Annoying hum with MTH protosound 1.0 and Lionel BW-80 transformer

[Anonymous]

Hello, I recently purchased a new MTH Railking loco w/ protosound 1.0 to use with my existing layout and Lionel BW-80 transformer. The new engine seems to work properly as per the user manual, however there is an annoying hum or buzz noise when the throttle is above 3 VAC. I did some basic checks with a multimeter and discovered that above 3VAC threshold, there is an accompanying DC signal that goes above 1/2 volt. At that point the engine makes an audible click sound and the hum is introduced. When I lower the throttle below 3VAC, there is another click when the hum stops.

I was wondering if anyone might know what was causing this annoying symptom, and how to get rid of it. The BW-80 is not on the MTH compatible transformer list, so I'm wondering if I may be faced with needing a new transformer.

Any info or help you can provide is greatly appreciated.

Thanks,
Steve

[spankybird]

Hi Steve,

Welcome to the CTT forum


Are you hearing the clink noise when in neutral or also in forward and reverse. If it is in neutral and you are increasing and decreasing the voltage, you are entering into a reset mode.

You are correct, MTH does not recommend the BW80 and CW80 transformer as it uses what is known as a chop sine wave. MTH likes a pure full sine wave.

BTW – if your engine is a PS1, it may be new to you and never run, but it was made before 2000, (1999 or before). Did you replace the battery? It should be at that age.

tom

[Anonymous]

Hi Tom, Thanks for your quick reply! Yes, first thing I did before I ran the new engine is put in a new fully charged battery (as well as perform the recommended initial lube.) The sound that preceeds the hum is more of a click, not a clink, and it is audible when the train is running as well as in neutral. I suspect the BW-80 is sending some sort of unwanted signal to the engine and that I may need to spring for a new transformer.

Thanks again,
Steve