Another DOOZY! - Mesa Boogie Tube Bass 400 Head Repair
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- Опубліковано 13 бер 2018
- CLICK HERE for Postmortem on this amp: • Does Mesa Boogie Inten... Well, here's another one that should have been a simple fix that ended up giving me fits and leading me on a wild goose chase instead. We'll start out with a simple recap and general clean, and end up chasing our tail in search of problems with coupling caps and the EQ board. This is the Mesa Bass 400, which puts out around 200W, not to be confused with the Bass 400+ Plus.
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Just ordered that Geekcreit tester. How cool is that thing? Thanks for the link.
I almost bought a Mesa Roadking i think it was called the mothership of there amps, but man i bet it would be a nightmare servicing it.
What was the blue tool you used to clean the PCB pads after desoldering? It made a funny click noise when you activated it
The Guitologist bro I think your skills are totally amazing!!! Also sounds like you can get down on some bass 2....
I have a kustom amp head I need repaired where are you located how to contact you thanks
Why am I watching this at 2:30am? Oh, because its virtually the only channel I watch now!
I had a Mesa 295 power amp back in the day (wish I still had it), and caused it to malfunction by running it through a Variac set at 140 volts! At the time I thought the way Eddie VH got his tone was by cranking the voltage - not by reducing it! Anyhoo - I had a heck of a time getting that amp repaired by local services. Mesa actually wrote me and explained that at the time, Randall Smith worked “intuitively”, and that local repair services may not be adequate. Michael Bendinelli at Mesa however, not only fixed my 295 (including added presence controls!) - but also modified my 1977 JMP Marshall with a killer gain mod!
Mike Bendinelli is a brilliant amp technician. Probably the very best with Mesa Boogie Amps. Especially vintage Marks. Yes Mesa amps can be a pain in the @$$ to work on, so rather than deal with it yourself, and listen all these hacks bitch about working on them, just send it to Mesa/M.Bendinelli. Depending on what your time is worth, you'll very likely be $$$ ahead to just let Mesa handle any repairs you have on any Mesa amp. My advice to this "guitologist" is if you don't like working them, then don't. It's that simple. Refer your Mesa Customers to Mesa and be done with it. And beware of so called Mesa Authorized repair centers. Most of them hate working on them (many will not tell you that though) too. Not only that, I would not let most of them work on a toaster.
@@dfwlistener7593 I was wondering about this subject... my 400+ was kind of baked in a cargo container in one of these damn forest fires (I live in Butte County, Northern California). The thing is looking a little rough. I don't even know if it's fixable but I can't find another one for less than $3,600. Sounds like I should probably take it straight to Mesa. Makes sense I guess. This is freaking me out because if I can't get it fixed I'm going to have to buy another one... and that's a lot of money. Shame of it is I saw one going for 900 bucks two years ago and I almost bought it...
I'm going to be honest here man- I'm almost in tears writing this... I'm starting to realize all my equipment was worth a lot more than I thought it was, and going without certain things is simply not an option. I imagine I know what you're going to say, so I'll probably be taking it to Mesa... I guess I'm just looking for words of encouragement or sympathy or something. Damn this is rough.
Peace.
After watching, I understand why you played a little Anesthesia... it definitely was like “Pulling Teeth” 🤘🏼
Comment of the day!
this is why i love your channel! big iron vintage tube amps! tons of videos out there about little oddball practice amps... but you're the only one who regularly tackles beasts like this. thanks for what you do... interesting stuff!
I do my best with this stuff and I learn something every time I do. Glad to have you and everybody else along for the ride! Thanks.
Here's the board for the EQ, I don't anticipate anything being wrong with that. lol
Famous last words.
Gotta say, nice Cliff Burton impression bro! You have inspired me to tackle some electronic projects in the future.
I have a Mesa Boogie Mk1 Triaxis going into a Simul 395!
Running 2x Mesa Slants. One side has a 12L + C90, and the other has 2x C90's! Nothing sounds like it! I've had em all over the years, Twins, Supers, all the Marshall's, JTM's Plexi's, The Boogie eats them alive! Those amps produce a 3D sound you won't get from anything else! And the power? Like 3 Marshall Stacks! There only real downside in my experience is the weight! They weigh a ton! And yes, I have had roadies drop one many moons ago! Not this one but a 290! It scratched a knob! Built like a tank! I'd never part with mine! Really enjoyed this vid and especially the tip on the loose jacks! Thanks!
Yeah dude. Those amps are ridiculous.. sound fantastic
Wonderful work man. And I really appreciate the knowledge you share. Cheers
Thanks, Scott.
I learn a lot watching, Brad! How did you gain so much knowledge and experience at such a young age, Brad? Learn in the military?
To clean pots like that you take the knobs off and spray the cleaner between the shaft and housing. That usually will allow enough cleaner to make its way into the pot to clean the wipers.
Those old Gum Drops will bite you on an older unit that has hi power and a lot of heat. A buddy told me once while looking at a similar unit "Recap means Recap, get em all." But Mesa has a reputation for problem child anyway.
You get 5 stars for staying with it partner!
I played in a band with a bass player who had one of these amps. He ran it through a Trace Elliot 4x10 bass cab. This is one of the best sounding bass rigs I’ve ever heard. Eventually he quit using it mostly because it went through tubes quickly and retubing this beast was expensive. Also picking up the amp was like picking up a manhole cover. Great sounding amp!
Hey man I just want to say you truly are one gifted and talented man. I wish I had a quarter of the understanding you do about electronics and how to fix them. If I did all of my amps would be working top notch. Thank you for these videos
I love these video!!! Keep them coming. Cheers!!!
Well done Brad,the words patience and saint came to mind as I watched you struggle,most of us have been in that situation without the right tool.
Cool Cliff Burton riff Brad
Cliff even played one of these amps
@@anders2772 was it a 400? Ive seen him use 2 mesa d180's
typically when you see the resistance value climbing or lowering it's as a result of charging a capacitor in the circuit. And I have found that the best way to test a transistor is to use an analog Ohm Meter, as the Digital Ohm Meters don't drive the transistor to conduct where you can see if the transistor is 'leaky'. Great stuff Brad, I thoroughly enjoy your videos and have spent many hours watching them!
I really enjoy your videos. Learned a lot about amps from you.
Thanks, Kevin. I appreciate that.
Got to hand it to you bro you stuck to it and got the sucker sorted. Ya now need a good set of magnetic screw dives on your wish list.
You and Boogies man......that said your perseverance is inspiring!
Lots of power and really nice tone!
Your work is so addictive!
This reminds me of the Ampeg SVT-Pro series. Interesting setup and a good look into rack mountable tube amplifiers quite common to high power applications.
What a beautiful beast! And little tricky EQ.
Excellent video! Good troubleshooting!
Really nice job on this Brad,,, good detective stuff.
Thanks, Carl. Good seeing you.
Sorry for the editing mistake making you sit through me putting those screws back in the damn EQ board. How tedious. Not even sure how that got left in. Guess that's what happens when you edit at 3AM.
The Guitologist No No! It was great! I was holding my breath the whole time.
I was chuckling to myself.... thinking about people with anxiety trying to watch it. Haha
Yeah man, I should have put a seizure warning on the video if I was going to leave that part in.
No problem. I watch everything in 1.8x anyways. :D
Your amp diagnosis/repair videos are excellent.
Thanks, dude. I appreciate that.
I used to have a super twin. Hard to deal with n alot of money for new tube set and i never got it past 2. Im pretty thankfull for all the new smaller amps
Re. the method of installing the caps, the only reason I heard against this was that you may inherit any problems associated with the connection to which you attach the caps. Also the heat may cause the existing connection to be a dry joint. Good on you for taking such a monster on!
Man it’s great watching you work. And no, I’m not gonna fuck around inside my tube amp. I’ll leave that to the pros.
caps the bane of old equipment. well done.
BASS player here, just started studying tube amps and thank you for the pro tips ;)
Great tip on leaving the leads!! thanks!!
I take it all the rustling came OUT of the volumes as well? ALOT of work but You got it ! I did learn a few things thanks !
Hey Brad, there is an attachment you can get that screws on to the front of a pot and allows you to squirt cleaner in around the shaft. I'm not sure who makes them but I've seen Dave's world of fun stuff use one from time to time. Something like that would make easy work of a job like this where you don'e want disassemble the entire amp just to clean the pots.
Thx for the doing the bass amps
Brad, I recently repaired a Mark 4 for a customer and what a nightmare. Well engineered and assembled but.......... not repair friendly. Anyway, just want to let you know how much I enjoy your videos.
I was right there with ya Brad putting the screws back in the EQ. I caught myself holding my breathe trying to help. Lol
those blackies look awesome in there, Nice work Brad. serriously cool album cover litterally and . Blessings as allways.
thumb up for the sloppy jack fix alone. good work.
EQ switch on my 400+ is also funky, but relents with a good nudge. 🤓 Currently using the 6L6x12 beast as a clean template for guitar (or to power my old Demeter VTBP 201) and the sound is just stunning. When conditions are right and the tubes good and warm, the guitars just sing through the venue. Rock solid for 30 years. 💪✌️🤙
I'm jealous... my 400 + was quite possibly destroyed in a forest fire: I don't know if it's fixable. I paid $900 bucks for it but I see that now they're going for at least $3,600. I am not okay with this situation... That amp was the only one that I could ever get to sound the way I wanted it to. Going without one is not an option.
Sometimes I played guitar through it... And it looks like I don't need to tell you how badass that is.
peace.
@@primateinterfacetechnologi6220 Wow, a forest fire? Sorry to hear that. It may be fixable if the pcb didn’t melt (unless you can find a replacement), but that sounds pretty disastrous. Boogies aren’t very service-friendly either, so all I can do is wish you luck and give you a heads up if I ever decide to sell mine. I had no idea they were selling for so much these days, but I get it. They deliver a certain sound and punch that one can grow attached to. It has given me some epic gigs over the years. All the best. Thanks for the friendly comment.
@@Damaraja Yeah man, thanks. The PCB on the inside of the front that holds the EQ and stuff is intact but some of the knobs half melted and I'm sure the pots would be replaced anyway... as well as probably most of the components on the board. I haven't looked at the area underneath the tubes and transformers but it's probably not melted. The other problem is that the fire department hosed everything down in there and then the authorities kept us out for a month (while various agencies tore through everybody's stuff, cutting locks, throwing people's weed out in the rain, and all manner of other violations for which there is zero recourse) so there was no one to dry the thing back out. there's a little rust on the transformers but probably not in them.
by all means if you lose your mind and decide to sell yours... I'm Probably buying... I guess we'll see. I'm going to check with my local repair guy and see what he says, Cuz I'm going to bring in my Orange "dual terror" for a tune up, but I've got a feelin' I'll be taking the boogie to Petaluma, if that is still where they're located.
again- Thank you. I appreciate the sympathy. most people don't really understand... Talkin' 'bout "your alive... things can be replaced" always makes me feel like saying- Oh good cuz I was getting worried. so when will my new Mesa boogie be arriving? Not to mention all the rest of my rare handmade instruments... and tools and artifacts and on and on and on.
peace.
So many of the old Boogies I've worked on have bad Orange Drop Caps, giving high DC voltage to the controls. In fact nearly All of them had that issue .
You wouldn't think those would be such unreliable caps...
Agreed. That isn't a failure I've seen much. As soon as you turned those pots I said, "Sounds like DC on the pots." Of course, they were still noisy, but...
if you buy cheap and simply paint them orange...the same goes for faked/counterfeit nichicon, NipponChemicon...and so on....;)
You did it man! Good for you!!!
Droooool...Always wanted one of these Old Mesa heads. Yea it may have been a pain in the ass but that thing will last another 30 yrs easily and still sound great!.
It'll be shaking rafters a long time to come.
This is an example of where an oscilloscope can be your best friend. Driving the input with a fixed constant signal from a generator, you can then go through the circuit place to place with the probe and see the actual signal and its level and/or distortion, and DC offsets. It makes finding faults like you have surrounding the volume control take only seconds to locate and verify. Same with tracing that EQ board. Obviously there are ways to work around, which you are becoming very skilled in, but once you make the big move to get a scope, and use it a few times, your going to love it.
This should be a tv show on discovery. Way better then hotrod shows!
Dont know didly about electronics - But always a pleasure to watch & learn
What a beast of an amp!
Thank you for the work you do good sir
Thanks for watching. Good to have ya.
The tubes on that beast! Damn...That's a stadium grade amp
bring that outside and its quiet at the 20 yard line, be great on a pair of 18's indoor in a small room, killer!
or just bi-amp w a couple pylepros
Thank you for sharing !
I’ve had issues with my Bass 400’s EQ and finally got around to looking into it. I purchased it new in 1987 and this is the first issue I’ve ever had. And, you’re right about that schematic. I ended up drawing mine own up to make it easier. Like yours, mine has a 470k resistor where the schematic says 1M right after the switch input splits to Q1. I’ve looked at the 400+ and it appears mine is a little bit of both. I also have a 180pF capacitor that isn’t in the schematic either. Still can’t get my EQ to work. Next step are the transistors.
Great stuff, thanks Guitologist. Looking forward to watching all of this. I fixed my own Mesa a year or so ago - the fault was one of the Sprague Orange Drop caps that had short-circuited and caused one of the 6L6's to red-plate. I'm kinda worried about all of the other Orange Drops now, wondering if/when they will fail short!
Any others seeing high voltage could become a problem. Probably would not hurt to replace them if you're doing the work yourself and get bored.
change them all if your amp is old.
Great job! It seemed like it was more frustrating to work on than hard to work on because it was difficult to narrow down what the problem was.
Some massive perseverance with this one!
Hi. Just a tip. I like to use 1 kohm/volt of capacitor rating for filter caps. 100 ohms is okay for photo-flash caps (or those designed for rapid discharge), but I like to take it easy on those filter caps. Also, use heat-shrink tubing on the wires of your discharging rig! Those caps will give you a nasty buzz! 🐝
Congratulations. Mainly for not giving on that nightmare of an issue :-)
I always want to buy a bass whenever I hear that riff, might just do it this time!
Many years ago I knew a tech that had a solution to your potentiometer problem. He would drill a tiny hole in the cover at the top, being careful no to let it go too deep. He would then spray the pot, and seal the hole with solder when done. He was a radio tech, but I believe it would work.
Nice video explaining the repair in detail. I’m also repairing a similar amp and found severe damage on the two power resistors (vertically mounted to the left side of the 62k bleeder resistors) that you mentioned at 3:17 of your video. Did you ever replaced those resistors? If so what value did you used? I did not find them in the schematic but following the traces they appear to go to the filaments of the tubes. Hope you can answer this. Thanks!
good job.. its a valuable thing..perseverance......thanx man.
In a Universe that's constantly pissed at you, it's all you got. :D
Enjoyed the video thanks.
Man what a chase!!! It was a Messa Boogie Amp!!!!
Hahaha, it was really entertaining me when you stuck on EQ board (it seems like try to not pissed off challenge).
If I were you, probably I tend to glue it with very strong epoxy rock solid rather than having a "good time" with wrong tools, but it was really satisfying when you're succesfully done with those amp.. very nice video!!
There was like 10 minutes of me putting the screws back in the EQ board that was supposed to have been edited out. Just tedious and tiresome.
I would have loved one of these amps & Guitar Denter usually has one kickin around but its pretty beat and working. But most musicians especially bass players don't take care of their gear. Meaning how they store it. I dread walking through the used section here in CT. I did the other day in the bass amp section and just stood in a daze at an SWR rig that looked like it was dragged through mud and dropped.
At the very least if you have a tube amp take the cover off once a year and and inspect it for dirt. A can of air will do wonders and tubes are easy to change out if needed.
Wow that was a Doozy! You earned your keep on that vid Brad!
Im 56 now bro and the number of shocks Ive had from HT,caps etc now is getting old.But Im still here so I was obviously born to it......or just incrediby lucky!
Really enjoyed this video and learned a lot. Thanks. Brad, do you know where I can get a schematic for a Mesa M9 bass amp? Powered it up one day and it has zero output - no his, hum, nothing.
I borrowed one of those for couple of years. An American bought amp, 110v so also carried round and 110v to 240v transformer brick. Lol. Crazy. And huge output. Only ran at 2. And one took breathing on master volume to blow my head off. Think it had been modded. Or maybe the voltage difference had it boost. Have seen touring guys run valve heads through variacks to find sweet spot
The plot of this video is better than a lot of movies and series.
When you have a pot needing cleaned and can’t reach the holes with your nozzle.....you can drill a small cleaning hole on the side of the pot....be careful that the shavings fall outside the pot and don’t let the drill bit drop way into the pot. It’s best to drill on the side of the pot and not the backside. I learned this trick from a now passed WW2 radio repairman jazz guitarist friend. It’s gotten me out of a couple spots.
They don't make pots like they used to. A lot of pots are pot metal (no relation). The shavings on those would get in there. But a hole for cleaner is also a hole for dirt.
Yes dirt, but most pots on guitar gear have 3 BIG holes anyway. I am not suggesting drilling holes if you don’t need to. But if you are in a tough spot like you’re in with this Mesa......drilling is an option..... but it’s not without risk.
These amps are great. They sound much better on 6550 output tubes, though you need to have the bias set by a proper tech so they work right.
That is how they shipped originally. When I bought mine it came with 6550 tubes. I took it in to Mesa (I used to live in Petaluma and work across the street at Lagunitas brewing) and they switched my amp to 6L6GC 'as a favor'.
The Mesa guy explained to me the 10 paralleled caps are supposed to sound faster than a couple big caps.
I never liked the Fenderish sound 6L6GC impart when overdriven. It's already the Fender tone stack!
A few years later I had a competent tech switch it back to 6550. It sounded flipping glorious at full tilt, but man it would get so hot.
BTW it's called bass 400 but it really only does 180-235 watts depending on your output tubes and how it's biased.
Sheer wizardry! Much enjoyed.
Thanks for turning down the static noise in the transitions.
The people spoke, and I listened.
how can filter caps cure a fx loop volume level issue ?
Wow love watching you work on this master bass amp mesa i wish i knew you when i had 2 of these. They needed some work. Do you do modification work? I have a peavey 700 fire bass head that i would like to have some features added to the head.. Like a bass boost switch . if so let me know . thanks.
Replacing caps that way is good for all of those reasons. However, It's possible to create a fractured solder joint at the original factory P.C./solder connection, especially if it was wave soldered. I do use the same method that you do but I clamp an alligator clip close to the P.C. board . This acts as a heat sink so the Factory solder connection is not disturbed.
I once gassed (for those not in the know, for some weird reason GAS = gear acquisition syndrome) over this amp, but the sheer cost of only changing the power tubes made me steer clear. Don't even want to guess how much the electrolytics would have set me back. D:
That measurement again... the time-constant experiment in action :)
An ohmmeter can test big electrolytics that way. Red to positive, black to negative, and watch the resistance decline as its voltage rises.
Patience is a virtue! The amp will last another 30+ years.
That's the hope. It's built for it.
This is why I have just about every screwdriver known to man. Watching you trying to manage dealing with those Phillips head screws with a regular screwdriver was enough to make me mix a couple of alcoholic "screwdriver" beverages.😂
That entire clip was supposed to have been edited out...for good reason. :P
Hey Brad.
Trivettes Gunsmithing on ebay sells some snazzy brass pot cleaning gizmos that screw on the pot to clean em from the topside.
Mesa Boogie.... Mess-o-problems. Fun stuff. Good job. It's always the caps. Even orange drops can die.
your a groovy bass player Cliff !!
RIP! Jamming with Dime and Randy most likely.
Every Mesa/Boogie you work on looks over-engineered to me. Brad, where did you learn electronics--the military? Your knowledge, experience and patience far outweigh your age. Kudos on a job well done!!
My stepdad is an electronics engineer, so I learned some basics from him. Mostly self-taught. Lots of reading and doing.
Not always, but most of the the time on the older fans there's a sticker with the brand and or the voltage, if you feel dead center there could be a hole, you peel that back and give it a drop of oil, clean any residue and reapply the sticker. The sticker doubles as a dust cover. Give a bit of life, maybe years.
I do not care for the sound of most Mesa stuff, but have to say the old equipment like this 400 was conservatively built
and used can be a great value
Quick tip for discharging caps (everyone has their own method, I know)..and what worked for me every time- clip one end of a test lead to ground, the other end to the plate of v1. May not be the fastest, but guaranteed to get all filter caps at the same time, and get them safely (100k+ plate resistor on v1 ensures that).
Anywhere along the power rail should suffice. Clipping on the large caps will drain those first.
I believe I saw a video a few years ago by Gerald Weber that said clipping onto V1 plate on some amps doesn't work to drain all filter caps. So watch that method and double check to make sure your power caps are discharged.
Hey man, any idea where to find the fuse caps for these amps? I have one and on my amp, the fuse cap only sits flush on half of it. Have you encountered this problem before?
43:15 - you have connected the probes, and rotated the switch on the meter afterwards, I am happy Fluke were thinking ahead when arranging the switch positions
Monster bass amp. Need to schlep an old ampeg 300w SVT. 95 pound head. Insane build.
Ampegs are some of the heaviest amps ever made. Fo' reals.
+The Guitologist Had a friend with a 400 watt Road Tube amp and 2-15 cab. Back killer. Loudest thing.
+G n' GF Remember playing it so loud that we did not hear the cop yelling through his bullhorn outside. Only got a warning! The 70's, cops were much cooler.
Hey guitologist, where do you source your components from? I’m having some trouble finding everytging
I just realized that the bass ditti you played at the end sounds just like something Lebanon Hanover would play.
A lot of us are proud of where we went to school and our subsequent work experience. Where di you get your engineering education and job experience? You actually remind me of a tech that worked with me at Westinghouse, back in the day.
Yay another "big glass" one!
Nice!!
Hey what kinda bass was that? Looked like a Tiesco or Telstar.
Wow you’re really good
These are a pain in the ass. We were a Mesa Boogie dealer at West LA Music when they were choosey, 89-90. We had these break down in the store before they were sold, very temperamental. Michael Anthony was using these at the time. Paul McCartney's backline was Mesa Boogie. We would bring back up gear to his LA Show just in case. I was backup to the store owner to go backstage if he couldn't make it...but...he made it. There were only 2 Mesa Boogie dealers in LA at the time. I think the other was Brauer's Maken Music (?)