HL-R6178W making a loud humming noise

[mweissinger]

our HL-R6178W is making a loud humming noise - it sounds like it is cycling up and down - kind of like when your internal computer hard drive starts to die... anyone have a clue what this is?

 

[soundguruman]

does it hum when the cable tv is disconnected?
Probably a bad power supply?