The LGB 55021 MTS (aka DCC) Decoder


LGB (Lehmann Gross Bahn) is one of the leading suppliers, and one might say the originator, of Large Scale garden railways as a product. They have a wide and well integrated range of products, including a full digital control system which they call MTS - Multi Train System (also known as MZS because of it's initials in German). While MTS is based on the Lenz-developed system since standardised as the NMRA DCC system, it still uses the original protocols and doesn't take much advantage of the newer facilities added more recently. Amongst the limitations of using the older technology are that it uses 14 speed steps (instead of the newer 28 and 128 standards), only supports two functions F0 (directional lights) and F1 (everything else), and can only address a maximum of 99 loco addresses.

However their current locomotive decoder product, the 55021 MTS Decoder, is actually well capable of handling all of the newer functions and only needs a small amount of reprogramming to make it work with newer DCC controllers from other manufacturers. This web page will outline some of the things I've discovered while trying to make my LGB MTS equiped locos (all using the 55021) work with a modern Lenz Controller. Of course, this is all based upon my personal experience, and your mileage may differ. Do be aware that using MTS equipment such as the 55021 with other equipment does officially invalidate any LGB warranty. I accept no responsibility for any damage following these instructions might cause. You have been warned.


LGB MTS decoders such as the 55021 have a slightly unusual way of configuring the higher numbered Configuration Values (CVs). These involve setting the register 6 to the CV number, and then setting the register 5 to the desired value for that CV.

Symptoms and Resolutions

Symptom CV Values Description
Headlights only work intermittantly CV29 0 (default)
6 (to solve)
When operating on a standard DCC controller, the loco moves normally but the directional lights (headlights) although enabled via Function 0 (F0) only come on intermittantly. When running on DC power, the loco works normally with the lights on at all times.

This appears to be a side effect of using 14-speed steps with a modern DCC controller - changing CV29 to 6 enables "Advanced Mode", ie 28 and 128 speed step modes and "Dual Mode" - ie both DCC and DC operation is allowed.

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