Kapucheen

Hi icastle, there is a company within 5 miles that advertises on the web. £35 to open up and £25 an hour after that :-( Hence the attempt to solve first. Looks like I'll have to grt used to my tinnitus of the amp !

Understood gents. Thanks. I've tried the amp in 3 locations around the house, with and without plug boards, away from all things electrical, 5 different mains leads, 4 different buildings etc The earth wire inside the head looks fine. I disconnected the earth wire inside the head and put a fully earthed mains lead on. It hummed then touching the screw then had the same affect ie the hum disappeared. I'm stumped.

Hi all, I've just bought a second hand ABM 300w 1x15 combo. Mint condition. Sounds beautiful. But it has an intrusive hum with nothing plugged into it. I have undertaken all the checks possible and the only thing that stops the hum is when I used a mains lead without the earth wired up. It still hums, but disappears if I touch a screw on the VU meter, or the fan at the back, or the D.I. input. Anyone any suggestions as to what could be causing it? and the exam question...how to fix it? LOL Thanks in advance, Kap