Legends, sorry to say there never was or will be a follow up video due to time constraints. If I encounter another of these amps when I have time, I will do another video.
Mannnn my Tubemeister 40 failed pretty much in the same way I was so curious to see the conclusion of your efforts! After seeing how much is packed in these things and speaking with a few local techs that are hesitant to work on it...I really regret my purchase lmao.
Like Scotty says "the more they overthink the plumbing, the easier it is to stop-up the drain". Thanks for this tear-down. That's another modern amp off the list. I can see now why these are so affordable on the used market.
Awesome video. Thanks for breaking down complex circuit designs like this and how to navigate the busy schematic. Plus for the thorough documentation and visible component designations on the circuit board…unlike “Messa”! And thanks for all your time making these videos.
You and Lyle are great guys. Can’t thank you both enough for all the free info. My parents were both public school teachers and your intelligence and work ethic are really inspiring. All the best from 🇨🇦
Really cool to see you dive into this one. The compartmentalization of the different parts of the circuit is so critical for diagnosing something this complex. It answers that question of, 'where do we even begin' on something like this. In other news, I ended up selling my Mesa head last weekend and keeping the 2x12 cab. The head was still running nice and quiet so it seemed like a good time to sell it. Also sold a couple electrics to score a nice (used) acoustic from a local shop. Net reduction of the collection, scored a cool Huss&Dalton acoustic, and rid myself of a liability. My musically formative years were the 90s having been born in the early 80s, so that Mesa was the sound of metal for me. I don't need that power now and I certainly didn't want a problem like I see on yours and Lyle's channels. Many thanks for what you do even if you're on the other side of the globe in the future 😁
Jeez Brad, your descriptions are getting into the realm of pure poetry! "An engineer's wet dream" and "convoluted fucked up system" are just wonderful.
I saw one of these amps for sale online, and found your video. I’m not going to buy it, but I still watched your whole video, 100% correct about engineers run wild
at 8:40 I just love the despair of the experienced tech!! the eternal question - yes but why?? I experience exactly the same thing as an older Software Developer, ooo look a new shiny wheel has been invented, its new and complicated so it must be far superior to the old one lol
Its a great amp , super duper versatile. I don't know of another tube amp that has all these features. 128 presets with a foot switch. I can change everything except the master volume which makes perfect sense. Looks cool, sounds better. Something has to give so I went ahead and bought it with a 4 year extended warranty and plan on shipping it if anything fails . the shipping expense is covered in those warranties so if I get 4 years out of it ,great. Does anyone know of another tube amp where you can make this many changes to the sound with one click.
This amp is like $1,000. And I can't imagine that it sounds so good that its worth $500-$600 to repair it. Its certainly never going to be a classic.The owner is very lucky that he found you, Brad.
Oh look it's a plexi !! I look at it like this... I could use those transformers in a ac30 build. Maybe salvage some jacks and tube sockets if they aren't pcb mounted. It would.be fun to jump up and down on the pcb before I toss it. The chassis would be fine for a single ended build..
At 18:10, It's worth noting that plugging those little pin-probe tips into the banana plug on the end of your multimeter cables leaves a small amount of metal exposed, so be really really careful around high voltages! I personally prefer the old style Pomona "Extenda-Probes" which had a jacketed/ insulated metal pin about 5" long that was adjustable via a collet clamp on the end of the probe handle, and so you could have 3" or 4" of insulated probe tip sticking out with which to probe into tight areas of the circuit. Unfortunately, the modern ones aren't made the same, and they're not designed to take 600 Volt rated, high flexibility silicone-jacketed wire.
great content buddy! do you know by any chance wether that biasing computer in the infinium line bugera amps work the same way? is that stuff reliable, or do they poop themselves all the time?
Hallo Brad, thanks for your Video and all your work!! I own a Tubemeister 36 wich is almost the same but a 3 channel amp.. Now i have a problem with the "crunch" and the "lead" channel... compared to the "clean" channel there is a huge output power loss.... it´s like 10 times quieter than the clean channel... Could this simply be one of the pre-amp tubes (12AX7)..? played in "clean" it´s loud as hell, but not the other channels... If anybody had same issues i´d be glad you´d let me know. cheers
Don't worry us Yanks still know that a valve = tube. 😉 I was looking for part 2 but didn't see it, so I assume the guy didn't want to pay to get it fixed or you never made the follow up. Just out of curiosity, if you did fix it what was the issue?
Hi Brad, Just stumbled on this. Good info in your video. Been searching for a direction on one of these that I’m in the process of trying to repair. Mine makes a really loud hum/screech when the tubes start conducting. Only does it when V4 and V7 are in place and not when V5 and V6 are in place. Seems to work fine otherwise. Starting to think it’s in the TSC system? Problem does not follow the tubes, it follows the outer pair sockets. Any thoughts?
That's a bit of a weird one and this amp is very difficult to troubleshoot due to the honeycomb-like construction needing the be assembled and therefore inaccessible in order to operate. All I could suggest is doing what you can with passive testing of the boards while disassembled. Something in the TSC may be presenting a negative resistance to one of those output valves in question during operation. How does it react with the power scaling switches, because they deactivate 2 or all of the EL84's depending on the setting.
@@BradsGuitarGarage the power scaling doesn’t change the problem. Even with the output completely disabled there is still an excessive power draw with the two outside tubes installed. Pulling the phase inverter tube doesn’t change it and installing just one of the outside tubes in either V4 or V7 introduces the problem so it seems to point to something they have in common. Give me an old Fender any day but these repairs can be really good learning experiences and the only reason I’d like to try to see it through. Thanks a bunch for trying to assist me!
Found a bad MOSFET last night and swapped it out for a new one. Weird thing is it corresponds to one of the tubes that was in the working pair. After replacing it, there was still no change. Then all of a sudden it stopped producing any sound. Lol, out of the frying pan and into the fire. Might have to cut my losses on this one or just try to get a new main board.
I saw the bias lights and it made me instantly think maybe this is where Bugera took their "infinium" junk which is also in my experience unreliable, putting the life of a quad of expensive tubes in the hands of a crappy IC. So you will never need to bias the amp but when the 11 cent IC fails, you have a broken amp and a new set of tubes.
Everyone has tried. They have all failed. There's just too many potential failures. A handful of components, a potentiometer, and a tech to adjust always was and always will be the best way.
This is not your usual standby switch. It controls many things simultaneously, none of which are the HT supply. Describe what you mean by "does nothing". Do you mean the amp plays normally with the switch in both positions?
Great job! So if I may ask, what was the issue in the end? Really just a poweramp tube + the fuse, or did you have fix something else? I'm asking because I just bought this amp (got a really good deal, to which I just couldn't say no) and it still has the original cheap chinese tubes in it. Wondering if I should swap them all out, even before trying this thing out. Thanks man!
This one had a bad preamp valve and some intermittency on the interconnecting cables from memory. I had 3 of them within short succession, but I think that was this one. The Chinese valves aren't that bad in these ones, I wouldn't worry too much about them. They mainly cook in Vox amps where they run them way over spec, but that's not the case with this amp.
No real inherent issues in the design, rather reliable given the complexity. I've had them with spontaneous EL84 shorts, likely not the amp's fault, but that bias computer infrastructure I described in the video then requires replacement, and every PCB has to be removed, and the entire amp disassembled to perform this repair. That least one was in the ballpark of $600+parts.
I have no way of knowing that. I don't know what's wrong with it, what your budget is, the competence of your local repair shops or if there even are any. I don't even know where you are.
Great video. I didn't see part 2 on your channel. Did the owner balk at the cost of repair, and get it returned U/S? I have a Mesa Boogie TA-30 2x12 combo.... also an "engineers wet dream" :) I got it cheap as it had solid state relay switching issues, but it turned out that Mesa had a service bulletin for it, and I just needed to solder in one cap.
Awesome bud!! I have a 36 and my bias shuts my amp down all together at random times.. hasn’t done it in months but I’m not convinced the short isn’t gone, I have to turn the amp off then turn it back on and everything will be fine… any ideas?😊
Could be a lot of things, mate. What do you mean exactly by "my bias shuts my amp down all together"? What are the TSC indicators showing? All hard on? It could simply be that the mute switch is dirty on the far right button, under "power soak". It could be dirty valve pins / sockets, loose interconnects, an intermittent EL84, dirty speaker jack, you name it. Essentially, the TSC is trying to protect the amplifier, likely due to an erroneous signal it's getting from one of the points in the circuit it is monitoring. These are one of the most unlikely amps to be successfully repaired by someone without extensive experience, unfortunately. Even then, they are very time consuming to work on, due to the construction techniques.
@@BradsGuitarGarage thanks for your time! Unfortunately there are no techs around my location that know anything about this amp. Most of them don’t know what a diode is.. I am an auto mechanic I figure if it gets bad enough I will try and find the short myself lol cheers!!
Could never afford school, always 1 week behind rent. Lol! Been playing with electronics since I was about 5yo. Learned a lot from Dad. And lots of late nights reading.
Geeze it's an automatic nightmare and you're a braver man than I Gunga Din... If I had any scratch It'd be coming your way just on general principles... What I can do is subscribe Cheerios matey
I remember the Triamp MKI when I was working for H&K in the mid 90s. It was a nightmare. An overengineered but underdesigned monster.When you crank it up, the power amp blew up and burned the board to crusty coal. I think, that's where this self biased shit is comming from.
That looks like one serious Big Bucks amp..! Jesus, my little Fender 65R will still knock your face off at 1/10 of the cost of that thing..Super interesting though, where do you start Brad..? Great info as usual, look forward to more..Ed..uk..😀
As a German I hate to say that this is one those cases of German over engineering assisted by cheap labor in the PRC being the enabler that this piece of electronic waste (which it will be the most of its lifetime).
Brilliant job.
For those of you who don’t know, vids like this take a lot of time to put together. Like/subscribe/tell your friends. Brad deserves it.
Huge amount of work, editing takes for ever!! I’m loving Brads vids.
Legends, sorry to say there never was or will be a follow up video due to time constraints.
If I encounter another of these amps when I have time, I will do another video.
Mannnn my Tubemeister 40 failed pretty much in the same way I was so curious to see the conclusion of your efforts! After seeing how much is packed in these things and speaking with a few local techs that are hesitant to work on it...I really regret my purchase lmao.
Like Scotty says "the more they overthink the plumbing, the easier it is to stop-up the drain". Thanks for this tear-down. That's another modern amp off the list. I can see now why these are so affordable on the used market.
Somebody saw a video about how over-engineered Mesas are and was like "Hold my beer." Fascinating work, you have a subscriber.
Awesome video. Thanks for breaking down complex circuit designs like this and how to navigate the busy schematic. Plus for the thorough documentation and visible component designations on the circuit board…unlike “Messa”! And thanks for all your time making these videos.
You and Lyle are great guys. Can’t thank you both enough for all the free info. My parents were both public school teachers and your intelligence and work ethic are really inspiring. All the best from 🇨🇦
How do you know?
We might be a pair of absolute c***s who are just good at acting.
Lyle does have a background in theater and an English major.
Lol!
Really cool to see you dive into this one. The compartmentalization of the different parts of the circuit is so critical for diagnosing something this complex. It answers that question of, 'where do we even begin' on something like this. In other news, I ended up selling my Mesa head last weekend and keeping the 2x12 cab. The head was still running nice and quiet so it seemed like a good time to sell it. Also sold a couple electrics to score a nice (used) acoustic from a local shop. Net reduction of the collection, scored a cool Huss&Dalton acoustic, and rid myself of a liability. My musically formative years were the 90s having been born in the early 80s, so that Mesa was the sound of metal for me. I don't need that power now and I certainly didn't want a problem like I see on yours and Lyle's channels. Many thanks for what you do even if you're on the other side of the globe in the future 😁
Great vid Brad, that is a scary amp to take on! Awesome work.
Thanks mate!
@@BradsGuitarGarage legends!
Jeez Brad, your descriptions are getting into the realm of pure poetry! "An engineer's wet dream" and "convoluted fucked up system" are just wonderful.
I saw one of these amps for sale online, and found your video. I’m not going to buy it, but I still watched your whole video, 100% correct about engineers run wild
at 8:40 I just love the despair of the experienced tech!! the eternal question - yes but why?? I experience exactly the same thing as an older Software Developer, ooo look a new shiny wheel has been invented, its new and complicated so it must be far superior to the old one lol
Its a great amp , super duper versatile. I don't know of another tube amp that has all these features. 128 presets with a foot switch. I can change everything except the master volume which makes perfect sense. Looks cool, sounds better. Something has to give so I went ahead and bought it with a 4 year extended warranty and plan on shipping it if anything fails . the shipping expense is covered in those warranties so if I get 4 years out of it ,great. Does anyone know of another tube amp where you can make this many changes to the sound with one click.
This amp is like $1,000. And I can't imagine that it sounds so good that its worth $500-$600 to repair it. Its certainly never going to be a classic.The owner is very lucky that he found you, Brad.
Just figured out my FU 1 fuse is blown. Thanks for this vid
Oh look it's a plexi !!
I look at it like this...
I could use those transformers in a ac30 build. Maybe salvage some jacks and tube sockets if they aren't pcb mounted.
It would.be fun to jump up and down on the pcb before I toss it.
The chassis would be fine for a single ended build..
A dear mate of mine is a Rush freak and wanted to get Alex's sig amp. I managed to steer him toward a HiWatt instead.
At 18:10, It's worth noting that plugging those little pin-probe tips into the banana plug on the end of your multimeter cables leaves a small amount of metal exposed, so be really really careful around high voltages! I personally prefer the old style Pomona "Extenda-Probes" which had a jacketed/ insulated metal pin about 5" long that was adjustable via a collet clamp on the end of the probe handle, and so you could have 3" or 4" of insulated probe tip sticking out with which to probe into tight areas of the circuit. Unfortunately, the modern ones aren't made the same, and they're not designed to take 600 Volt rated, high flexibility silicone-jacketed wire.
I should have mentioned that they're to be used during passive testing only, or just not touching the bloody things works, too. Lol.
Did this one get fixed?
Thanks, J
Excellent vid, thanks for sharing with us
Was there ever a follow up to this ?
great content buddy!
do you know by any chance wether that biasing computer in the infinium line bugera amps work the same way? is that stuff reliable, or do they poop themselves all the time?
Was there a part 2?
Awesome video! Can't wait for pt2!
I know this may seem awfully presumptuous of me... but was there/is there ever a part 2?
Hallo Brad, thanks for your Video and all your work!! I own a Tubemeister 36 wich is almost the same but a 3 channel amp..
Now i have a problem with the "crunch" and the "lead" channel... compared to the "clean" channel there is a huge output power loss.... it´s like 10 times quieter than the clean channel... Could this simply be one of the pre-amp tubes (12AX7)..? played in "clean" it´s loud as hell, but not the other channels... If anybody had same issues i´d be glad you´d let me know. cheers
No idea without actual measured diagnosis.
Don't worry us Yanks still know that a valve = tube. 😉 I was looking for part 2 but didn't see it, so I assume the guy didn't want to pay to get it fixed or you never made the follow up. Just out of curiosity, if you did fix it what was the issue?
Just when I thought the standby circuit in my Traynor TCV40WR was a bit over-engineered, here comes HK saying naw mate, check this out!
Hi Brad,
Just stumbled on this. Good info in your video. Been searching for a direction on one of these that I’m in the process of trying to repair. Mine makes a really loud hum/screech when the tubes start conducting. Only does it when V4 and V7 are in place and not when V5 and V6 are in place. Seems to work fine otherwise. Starting to think it’s in the TSC system? Problem does not follow the tubes, it follows the outer pair sockets. Any thoughts?
That's a bit of a weird one and this amp is very difficult to troubleshoot due to the honeycomb-like construction needing the be assembled and therefore inaccessible in order to operate. All I could suggest is doing what you can with passive testing of the boards while disassembled. Something in the TSC may be presenting a negative resistance to one of those output valves in question during operation. How does it react with the power scaling switches, because they deactivate 2 or all of the EL84's depending on the setting.
@@BradsGuitarGarage the power scaling doesn’t change the problem. Even with the output completely disabled there is still an excessive power draw with the two outside tubes installed. Pulling the phase inverter tube doesn’t change it and installing just one of the outside tubes in either V4 or V7 introduces the problem so it seems to point to something they have in common. Give me an old Fender any day but these repairs can be really good learning experiences and the only reason I’d like to try to see it through. Thanks a bunch for trying to assist me!
Found a bad MOSFET last night and swapped it out for a new one. Weird thing is it corresponds to one of the tubes that was in the working pair. After replacing it, there was still no change. Then all of a sudden it stopped producing any sound. Lol, out of the frying pan and into the fire. Might have to cut my losses on this one or just try to get a new main board.
Excellent !
Please keep the faith, I’m getting used to Australian accent 😉
I couldn’t see where the fuses were. They were off camera
I saw the bias lights and it made me instantly think maybe this is where Bugera took their "infinium" junk which is also in my experience unreliable, putting the life of a quad of expensive tubes in the hands of a crappy IC. So you will never need to bias the amp but when the 11 cent IC fails, you have a broken amp and a new set of tubes.
Everyone has tried.
They have all failed.
There's just too many potential failures.
A handful of components, a potentiometer, and a tech to adjust always was and always will be the best way.
My standby switch does nothing. It’s just on all the time. What do you think?
This is not your usual standby switch. It controls many things simultaneously, none of which are the HT supply.
Describe what you mean by "does nothing".
Do you mean the amp plays normally with the switch in both positions?
The line out works and the xlr out works but the speaker out is being dodgy and the amp is making strange noises
Great job! So if I may ask, what was the issue in the end? Really just a poweramp tube + the fuse, or did you have fix something else? I'm asking because I just bought this amp (got a really good deal, to which I just couldn't say no) and it still has the original cheap chinese tubes in it. Wondering if I should swap them all out, even before trying this thing out. Thanks man!
This one had a bad preamp valve and some intermittency on the interconnecting cables from memory. I had 3 of them within short succession, but I think that was this one.
The Chinese valves aren't that bad in these ones, I wouldn't worry too much about them.
They mainly cook in Vox amps where they run them way over spec, but that's not the case with this amp.
@@BradsGuitarGarage Ok, thanks! So what are really the common issues with these amps? Besides being cramped and having heat issues?
No real inherent issues in the design, rather reliable given the complexity.
I've had them with spontaneous EL84 shorts, likely not the amp's fault, but that bias computer infrastructure I described in the video then requires replacement, and every PCB has to be removed, and the entire amp disassembled to perform this repair. That least one was in the ballpark of $600+parts.
where do i can find the schematic?
The internet.
I have that amp and today something has gone wrong with it do you think any repair shops I take it too are likely going to be able to fix it
I have no way of knowing that.
I don't know what's wrong with it, what your budget is, the competence of your local repair shops or if there even are any. I don't even know where you are.
Great video. I didn't see part 2 on your channel. Did the owner balk at the cost of repair, and get it returned U/S?
I have a Mesa Boogie TA-30 2x12 combo.... also an "engineers wet dream" :) I got it cheap as it had solid state relay switching issues, but it turned out that Mesa had a service bulletin for it, and I just needed to solder in one cap.
Do you think, rebuilding the amp into a bigger cabinet would avoid some issues? I would like to buy this amp but I am reading lots of issues....
Nope.
Awesome bud!! I have a 36 and my bias shuts my amp down all together at random times.. hasn’t done it in months but I’m not convinced the short isn’t gone, I have to turn the amp off then turn it back on and everything will be fine… any ideas?😊
Could be a lot of things, mate.
What do you mean exactly by "my bias shuts my amp down all together"?
What are the TSC indicators showing? All hard on?
It could simply be that the mute switch is dirty on the far right button, under "power soak".
It could be dirty valve pins / sockets, loose interconnects, an intermittent EL84, dirty speaker jack, you name it.
Essentially, the TSC is trying to protect the amplifier, likely due to an erroneous signal it's getting from one of the points in the circuit it is monitoring.
These are one of the most unlikely amps to be successfully repaired by someone without extensive experience, unfortunately. Even then, they are very time consuming to work on, due to the construction techniques.
@@BradsGuitarGarage yes all light up and no sound, could an undersized power cord or bad power be the cause??
Not sure. I haven't tested what the TSC does in that scenario.
I'd suggest taking it to a tech for testing at least.
@@BradsGuitarGarage thanks for your time! Unfortunately there are no techs around my location that know anything about this amp. Most of them don’t know what a diode is.. I am an auto mechanic I figure if it gets bad enough I will try and find the short myself lol cheers!!
Where are you, mate?
I've got an extensive database of techs I know and can trust, worldwide.
Hey man just curious, did you go to school for electrical engineering? Or have you just studied a good bit on your own?
Could never afford school, always 1 week behind rent. Lol!
Been playing with electronics since I was about 5yo.
Learned a lot from Dad.
And lots of late nights reading.
Geeze it's an automatic nightmare and you're a braver man than I Gunga Din...
If I had any scratch It'd be coming your way just on general principles...
What I can do is subscribe
Cheerios matey
I remember the Triamp MKI when I was working for H&K in the mid 90s. It was a nightmare. An overengineered but underdesigned monster.When you crank it up, the power amp blew up and burned the board to crusty coal. I think, that's where this self biased shit is comming from.
That looks like one serious Big Bucks amp..! Jesus, my little Fender 65R will still knock your face off at 1/10 of the cost of that thing..Super interesting though, where do you start Brad..? Great info as usual, look forward to more..Ed..uk..😀
As a German I hate to say that this is one those cases of German over engineering assisted by cheap labor in the PRC being the enabler that this piece of electronic waste (which it will be the most of its lifetime).
That amp could only be brought to you by the nation that built the Tiger tank 😹
👍👍👍🙏
When you see the schem you know it will be a pain in the ass...