Kato SD90MAC noisy with DCC

[Anonymous]

I have just recently converted my layout from DC to DCC control, (Digitrax Zypher) and I love it! But there is one thing that is bothering me. One of my locomotives is a UP Kato SD90/43MAC. I have installed a Digitrax DH163P decoder in it and it runs fine, except that it makes A LOT more noise when running than it did when I was just using a regular DC power pack. Is there anything I can do about this? If someone knows of a good fix please let me know! Thanks

[Jacktal]

Do you have another loco which uses the same decoder?If yes,I suggest that you interchange them to see.What's the noise like?If it's like the sound of a DC loco when running on a DCC layout,I'd suspect a defective decoder that allows some AC current to reach the motor.Is it possible?I can't really tell but I feel this is the only reason why your loco could be noisier than on DC.

[rrinker]

Get copy of the full decoder manual from the Digitrax site (PDF file). You probably need to fiddle with the CV that controls the SuperSonic drive frequency, as the default frequency probably causes a resonation in the motor, making it noisy. I'm not sure of the exact CV nad valid values off the top of my head, but it does make a difference - I was altering it on one of my P2K GP-7's and depending on the setting I picked, the motor was incredibly noisy.

--Randy

[Dayliner]

I have had exactly the same problem with my N scale Kato RDC after I installed a DN122K2 decoder. I haven't been able to fix it yet, but rrinker's diagnosis sounds pretty good to me. "Resonation" is exactly the word to describe the sound. I will fiddle around and report back.

Thanks for the tip Randy.

[Anonymous]

Hey, guys thanks for all the ideas, but I Think the problem is fixed. I had to do a "Reset all CVs back to Factory Default" on the decoder for an unrelated problem, and now the engine runs much quieter! Not sure how or why, but it seemed to fix the problem! Again, thanks for your help. Now I have to get back to reprogramming my speed table for this unit again!! What a pain, but oh well, what can you do!!! ;-)