# My athearn is making a buzzing sound?



## poopversity (Dec 29, 2020)

It is a relatively new Athearn Ac4400 and it keeps making an annoying buzzing sound. The model runs perfectly fine at low speeds but usually when it make it faster it speeds up normally without any buzz then suddenly slows down and starts buzzing. Every once in a while I can make it run at a faster speed with no buzzing but it isn't very often. I've tried removing the shell, but it still makes the sound. Does anyone know how to fix this? I'm using a lionel controller with dc power and all my other locomotives run fine.


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## CTValleyRR (Jul 26, 2014)

It sounds like you are trying to run a DCC-only model with a DC powerpack. While most new DCC decoders are dual mode, IOW capable of running on either DC or DCC, some aren't, and almost all of the dual mode ones can have DC electronically disabled.

Check the packaging and manual that came with the loco and see if there is a decoder installed, and if so, the make and model.


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## poopversity (Dec 29, 2020)

I can’t find the manual but I searched up the model online and it simply says it has a soundtraxx decoder.


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## bewhole (Dec 31, 2016)

Just google Athearn Ac4400 buzzing and It brings up a lot of the same complaint using soundtraxx decoders.


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