You will need to try and locate the source of the noise. If something is humming then narrow down the location with your ear then by touching each component in the area try and locate source of the vibration. A stethoscope would be handy in this process but you should be able to feel whatever is vibrating by hand. If you find an electrical component buzzing, disconnect it and see if the noise stops.
Let me know what you find.
Saturday, July 27th, 2019 AT 12:21 PM (Merged)