LGB Decoders & Sound Boards Overview: This page is just some collected information on LGB decoders 55021 older LGB decoders (55021 and 55027) do have standard features and have manuals. The onboard decoder does have standard connections but cv's are preprogrammed differently. CV 106 is the number for the factory load on these decoders. 73 - small single motor porters are 129 - Unitah mallet, and Coke Mogul, and most American steamers with the 2 motor board 146 - American trolley and F7, and most American 2 motor diesels148 - Track cleaner loco 55027 LGB sound board. model 20252 part number 8.837010.1 ME101045