Blue flash. Dark tubes.

[dogboy131]

I had a triple recto delivered yesterday and when I switched it on, there was a blue flash from within the chasis, and an electrical burning smell. Not the smell of burned plastic but "that" smell.

I looked at the back and one of the tubes, was dead (not hot) and there was not much volume.

There were 4 new Sovtek 5811 that were glowing fine, the rest (JJ) were not looking so good.

There were HUGE drops in volume when flicking the switching from vintage to raw, but the modern switch seemed fine.

There was a mix of Mesa, Sovtel and JJ power tubes in there. I was playing it at half power.

My first move tells me to buy a quartet of sovteks to match the ones that are glowing normaly in the back.

Goo move or should I go amp tech?

And what tube dealers know how to match tubes for Mesa Rectos fixed bias?

 

[jay]

SOUNDS LIKE A TUBE. IF ONE IS NOT GLOWING COULD BE THE PROBLEM. I BOUGHT A MARK IIC+ AND HE SHIPPED THE TUBES IN THE SOCKETS AND WHEN I TURNED IT ON IT SOUNDED OK THEN I COULD SMELL SOMETHING OVERHEATING AND SAW A POWER TUBE BURNING BRIGHT RED AND IT BLEW A FUSE BEFORE I COULD TURN IT OFF. SHIPPING THE TUBES IS HARD ON THEM, ALOT OF VIBRATION. I KNOW OF TUBE FAILURE HAPPENING RIGHT AFTER THE AMP BEING SHIPPED IF THE TUBES WERE LEFT IN. WERE YOUR TUBES LEFT IN THE SOCKETS WHEN SHIPPED?
JAY

 

[dogboy131]

They were packed okay. Inside the amp but in boxes or wrapped in bubble wrap.

I suppose I will change out the power tubes that are dead/dark/cold etc.

 

[stokes]

Dont just change the tubes that are dead,change the power tubes in matched sets.I believe KCA can sell you tubes that will fit your amps bias range,also Eurotubes.