Smoking amp... and not in the good way

[jdurso]

Ok here's the deal... I hadn't had time to play in about 3 weeks so i finally get today to sit down and play to my heart's content. After about 5-10 minutes of playing, i notice a my tone starting to breakup and weaken and then i see and smell smoke coming up from the top vent/grille of my Roadster. I immediately turn the amp off, unplug everything and taking a look around back to see if i could locate where the smoke was coming from. My room isnt that big so i relocate my gear to another room where i could sit and play while looking in the back. This time i play for about an hour and no issues, no smoke, just the sweetness that is the Roadster.

Fast forward to 10 minutes ago and i plug in and sure enough after about 10 minutes, my tone starts dying and the amp starts smoking. This time i happen to catch the two power tubes closest to the OT glowing really bright and smoke coming from the OT (also looked like from near v3-v4 but that could have been the smoke circulating around them not coming from them). Anyway could it be the power tubes going? Or a bigger issue with the OT? At this point i'm waiting for the amp to cool so i can throw some different power tubes in but any wisdom or suggestions are more than welcome.

BTW my tube setup isnt stock so as far as power tubes i'm running JJ KT77s in el34 mode and the preamp tubes are all NOS of varying types and brands. I was running straight into the amp from my PRS and directly into my Mills cab.

 

[fishyfishfish]

Tubes (Power) were redplating and burning up grid resistors. Simple fix if you are handy with a soldering iron. I don't think your tranny was hurt in this escapade, just your power tubes and resistors.
Take the chassis out of the box (Be Careful not to touch anything inside the amp with your fingers!) and look closely at the underside of the power tube sockets, you should see some burnt black diodes.

 

[jdurso]

Tubes (Power) were redplating and burning up grid resistors. Simple fix if you are handy with a soldering iron. I don't think your tranny was hurt in this escapade, just your power tubes and resistors.
Take the chassis out of the box (Be Careful not to touch anything inside the amp with your fingers!) and look closely at the underside of the power tube sockets, you should see some burnt black diodes.

I dont trust myself with that type stuff so i'll be bringing it to my amp tech but thanks for the input... from searching around the internet that was the conclusion i was coming to.

 

[fishyfishfish]

Nothing to worry about, just normal tube amp stuff. I had my Lonestar plugged into 240 once and it was fixed for $58.00

 

[grunge782]

Are you sure the front of the amp doesn't say "Bugera"?

 

[ESP123]

Are you sure the front of the amp doesn't say "Bugera"?

funny but "NOT" helping grunge...

 

[jdurso]

Are you sure the front of the amp doesn't say "Bugera"?

funny but "NOT" helping grunge...

haha... thats actually the first thing i thought of. i imagined the inside of the chassis covered in cola brown liquid from a busted cap or a few fried resistors, like that post i saw on HC. I'm bringing it to my amp tech today to get it checked out and possibly get it tunedup if needed.

One thing that i've been pondering is if it was the power tube/screen resistor could it have had any nill effects on my preamp tubes? Or is it so far along in the chain of the signal it would only effect the power section?

 

[Turumbar82]

Are you sure the front of the amp doesn't say "Bugera"?

Hey now :lol: I owned a Bugera for about a year and played it with a band weekly and never had any problems. lol

and then I sold it, and was afraid for about a week after that the guy I sold it too would show up at my door pissed off saying it broke.

 

[jdurso]

Small update... called Mesa up and spoke with Mike in customer support. When i told him the issue and our collective diagnosis he was suprisingly thrilled at how much we knew (go us). So i told him that i'm an idiot and forgot to mail out my warranty card 2.5 years ago when i bought the amp (actually sitting in my room still filled out in a stamped envolope) and he said it was no problem, as long as i brought the original receipt with me. He was even so kind as to call my amp tech up (who is also a certified Mesa tech) and told him that i was coming in, and that they would cover the whole repair (aside from new tubes).


Now if thats not grade A customer service I dont know what is.... i was on the phone with them for a total of 3 minutes. I have dealt with a lot of customer services through the years and for a company the size of Mesa there is no one better.

 

[fluff191]

Small update... called Mesa up and spoke with Mike in customer support. When i told him the issue and our collective diagnosis he was suprisingly thrilled at how much we knew (go us). So i told him that i'm an idiot and forgot to mail out my warranty card 2.5 years ago when i bought the amp (actually sitting in my room still filled out in a stamped envolope) and he said it was no problem, as long as i brought the original receipt with me. He was even so kind as to call my amp tech up (who is also a certified Mesa tech) and told him that i was coming in, and that they would cover the whole repair (aside from new tubes).


Now if thats not grade A customer service I dont know what is.... i was on the phone with them for a total of 3 minutes. I have dealt with a lot of customer services through the years and for a company the size of Mesa there is no one better.

WOW! I have only had to Call Mesa once to order some parts and ask some questions and I had the same experience. Glad you are getting your amp fixed!

 

[TFridgen]

Is this a function of running the kt77's with gz34 rec tubes in there? Hopefully it's just an isolated incident, my kt77 power section will be here tomorrow.

 

[jdurso]

Is this a function of running the kt77's with gz34 rec tubes in there? Hopefully it's just an isolated incident, my kt77 power section will be here tomorrow.

My friend the same thing went through my mind. I'm actually going to see what these new tubes sound like because when i told the tech i have two spare sets of 6l6s he said he could gaurentee the work unless it was with new tubes that he selected. his reasoning wasnt to give me more of what i have already but because of his distaste of tubes these days. He said he could go through 10 sets of new Mesa and JJ tubes and may only find 3 or 4 tubes suitable for an amp. I've been taking my amps to him for 10 years now and he's as good as they come in these parts... his bench fee is mroe than fair and his work is flawless. I almost want to overpay for his work because i know how much time and care he puts into each repair. Needless to say I'm going to see/hear what the amp sounds like when it gets back and if i like it i'm not going to bother buying new kt77s.

 

[jdurso]

Small update... called Mesa up and spoke with Mike in customer support. When i told him the issue and our collective diagnosis he was suprisingly thrilled at how much we knew (go us). So i told him that i'm an idiot and forgot to mail out my warranty card 2.5 years ago when i bought the amp (actually sitting in my room still filled out in a stamped envolope) and he said it was no problem, as long as i brought the original receipt with me. He was even so kind as to call my amp tech up (who is also a certified Mesa tech) and told him that i was coming in, and that they would cover the whole repair (aside from new tubes).


Now if thats not grade A customer service I dont know what is.... i was on the phone with them for a total of 3 minutes. I have dealt with a lot of customer services through the years and for a company the size of Mesa there is no one better.

WOW! I have only had to Call Mesa once to order some parts and ask some questions and I had the same experience. Glad you are getting your amp fixed!

Mike from Mesa was awesome... very personable, very friendly and went above and beyond anything i expected. I'm a big boy and can call my own tech but he insisted on calling ahead and taking care of everything. All dennis had to do was see the amp (let alone me) to know the situation. THAT is what i call customer service and IMO is huge in keeping a dedicated user base. I know as long as I'm playing a guitar, a Mesa will in some way be amplifying it.

 

[jdurso]

Oh and the cool part is that while i lose my Roadster for about 2 weeks... my boy and fellow forumite, JohnDNJ let me borrow his 2:90 to power my Axe-fx so at least i wont miss a beat playing.

 

[grunge782]

Good to hear you got it resolved. It's a shame though about those NOS tubes...

 

[jdurso]

Good to hear you got it resolved. It's a shame though about those NOS tubes...

It wasnt the NOS tubes it was the power tubes... NOS preamp tubes are fine

 

[jdurso]

all is now good... fried a couple screen resistors. Power section is now totally retubed both and things are sounding good.

Amp tech told me he had to go through about 8 sets of power tubes to find solid ones, apparently the quality control of who ever is supplying mesa with power tubes is going down the drain. Whats in there now are 4 6l6s each from a different set and 2 recto tubes each from a different set. All he could do is shake his head... but he brought the beast back to life.