Peavey 6505+ Head (USA Made) Loud Humming Noise

[Charvel1975]

Hello, my 6505+ recently started getting an annoying loud hum on the Lead channel, any idea what might be causing this?

 

[japetus]

Start with preamp tubes. Check v1 and so on.

 

[glpg80]

Spray some contact cleaner on the effects loop and input jacks and plug in/out a trs connector a dozen times.

Check the preamp tubes.

Is the hum low frequency 60Hz or higher pitched 120Hz?