Re: Noisy Decoder

Some time ago someone posted instructions for eliminating the hum in a
> decoder by changing a CV. Now I have that problem too and don't recall
> which CV gets changed to what.
> Could that person, or some other knowledgable reader, help me with that
> information please?
> Thanks/Carter
CV9 controls the Pulse Width Modulation frequency of the motor drive.
On NCE SR series decoders setting CV9 to zero (0) will engage the
silent running feature. TCS decoders are set there as default. Other
decoders may need the CV set somewhere between 0 and 255 to get the
right effect. It seems to vary by loco, but a good starting point
seems to be a value for CV9 around 180, adjust the value by 10 until
you get close, then zero in on it from there. I recently installed a
Soundtraxx LC in a brass loco and it was quietest set at 214. You may
also might want to check your decoders manufacturers web site for more
info or downloadable manuals.
visit the FCSME at
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Karl Bond
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I talked to a guy at the LHS one night who had this problem with an Athearn loco remotored with the Athearn can motor. He said his CV9 worked best at 72 where the website recommended something like 120. Anything more than 74, he said, and the motor would wail like a banshee. Anything lower than 72, ditto.
I guess my point is the manuals make a starting point, but each motor slightly different, you need to zero in on each one individually.
Jay Modeling the North Shore & North Western C&NW/CNS&M in 1940-1955 E-mail is now open
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