I recently bought a used Lonestar in mint condition that was on consignment at Atlanta Discount Music. It played fine in the store, but after a few days residing in my studio it started losing output intermittently...and now I can't get any output from it other than some low volume from the preamp section. I tried replacing the output tubes with some brand new EL34 groove tubes (and yes I switched the bias to EL34), but this didn't help any. Could it be a bad rectifier tube (5U4/GB) causing this? I put in an order for all new Mesa tubes (6L6's and 5U4) to try to get it to work. Or do I need to just go ahead and ship it back to Mesa Boogie for a warranty repair?
Lonestar Problem - no output
- Thread starter knightkw
- Start date
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After reading the manual, I'm thinking this problem might be due to a bad preamp drive tube, since the problem manifests itself in all channels. Has anyone else experienced a similar problem that was caused by the preamp drive tube?
tiger roach
Well-known member
The rectifier tube is indeed a possibility.
Another thought....if it were really the rectifier tube, wouldn't the problem go away when I switched the rectifier tracking to diodes? I tried this and it didn't fix the problem. Now I'm thinking it must be the preamp driver tube....
Dennis Shaw
Active member
Have you tried moving the effects loop dial on the rear panel to hard bypass?
knightkw said:
Not necessarily but a good thought. I had a problem with my rectifier tube and moving to diode did not fix the issue.
I would bet preamp tubes hands down in this case, replace them with known good ones before contacting Mesa.
Dennis Shaw
Active member
Still try the bypass e/l bypass on the back. It's cheap.
Dennis
Dennis
Thanks for the input guys....I'm going to try the hard bypass solution first (since it's quick and easy), and then move on to checking the V5 preamp tube if bypassing the effects loop doesn't work. I'll post and let y'all know what happens...
Ken
Ken
Dennis, you're a genius dude. It worked immediately with the hard bypass on, which told me it was the V3 preamp tube (that means Platypus was correct as well) that powers the loop. I replaced that tube and the amp is working fine!! And I must say that I like the sound from the groove tube EL-34's. Of course I'll keep the stock 6L6's too, and swap them out occasionally when I want to record with that Fenderish clean tone. I just ordered some gold groove tube 12AX7's to replace the stock Mesa ones. I'll let y'all know how that works out.
Peace out
Ken
Peace out
Ken
Dennis Shaw
Active member
Glad it worked out so easily dude. Hang in there and keep on boogien'.................
Dennis
Dennis
Well, I have an update to this situation. The problem reared its ugly head again after retubing the whole amp, including all preamp tubes. When the loop is activated, after playing maybe 10 minutes or so the amp loses output unexpectedly. Flipping the hard bypass switch to bypass allows output again, but there HAS to be a true manufacturing defect in the loop circuit for this to continue to happen with all new tubes.
I'll be calling Mesa today to let them know about the issue and that I'll be shipping it to them for service.
I'll be calling Mesa today to let them know about the issue and that I'll be shipping it to them for service.
Dennis Shaw
Active member
I'm guessing either diodes or a relay. Let us know what happens.
Dennis
Dennis
Mystery solved, thanks to Rich in Mesa's repair department. I described the problem to him and he suggested it was a dirty return jack for the loop and all I needed to do was insert a cord in and out of the jack several times fast to clean the connection. I was skeptical of this actually working, and I told Rich that....and I owe him an apology. When I got home tonight I did what he said and it worked fine with no problems while I was playing for over an hour. Mesa definitely has some smart people working for them..that advice saved them a service call and me a lot of hassle of having to ship the amp in for repair.
Kudos to Rich at Mesa
Kudos to Rich at Mesa
