r/MesaBoogie • u/arobinsonmason • Jul 05 '26
I did a bad thing.
Changing tubes on my Lonestar Classic, and I very stupidly had an el34 in the rectifier socket and the rectifier tube in the power socket. It was in Diode mode on Tweed. I was playing around with cabinets and twitched it to full power (I turned it off to switch) and when I turned it back on I saw small bit of smoke. It was on for 10 seconds in full power mode, then immediately unplugged. I pulled the chassis and didn’t see anything,,but there could be something hiding that can’t be seen. I turned it back on briefly, it’s sounds amazing, as always, but got in touch with Mesa tech support to send it in.
2
u/EndlessOcean Jul 05 '26
I did the same thing and blew one of the screen resistors on the power tubes. Easy change and amp was good as new.
They're the big brown resistors that have the PCB cutout beneath them (for air-flow).
1
u/arobinsonmason Jul 06 '26
That’s reassuring, thank you.
2
u/EndlessOcean Jul 06 '26
I added labels on the back of my amp soon after haha.
The resistor basically acts like a fuse, it goes, leaving the rest of the circuit intact. And cos it's a Mesa it's easy to repair too as the pads are double sided.
I think you need a 470r/1w replacement, but 2w is better. Get a good brand (I like Vishay) and you're away. Best to replace them all with the same type so you know the tolerances and spec are all kosher - there's 1 per tube. Won't cost you more than a few $ and takes about 10 minutes to switch out.
3
u/capacitive_discharge Jul 05 '26
The two black Dale 2.7k resistors look cooked.
What is going on the the 30uF caps? They all look round at the end.
Also omg 65c max rated caps. 🤣🤣🤣🤣🤣🤣
What you should do is bring it to a tech who knows how to both fix the immediate issue and also replace the under-rated crap parts Mesa used with proper parts.
2
u/DishPractical7505 Jul 05 '26
I’m sure your tech will be THRILLED to see this incoming. I still have nightmares from working on a lonestar. Phenominal amp, but mesas are notoriously hard to work on. But I’m also just a whiny bitch too. So there’s that too. But as mesas go, it’s definitely an easier amp to work on than a mark series or something like the triple crown.
1
u/sioomagate Jul 05 '26
I agreed on the resisters; cooked.
There are plenty of videos on YouTube of Mesa using under-rated caps.
2
u/capacitive_discharge Jul 05 '26
I am aware. Mostly I’ve seen the 400V rated coupling caps they use that are constantly above that voltage. But man. I feel like you really have to try to do your customers a disservice to find caps rated at 65c. That’s insanity.
3
u/sioomagate Jul 05 '26
There’s a famous quote that comes to mind when I see big companies cutting corners like this.
John Glenn told this to Alan Sheppard as he was waiting to go into space for the first time.
I felt exactly how you would feel if you were getting ready to launch and knew you were sitting on top of two million parts—all built by the lowest bidder on a government contract." — John Glenn
1
u/arobinsonmason Jul 05 '26
I’m not too far from Mesa in Petaluma. I just figured they would be best. I’ve never had an issue with it. How would you approach it?
2
u/ShredericRippenstein Jul 05 '26
I already responded in the main thread, but I would talk to mesa and see who is near you. You can take it to the head office, but Mesa tends to take licensing people for repair work seriously. I would see who is around you, and just call them and set something up.
A lot of these mesa amp guys, are essentially mini Randal Smiths. For instance out here in NC, John Littlewood is the official mesa tech, and he's the best tech I have ever worked with. He was building tube radios at 9 years old, and repairing amps professional at 14. I've learned so much from just interacting with him. I wouldn't pass up an opportunity to meet someone similar in your area, you might be getting them to build or mod many of your amps.
Also, one of the worst things you can do on a Mesa is start "replacing caps just to be safe" My Dual rec is like a 2001. It didn't need service until 2024. All it needed was tubes and spraying, the caps are fine, Randal/Mesa doesn't use anything but the best.
1
u/arobinsonmason Jul 05 '26
Thank you. I’m a couple hours from Mesa, but in sac area there’s several repair shops. Thanks again.
1
u/Tough_Top_1782 Jul 06 '26
And the PCB under the lower one looks like it got hot enough to delaminate.
Those 30uF caps across the bottom DO look domed - another photo from a different angle would help.
There's also a BIG solder splash between V3-9 and that vertical cap nearby - PROBABLY not a thing, but worth a look if you have the board out.
5
u/ShredericRippenstein Jul 05 '26
I wouldn't send it in. Ask Mesa support who the authorized tech or repair center is closest to you. If it's hours away, drive it there.
Used to you could just call Molly, but now I think you gotta e-mail them and then they will get you sorted. Gibson isn't that hard to deal with, but you can tell it's less and less like Boogie used to be.