I'm in the process of adding a Märklin sound decoder to my older 3032 (BR 81) and ran into a problem that I like to share. I have added ball bearings to the motor before and had tested it with a normal DC power pack just to be sure that the motor was operating correctly. After installing the decoder I went to do a test run and all the functions would work but the engine would not move in either direction. I then re-checked the motor and it ran fine.
I then thought to check the motor by connecting the leads to the chokes instead of directly to the brush brackets and the motor wouldn't run. So I checked each choke individually and found that one was indeed not allowing any current to pass through. I replaced the defective choke and the engine is running fine now.

Something to consider if anyone here runs into a similar problem.

Chuck

Probably something to do with living Down Under....

Yes it is annoying when a choke is faulty, lucky you've found the problem in no time with me it took a bit longer before realizing it and as Adrian mentioned age has something to do with it, not the age of the loco but the mechanic who is working on it. some of the steam locos it takes a while to undo all the screws to take off the boiler and yes its the brushes I've forgot to insert or it also happened the slider.

John

When I initially had this problem, the first thing I thought that I had forgot to install the brushes but then since I had also upgraded the motor to ball bearings and had tested it out, I knew that wasn't the problem. But yea, forgetting to install the brushes is a classic faux pa.

As to which color wire, the blue or the green wire to install on the brush bracket of the DCM, I've found that the green wire should almost always be soldered to the brush bracket closest to the front of the engine. I remember this by thinking blue to the back as both words in English begin with "b".

Chuck

I don't think it is stupidity as much as good old fashioned wool gathering. It is hard to stay focused on a repetitive task and IMO anyone who says they have never left out the brushes is lying. I seem to have about a 50% success rate on brush replacement, which really is pretty lame when you think of it.

Oh well, I get there in the end.

Excuse my ignorance...... Just what is a choke????.....
Joe M
Cape Town

These chokes/inductors (sometimes mistaken as resistors since they look similar) are there to suppress higher frequencies to & from the Märklin motors which might cause "radio disturbances" from the motor but also to protect the decoder from sudden voltage spikes from the motor. This is not so needed with high-revving Maxxon DC motors used nowadays in many newer models, but the Märklin FCM/DCM motors (rotating 3-pole, 5-pole) need it.

These chokes/inductors are mounted to the motor feed leads, see this picture by member intruder (RIP) for a clear view of it.