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DCC Gotcha for HO MDC two truck shay

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  • Member since
    April 2003
  • 305,206 posts
DCC Gotcha for HO MDC two truck shay
Posted by Anonymous on Saturday, March 22, 2008 9:24 PM

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! 

  • Member since
    November 2002
  • From: Colorado
  • 3,990 posts
Posted by fwright on Saturday, March 22, 2008 9:57 PM
 davidmbedard wrote:

Thanks for the heads up.  Perhaps a letter to Athearn might fix this issue (I wonder if they know of the issue).

David B


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. 

just my thoughts, yours may differ

Fred W 

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Saturday, March 22, 2008 10:54 PM
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.
  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Sunday, March 23, 2008 10:36 AM

Here is a link to the new Roundhouse site.

All the MDC parts where old of. The below link still has some of the parts.

NWSL link.

I have a older MDC Climax which has a similar drive I believe. It has been completely rebuilt into a much quieter running Climax.

The motor is held in place with liquid nails. The tape hides the wiring from the trucks and decoder.

The can motor is from ebay, the new gear and flywheel from NWSL. The larger than normal gear results in a slower running motor, thus less noise.



If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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