Revisiting Bachmann Spectrum DCC Ready Locos

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Bachmann Spectrum DCC ready locos require some modification to run properly on DCC.

Many locos in the Bachmann Spectrum line have been released DCC ready with the NMRA plug or other terminations making DCC installation simpler. There have been constant problems with the DCC ready circuit boards in these locos because Bachmann in order to meet international and European specifications requires a type of filtering that effects DCC performance.

Generally there are capacitors, resistors and the like being used for filtering, that interfere with DCC ops. These can be removed. The following examples give you specific info:

(used with permission, Audie C. Bell)

The Bachmann Spectrum Series is still having problems with those pain in locomotive circuit boards being professed to be DCC Ready. To date, I have been required to remove these boards from their 2-8-0, 4-6-0, 3 truck Shay, 4-8-2 and NW-J5 4-8-4 engines to fully operate as DCC. After giving this company the benefit of Doubt, I again tried to install a DCC decoder in the last engine I bought. Below is the letter and check I am now sending to Digitrax to correct another Bachmann design Flaw. Here is the Picture of the Flawed Part?

The Digitrax DN-121 in question was being used in a Bachmann Spectrum GE-44 Ton Locomotive. This was one of their new units that are reportedly DCC ready. When after about a week of running (Combined time) it started acting strange. The combined units (DN-121 & Loco) started running Jerky, both in forward & reverse. After cleaning wheels and track the setup continued running in this jerky mode. I changed over to analog mode and the unit would run only in reverse, and no lights. Removed the DN-121 and tried testing the DN-121 using my test box, which has no wheels or Chassis s to short out. Same results, the decoder would only run in reverse mode and didn't respond to program changes. Opened the Red/Orange cover and see no indications of burnt. Leaving the shell off the engine (Spectrum GE-44 ton) I wired in a New DH-123 to Bachmann's DCC ready board and it to started running Jerky, only now as it would run forward the lights would blink on & off as the loco made the short distance on my program track (32"). I took the DCC board out and checked all points in the Chassis and motor, for grounds or shorts using a Fluke Meter. None found. I then tested the Bachmann DCC Board using a spare Athearn motor and Power pack, which is when I found the Shorting problem. By Chance or Coincident the two Wire Wrapped Resistors/components will touch each other when the decoder is installed and closed within the shell causing a short between the resistors and DCC connection soldier points.

Used with permission, Train Control Systems.

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