10-05-2014, 05:46 PM
What Mondial said.
Also: Check your ground on the audio preamp, and wiggle the tube (27, isnt it?) , and also others, see if hum gets choppy or disapear when you do it. Also, just pick the chassis with both hnds while it is working (be careful not to touch inside or you will suffer painful/ lethl consequences) and flex it (it is thin) and see if the hum does the same, gets choppy or disappears.
This would point to a bad rivet or bad tube soket contact.
Also: Check your ground on the audio preamp, and wiggle the tube (27, isnt it?) , and also others, see if hum gets choppy or disapear when you do it. Also, just pick the chassis with both hnds while it is working (be careful not to touch inside or you will suffer painful/ lethl consequences) and flex it (it is thin) and see if the hum does the same, gets choppy or disappears.
This would point to a bad rivet or bad tube soket contact.
