Anybody who's worked on anything electronic has had repairs like this. I applaud your humility in posting this. One of the things I like best about your videos is that you don't always get it right the first time, and you leave your mistakes in. That gives hope to the rest of us.
"Towards thee I roll, thou all-destroying but unconquering Mesa-Boogie; to the last I grapple with thee; from hell's heart I stab at thee; for hate's sake I spit my last breath at thee. Ye damned amp."- A-Brad
What we have here is an interesting case study in psychiatry more than anything else, watching the slow unravelling of a man's mind in the face of overwhelming adversity. The crushing of his already fragile ego. The feelings of victimhood and persecution. Captain Ahab is a very well chosen analogy indeed. Still, he'll probably recover once the source of his anguish is removed, and once he stops smoking so much pot! That was comedy. I love Brad the Guitologist!
I’m an old aircraft mechanic - retired, you do more real world troubleshooting than anyone I’ve come across. Regarding Mesa - marketing A++. Beyond that fact, less is more.
Dude, you're amazing! I love the honesty. I'm a Lineman and I've had monsters like this in my 25 years. No one retires un-beaten. I like to drive out to the middle of nowhere and scream.
Beautiful work of art Brad , the Ahab analogy was perfectly realised and conversely I now understand Melville's tale better! I have thoroughly enjoyed the dramatic series of videos about that arguably badly designed amp and the ending was perfect , not a patsy Hollywood ending but a real life one where we all learn something valuable. From the Nemesis of ancient Greece to Job's tribulations or the labours of Hercules , to the trials of our everyday jobs , c'est la vie!
You’ve exposed some awful truths about today’s gear Brad and every musician should pay attention. Here’s the problem - Tubes are really really hot. PCBs hate really hot. Mesa (and others too no doubt) is/are trying to defy the laws of the universe by cramming 10x more shit that all hates hot, directly over a bunch of very hot vacuum tubes, and then restrict the cooling even more by putting it all in an insulated wooden box that’s half the size it should be. Worse, they’ve created a monster that no human can really troubleshoot or repair without spending hours in disassembly/reassembly between testing procedures. So really- it’s a disposable product. The cost of diagnosis is always going to exceed the value of the product as soon as it’s out of warranty. Well - That’s bullshit. If a manufacturer really wants to build the International Space Station inside what should be a very simple tube amp, what they should do is what the auto industry has done. Provide a diagnostic port and a way for the device to generate error codes, then break up the main board into chunks, each sealed in epoxy so they can’t be reverse-engineered - and make it modular. If you get code 0000101 - you unplug module B and put in a new one. It costs the owner $500 for each module but tough shit- if you really need a 112 TUBE combo with 15 switchable levels of gain and 4 channels of assignable EQ and 7 different routable signal paths and midi and all the other shit they cram in that nobody playing a bar gig ever utilizes.... then there you go. It would still cost north of $2K but at least it would be serviceable. It’s not just amplifiers- my in-laws had a $6500 refrigerator with all the IoT bullshit - yes it let you know when the milk was getting old. But then one foggy Xmas eve a lightning strike happened 100 yds from their house and despite having arresters in their circuit panel - it fried everything electronic in the house. I watched as half a dozen techs came and went trying to make that refrigerator work - they replaced every component in the thing before it was over and the company finally gave up and shipped them a new one. Luckily insurance covered all of that but it was exactly the same cluster as your Mesa amp. Something relatively simple being overly complicated with bells/whistles and no easy way to repair it. End of rant - keep doing what you’re doing!
PC boards are used for mass production. Point to point wiring is expensive to manufacture. That may work for a $5k Dumble but it doesn't work for a $849 whatever. You are absolutely right about controlling heat and it is a problem for all amplifiers.
Stack enough analog circuits together without taking pains to isolate them, and they may work but become impossible to repair. Why do you think everything is trending digital? Because it's much easier and much cheaper to do consistently and repeatably, even if it's not quite as good as analog gear in perfect condition. The problem is that it's not economically viable to keep the analog gear in perfect condition. Enjoy your vintage amps, but it matters most when playing alone. Once you get into a band, nobody will care -- not even you, after a while -- if you use a Kemper or a Hughes & Kettner instead. The differences are just too subtle to survive a full contact scrum. That is why more and more gigging musicians are opting for modeling amplifiers, even ones who play on vintage amps at home.
Hey just to be clear - I have no problem with PCBs for low cost amps or for tube amps for that matter - but they still have to be serviceable and reliable. This Mesa design is neither.
Mal-2 KSC no disagreement here - I gave up gigging with all valve amps long ago because of the reliability issues. I played for 20 yrs with a hybrid- solid state power amp and tube preamp. If I was still doing it today I’d definitely be using a digital modeler. Nuance of tone is totally lost in a noisy bar. UR correct- it makes zero difference to anyone.
hmm, i got myself some really old 50s/60s pro audio tube amps made by philips and they also used PCBs sometimes. But they knew what they did back then...the PCBs is at the bottom and the tubes sockets are soldered onto the component side as well and the tubes are upright. And the PCB material used being only FR2...but they also have their own problems nowadays...FR2 is known to absorb/resorb liquid from the air and even the best ceramic sockets desolder themsevels over time when the FR2 moves (expand and shrink again as the liquid will evaporate) and the solder gets warm...therefore they need some reflow every now and then, as the FR2 is almost 60/70 years old..... The main problem is, you already said that....careless designers...glass reinforced FR4 has a temp range of around 300degreeC... so no issues with that, now do it all in a software PCB designer and simulate it....use DRC according to main standarts (which are not covering tubes anymore) the DRC come up with no errors....lets start production....See these traces...some are carrying 300+ Volts DC....they sould have at least 7mm clearance and creapage distance to any other electric potential....the same goes for the components...as laquer, plastic and/or shrinktubes are not concidered as a sufficient insulator. And this is what all these younger designers tend to forget/don´t know...as tubes and their handling/design rules are not longer a center spec, what you come across every electronics lectures/books/savety standarts....you either get to know these separately all yourself, or read old books and try to get all these all electric standart issues from the golden tube days...
I love watching your channel for this sort of thing. I give you a ton of credit for not only thinking through your issues but vocalizing them to a camera and then posting it to the 'tube. Watching your thought process is enlightening.
I thought for a moment there, after doing the end view of the parts you were going to say... "Oh wait, I can see a burnt component... you've got to be kidding me!!".
Hey Brad...2 years on. I'm curious of of the final destiny of this amp...But cheer up! Help is on the way.They are now Mesa owned by GIBSON! As the saying goes, " I didn't think it could get any worse!"
With over 50 years fixing stuff like this, I feel your pain. If you're up for one more round, I would offer these few tips that may help you slay the beast. At the end of this vid your were on a track down the PS section. As ALL 3 sources came from the same main supply. You could start suppling the isolated C node load with an external bench supply to see if this stays stable in the amp. Then the B node and finally the A node. As the A node supply determine the performance of the B and C nodes, I would spend some time looking at the PS. I have seen many devices defy repair that turned out to be ether a PS componet failure and/or a soft ground failure. I wouldn't assume the transformer without testing it removed from the PS components. These steps wouldn't take much more of your time. And wouldn't it great if YOU were the one guy that MASTERED the Boogie Amp Beast? Hum?
This reply is the correct next step for troubleshooting. I rewatched this video again and went to click the like button on this comment. Then I realized I had already clicked it, two years ago.
Hello all. I have been rethinking this problem and by rewatching this video it occured to me that the math to determint he primary winding on the plate transformer was good to a point. That point is where a single plate is used. When TWO plates are paralleled on each side of the winding, I think you need to see the combined the impedance of the two plated much like two paralleled resisters. In this case the result would be one half of a single tube. ie: if a single tube plate impedance is 4k then two paralleled would be 2k. I have no easy way to confirm this on my bench and I haven't seen any docs to say one way of the other. I think this could be what is causing the red plating issue, impedance mismatch.
This was thoroughly entertaining and instructive! I have a DC-3 and really like it, though I did need to cool down the bias (resistors) to stop the red plating. Eurotubes knows this problem, and sells matched JJ EL84s running on the "coolest" end of the spectrum.
WOW Bro. Best TH-cam video I've ever seen thank you for dealing with just reality! I felt every emotion you were going through because I have been exactly there myself. But truly from a filmmaking point of view that was amazing, I felt every uppercut that connected with your jaw. And every swing that missed. You are truly as good of a filmmaker As You Are a guitarist. And that is no insult! This Saga also reminded me of the movie "The Old Man and the Sea"
Epic series! Thanks for posting and being so candid. I've had years of electronic troubleshooting experience and I can relate to your journey to hell and back. I was rooting for you the entire time. I'm new to audio amps so watching you work through logic trains was very educational for me. I love the ease of access and resiliency of eyelet boards and tube sockets mounted directed to chassis. When I saw you staring down that over-sized PCB and wrestling it out of the chassis I was cursing too! Keep up the good work. Between you and Uncle Doug, I've getting a great education!
I was rooting for ya! Thanks for showing everyone that we are all human. I don’t know jack about amps but I have a need to fix things and love learning. Keep up the great work!
That rant is the reason I subscribed. Too many things are sugar coated these days because everyone is so sensitive. When you're right, tell it like it is. Because you were right! Thanks for the series of videos on this amp. Good stuff!
We’ll see if the devil is done with you when we see how ‘vintage’ that Ampeg he sends you is. I just spent two months restoring a 1964 M15 with much time dedicated to picking through the fifty-four-year-old dried out Satan’s snot encasing every single wire bundle and component. All I got was a sweet amp and an addiction to sniffing mineral spirits…
Brad, This was one of the funnest tech videos I have ever watched! I have worked on all my own amps since I was a kid and know this frustration very well. I want to congratulate you on leaving the 'reality' in your videos - it's my favorite part - watching you work through the problems. I have watched a bunch of them and I always learn something good. You're an awesome tech, man. Don't let this one amp get to you (yeah, I know it was in 2018, and it's 2020 now).
I watch all parts of this series with this amp I want to thank you for showing what you did and being honest and hope you continue doing what your doing on TH-cam
I’ve been an Electronics tech since 1975. I had my ass kicked on several occasions by different circuits I’ve worked on. And remember the frustration that went with not being able to find the problem. There was a Friday night after work, years ago that me and a few other techs even took a board that we had all troubleshot and failed at repairing to a bar. We put it on the table we were at and took turns yelling obscenities at it. Unfortunately, it still didn’t work when Monday came. 😉 We’ve all been there.
Well, what an absolute bastard of a problem. I can only salute you for your determination. I guess the Moby Dick analogy is just about perfect, lol. Fascinating video and learned more from this than many of your vids with quickly located issues. Thanks dude!
*Mesa Boogie... the heart of toneless and soulless sound. I had a Mark IIb years ago, and was able to sell it and use the money to buy my 65 Vibrolux!*
Man, I understand your frustration!!! I'm not an amp repair guy but I know the feeling of, after trying everything, putting your hands on your head and wondering "What ELSE could it be?!".
Well, it was an interesting journey and I shared your frustration. I think we all have repairs like that. My one major failure still sits under my bench daring me to try again. Maybe I should dismantle it as you've done. At least you can now forget it and move on, or check out that pcb in detail. In any case, well done, you gave it more than any man could.
@ Haha, no way, I gave up on it back in 2014 and under the bench it will remain unless I find some new information that might help move the diagnosis forward. I should mention (in my defense) that the device in question is a tad more complex than a guitar amp.
Your comments at the end are the best. And i wouldn't take any shit from the trolls either. The last scene with the amp disassembled and the sound of the birds and ocean were great. LOVE your channel and always learn something and get entertainment as well. Kudo's !! Oh and you did the world a great service by taking that damn amp apart so it will never torture another human again. Thank you !
I notice that you didn't bang on the sides Brad that may have been the problem, here's what I like about your video's, Your truthful and that goes along way with most folks.
You are a blast to listen to!! Thank you!! I laughed more at your tone and vocal style than I do at most comedians!! I mean it! THANK YOU!!! I'm subscribing!! Love your style! To be clear I'm laughing with you :)
I love your ending. If you replay the part where the whale dives as Ahab spears the whale you can hear the whale gasp. "you're over acting, I'm not really an evil whale"
Lmfao great rant near the end. It beat you and now it's yours. It would be interesting to cut everything off the board and throw a few hundred volts onto some traces to test for conductance. Good video and uncut honesty is the way to go!
Take the chassis and build something cool! Point to point how you’d like it to be. Sad to see this struggle end, it’s been entertaining to watch. Ha ha. Cheers!
Russell E Simonetta - that would be rad. It would be cool for him to touch on something different - I’ve got a 1961 CF Martin 112 combo, basically an upgraded deluxe circuit and made for Martin by DeArmond. Would be a great project to use that transformer on too.
I have been following this series intently. It was like re-living my years as a computer tech. I once spent over a week trying to troubleshoot a POS PC that the customer refused to replace with an actual useable tower. Turned out to be a failed modem. There was no logical reason for that to fail the computer but it did. After I finally figured it out, I put the old modem card out in the street in front of the shop and watched with great satisfaction as cars and trucks turned it into dust. We've all been there.
from troubleshooting experience, the things i often rule out early... "can't be this thing!"... often it turns out it WAS. so frustrating. but congrats! only halfway through the video but from the title i assumed you conquered it. awesome to hear your troubleshooting/thinking through the process. thanks for sharing this kinda thing brad!
ahhh just got to the end! i mean, what a PITA! watching you troubleshoot is awesome learning material... but the best point here, know when to quit! you're the best for showing not just the glories, but failures too. cheers!
Strange, I'm gonna miss that DC3. I owned one for a year, it was a crap sounding amp. BUT I've really enjoyed watching Brad's work on it and was really hoping he would eventually fix it. Merry Christmas Brad and thanks for all the entertainment this past year.
Oh man too bad. I was hoping for a happy ending triumph after all you've been through. It was still good to watch and I appreciate the unfiltered / unedited real world approach. I find that more helpful for learning and setting expectations. Looking forward to hopefully more successful amp service videos!
you can get a transformer rewound. i use guys that re-wind motors, an output transformer is easy compared to most motors, and for a reasonable fee they'll rewind to original, or better specs.
Part V: Brad suspects the variac Part VI: Variac vindicated - Wall socket under scrutiny to be continued :) Taking on that repair was a true Moby Dick-move, ey? However ... two things: a) you need some trustworthy gadgets that can simulate transformers and b) expect a xmas-sock in your PayPal-mantelpiece for the output trafo. Good show, despite the ending.
Brad, you did a great job on this amp. If I can offer some words of encouragement I’d like to remind you that we learn the most from our failures. The amount of experience that you gained from this is invaluable. Some more advice that I live by with failed equipment is “I’m either going to return it. Try to repair it. Or enjoy smashing it”. I think you live by the same mantra.
Slowly descending into madness, som men in white coats will come to get you and put you in a room with padded walls where you can bang your head and slowly whisper to your self - ”it’s running away... it’s running away”.
I get it - I use to work on Aircraft avionics in old days when things where all tubes or mixed tubes/transistors and early solid state, and that's how you trouble shoot - the way you did on this amp. That's still pretty much how I do all my OWN repair & troubleshooting GOOD LUCK and LOVE the SPF's
squealing is not due to mismatched impedance, but most likely you flipped the polarity and turned negative feedback into positive feedback loop. I would try to flip either the primary or the secondary. Tubes are not that sensitive to impedance and will work in most cases +-50% of the spec'd values.
I'm with you on the impedance thing. I would have expected SOME function too, but it was just too far off. I don't think it was the polarity. I believe I did flip at one point, but admittedly can't say for sure.
Well, you' ve might have fallen as 'the great amp rebuilder' but you've raised your star as an art director. The ending with those seagulls backing that shot over the 'disintegrated' :P board; i think i've just seen the best peace of art-house in a long time! By the way, tonight i learned a thing or 2 about output xformers and impedance. Btw did you rant? Where??? ;) I mean i really dig your quest and letting us take part. Really enjoyable and instructional.Keep it up!
That was a sad ending. I thought you'd come up with something and fix the amp. You should rebuild it for yourself. That's the only way to actually beat it.
I have had these types of repairs that drove me crazy. I keep going back to the zener diode in the low voltage supply. Watching your vids helps me to say no to certain amps that come my way.
hey Brad I'd like to say first off I listen to all your videos I love them I happen to be legally blind at this point in my life but in the late sixties and early seventies I used to work on electronics with my dad was there was no digital back then I are going to build the heath kid stuff like that but anyway I get so much information out of you are videos not even being able to see them it's a shame for me that I'm not able to put a lot of what I learned from you to practical use I have to say also you have an amazing amount of patience and integrity to put this thing on the internet like you had mentioned in your little rant just curious if you ever get around to seeing this how many hours and labor did that cost you what did that take go and either way love you videos I watch him from beginning to end and of course if there's any misspelled words or anything weird no punctuation Etc it's because I'm legally blind and speech-to-text is not often that accurate thanks for your videos.
Your speech to text software must be very good. You came out very clearly. I'm glad you dig the channel, Robert. A lot of my subs say I talk to much, but in your case, that's probably a good thing, right? Blessings to you and yours this Christmas and Happy New Year!
Thanks for the honesty Brad. You've just got to laugh sometimes. This makes me so appreciative that I dumped my Mesa Mark III way back in 1995 and have been a vintage Fender amp guy ever since. I even learned how to repair those myself because they are so simple. That is why I watch your channel because I will never have the knowledge to attack the Leviathan and I'm curious how the pros go about doing it.
OUTSTANDING!!! Without a doubt, one of your best! The over-engineered wank-fests, like this piece of foolishness, that are being sold, these days, defy all logic. Instead of looking at classic designs (Marshall Plexi, Fender Twin Reverb, etc., etc.), and emulating them, with *maybe* a few simple tweaks to make them a bit more user-friendly or tone-rich, the most recent generation of engineers (that have gotten themselves into positions of influence) insist on using every imaginable little morsel of the latest technology to produce amps that are 'just like a Plexi, 'cept better!' for the sake of trying to eliminate .5dB of noise...that nobody (except non-musician audiophile snobs) ever noticed or cared about! In the process, they concoct a beast that costs three times as much, and can't be serviced except by a team of Nobel Prize winners dancing naked around a fire at midnight under a full moon, using tools salvaged from the Roswell crash site! I only take solace in knowing that, by the time the *next* generation of incredibly stupid amp designs is born, I'll probably be dead! Dear Mesa Boogie....Get off my lawn!! :-)
A big part of me still admires the engineering skill it takes to design a channel-switching thing with all these features guitarists seem to be asking for, but in this striving for greatness our human limitations and the limitations of our physical Universe are underscored.
@@TheGuitologist ... Once upon a time, we had single-channel amps, or two-channel amps that required moving a cable from one input to the next. In adding effects, we simply chained them between guitar and amp. It was (depending on the effects you used) maybe a little noisy, but the end product (sound/tone) was the stuff that 'old school' dreams were made of!! Technology is wonderful....hell, it's a gift! Gratuitous use of technology, however, can only be described as self-aggrandizing and stupid! Too many newly-minted guitar players are convinced that buying the latest tech will make them Clapton, or Yngwie, or Chet Atkins, or (pick your favorite picker)....and then suffer disappointment and abandon the instrument. Fifty years ago, we had rich kids with similar ideas...and results...but generally the perspective was much more realistic (Guitar - practice - rinse and repeat), and you had a much tougher time hiding behind your equipment! Some of the best players played Silvertone gear because it's all they could afford. Modern technology is too affordable and too accessible...and accomplishes very little, musically....and that doesn't even begin to address modern-day techs' nightmares! You lasted way longer than I would have, and way longer than most tech I know. Most guys I know would have handed it back with a note attached, that read, "Call Mesa. Good luck. Apply for financing now. You'll need it." Same goes for the latest and greatest from most manufacturers. Competent tech work used to require training. Now, it requires at least a Masters' degree in engineering (MSEE)!
@Norm Jacques, it's edemic. I saw a Cadillac recently that had so many systems running in the background (while the car was not in use) that, it would drain the battery it not driven regularly. So I went to charge the battery and I found that the battery was in the trunk. And, you couldn't open the trunk without battery power.
Aaaand finally finished watching. I am a little disappointed that we didn't see current measurements from the ptx but fully understand your frustration (and the original owner's) and this is a fitting end to the thing. Even if you'd done that & pinpointed the issue, it was an economical total-loss at that point anyway & saving the parts might at least help save stuff worth saving. At least you got an epic series out of it, just wish I could double-like the video for the outro alone !
I know how you feel about the whole "parts changer" thing. I work in car restoration and all these B.S. shows have people very blindfolded about how long it takes to actually do that kind of job. Sure they'll finish a project in a couple of episodes, they don't acknowledge the fact that it took 2yrs to film, or they have a truckload of sponsors that keep them supplied with parts, or if you have to do metal work that anything aftermarket is made in China and never fits right which involves a lot of work just to get in on the car. Hmmmm, I'm rambling, I'll stop now sorry lol
I did consider that too, but following Moby Dick down the power supply was more than I cared to bear 4 videos in. Part of me wanted to keep going, but I have plans for 2019 that don't involve Mesa-Boogie. :P
What I was thinking too. Something in the rectification. I would have swapped out the main filter caps too. Just because they don’t get hot doesn’t mean they aren’t leaky at voltage. Caps are cheap enough. Your Fluke meter will measure AC content with your DC measurements. That would give you a good clue. That’s why I own a Fluke 189 and Brymen 869s to measure AC and DC at the same time with the dual display.
No offense taken! TVs would be a whole other level if one decided to go Poltergeist! They even have snow to stare into, and shit can crawl out of those.
Hi, Your channel has been very helpful for me, I've been fighting with a Roadster for 2 weeks on and off (as you do) another tech had it for a year b4 me and destroyed most of the evidence, and the pcb! Just fixed it (fingers crossed). I've been been building and fixing tube/valve amps for 45 years, so I feel your pain on this one. I have a habit, personally, of redesigning things I can't fix. The obvious culprit in your amp here has to be the high ohm resistors on the grids of the output valves going down to ground, I can't imagine what else would have caused your problem. sorry I didn't see your post 2 years ago, I'm sure I could have helped. Anyway, Great stuff! Please keep posting. Cheers. Mike
I have been working on a Mesa 50 Caliber 6L6 1x12 combo from March 1989. The cabinet and chassis construction are great. The entire chassis is mounted on dampeners that float it in the cabinet and isolate it. The power tube sockets are chassis mounted. I just do not like the 220k power tube grid resistors and the negative bias fed to the phase inverter among a few other things, like the amount of NFB. I am going to fix it up and make it play with some soul, which is what Mesa amps lack. They feel stiff and "solid statey" in general, mostly because of the things I mentioned. Why exactly do you not like them?
@@hyperluminalreality1 For the same reasons Brad posted this series of vids. I wasted a whole day of my life trying to repair a Mesa Nomad 45. I finally gave up and told the owner to take it to a Mesa authorized tech which he did. The Mesa tech told him the mother board needed to be replaced. After shelling out $570.00 for the repair he played it for less than 30 minutes and guess what? Same problem...Power tubes red plating. After taking it back three times to get it repaired the tech gave up on it too. I also had someone come by with a Mesa Triple Rec with the same problems. All I could do was wish him luck and send him down the road. Sometimes the best thing you can do is learn how to say "NO"
Fart at the 26:00 minute mark also. Man Brad, you weren’t kidding about this amp and it’s definitely doing something to your ass, but kicking might not be the right word. Lol, more like pumping, oh damn lol. Sorry duder, I mean no disrespect and I’m sorry for the “blue” humour. Best of luck my man
I know this wasn't a fun amp to work on, but it was great entertainment. I appreciate that you show us your whole trouble shooting process and share your thought process as well.
Yes. Yes I do. Absolutely. Also, they deliberately design their amps so you cannot use other manufacturer's off-the-shelf parts, so you have to come to them for parts.
@@TheGuitologist my go to tube tech actually told me a story one time about a Mesa that would go into oscillation and he couldn't get it to stop. I believe after he spoke to someone in the know on that particular problem it turns out that it was because he was using decent tubes in it. They were higher gain tubes than the Mesa tubes, which I believe were rebranded Chinese tubes? The higher gain of the better tubes was sending the amp into oscillation. Interesting story if true.
The Guitologist You should have at least taken it outside and let us observe a full red plating melt down eruption!♨️🎆✨🎇Now youve got to put it all back together and have it ready for the new years festivities!ha ha!
What an epic, just been binge-watching this & got 8 minutes left. Have to say though, my thoughts with it narrowed to power trans/board is I'd get an ammeter between the rectifier and 400v tap and see if the amps went up as voltage went down. Guessing thats the next step though, as there's 8min left on the video. Thanks for sharing all this, it reminds me of a saying "if I have seen further than others, it is only because I was standing on a pile of my failures"
I value your work and effort to try to sort it out the voltage drop problem . You have been follow everything through the schematics and looking closer to the PCB's itself . The only thing I can say is that is not a lack of knowledge , I've watched the 4 videos and I can tell that I would trust you repairing my amps without a doubt . I believe that you were really close to it ... maybe the power trans !? Thanks a lot for the endure workshop .
One day you are really going to have to break down and get an oscilloscope. You have no clue whats going on with the grid bias other than DC. I have seen this kind of runaway fail over and over for 50 years. Uncle Doug and El Paso Tube Amps will tell you the same thing. The general layout of this amp is horrid, and may well lead to parasitic oscillations. You done very good at logic and method to work out what is causing the runaway... but at some point the combination of crap design and weird behavior will drive the necessity of seeing waveforms. Frankly, I like what you did to it... These are a bad design.. better off taken to useful parts than spreading the curse of arrogance and incompetence of the designers. I would have taken it to range... seeing bad stuff disassembled by velocity has its own rewards.
I agree. Mr. Guitologist would rarely if ever need a sooooper-dooooper scope since he isn't working on computers or nuclear reactors. He could get away with an older Heathkit or equivalent quality used one. Maybe one of his fans has an old scope to donate or take donations for. I would love to see Brad use a scope so wee can see the waveforms. That is how amplifiers were biased back then other than just setting the bias cold.
Jennifer WhiteWolf I agree about needing a scope. I also believe newbies should use a scope. I have no doubt that I would have learned electronics faster if I had a scope at the beginning. And I believe that I will repair devices quicker and easier if I start using my scopes more often.
When your a newbie you don't usually know yet WHY you need a scope. Brad is not a newbie and he owns a scope. I agree that a scope is the best tool to verify extreme high frequency oscillations. Usually best to remove negative feedback on output of the amp. Personally I would have kept the amp and put it on a back burner in the shop. My curiosity would have continued till I could diagnose the fault. To never know 100% what is at fault would drive me crazy. So I pose the question how could this amp be oscillating? Explain it here please
When I was a newbie and learning to use transistors and build oscillators, you don't think I would have learned faster using a scope instead of only watching voltage/current with my DMM's?? I believe that I would have learned faster being able to actually "see" what was going on.
Personally, I think changing parts is a perfectly valid method of fixing a fault in a piece of electronic equipment, for one, if the fault is still present after the suspect part has been replaced, then at least you can rule-out that part as being the cause of the fault, fault-finding in a piece of electronic equipment is analogous to solving a mystery, once all the suspects have been eliminated, whatever is left has to have something to do with the fault.
The problem with an approach which does NOT include "parts changing" in this instance is, the issue was heat related. It was only happening under load with the amp being on for some time first. So whatever part was failing was not going to show a fault at room temperature with a 2V test lead attached to it.
I seem to remember reading in an online forum somewhere on the internet, about a Marshall DSL 100 amplifier head that was exhibiting an unstable power tube bias issue which turned out to be caused by some slightly conductive FR-4 fiberglass PCB material, that definitely proves that it most certainly can happen, the fiber eyelet boards in vintage Fender amps had a tendency to soak up moisture which caused slightly conductive paths to develop between some of the eyelets, my mid 70's (I'm guessing) Fender Super Twin amp uses three of those vintage style fiber eyelet boards, if I had the time, and all materials needed, I'd upgrade them to a set of three FR-4 Fiberglass Turret Boards.
Anybody who's worked on anything electronic has had repairs like this. I applaud your humility in posting this. One of the things I like best about your videos is that you don't always get it right the first time, and you leave your mistakes in. That gives hope to the rest of us.
Anyone who has never gotten their butt kicked by a repair is either a noob or lying. It happens to the best of us.
It's all learning and yup humility is actually a strength.
@@russellhltn1396 word
This is real shit
@@russellhltn1396 Ditto....
legend has it the amp is still running away ever after it was completely taken apart..
All of a sudden wild horses appeared and dragged the amp kicking and squealing and redplating away.
Maybe it's the holy diver then?
@@goodun6081 Oh, make no mistake, I ran! Just about 6 weeks too late. :D
This amp is the Forrest Gump signature model.
"If this turns out to be a fuckin' phase inverter tube, I'm gonna puke" lol pure gold Brad
"Towards thee I roll, thou all-destroying but unconquering Mesa-Boogie; to the last I grapple with thee; from hell's heart I stab at thee; for hate's sake I spit my last breath at thee. Ye damned amp."- A-Brad
In this unfortunate work of non-fiction, we see a man's slow descent into madness.
Lovecraft would've been proud of this story.
It truly has become a classic. Not sure how many times I’ve watched it by now. Hurts so good 🤙
What we have here is an interesting case study in psychiatry more than anything else, watching the slow unravelling of a man's mind in the face of overwhelming adversity. The crushing of his already fragile ego. The feelings of victimhood and persecution. Captain Ahab is a very well chosen analogy indeed. Still, he'll probably recover once the source of his anguish is removed, and once he stops smoking so much pot!
That was comedy. I love Brad the Guitologist!
I’m an old aircraft mechanic - retired, you do more real world troubleshooting than anyone I’ve come across. Regarding Mesa - marketing A++. Beyond that fact, less is more.
Dude, you're amazing! I love the honesty. I'm a Lineman and I've had monsters like this in my 25 years. No one retires un-beaten. I like to drive out to the middle of nowhere and scream.
Beautiful work of art Brad , the Ahab analogy was perfectly realised and conversely I now understand Melville's tale better! I have thoroughly enjoyed the dramatic series of videos about that arguably badly designed amp and the ending was perfect , not a patsy Hollywood ending but a real life one where we all learn something valuable. From the Nemesis of ancient Greece to Job's tribulations or the labours of Hercules , to the trials of our everyday jobs , c'est la vie!
You’ve exposed some awful truths about today’s gear Brad and every musician should pay attention. Here’s the problem - Tubes are really really hot. PCBs hate really hot. Mesa (and others too no doubt) is/are trying to defy the laws of the universe by cramming 10x more shit that all hates hot, directly over a bunch of very hot vacuum tubes, and then restrict the cooling even more by putting it all in an insulated wooden box that’s half the size it should be. Worse, they’ve created a monster that no human can really troubleshoot or repair without spending hours in disassembly/reassembly between testing procedures. So really- it’s a disposable product. The cost of diagnosis is always going to exceed the value of the product as soon as it’s out of warranty.
Well - That’s bullshit.
If a manufacturer really wants to build the International Space Station inside what should be a very simple tube amp, what they should do is what the auto industry has done. Provide a diagnostic port and a way for the device to generate error codes, then break up the main board into chunks, each sealed in epoxy so they can’t be reverse-engineered - and make it modular. If you get code 0000101 - you unplug module B and put in a new one. It costs the owner $500 for each module but tough shit- if you really need a 112 TUBE combo with 15 switchable levels of gain and 4 channels of assignable EQ and 7 different routable signal paths and midi and all the other shit they cram in that nobody playing a bar gig ever utilizes.... then there you go. It would still cost north of $2K but at least it would be serviceable. It’s not just amplifiers- my in-laws had a $6500 refrigerator with all the IoT bullshit - yes it let you know when the milk was getting old. But then one foggy Xmas eve a lightning strike happened 100 yds from their house and despite having arresters in their circuit panel - it fried everything electronic in the house. I watched as half a dozen techs came and went trying to make that refrigerator work - they replaced every component in the thing before it was over and the company finally gave up and shipped them a new one. Luckily insurance covered all of that but it was exactly the same cluster as your Mesa amp. Something relatively simple being overly complicated with bells/whistles and no easy way to repair it. End of rant - keep doing what you’re doing!
PC boards are used for mass production. Point to point wiring is expensive to manufacture. That may work for a $5k Dumble but it doesn't work for a $849 whatever. You are absolutely right about controlling heat and it is a problem for all amplifiers.
Stack enough analog circuits together without taking pains to isolate them, and they may work but become impossible to repair. Why do you think everything is trending digital? Because it's much easier and much cheaper to do consistently and repeatably, even if it's not quite as good as analog gear in perfect condition. The problem is that it's not economically viable to keep the analog gear in perfect condition.
Enjoy your vintage amps, but it matters most when playing alone. Once you get into a band, nobody will care -- not even you, after a while -- if you use a Kemper or a Hughes & Kettner instead. The differences are just too subtle to survive a full contact scrum. That is why more and more gigging musicians are opting for modeling amplifiers, even ones who play on vintage amps at home.
Hey just to be clear - I have no problem with PCBs for low cost amps or for tube amps for that matter - but they still have to be serviceable and reliable. This Mesa design is neither.
Mal-2 KSC no disagreement here - I gave up gigging with all valve amps long ago because of the reliability issues. I played for 20 yrs with a hybrid- solid state power amp and tube preamp. If I was still doing it today I’d definitely be using a digital modeler. Nuance of tone is totally lost in a noisy bar. UR correct- it makes zero difference to anyone.
hmm, i got myself some really old 50s/60s pro audio tube amps made by philips and they also used PCBs sometimes. But they knew what they did back then...the PCBs is at the bottom and the tubes sockets are soldered onto the component side as well and the tubes are upright. And the PCB material used being only FR2...but they also have their own problems nowadays...FR2 is known to absorb/resorb liquid from the air and even the best ceramic sockets desolder themsevels over time when the FR2 moves (expand and shrink again as the liquid will evaporate) and the solder gets warm...therefore they need some reflow every now and then, as the FR2 is almost 60/70 years old.....
The main problem is, you already said that....careless designers...glass reinforced FR4 has a temp range of around 300degreeC... so no issues with that, now do it all in a software PCB designer and simulate it....use DRC according to main standarts (which are not covering tubes anymore) the DRC come up with no errors....lets start production....See these traces...some are carrying 300+ Volts DC....they sould have at least 7mm clearance and creapage distance to any other electric potential....the same goes for the components...as laquer, plastic and/or shrinktubes are not concidered as a sufficient insulator. And this is what all these younger designers tend to forget/don´t know...as tubes and their handling/design rules are not longer a center spec, what you come across every electronics lectures/books/savety standarts....you either get to know these separately all yourself, or read old books and try to get all these all electric standart issues from the golden tube days...
Used to have the 20 watt version of this. After watching this series, I'm glad the damn thing got stolen.
Check your guitar shop for the 20 watt Mesa that's been in 19 times.
The seagull sounds at the end as we pan in close, that’s freaking gold.
I love watching your channel for this sort of thing. I give you a ton of credit for not only thinking through your issues but vocalizing them to a camera and then posting it to the 'tube. Watching your thought process is enlightening.
I thought for a moment there, after doing the end view of the parts you were going to say... "Oh wait, I can see a burnt component... you've got to be kidding me!!".
Hey Brad...2 years on. I'm curious of of the final destiny of this amp...But cheer up! Help is on the way.They are now Mesa owned by GIBSON! As the saying goes, " I didn't think it could get any worse!"
With over 50 years fixing stuff like this, I feel your pain. If you're up for one more round, I would offer these few tips that may help you slay the beast. At the end of this vid your were on a track down the PS section. As ALL 3 sources came from the same main supply. You could start suppling the isolated C node load with an external bench supply to see if this stays stable in the amp. Then the B node and finally the A node. As the A node supply determine the performance of the B and C nodes, I would spend some time looking at the PS. I have seen many devices defy repair that turned out to be ether a PS componet failure and/or a soft ground failure. I wouldn't assume the transformer without testing it removed from the PS components. These steps wouldn't take much more of your time. And wouldn't it great if YOU were the one guy that MASTERED the Boogie Amp Beast? Hum?
This reply is the correct next step for troubleshooting. I rewatched this video again and went to click the like button on this comment. Then I realized I had already clicked it, two years ago.
Hello all. I have been rethinking this problem and by rewatching this video it occured to me that the math to determint he primary winding on the plate transformer was good to a point. That point is where a single plate is used. When TWO plates are paralleled on each side of the winding, I think you need to see the combined the impedance of the two plated much like two paralleled resisters. In this case the result would be one half of a single tube. ie: if a single tube plate impedance is 4k then two paralleled would be 2k.
I have no easy way to confirm this on my bench and I haven't seen any docs to say one way of the other. I think this could be what is causing the red plating issue, impedance mismatch.
This was thoroughly entertaining and instructive! I have a DC-3 and really like it, though I did need to cool down the bias (resistors) to stop the red plating. Eurotubes knows this problem, and sells matched JJ EL84s running on the "coolest" end of the spectrum.
WOW Bro. Best TH-cam video I've ever seen thank you for dealing with just reality! I felt every emotion you were going through because I have been exactly there myself. But truly from a filmmaking point of view that was amazing, I felt every uppercut that connected with your jaw. And every swing that missed. You are truly as good of a filmmaker As You Are a guitarist. And that is no insult! This Saga also reminded me of the movie "The Old Man and the Sea"
I really appreciate that compliment. I approach a lot of these videos like vignettes, and I want to show the human side of tech as well, so thank you.
Your videos are like hanging out with a good buddy. Thank you
Epic series! Thanks for posting and being so candid. I've had years of electronic troubleshooting experience and I can relate to your journey to hell and back. I was rooting for you the entire time. I'm new to audio amps so watching you work through logic trains was very educational for me. I love the ease of access and resiliency of eyelet boards and tube sockets mounted directed to chassis. When I saw you staring down that over-sized PCB and wrestling it out of the chassis I was cursing too!
Keep up the good work. Between you and Uncle Doug, I've getting a great education!
Thanks for the moral support. :D
Brad. I love this amp. I love it because its provided me with an EPIC amount of content! You sir are a trooper!
Set up a go fund me page for the cost of the transformer, we all want to see it fixed 🤣
I must say I'm not a tech but I really enjoyed all the videos on this Mesa Boogie
I was rooting for ya! Thanks for showing everyone that we are all human. I don’t know jack about amps but I have a need to fix things and love learning. Keep up the great work!
That rant is the reason I subscribed. Too many things are sugar coated these days because everyone is so sensitive. When you're right, tell it like it is. Because you were right! Thanks for the series of videos on this amp. Good stuff!
Call me Ishmael... epic ending, Captain Brahab!
We’ll see if the devil is done with you when we see how ‘vintage’ that Ampeg he sends
you is. I just spent two months restoring a 1964 M15 with much time dedicated
to picking through the fifty-four-year-old dried out Satan’s snot encasing
every single wire bundle and component. All I got was a sweet amp and an addiction
to sniffing mineral spirits…
Brad,
This was one of the funnest tech videos I have ever watched! I have worked on all my own amps since I was a kid and know this frustration very well. I want to congratulate you on leaving the 'reality' in your videos - it's my favorite part - watching you work through the problems. I have watched a bunch of them and I always learn something good. You're an awesome tech, man. Don't let this one amp get to you (yeah, I know it was in 2018, and it's 2020 now).
I watch all parts of this series with this amp I want to thank you for showing what you did and being honest and hope you continue doing what your doing on TH-cam
This amp sorta broke me psychically, if I’m honest.
I’ve been an Electronics tech since 1975. I had my ass kicked on several occasions by different circuits I’ve worked on. And remember the frustration that went with not being able to find the problem.
There was a Friday night after work, years ago that me and a few other techs even took a board that we had all troubleshot and failed at repairing to a bar. We put it on the table we were at and took turns yelling obscenities at it.
Unfortunately, it still didn’t work when Monday came. 😉
We’ve all been there.
In high tech we toss the ones we can't fix in 10 minutes. There is no sense wasting a lot of time on something that can be replaced.
That is the correct attitude in a factory old unique Steffens not at all
Well, what an absolute bastard of a problem. I can only salute you for your determination. I guess the Moby Dick analogy is just about perfect, lol. Fascinating video and learned more from this than many of your vids with quickly located issues. Thanks dude!
*Mesa Boogie... the heart of toneless and soulless sound. I had a Mark IIb years ago, and was able to sell it and use the money to buy my 65 Vibrolux!*
I dont think Mesa amps sounds bad, they sounds amazing. But...they are a nightmare to repair
Man, I understand your frustration!!! I'm not an amp repair guy but I know the feeling of, after trying everything, putting your hands on your head and wondering "What ELSE could it be?!".
Well, it was an interesting journey and I shared your frustration. I think we all have repairs like that. My one major failure still sits under my bench daring me to try again. Maybe I should dismantle it as you've done. At least you can now forget it and move on, or check out that pcb in detail. In any case, well done, you gave it more than any man could.
@ Haha, no way, I gave up on it back in 2014 and under the bench it will remain unless I find some new information that might help move the diagnosis forward. I should mention (in my defense) that the device in question is a tad more complex than a guitar amp.
Your comments at the end are the best. And i wouldn't take any shit from the trolls either. The last scene with the amp disassembled and the sound of the birds and ocean were great. LOVE your channel and always learn something and get entertainment as well. Kudo's !! Oh and you did the world a great service by taking that damn amp apart so it will never torture another human again. Thank you !
I thought about a grand time-lapse with heavy music showing the disassembly, but this was more poetically appropriate.
Rich Firyn n
My bad, didn’t mean to send anything
Brad you’re the best! I’ve enjoyed this series. I look forward to you blowing this amp up in your driveway
You've the patience of a saint. If it was me it would have been chucked out the window long ago.
I notice that you didn't bang on the sides Brad that may have been the problem, here's what I like about your video's, Your truthful and that goes along way with most folks.
"I´m gonna eat this transformer" Well, Bon appetit then :-)
You are a blast to listen to!! Thank you!! I laughed more at your tone and vocal style than I do at most comedians!! I mean it! THANK YOU!!! I'm subscribing!! Love your style! To be clear I'm laughing with you :)
I love your ending. If you replay the part where the whale dives as Ahab spears the whale you can hear the whale gasp. "you're over acting, I'm not really an evil whale"
Lmfao great rant near the end. It beat you and now it's yours. It would be interesting to cut everything off the board and throw a few hundred volts onto some traces to test for conductance. Good video and uncut honesty is the way to go!
Old Man and the Mesa... \m/
I could have taken Hemmingway in a fist fight.
Brad, you have the patience of a Saint !!! But it is highly addictive watching and listening. Keep it up pal.
Thank you so much for your correspondence on Messenger. Thank you so much for all you do, brother.
"He heaps me". My friend has a similar problem on an older Mesa bass amp. I'll let him know the fix.
it works wonders.
Take the chassis and build something cool! Point to point how you’d like it to be.
Sad to see this struggle end, it’s been entertaining to watch. Ha ha.
Cheers!
Russell E Simonetta - that would be rad. It would be cool for him to touch on something different - I’ve got a 1961 CF Martin 112 combo, basically an upgraded deluxe circuit and made for Martin by DeArmond. Would be a great project to use that transformer on too.
name it the "Satanic Piece of Shit", do a giveaway, smoke a carton of cigarettes at once and move on.
I have been following this series intently.
It was like re-living my years as a computer tech. I once spent over a week trying to troubleshoot a POS PC that the customer refused to replace with an actual useable tower. Turned out to be a failed modem. There was no logical reason for that to fail the computer but it did. After I finally figured it out, I put the old modem card out in the street in front of the shop and watched with great satisfaction as cars and trucks turned it into dust. We've all been there.
from troubleshooting experience, the things i often rule out early... "can't be this thing!"... often it turns out it WAS. so frustrating. but congrats! only halfway through the video but from the title i assumed you conquered it. awesome to hear your troubleshooting/thinking through the process. thanks for sharing this kinda thing brad!
ahhh just got to the end! i mean, what a PITA! watching you troubleshoot is awesome learning material... but the best point here, know when to quit! you're the best for showing not just the glories, but failures too. cheers!
41:59 Brad takes up the Tuba
Strange, I'm gonna miss that DC3. I owned one for a year, it was a crap sounding amp.
BUT I've really enjoyed watching Brad's work on it and was really hoping he would eventually fix it.
Merry Christmas Brad and thanks for all the entertainment this past year.
This was a nail biter for sure ... I thought he was gonna succeed. Surprise ending!
Thanks for making this videos!
Oh man too bad. I was hoping for a happy ending triumph after all you've been through. It was still good to watch and I appreciate the unfiltered / unedited real world approach. I find that more helpful for learning and setting expectations. Looking forward to hopefully more successful amp service videos!
you can get a transformer rewound. i use guys that re-wind motors, an output transformer is easy compared to most motors, and for a reasonable fee they'll rewind to original, or better specs.
Part V: Brad suspects the variac
Part VI: Variac vindicated - Wall socket under scrutiny
to be continued :)
Taking on that repair was a true Moby Dick-move, ey? However ... two things: a) you need some trustworthy gadgets that can simulate transformers and b) expect a xmas-sock in your PayPal-mantelpiece for the output trafo. Good show, despite the ending.
At this point, I would suspect it's a Mesa.
Brad, you did a great job on this amp. If I can offer some words of encouragement I’d like to remind you that we learn the most from our failures. The amount of experience that you gained from this is invaluable. Some more advice that I live by with failed equipment is “I’m either going to return it. Try to repair it. Or enjoy smashing it”. I think you live by the same mantra.
I never thought I'd see the day. A parts boogie. You gave it your all Brad. This was a super fun series to watch man. Thanks.
Slowly descending into madness, som men in white coats will come to get you and put you in a room with padded walls where you can bang your head and slowly whisper to your self - ”it’s running away... it’s running away”.
Had my money on the standby switch going high resistance
One of many possibilities.
I get it - I use to work on Aircraft avionics in old days when things where all tubes or mixed tubes/transistors and early solid state, and that's how you trouble shoot - the way you did on this amp. That's still pretty much how I do all my OWN repair & troubleshooting GOOD LUCK and LOVE the SPF's
Thank you for this great video. One of your best.
squealing is not due to mismatched impedance, but most likely you flipped the polarity and turned negative feedback into positive feedback loop. I would try to flip either the primary or the secondary. Tubes are not that sensitive to impedance and will work in most cases +-50% of the spec'd values.
I'm with you on the impedance thing. I would have expected SOME function too, but it was just too far off. I don't think it was the polarity. I believe I did flip at one point, but admittedly can't say for sure.
I know for a fact any tube amp using negative feedback will freak the f%$k out when you reverse the phase of one winding. Both is ok.
that's right
correct
Hmmm, if the output was oscillating, the the changed impedance could have shifted the frequency down into the audible range. Just sayin'.
Well, you' ve might have fallen as 'the great amp rebuilder' but you've raised your star as an art director. The ending with those seagulls backing that shot over the 'disintegrated' :P board; i think i've just seen the best peace of art-house in a long time! By the way, tonight i learned a thing or 2 about output xformers and impedance. Btw did you rant? Where??? ;) I mean i really dig your quest and letting us take part. Really enjoyable and instructional.Keep it up!
Geeveebee Loves Guitars 😂😂😂
Thanks for all the great info , I learned a lot .
I would have just thrown it out the window.
you are the calmest person I've ever seen anywhere!
Haven't you seen ' No time for Sergeants ' ? Andy Griffith just spits in thru the back and gives it a good wallop , works every time . HELLO
I have not, but it's now on my list! Anything with Andy Griffith i good in my book.
HELLO?
@@TheGuitologist I think it is his best . th-cam.com/video/U2fSw0ua5K0/w-d-xo.html
That was a sad ending. I thought you'd come up with something and fix the amp. You should rebuild it for yourself. That's the only way to actually beat it.
I have had these types of repairs that drove me crazy. I keep going back to the zener diode in the low voltage supply. Watching your vids helps me to say no to certain amps that come my way.
I would have been tempted to rip out the board and point to point the whole thing, then rename it the Anti-MESA-Boogie.
Brad I've got a problem with my Mesa-Boogie.................
th-cam.com/video/XrwK-zS2HZ8/w-d-xo.html
Don't we all ....
Do You Need mesa boogies address so you Caan ship it back😨?
@@slanford6767 Yes. I'll ship it one part at a time. It'll take 17 years at a rate of one part per day, but the satisfaction will be worth it.
Matthew 16:23
hey Brad I'd like to say first off I listen to all your videos I love them I happen to be legally blind at this point in my life but in the late sixties and early seventies I used to work on electronics with my dad was there was no digital back then I are going to build the heath kid stuff like that but anyway I get so much information out of you are videos not even being able to see them it's a shame for me that I'm not able to put a lot of what I learned from you to practical use I have to say also you have an amazing amount of patience and integrity to put this thing on the internet like you had mentioned in your little rant just curious if you ever get around to seeing this how many hours and labor did that cost you what did that take go and either way love you videos I watch him from beginning to end and of course if there's any misspelled words or anything weird no punctuation Etc it's because I'm legally blind and speech-to-text is not often that accurate thanks for your videos.
Your speech to text software must be very good. You came out very clearly. I'm glad you dig the channel, Robert. A lot of my subs say I talk to much, but in your case, that's probably a good thing, right? Blessings to you and yours this Christmas and Happy New Year!
It takes a real tech to be able to humor himself. Love it!
Thanks for the honesty Brad. You've just got to laugh sometimes. This makes me so appreciative that I dumped my Mesa Mark III way back in 1995 and have been a vintage Fender amp guy ever since. I even learned how to repair those myself because they are so simple. That is why I watch your channel because I will never have the knowledge to attack the Leviathan and I'm curious how the pros go about doing it.
Excellent existential zen ramblings. I shall call you grasshopper! You must now leave the temple!
OUTSTANDING!!! Without a doubt, one of your best! The over-engineered wank-fests, like this piece of foolishness, that are being sold, these days, defy all logic. Instead of looking at classic designs (Marshall Plexi, Fender Twin Reverb, etc., etc.), and emulating them, with *maybe* a few simple tweaks to make them a bit more user-friendly or tone-rich, the most recent generation of engineers (that have gotten themselves into positions of influence) insist on using every imaginable little morsel of the latest technology to produce amps that are 'just like a Plexi, 'cept better!' for the sake of trying to eliminate .5dB of noise...that nobody (except non-musician audiophile snobs) ever noticed or cared about! In the process, they concoct a beast that costs three times as much, and can't be serviced except by a team of Nobel Prize winners dancing naked around a fire at midnight under a full moon, using tools salvaged from the Roswell crash site! I only take solace in knowing that, by the time the *next* generation of incredibly stupid amp designs is born, I'll probably be dead! Dear Mesa Boogie....Get off my lawn!! :-)
A big part of me still admires the engineering skill it takes to design a channel-switching thing with all these features guitarists seem to be asking for, but in this striving for greatness our human limitations and the limitations of our physical Universe are underscored.
@@TheGuitologist ... Once upon a time, we had single-channel amps, or two-channel amps that required moving a cable from one input to the next. In adding effects, we simply chained them between guitar and amp. It was (depending on the effects you used) maybe a little noisy, but the end product (sound/tone) was the stuff that 'old school' dreams were made of!! Technology is wonderful....hell, it's a gift! Gratuitous use of technology, however, can only be described as self-aggrandizing and stupid! Too many newly-minted guitar players are convinced that buying the latest tech will make them Clapton, or Yngwie, or Chet Atkins, or (pick your favorite picker)....and then suffer disappointment and abandon the instrument. Fifty years ago, we had rich kids with similar ideas...and results...but generally the perspective was much more realistic (Guitar - practice - rinse and repeat), and you had a much tougher time hiding behind your equipment! Some of the best players played Silvertone gear because it's all they could afford. Modern technology is too affordable and too accessible...and accomplishes very little, musically....and that doesn't even begin to address modern-day techs' nightmares!
You lasted way longer than I would have, and way longer than most tech I know. Most guys I know would have handed it back with a note attached, that read, "Call Mesa. Good luck. Apply for financing now. You'll need it." Same goes for the latest and greatest from most manufacturers. Competent tech work used to require training. Now, it requires at least a Masters' degree in engineering (MSEE)!
@Norm Jacques, it's edemic. I saw a Cadillac recently that had so many systems running in the background (while the car was not in use) that, it would drain the battery it not driven regularly. So I went to charge the battery and I found that the battery was in the trunk. And, you couldn't open the trunk without battery power.
@@rchavez2112 ... The older I get, the more I understand my father...and if you're me, that's pretty scary! LOL
Ive always likened Mesas to the cockpit of an airliner. They are wayyyyy over complicated for guitar amp.
"Mesa Boogies have nothing to offer but blood, toil, tears and sweat" - Bradley Churchill
Aaaand finally finished watching. I am a little disappointed that we didn't see current measurements from the ptx but fully understand your frustration (and the original owner's) and this is a fitting end to the thing. Even if you'd done that & pinpointed the issue, it was an economical total-loss at that point anyway & saving the parts might at least help save stuff worth saving. At least you got an epic series out of it, just wish I could double-like the video for the outro alone !
I know how you feel about the whole "parts changer" thing. I work in car restoration and all these B.S. shows have people very blindfolded about how long it takes to actually do that kind of job. Sure they'll finish a project in a couple of episodes, they don't acknowledge the fact that it took 2yrs to film, or they have a truckload of sponsors that keep them supplied with parts, or if you have to do metal work that anything aftermarket is made in China and never fits right which involves a lot of work just to get in on the car. Hmmmm, I'm rambling, I'll stop now sorry lol
Why wouldn’t you just send it to MESA Boogie??
For instance.
The chronics of Brad. Loves these videos. I've been learning a lot. Thanks, man.
Love your channel Brad. Keep up the good work!
what about the 1N4007 diodes?
wickedxe that’s what I’m thinking
Something silicon, anyway. Seems thermal related.
I did consider that too, but following Moby Dick down the power supply was more than I cared to bear 4 videos in. Part of me wanted to keep going, but I have plans for 2019 that don't involve Mesa-Boogie. :P
What I was thinking too. Something in the rectification. I would have swapped out the main filter caps too. Just because they don’t get hot doesn’t mean they aren’t leaky at voltage. Caps are cheap enough. Your Fluke meter will measure AC content with your DC measurements. That would give you a good clue. That’s why I own a Fluke 189 and Brymen 869s to measure AC and DC at the same time with the dual display.
NO OFFENCE INTENDED AT ALL BUT I WAS A TV TECH AND PROBLEMS LIKE THIS IS WHY I HAVE NO HAIR LEFT :p
No offense taken! TVs would be a whole other level if one decided to go Poltergeist! They even have snow to stare into, and shit can crawl out of those.
Triplett makes good stuff. They've been at it for a long, long time. Love watching your videos, keep up the great work!
Hi, Your channel has been very helpful for me, I've been fighting with a Roadster for 2 weeks on and off (as you do) another tech had it for a year b4 me and destroyed most of the evidence, and the pcb! Just fixed it (fingers crossed). I've been been building and fixing tube/valve amps for 45 years, so I feel your pain on this one. I have a habit, personally, of redesigning things I can't fix. The obvious culprit in your amp here has to be the high ohm resistors on the grids of the output valves going down to ground, I can't imagine what else would have caused your problem. sorry I didn't see your post 2 years ago, I'm sure I could have helped. Anyway, Great stuff! Please keep posting. Cheers. Mike
For the love of God, Brad - be careful with those parts you've scavenged. For all we know this amp could be like James Dean's Porsche 550 Spyder!
That fart at 41:50 sums up how I feel about Mesa amps. :-)
I have been working on a Mesa 50 Caliber 6L6 1x12 combo from March 1989. The cabinet and chassis construction are great. The entire chassis is mounted on dampeners that float it in the cabinet and isolate it. The power tube sockets are chassis mounted. I just do not like the 220k power tube grid resistors and the negative bias fed to the phase inverter among a few other things, like the amount of NFB. I am going to fix it up and make it play with some soul, which is what Mesa amps lack. They feel stiff and "solid statey" in general, mostly because of the things I mentioned. Why exactly do you not like them?
@@hyperluminalreality1 For the same reasons Brad posted this series of vids.
I wasted a whole day of my life trying to repair a Mesa Nomad 45.
I finally gave up and told the owner to take it to a Mesa authorized tech which he did.
The Mesa tech told him the mother board needed to be replaced.
After shelling out $570.00 for the repair he played it for less than 30 minutes and guess what?
Same problem...Power tubes red plating.
After taking it back three times to get it repaired the tech gave up on it too.
I also had someone come by with a Mesa Triple Rec with the same problems.
All I could do was wish him luck and send him down the road.
Sometimes the best thing you can do is learn how to say "NO"
Fart at the 26:00 minute mark also. Man Brad, you weren’t kidding about this amp and it’s definitely doing something to your ass, but kicking might not be the right word. Lol, more like pumping, oh damn lol. Sorry duder, I mean no disrespect and I’m sorry for the “blue” humour. Best of luck my man
Wow, what a saga. I'm at the same time both happy and sad to see it end. Ever forward, friend.
I know this wasn't a fun amp to work on, but it was great entertainment. I appreciate that you show us your whole trouble shooting process and share your thought process as well.
Replace tue 4 rectifier Dioden. One is leaking and loading tue correct working power transformiert after Hearing up tue diode-
Hucky Bruegger My thoughts too.
Call a priest.
We've taken too much for granted
And all the time it had grown
From techno seeds we first planted
Evolved a mind of its own
The real world, when mesa boogie goes down, it just takes everything thing with it, sanity, time, and money. Been there before. I feel the pain. Amen
Morning, Brad...
Hope you and yours are good.
Best to all for the Silly Season.
@34:32 Brad drops THE BROWN acid in 3....2....1.....
LMFAO
i spit out my coffee in laughter when i saw that.
It comes in colors?
You reckon Boogie runs the tubes so hot to sell more tubes? Nice try fixing it.
Yes. Yes I do. Absolutely. Also, they deliberately design their amps so you cannot use other manufacturer's off-the-shelf parts, so you have to come to them for parts.
@@TheGuitologist my go to tube tech actually told me a story one time about a Mesa that would go into oscillation and he couldn't get it to stop. I believe after he spoke to someone in the know on that particular problem it turns out that it was because he was using decent tubes in it. They were higher gain tubes than the Mesa tubes, which I believe were rebranded Chinese tubes? The higher gain of the better tubes was sending the amp into oscillation. Interesting story if true.
The Guitologist You should have at least taken it outside and let us observe a full red plating melt down eruption!♨️🎆✨🎇Now youve got to put it all back together and have it ready for the new years festivities!ha ha!
What an epic, just been binge-watching this & got 8 minutes left. Have to say though, my thoughts with it narrowed to power trans/board is I'd get an ammeter between the rectifier and 400v tap and see if the amps went up as voltage went down. Guessing thats the next step though, as there's 8min left on the video.
Thanks for sharing all this, it reminds me of a saying "if I have seen further than others, it is only because I was standing on a pile of my failures"
I value your work and effort to try to sort it out the voltage drop problem . You have been follow everything through the schematics and looking closer to the PCB's itself . The only thing I can say is that is not a lack of knowledge , I've watched the 4 videos and I can tell that I would trust you repairing my amps without a doubt . I believe that you were really close to it ... maybe the power trans !? Thanks a lot for the endure workshop .
One day you are really going to have to break down and get an oscilloscope. You have no clue whats going on with the grid bias other than DC. I have seen this kind of runaway fail over and over for 50 years. Uncle Doug and El Paso Tube Amps will tell you the same thing. The general layout of this amp is horrid, and may well lead to parasitic oscillations. You done very good at logic and method to work out what is causing the runaway... but at some point the combination of crap design and weird behavior will drive the necessity of seeing waveforms. Frankly, I like what you did to it... These are a bad design.. better off taken to useful parts than spreading the curse of arrogance and incompetence of the designers. I would have taken it to range... seeing bad stuff disassembled by velocity has its own rewards.
Jennifer WhiteWolf I own one. It isn't oscillating. Watch, you'll see.
I agree. Mr. Guitologist would rarely if ever need a sooooper-dooooper scope since he isn't working on computers or nuclear reactors. He could get away with an older Heathkit or equivalent quality used one.
Maybe one of his fans has an old scope to donate or take donations for. I would love to see Brad use a scope so wee can see the waveforms.
That is how amplifiers were biased back then other than just setting the bias cold.
Jennifer WhiteWolf I agree about needing a scope. I also believe newbies should use a scope. I have no doubt that I would have learned electronics faster if I had a scope at the beginning. And I believe that I will repair devices quicker and easier if I start using my scopes more often.
When your a newbie you don't usually know yet WHY you need a scope. Brad is not a newbie and he owns a scope. I agree that a scope is the best tool to verify extreme high frequency oscillations. Usually best to remove negative feedback on output of the amp. Personally I would have kept the amp and put it on a back burner in the shop. My curiosity would have continued till I could diagnose the fault. To never know 100% what is at fault would drive me crazy. So I pose the question how could this amp be oscillating? Explain it here please
When I was a newbie and learning to use transistors and build oscillators, you don't think I would have learned faster using a scope instead of only watching voltage/current with my DMM's?? I believe that I would have learned faster being able to actually "see" what was going on.
Personally, I think changing parts is a perfectly valid method of fixing a fault in a piece of electronic equipment, for one, if the fault is still present after the suspect part has been replaced, then at least you can rule-out that part as being the cause of the fault, fault-finding in a piece of electronic equipment is analogous to solving a mystery, once all the suspects have been eliminated, whatever is left has to have something to do with the fault.
The problem with an approach which does NOT include "parts changing" in this instance is, the issue was heat related. It was only happening under load with the amp being on for some time first. So whatever part was failing was not going to show a fault at room temperature with a 2V test lead attached to it.
I seem to remember reading in an online forum somewhere on the internet, about a Marshall DSL 100 amplifier head that was exhibiting an unstable power tube bias issue which turned out to be caused by some slightly conductive FR-4 fiberglass PCB material, that definitely proves that it most certainly can happen, the fiber eyelet boards in vintage Fender amps had a tendency to soak up moisture which caused slightly conductive paths to develop between some of the eyelets, my mid 70's (I'm guessing) Fender Super Twin amp uses three of those vintage style fiber eyelet boards, if I had the time, and all materials needed, I'd upgrade them to a set of three FR-4 Fiberglass Turret Boards.
One of the most effective tools for fault-finding in electronic equipment, is the human brain's capacity for deductive reasoning.
I can’t believe I just spent 3 hours staring at the inside of this amp. Bravo