Aw crap!!! MK III one 6L6 Glowing angry orange

[dmaneleven]

Shoot :evil: , I just got my MK III(simul/rev/geq) from the shop for a cap job , but now a few weeks later I noticed a strong tubey smell and a glow coming from the back of my amp. I thought it was on fire cause it reflected orange on the wall behind it. one 6l6 the outer tube closest to the input jack is like filled with lava!!! :shock:I swiched out for a pair of EL-34's but the same thing happened. It started with a crackling sound then the sound faded out . Is this a bias resistor gone bad? in any case it's back to the shop. Has new tubes too.

 

[zodiac272]

no need for a meltdown :shock: I'm sure it will be fine,like you said, probably just a resistor

scott

 

[Xtravigent]

hey lads, im glad i found this post too, my 60W iiC+ has literally suffered the same symptom. Intermittent problem, the first time it happened i just shut it down and didn't investigate, then it seemed to relieve itself.

I took the chassis out and fired it up, and prodded around the circuit board, just tapping (gently) different components. This bare bones method suggested it was power section related, as i had also connected the guitar into the recieve line, eliminating the pre amp. I was considering purchasing new power tubes, but then i thought i had better tighten up the tube sockets, incase of poor connection.

This seemed to rectify the problem for a short while, but within a week i had the exact same event mentioned above, witnessed a bright red tube on non transformer side (looking from back), the other tube was basically dead.

I too am convinced a resistor has basically shorted or open circuited, in an intermittent fashion, as tapping the unit can either induce or relieve the problem.

Can any of the tech guys on here help me locate which one it might be, or give us a method for which we can check ourselves? I have visually inspected all components for burn out ect., but i know this isnt enough!

any help would be appreciated, as i am from australia and cant easily get it back to the mesa boys!

thanks, Mason

 

[dodger916]

hey lads, im glad i found this post too, my 60W iiC+ has literally suffered the same symptom. Intermittent problem, the first time it happened i just shut it down and didn't investigate, then it seemed to relieve itself.

I took the chassis out and fired it up, and prodded around the circuit board, just tapping (gently) different components. This bare bones method suggested it was power section related, as i had also connected the guitar into the recieve line, eliminating the pre amp. I was considering purchasing new power tubes, but then i thought i had better tighten up the tube sockets, incase of poor connection.

This seemed to rectify the problem for a short while, but within a week i had the exact same event mentioned above, witnessed a bright red tube on non transformer side (looking from back), the other tube was basically dead.

I too am convinced a resistor has basically shorted or open circuited, in an intermittent fashion, as tapping the unit can either induce or relieve the problem.

Can any of the tech guys on here help me locate which one it might be, or give us a method for which we can check ourselves? I have visually inspected all components for burn out ect., but i know this isnt enough!

any help would be appreciated, as i am from australia and cant easily get it back to the mesa boys!

thanks, Mason

I hope you know what you're doing, because you could cook yourself. In fact, you could easily cook yourself with the power off if the supply caps are not properly drained.

 

[Xtravigent]

hey lads, im glad i found this post too, my 60W iiC+ has literally suffered the same symptom. Intermittent problem, the first time it happened i just shut it down and didn't investigate, then it seemed to relieve itself.

I took the chassis out and fired it up, and prodded around the circuit board, just tapping (gently) different components. This bare bones method suggested it was power section related, as i had also connected the guitar into the recieve line, eliminating the pre amp. I was considering purchasing new power tubes, but then i thought i had better tighten up the tube sockets, incase of poor connection.

This seemed to rectify the problem for a short while, but within a week i had the exact same event mentioned above, witnessed a bright red tube on non transformer side (looking from back), the other tube was basically dead.

I too am convinced a resistor has basically shorted or open circuited, in an intermittent fashion, as tapping the unit can either induce or relieve the problem.

Can any of the tech guys on here help me locate which one it might be, or give us a method for which we can check ourselves? I have visually inspected all components for burn out ect., but i know this isnt enough!

any help would be appreciated, as i am from australia and cant easily get it back to the mesa boys!

thanks, Mason

I hope you know what you're doing, because you could cook yourself. In fact, you could easily cook yourself with the power off if the supply caps are not properly drained.

yeah mate, all good, im an electronic engineer by trade, done alot of 'poking around' high voltage stuff! had a few zaps through history i might add!

I have also read, since posting this, in the mesa handbook for a mark III, that a dying tube can also be the cause of this, any comments?