mesa boogie dual recto problem

T

tom18222

yes
i have a mesa boogie dual rectifier roadster.

today randomly channel 4 stopped working, which is the overdrive channel. i dont use channel 3 so i am not sure it that works or not yet.

channel 1 and 2 are fine (clean and light od)

power tubes 1 2 and 4 are glowing but not that bright

tubes 3 5 6 are bright red with blue.

did some tubes go for some reason or something?

i went away last week and my brother left it on for 2 straight days while i was gone. did he use them up? the amp is only about a year old.
 
Depends. Red and blue glow might be normal, depending on what parts of the tube you're talking about and how they are biased blah blah. Red glowing plates on the tubes is generally not good. Blue isn't necessarily a bad thing, have a google around and you'll find pics of good and bad tube glows.

Leaving an amp on for 2 days shouldn't kill the tubes really, even playing through it for 2 days straight really loud shouldn't really hurt it either.

I'm not 100% sure on how roadsters are built so someone else may chime in with better advice. I'd check your preamp tubes are okay on the overdrive channel too. But really, take it to a repair person (if it's an option) rather than just buying a fresh set of tubes (ie the tubes may not be the actual issue, they may just be a symptom). A good tech should tell if it just needs some new tubes or if it's something else.
 
Good glow;

blueglow.jpg

The blue is just fluorescence. Not bad. The 'red' you see can be the filament lit up. However, if the plate material itself shows a 'hot' spot;

redglow.jpg

..... this is bad. The tube is drawing too much current. Once again, the red you see in the middle of the structure is the filament lit up, but the outside piece of metal is the Plate, and shouldn't have that red spot like a lit poker.
If Boogie spent an extra dime and added a bias control, you could raise the bias voltage and have a 50-50 chance the tube is still good. But as is, the only option is to try a different tube, and hope like Hell it doesn't run red hot as well. Ah, the joys of spending $2K on a tube amplifier made by people who won't add a bias control :confused:. Have fun.
 
Hey! There you go! They'll have Robo-Tube pick a new set! You'll be good for a while after that, as long as your brother keeps his hands off of your Boogie.
 
btw i think the purpose of no bias is so their tubes always work no matter what, you just buy one and put it in, no need to adjust anything. all the tubes are matched.
 
tom18222 said:
btw i think the purpose of no bias is so their tubes always work no matter what, you just buy one and put it in, no need to adjust anything. all the tubes are matched.
Click to expand...
Yeah, keyword being "their" tubes. Which are really just rebranded (and graded, obviously) sovteks or chinese tubes. Would be nice if they would use JJs!
 
ok after further inspection, both high gain channels do not work work (3 and 4)

there is VERY low volume. this is the third problem i have had with this amp since i have gotten it, only about 10 months.

bullshit, i wonder if i can get a replacement.
 
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