Problem w/ a dual rectifier two channel (help)

[Gibbyage]

I just got this head in a trade from a guy on this board.

Amped worked fine for the first day. I jammed on it for maybe an hour. Never got it to crank since it was late at night.

So today was gonna be the first practice with it with the whole band.

The amp started making a crackling noise and kept doing it. Then the amp had no power what so ever!

Took the fuse out and it was blown.

Bought the same exact fuse and put it in. And it blew also!

Any ideas? BTW I put in brand new el34's and the 5u4gb tubes are less than a year old and the pre amp tubes are less than 6 months old.

I'm gonna take it into the local amp guy and have him work on it. But I wanna sound like I know what the problem might be.

 

[electrickn]

I would start swapping out the power tubes first. Did you keep the old ones? Could be a few things. This is probably obvious, but did you switch the bias for 34's?

 

[Gibbyage]

Yeah I switched it in the back to el34. I'm gonna try putting back the 6l6's in and see if happens.

But when it did power on again with the new fuse I looked in the back and I guess one of the el34 tubes (mind you were brand new) was pretty much dead in color compared to the other ones.

 

[Gibbyage]

I put the 6l6's back in (which were working perfect in my other dual three channel I traded) and they lite up in the back. But I noticed one of the 5u4gb tubes wasn't lighting up nor was it warm like the other one.


Before I take it to the tech should I buy new 5u4gb tubes and install them?

All ideas are welcomed. The fuse hast blown with dead 5u4gb tube in. But I also have cranked it yet.

 

[R_ADKINS80]

Try pulling the rectifier tubes out and switching to silicon diode rectification....if it runs fun then it might be a dead rectifier tube.

 

[Gibbyage]

Try pulling the rectifier tubes out and switching to silicon diode rectification....if it runs fun then it might be a dead rectifier tube.

The amp worked without the 5u4gb tubes in it. So does this mean it was just the 5u4gb tubes?

 

[Jay22]

I would say so up front. Get some new rectifier tubes and see what happens. Hopefully nothing else is wrong behind the scenes. If the new rectifier tubes are in and the amp still doesnt work then take it to a tech but what you have described so far is right out of the manual which is referring to dead tubes...

 

[Gibbyage]

I would say so up front. Get some new rectifier tubes and see what happens. Hopefully nothing else is wrong behind the scenes. If the new rectifier tubes are in and the amp still doesnt work then take it to a tech but what you have described so far is right out of the manual which is referring to dead tubes...

Alright, thanks for the help!

 

[Gibbyage]

Retubed the amp and it still had some crackling noises.

Took it to the local amp repair guy to see whats a matter with it.

 

[Gibbyage]

It was a bad preamp tube. I changed everything except those since they looked good.

BUT!

When I set my head on my cab I still get the crackling noise! But when my head is off the cab theres no noise at all!!

I put my pedal board on top of my cab and got the same noise.

Any ideas why?