decoders & Riverossi cab-forward : LUSENET : Wiring for DCC : One Thread

My cab-forward has a Lenz decoder. It also had a MRC preveosly(torched it). It wont run unless I lift it off of the tracks to get the drivers up to a full head of steam. No pun intended. The motor will not start the without help. The motor on its' own does not seem to be binding. Turning the flywheel by hand seems to be very easy. Any suggestions? Jeff Steuer

-- Geoffrey(Jeff) Steuer (, July 13, 2001


It's hard to tell without seeing the loco. It could be any number of things. You say your torched the MRC decoder (darn, I'd like to haven seen that!) Seriously, could you have damaged the motor at that time? Does it have an odor to it?

Rule #1 of electronics ESPECIALLY applies to motors - if you let the smoke out, they don't work any more. If you damaged the motor, that is truly it. You will have to replace it.

You say the motor doesn't bind, but what about the rest of the drive mechanism. Does it turn freely, too?

If anyone else wants to jump in with ideas on this one, feel free.

-- Allan Gartner (, July 13, 2001.

I agree with Allan. Test the motor by disconnecting the motor wires from the existing decoder and applying 6Vdc from a known source - like a lantern battery. It should run at ~1/2 maximum speed. Cause wheel drag with your finger on a driving wheel. If it does not run, or seems to draw too much current, the internal wires are broken or the internal magnets are damaged. In either case the motor needs to be replaced.


-- Don Vollrath (, July 15, 2001.

I would suggest disconnection the decoder leads from the motor and connecting a DC supply directly to the motor to see if the motor is okay, it should pull about 1/4 to 1/2 Amp no-load and start turning over at about 1.5 VDC. Another thing to look at is that the weighted "frame" is hot from one side of the track, so you could have a possible short going on. I just installed a Digitrax DH-121 into a Cab-Forward (newer design) and have found that it would benefit from better electrical pick-up. Any ideas for modifying the lead truck for dual pick-up? It looks tough because of the metal weight. For those who haven't seen one the leading truck and front engine pick-up power from one rail and the rear engine and trailing truck picks up power from the other (no pick-up from the tender).

-- Gary Cook (, July 20, 2001.

One field of the armature could have shorted turns. If this is so, the motor does not want to run oast this segment. The Motor has to be rewound or replaced.

-- John O, Malley (, June 24, 2002.

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