davidl Posted December 25, 2011 Share Posted December 25, 2011 Hi folks. Merry Christmas first off. I discovered that one of my amps was left on for 3 days. My stuff is in a building separate from the house so didn't notice. My wife went into the building yesterday and heard a loud constant hum. I checked it out and yup, loud and disturbing. I'm guessing tube damage. Anyone else been this stupid before? How do I tell which tubes are done? I know, I should know this stuff already but I don't mess around with my amps and never had any difficulty before. At least it isn't my Marshall, which I intend to use today with my new original Cry Baby Wah. Have a fantastic day everyone. Dave Link to comment Share on other sites More sharing options...
Jeff-7 Posted December 25, 2011 Share Posted December 25, 2011 You probably had a tube burnout, easiest way I've found is black residue inside the tube similar to an incandescent burning out. Other than that you can trial and error a new tube into the sockets until you find the bad one. Link to comment Share on other sites More sharing options...
badbluesplayer Posted December 25, 2011 Share Posted December 25, 2011 You can get a pencil with an eraser on it and tap each tube lightly with the eraser end of the pencil and see if the amp makes a noise or makes the hum worse or better when you tap any of the tubes. If so, then that particular tube is probably the one that's giving you trouble. Then you can start by replacing that tube and see if that solves the problem. Link to comment Share on other sites More sharing options...
milod Posted December 25, 2011 Share Posted December 25, 2011 I think Moishe has a good point on the amp. Other possibilities: Is there an instrument cord possibly getting some crossover so it's actually giving input to the amp? What's the polarity and does switching the polarity switch drop the hum? Also is the building well-grounded because even a ss amp can hum mightily if not. m Link to comment Share on other sites More sharing options...
Bluemoon Posted December 25, 2011 Share Posted December 25, 2011 It was connected to a speaker, right? So it had a full load? If so, probably a tube. Link to comment Share on other sites More sharing options...
davidl Posted December 25, 2011 Author Share Posted December 25, 2011 It was connected to a speaker, right? So it had a full load? If so, probably a tube. It is a combo and was under full load with a piano plugged into it. The place is well grounded and that amp never made any unwanted noise before. I'll try the pencil trick as well as getting a real good physical look too. Thank everyone for your responses. Dave Link to comment Share on other sites More sharing options...
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