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- Feb 21, 2017
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So eBay can be wonderful and terrible. I thought I was lucky to get an old Mesa .50 caliber for 250 because guys, I just want to have an obnoxiously middy thrash tone. But, some people are awful and will list an amp as "working. Turns on" even when it was clearly on fire at some point. Tech at Mesa took one look at my JJs and said there was nothing he could do.
After reading three forum posts and buying a multimeter, I've pretty much got it narrowed down to leaky coupling caps messing with the bias, or out of spec 470 ohm resistors on pin 9 of the power tubes affecting the g2 voltage. These are all things I learned in a few hours of research (maybe years of experience have led this tech to see a hopeless situation? Maybe he assumes that any non standard equipment makes a Mesa garbage?). Anyway, does this sound reasonable? Should I look at other stuff? And most importantly, since this is clearly a project amp not a collectable, what are some crazy mods I could do to it?
After reading three forum posts and buying a multimeter, I've pretty much got it narrowed down to leaky coupling caps messing with the bias, or out of spec 470 ohm resistors on pin 9 of the power tubes affecting the g2 voltage. These are all things I learned in a few hours of research (maybe years of experience have led this tech to see a hopeless situation? Maybe he assumes that any non standard equipment makes a Mesa garbage?). Anyway, does this sound reasonable? Should I look at other stuff? And most importantly, since this is clearly a project amp not a collectable, what are some crazy mods I could do to it?