Need help deciding what to do with my TMCC 6-28521 Southern Pacific RS-11. I picked it up online for cheap as a project. Out of the box, the sounds worked and the can motors were “twitching” in conventional mode but that’s about it. Nothing but sound in command mode. In command mode, the radio board wasn’t receiving a signal. I pulled the boards and inspected all wiring and connections. I noticed a motor wire was pinched by the rubber band around the can motor and rubbed through the insulation. This seems to be a reoccurring issue. I’ve seen this before and assume some loco’s have met their demise due to this usually overlooked problem and ultimately get parted out online. I corrected that and then reassembled the boards but left the DCDS board hanging loose from the chassis (this was critical in the diagnosis). This stopped the erratic motor twitching but still no radio board communication. The motors worked correctly in conventional mode. I had an identical R2LC from my TAS board project (found a tach reader btw and it’s working great) and swapped those and it worked! I noticed when I first removed the R2LC board, it didn’t have much resistance. It pressed on very easily too. I pulled the plastic 24 pin plug off of the original R2LC board and found a few misshapen prongs. I tightened them up and pressed the plastic plug back on and tested it. The original R2LC was back up and running in command mode. Smoke unit works, sounds work, but the motors didn’t have speed control. It was either full throttle at the first step or nothing. I started to think it was the DCDS so I looked at it more closely. The factory insulation pads between the transistors and heat sink had deteriorated or compressed over time and possibly allowed contact to ground therefore damaging the DCDS board. I’ve seen GRJ‘s response about the flywheel magnet issues in other posts and that can be a possibility too. But reattaching the heatsink to the chassis yields the initial problem, the motors twitch. So I’m left with the decision to either buy a factory DCDS board from Lionel or install an ERR Cruise Commander M for the same coin. Any suggestions?
Thanks,
Dan
