We have a new CS3 and all the auto registrations have gone perfectly until we put the E50 (39500) on the programming track. No activity at all. I've tried to manually register it on Address 50 without any luck. I've got the loco open and it looks absolutely perfect. Any suggestions what I might test for 'under the hood'?

Hi John
The 39500 is a 2007 digital E50 loco with a SDS (Soft Drive Sinus)motor and a sound module.
The first thing to check is that the power-source switch is set to rails and working.
The other thing to check is the slider and its connection to the loco.
Check very delicately that the SDS motor is connected to its platina (a lock/unlock connector) and that the cable has not been pulled away
Here is the exploded view of the central / Electronic part of the loco


The good and bad
- SDS motors are the best Märklin ever produced but alas cannot be replaced not its electronics with drivers
- the decoder (21 MTC interface) can be replaced by an mLD3 or an mSD3 for sounds BUT it must be programmed at least to change the motor type to a SINUS motor

Here are two electric Märklin locos of the exact same era (39401 and 26540 set) with an SDS motor and separate - simplified - sound module


Cheers
Jean

Hi John
"Could the decoder fails?" Yes it could have but other things may also be wrong.
I suggest to test the loco with AC power (from 6 to 14 VAC) and see if something happens (light, motor turning, etc). DO NOT try to reverse direction with an old Märklin transformer.
By testing using an mLD3 (60972) or mSD3 (60977) AND updating the motor type (CV 52=1 und CV 56 =0 and CV 51 =24 or =0 depending if AUX3 and AUX4 or logical or buffered.

If the test is negative, you may still use the decoder used for test for another loco.

Make sure FIRST that the power reaches the decoder (21MTC interface). Use a multimeter to check the continuity
Pin 21 connected to wheels
Pin 22 connected to slider


Cheers
Jean

That only makes sense if you disable mfx in the CS at the same time.
It is worth a try as with those old mfx decoders, often the "mfx sender" on the decoder fails and loco cannot register.
There is a (good) chance that the loco will work using MM protocol if mfx is disabled in the controller.

If it works, then you can check if motor and lights work fine - and then maybe order a new decoder.

johnhendry, you disable/enable protocalls in the syhstem settings menus. Go through and look at them to familiarize yourselve's with the system. As long as you don't click OK afterm you check a change, it won't change. Maybe order the newest CS3 big book. It has more detailed user guides.

Thank you, Jean. I'm going to go through each of these steps. I'll let you know.

Well, I sat down and got ready to go through every suggestion that you guys made but I started with this one, Eduard71. Turns out the slider was clicked into the wrong position and was not making any contact with the connector. It's moved the slider, put it on the programming track and it's running beautifully. You can't help stupid!! We now have every single loco running from my Dad's set (16) and we're starting the layout build. Thank you guys for all the help!!