I bought a Bachmann diesel locomative recently. The seller told me he had installed an MRC sound decoder in it. When I got home, I put it on my program track to read the address that had been assigned to it. I then placed it on the main, called up the address on my throttle, and it came to life. However, I could not find which F function mutes the sound. I went to MRC's website, but failed to find the information that I was seeking. I'm sorry to say that I don't know what MRC decoder model it is, but any help would be appreciated.