Warning: When I plugged a nice Lenz silver decoder into my infamous RTR HO MDC 2 truck shay, the center of the main chip on the decoder became red and produced a small column of smoke and a nasty smell turning the decoder into an expensive and short lived smoke generator.
I checked the NMRA plug and pins 1 & 8 were reversed, so pin 1 went to the right rail instead of motor right, and pin 8 went motor right instead of to the right rail. This is a sure way to toast a decoder.
Luckily, Bruce at Litchfield Station was able to replace the decoder under warranty; otherwise, I’d be out about $30.
I say infamous because this is the model that, under DC, the motor would go but the wheels would not because all 4 wheel axle gears were split, DOA from the box. I bought a NWSL axle and bull gear replacement kits for about $40. The unit ran tight and I have not broken it in more than 30 minutes each direction.
So, now I will fix the reversed wires and try the new decoder.
Please check your MDC shay if you want to convert it to DCC!
The Shays have not been produced since MDC was sold to Athearn/Horizon Hobby. The semi-skilled Chinese labor used to assemble the RTR Shays didn’t have top quality parts (like gears) to begin with, and certainly hadn’t learned the “tricks” the kit builders had to to make the MDC Shay into a decent running model. Very few of the MDC RTR Shays run well out of the box, and if they do, they often don’t for long.
Without a doubt, re-engineering the mechanism while keeping a reasonable price point is what is preventing Horizon/Athearn from re-issuing the Shay. I’m sure it would sell well again if the mechanism problems could be fixed and a reasonable price point met.
The Roundhouse parts are available from Athearn, but only by part number. But in the case of the Shay (and Climax and Boxcab Diesel which shared similar drive trains), you are generally better off using a regear kit from NWSL.
There are obviously different versions of this puppy floating around. The one I bought when they were first released several years ago had to have the decoder hard wired into it. My big complaint with it was the high-pitched whine the gearing made and the too bright headlight.
