I am having a problem with an MRC 1007 steam sound module in an older IHC steam loco that was not DCC ready. I isolated the existing wiring and tested with the jumper from a DCC ready steam loco and it ran fine. Installed the module and the engine will run forward but the motor only pulses in reverse. If I reverse the module connection it runs in reverse but only pulses in forward. This is on a MRC 2500, 16.5 volt, power pack. If I change to a MRC 55 handheld unit (max output 12.5 volts) from a straight 16 volt DC power supply the loco runs in forward and reverse but at a slow speed with no pulling power (It won’t make it up a 2.5% grade). I have a second MRC module in a DCC ready IHC steam loco which runs fine. If I swap out the modules between the locos the older unit does the same thing and the DCC ready runs fine.
OK, It sounds like it’s the older loco itself that’s the problem. ( both decoders work fine in the DCC ready loco, but both decoders run weird in the older non-DCC loco. Right??)
I would check your amperage draw on the motor. I would also check to see if you have some kind of short in the wiring on the loco. A pinched wire maybe? Motor might be going bad??
Make sure all your solder connections are OK.
Dirty wheels can give a decoder trouble. Does it run OK on DC?
Thanks for the reply. Yes the loco runs fine with the module removed and a jumper installed. I rewired all the connections between the loco and the plug and cleaned the wheels with no change. It runs in both directions on a MRC 55 hand held cab control with a max output of 12.5 volts and 0.8 amps but is slow with no pulling power. On the MRC 2500 with 16 volts and 1.5 amps it runs faster in forward only and with very little pulling power. When I try to reverse it on the MRC 2500 all it does is pulse the motor and emit idle and break squeal sounds. I do not have a working amp meter and it has been many many years since I worked on an electrical project. I called MRC and IHC about the problem and they both said it was the other guys. They would not express any possible remedies. The unit sound great in the DCC ready IHC loco that I have and I would like to resolve this problem with the older loco.
I had a similar problem with an older IHC engine and it was caused by a bad motor.
the motor doesn’t by any chance have a capacitor wired across it?(one or more orange round or square disks) if it does, there’s your problem.
I want to thank all that have replied. I finally gave up on the MRC modules. I totally rewired the loco, checked the motor, cleaned the wheels and it ran fine with very little amp draw under load. As soon as I installed the MRC module the amp draw went considerably up and the problems returned. I think the problem is with the modules. They would be OK for a childs layout that is basically flat with short trains. This experience has definately turned me off on MRC modules. I will just stay with soundless locos, except for any that I may purchase that already have factory sound modules, as I have been for over the past 40 years.