I recently installed the Quantum "plug and play" sound system in my beautiful K-27 locomotive. I have installed the NPN (radio shack#276-20 17) transistor per instructions. The sound starts up beautifully and the chuff's are perfectly timed. I find that as I slow down my locomotive the sound shuts off long before the locomotive stops. It have been told that the start up voltage required for the locomotive is different then that of the sound system. I am using my existing Aristo-Craft Train Engineer 10 amp power supply with the CRE-55473 controller. I also purchased and tried out the Quantum Engineer 28 button activator, (same problem either way). I also tried switching the train engineer from linear to P.W.C.,(same problem) Has any one else experienced similar conditions. I currently have 18 Bachmann Locomotives and have never had a problem with any of them before. I therefore assume that this condition is due to something that I did incorrectly. I had the transistor installed by a friend of mine that is an electrical engineer with experience in soldering delicate circuit boards.
I will give you my wild guess at this. My Quantum decoders all shut off the steam chuff when I decelerate the engine. The cutoff value is closed by the engineer and there will be no chuff sound as the engine is coasting to a stop. The key here would be, if you increase the the speed does the chuff return?? If it does then, it is right as far as I can see.
Hope this helps.
HO-Ron