Lonestar Classic.....What's Up???

[LSCMan]

Was out playing the LSC tonight, at the drummer's place, kinda like an informal jam type thing.
It was the first time cranking the new el34 Siemens tubes I got from Mesa a couple of weeks ago.

Everything was sounding awesome, the amp was just singing, like never before. Then we started noticing a smell, like burning plastic, coming from the vent holes in the back. It got fairly strong, we had to open up the doors and windows, and it was about 10 degrees out. It just kept on coming, too, even after we turned it off, and let it sit and cool off for a while.

Any y'all got a clue what might be going on? SOMETHING sure smells like it's burning. :shock:

The tubes didn't look abnormal in any way...

 

[Boogiebabies]

I would check the bias on the EL34's first. Then, if it was allright, I would pull the chassis and look for what might be causing the burning smell. I you can find it, I would call Mesa on Monday. If it is a real acrid, eay tearing smell it is usually the PCB. It could be the Siemens running hot and heating up the power board or the power amp circuit hot enough to melt something.

 

[Anonymous]

Post removed.

 

[LSCMan]

Well, I opened the thing up and looked around in there, didn't see anything that looked fried, but I didn't look underneath the circuit board...

on one of the tubes, the little plastic guide in the center of the pin ring broke off, and the glass underneath looks all melted

 

[cnumb44]

Are you talking abou the key that is on the large plastic pin in the middle of the tube? If so, that means that the tube might have been rotated the wrong way when you inserted it and that the wrong tube pins went into the wrong holes in the socket - so you could be sending voltage across the wrong part of the tube. If that's the case, you blew the tube.

I am surprised that the fuse didn't go. I blew a power tube a few weeks ago. I got a bit of that same smell, but the amp started to lose volume and then shut off. That was the slo-blo fuse saving the rest of the amp.

I was going to give you some hints on trouble shooting, but I think you are best to call Mesa first thing on Monday. While you are waiting, go to Radio Shack or an electronics store and get some replacement fuses. You may have a bad one in there and that may be one of the first things Mesa asks you to do while they help you work through it.

let us know what happens.

 

[LSCMan]

The tube wasn't rotated wrong, I took special care to put them in right, besides, you would have to try pretty hard to get one in with the key pointed wrong.

That tube is messed up, I hope it didn't **** up the amp, but it's brand new, so the warranty is good.

 

[boogiemon]

the one on the back panel that let's you select 6l6 or el34...

 

[LSCMan]

the one on the back panel that let's you select 6l6 or el34...

I changed it, but it had a bad relay from the factory.

 

[cnumb44]

Hate to be dense, but was the problem a bad switch to change from 6L6 to EL34 bias? Guess that would have done it. Hope they got you new tubes!

 

[LSCMan]

That's right cnumb, the bias switch relay was bad. Everything seems to be fixed now, but I went back to 6l6's in the Lonestar, like that fat bottom. They changed out a couple of burnt resistors and put in a new relay.

I tried those same el34's in my new Mojave and they work just fine.