I've got a Valvestate S80 8240 which has developed a loud hum whether instrument plugged or not.
The hum disappears when it is tilted forward. Can anyone suggest a home fix?
I put up this question before but for some reason it seems to have been deleted!
Regarding your 8240, the way you have described the fault would suggest there is a fault in the smoothing capacitors in the power supply, we would recommend that you have it looked at by a qualified engineer.