HELP!!! Problem with my Mesa Triple Rectifier!!!!

[obraskai]

Ok guys, I have something going on with my Triple Rec! My head was fine and then all of a sudden it started making this loud hum noise. I turned if off and back on and it was still doing it. If i strum the guitar it takes it away, but then comes right back. It is doing it on all 3 channels and without a guitar plugged in. A friend recommended that I test the tubes by turning the head on without a guitar plugged in and hooked to a cab and tap the tubes with a pencil to see if I got any crazy sounds. It was kinda wierd! Sometimes the tubes would make a thud sound when I tapped them and then sometimes they wouldn't make any noise at all. I tapped them all over and over for about 5 mins and one sec I would get a thud and the next second nothing... Then all of a sudden the 1st 3 power tubes lit up blue and the hum started. A few seconds later the blue went away and the hum stopped... I tapped all the tubes and a few times I got crazy feedback, but it wasn't consistent..... Any ideas????

I was told it was prob a rec tube or power tube going bad, or that there is something wrong in the Bias circuit in the 1st 3 power tubes...

PLEASE HELP!!!!

 

[some dude]

I'd guess there's an intermittent mechanical problem in the one tube that isn't going blue. Usually it means something inside the tube has come apart, which explains the intermittent thump sound. If you pull that tube from the amp and shake it you'll probably hear something rattle around inside it that sounds similar to a broken lightbulb.

The blue haze is the electrons flowing through the tubes. You're getting more blue when it hums because the amp is amplifying the hum. The tube that isn't going blue is probably not amplifying anything.

 

[obraskai]

Well, I have 6 power tubes and only 3 of them lit up blue. They normally don't glow blue. It was just a BAM they lit up blue and I heard the hum and the blue went away and it stopped... Only the 1st 3 lit up blue. And they are all having the intermittent thump sound... One second they have a thud sound and the next second nothing... I'm not losing signal when I have a guitar plugged in though... Just a hum. And the hum is intermittent as well...

 

[some dude]

Ah... I was thinking you had 4 power tubes for some reason.

Either way, I'd pull them and give them a shake. If only half of them light up I'd also check out the phase inverter.

You can eliminate the rectifier tubes by running the amp on diode. If you still get the thump, it's not the rectifier.

 

[obraskai]

I don't think it's a rectifier tube, because I use the Diode setting.

 

[mchn13]

Chris; its steve. Clean the sockets and reseat the tubes. If it doesn't help, I've got a set of mesa tubes at the house, and then it might be something internal...

 

[obraskai]

BUMP... Anyone every have any similar issues??? Any Ideas???

 

[fluff191]

I had a very similar problem with my dual Recto. It would hum and make lots of noise ONLY when nothing was plugged into the input. It turned out to be a bad V1 on one side.