Mesa Lonestar 23: Hum from behind the amp.

[Deneteus]

Hello I was wondering if any of you have encountered a Mesa Lonestar 23 10/50/100 that Hummed from behind the amp. It's a 2011.

It has EL34's in it. Guitar is connected. You can turn the fan off. Turn the Reverb down. It hums on all power settings. You can hear the hum through the speaker when you turn it all the way up. But not at lower volumes.

Yesterday I tried taking the 5GU4G rectifier tube out and using diode rectifier. Still the same issue. Tapping to tubes produce no audible sounds. I don't know anyone with a Lonestar 23 Head to compare it too.

Today I took the amp out and removed all the tubes and re-seated them. The hum sounded like it is coming from the transformer itself.

I have a sound sample posted here. http://snd.sc/HFkibq

Any info on where to start would be appreciated greatly.

 

[plan-x]

Ok, explain the noise going away? Were you flipping in/out of standby a couple of times? I hear what sounds like some static during the large sound wave portion, and it doesn't sound right. V1 or V2 might be acting up. Put a known good tube in those positions and see what happens.

 

[Deneteus]

I talked to Mesa this morning and they said the mounting bolts for the transformer may be loose. In the recording I was flipping the switch for the fan and diode rectifier and in an out of standby. That part at the end was the reverb. I had static too at one point. Upside down the amp is fine. I had to tighten a couple of loose bolts.

 

[plan-x]

So tightening the transformer(s) bolts did the trick?

 

[Deneteus]

Yes sir. Some of the bolts were loose. (Hand Tightened Loose) Marco at Mesa said that happens sometimes during shipping.