I had just started playing my mark IV and it cut out all of a sudden. A mesa 6l6 with maybe 5 hours of play time on it had exploded. The top blew off of it and the fuse blew. Is this common? Could I have just received a bad tube? Should I replace them and try again or could something be wrong with my amp?
Just had a tube explode!!!
- Thread starter firmani99
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I've had a tube explode only once. It was in a 1980s Dean Markley (that had a reputation for eating tubes).
This is what I did:
(1) Inspected the back of the amp. I did not see any burn marks and nothing smelled "burnt".
(2) Took tubes out.
(3) Replaced fuse.
(4) Turned amp on, but left it in standby.
(5) Fuse did not blow, so I kept going.
(6) Replaced the tube pair.
(7) Powered up - left it in standby.
(8) The fuse still did not blow yet, so, took it out of standby and played.
If you do this and the fuse blows again at any point - I would stop and take it to a tech.
If you smell anything burning at any point - I would power down and take it to a tech.
The "keeping it in standby" may not be absolutely necessary. I was paranoid and did it just in case it mattered.
On mine, the fuse did blow, but all was okay with new tubes.
Hopefully your story will be the same.
This is what I did:
(1) Inspected the back of the amp. I did not see any burn marks and nothing smelled "burnt".
(2) Took tubes out.
(3) Replaced fuse.
(4) Turned amp on, but left it in standby.
(5) Fuse did not blow, so I kept going.
(6) Replaced the tube pair.
(7) Powered up - left it in standby.
(8) The fuse still did not blow yet, so, took it out of standby and played.
If you do this and the fuse blows again at any point - I would stop and take it to a tech.
If you smell anything burning at any point - I would power down and take it to a tech.
The "keeping it in standby" may not be absolutely necessary. I was paranoid and did it just in case it mattered.
On mine, the fuse did blow, but all was okay with new tubes.
Hopefully your story will be the same.
Poor glass could result in an implosion since it is under vacuum. Arcing at the base of the tube is also possible that may cause a weak spot in the tube. I bet is was a result of poor quality glass that could not take the heat cycle very well. Tubes generally do not explode unless there is a flaw in the bottle. Hopefully the fuse protected components that could be damaged by tube failure.
Were they JJ tubes? I have had issue with a quad of 6CA7 that only worked for 2 weeks then poof, they turned into arc welders literally (glass remained intact though but the internals were practically vaporized at the base below the first mica spacer). My Mark IV at them up (outer pair), the Mark V killed the first one. They may have sounded great for the short run but not worth the savings if it would lead to amplifier damage.
Were they JJ tubes? I have had issue with a quad of 6CA7 that only worked for 2 weeks then poof, they turned into arc welders literally (glass remained intact though but the internals were practically vaporized at the base below the first mica spacer). My Mark IV at them up (outer pair), the Mark V killed the first one. They may have sounded great for the short run but not worth the savings if it would lead to amplifier damage.
Old BF Shred
Well-known member
It usually does...that's its job.firmani99 said:
Pull the output tubes and see if it still blows a fuse when taken out of standby. If not, it's likely just a tube problem.
You can put the other tubes back in, one at a time, to see if it blows then. If so, then you got other bad tubes, but it is likely you had only one defect.
Mesa has a 6 month tube warranty. They should replace it, no problem.
Old BF Shred said:It usually does...that's its job.firmani99 said:
Pull the output tubes and see if it still blows a fuse when taken out of standby. If not, it's likely just a tube problem.
You can put the other tubes back in, one at a time, to see if it blows then. If so, then you got other bad tubes, but it is likely you had only one defect.
Mesa has a 6 month tube warranty. They should replace it, no problem.
Cool!
Called mesa and they said that chances are it was just a damaged tube. Probably was damaged in shipping. Even though I just put the tubes in, I had purchased them in December so they were out of warranty. They said they would replace it anyway which impressed me.
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