx
Open the old boxes take a screw driver and a soldering iron and GO ON!!!!
Regards
Costas