Do I have dead tubes? (Fender Blues Junior)

sanityclause

Member
Messages
8
Sorry, this is a total tube-amp-NOOB question:

I have a less-than-two-year-old Fender Blues Junior III, which is a perfectly FINE and satisfying amp for a player of my uh, caliber.

Tonight I turned it on and, no sound. Verified there was signal getting to its input, etc., and when I looked at the back, the three preamp tubes were glowing, but the two power tubes (Groove Tubes EL84-R) were not glowing, as far as I can tell.

I assume this means I have two dead power tubes, and I know I can replace them myself with a matched pair of JJs for a reasonable cost.

Note that they were working just fine as far as I can tell, until now. I handle the amp carefully, but I DO take it to rehearsals and the odd gig - so it probably rides in the trunk of my car once or twice per month.

So should I just replace the tubes and see what happens, or it is possible that something else is wrong? Is it odd to see both power tubes fail at once?

This is my first tube amp, and I expected something like this might happen sooner or later, but any wisdom or advice is appreciated.

TIA…
 

Crowbar

Member
Messages
570
Well replacing is easy enough, but I bet something is broken. Even bad tubes will still glow.
 

kiki_90291

Member
Messages
4,215
You may have blown a fuse. I had that happen on a Blues Jr. a few years ago - could be a simple fix.
 

sanityclause

Member
Messages
8
OK, I replaced both tubes and now all seems fine. One of the old bottles was broken, though I couldn't tell until I removed it. I wonder if one having broken glass would make the other appear dead too. Neither of the old ones were glowing.
 

VaughnC

Silver Supporting Member
Messages
18,010
Strange. Unlikely both tube's filaments (the part that lights up) would open at the same time. A tube can light up but still be bad...but if a tube doesn't light up, there's something wrong with the tube or the amp.

Oh well, replacing both tubes seems to have fixed the amp...but you should have the bias checked to make sure your new tubes are conducting properly and don't go into meltdown.
 




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