I have 3 MDC locos with 8 pin plugs for DCC decoders. I have installed several different brands of decoders , some have experienced catastrophic failures while others just failed to work. I have successfully modified other locos to DCC. Has anyone experienced the problem with MDC locos?
Which MDC locos are these? The only ones I was aware of that came with the 8 pin socket already in them were the Critters, and these have a known flaw int he circuit board that will destroy the function outputs of a decoder that is just plugged in. The stock diodes for the directional headlights are installed backwards and will short the decoder’s function outputs. There is a good picture of how to fix this on the TCS web site.
If this is some other MDC loco - blowing of the decoders generally means the motor is not properly isolated, or some manner of movement is allowing say the frame to contact the motor frame, assuming the loco frame is grounded to one wheel. Either a loose wire or incomplete insulation between the motor and the frame.
–Randy
Randy,
Thanks for the quick reply. The MDC Critter works great with the Lenz decoder. The 3 troublemakers are an old-time 2-8-0 and two 2-truck shays. When I put the jumper plug back in they work fine on DC.
Larry
It must be a short between the motor and the frame. This would allow it to run fine on DC but kill a decoder. I think you need to do some exploratory surgery.
Joe,
You are probably right about the exploratory surgery. It must be poor engineering to have the same symptoms on all 3 locos. I will put it back on my to-do list. Thanks.
Larry
I have two MDC shays,A slight mod is needed you have to isolate the motor from the frame,I replaced my open frame motors with can motors,they both are DCC now and run fine.
JIM
Jim,
Did your shays come equiped with the 8-pin plug from the factory? The 3 locos that area giving me problems did.
Thanks, Larry