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Mesa 400+ Tube and Fuse HELL!!!

humbleleon991

humbleleon991

Oct 12, 2009
172
93
#1
Ok sooooooooo my 400 + was making a strange little sound (kinda like really light wind, it would do it sparadically, not very loud, but a tad annoying) at practice the other night so the first thing i did was check my tubes, and to my relief two of the pre amp, 12ax7s were completely dead. The next day i replaced the two dead tubes with some others that i knew worked, and i could notice a huge improvement in tone and the weird sound was gone :hyper:. I played for about an hour at good volume just to make sure the sound didnt come back. I turned it off and waited 3 hours and decided to test it one more time just to be double sure. I turn on the power and let it warm up a bit, then when i hit the standby off, it made no noise and i saw lightning in a power amp tube and it died. I checked the fuse and its blown, I did some research on mesa's FAQ section and by the looks of things, one of my power tubes blew and it blew my fuse. I think the tube blew probably because of age ( i bought the amp used about a year ago,(i havent changed the tubes yet, i dont know how long the original owner changed the tubes, some of the tubes look older(have different labels) but are still mesas)) instead of not being pushed in all the way. So naturally my plan of attack is to buy a re tube set and some new fuses. Im kinda nervous though, this is my first time with an all tube amp and i dont want to put a new fuse in and the new tubes, and have another tube fail and fuse blow. Should i go ahead and buy the tubes and fuses, or should i just take it to a tech. (id love not to take it to a tech though!)
 
#2
Take it to a tech. Tubes generaly don't just go poof because they are old. Something else is causing them to die and if you just replace the tubes that went, I would bet those die too.
 
#3
While the tube may have simply failed, it would probably be a good idea to take it to a tech anyway, because there's a good chance it took out its socket's screen grid resistor when it went poof. Then, you can have the tech give it a good once over and sleep easy once you retube it.

Also, while there's nothing wrong with Mesa's rebranded tubes, they are freakin' expensive. If if you get a matched 400+ retube kit from a place like Eurotubes, you would still probably come out saving money even after the tech bill.
 
#4
I've has several Mesa's and my experience is those tubes often fail from mis-handling damage (aka impact shock).
I always tell people when you buy one used, replace the tubes so you know what you're starting with.
Yes, when a tube fails it pops the fuse.
 
#6
so i went to ace and the had some fuses, got home put em in, and the amp powered on (thank god lol) and i looked in the back and my whole entire power amp section is dead, but the pres are still good. I had 4 spare 6l6's so i put them in around the area where i saw the lightning and powered it up and they had power to them :eyebrow:? intrigued, i moved them around in all the spots and every spot has power to it. So ummm... what the hell happened?
 
#7
Quit doing that.

Don't turn it on again. Go and take it to get serviced. You've got bigger problems than just dead fuses and 'old tubes'. Fer Real. You'll end up doing more damage to your amp. Take it somewhere competent for tube amp repair and have them diagnose the problem rather than just switching out tubes, which is a symtom of something else going wrong.
 
#9
timv said:
What do you mean by the whole power section was dead???
They didn't light up as in the filaments weren't glowing???
That is very unlikely.
Definitely, as already said, take it to a tech.
Where are you located?
Click to expand...

+1 Not saying I doubt you, but are you sure none of the tubes were working? Some tubes don't glow very brightly. I've had tubes in my 400+ that the only way to see they were on was to turn off the light in a dark room.

Either way, take it to a tech.
 

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