I just came across this tonight. I’ve got two engines with the soundtraxx LC decoders in them. When I first apply power to the layout with only one engine on the track, the diesel sounds normal. As soon as I apply the horn or bell or move the engine with the throttle a distinctive hum emits from the speaker. When the engine is stopped and is sitting idle, the hum is noticably there and does not go away. This happens to both engines when placed at different times on the track ( not at the same time). Very strange…I’ve had these engines fitted now for a few weeks and have not observed this problem before. When I remove the engine from the track and then place it on the track again, the hum is gone with it just idly sitting there with the sound of the engine purring. Only after I apply power or ring the bell or horn does it come back.
Anyone have any ideas? I’m using an NCE powercab for the controller. Like I say, it just appeared tonight out of no-where, two different engines, same decoder manufacturer.
I’m not familiar (at all) with how to wire these things, although I have inadvertantly miswired speakers in other applications, and have blown them out…
also happens if the volume is way too high for the speaker…
It could be that for some reason the decoder is not completely powering down the motor circuit after it starts taking commands. A low amount of power to the motor, not enough to make it turn, can cause a humming sound. I dont remember if you can turn the sound off on those decoders, but if you can, turn the sound off and see if you still hear the hum. If you do, feel the loco as it might be slightly vibrating. The only thing I can think of right now is to do a reset on the decoder.
I agree with reseting to factory settings. I think you will find that one of your CVs is set so that your motor is still getting voltage when the throttle is at zero. That would be CV #2. In fact, set CV 2 to a value of 24 and see if it still does it. If it seems to have cured it, then add 4 to the last value for CV 2 and enter that value to the CV. Turn your throttle to speed step one, and that is the point at which your loco should begin a very slow crawl. Does it growl or hum at that speed? Then you have a decoder that needs to have the pulse width modulation changed, and you will have instructions on how to do that with your decoder manual.
I had a Soundtraxx DSD 100LC in a P2K USRA 0-6-0 that growl something fierce on roll-out, but it got a fair bit quieter once it was up to a scale speed of 20 mph. I could never get the growl to go away completely, no matter how many times I tweeked the CV value for PWM.
I’ll try playing with the CV’s, although I’m not sure why it would change in 4 weeks. When I kill the sound (8 on the decoder) the hum disappears. It is only apparent when the decoder audio is ON and ONLY after the decoder receives a horn or bell command, or after the diesel moves slightly.
The only thing I can remember last night is I changed the short address to a long address on both engines. That shouldn’t change anything, but who knows?
I found it! I inadvertantly pressed the function 4 key which is the “dynamic brake” sound in the soundtraxx decoders. I couldn’t figure out why there was a “4” lit up in the LCD display. So the brake sound was ON all the time. It sounds like an audio hum.
Geeeesh…some experts you guys are…helping the helpless[:D]
Whew! Good thing your brakes lines weren’t pressurized. You could have ground down those metal wheels to a nub. [:O] Don’t you just love those easy fixes? [:)]
So far I like the layout you designed for me. All I’ve got is the turntable to wire and I’ll be done with wiring. I wish I had more room for more industries…but I simply wanted to “run” trains and with limited space of only 11X7 and around the wall shelf layout, it is what it is. Someday I’ll get approval to move into the rest of the rec. room, but until then, I’ll be happy with what I’ve got. I plan on perfecting my scenery skills and really doing some detailed building.
What really makes the layout come alive is the addition of DCC. I’ve got two locos that I installed sound into and they add a dimension of reality that I simply could not have gotten in DC.