FULL HOUR of Marshall Amp Repair Goodness - 1981 JMP Mk2 Master Model 100W Lead Head (2203)
Вставка
- Опубліковано 8 січ 2020
- Save 10% on Native Sons Straps with this code: GUITOLOGIST10 www.nativesonsgoods.com/
SUBSCRIBE TO CHANNEL 2: bit.ly/Guitologist2
You asked for another amp repair or restoration video, well here you go... In this EPIC, hour-long amp video, we'll look at a 1981 Marshall JMP 2203 Super Lead 100W Master Volume Head. This is the last of the JMP line, which ended in 1981 when the JCM800 line began. This amp has a LOT of issues which we'll go over in this hour-long fixing, repair, electronics restoration extravaganza! A couple of the things we'll touch on include how to clean a square marshall lighted rocker switch, how to rebias the amp from EL34 or 6CA7 to 6550 tubes, and how to troubleshoot for shorts in the power supply. At the end, we'll demonstrate the tone of this beast with my Fender Telecaster.
----------------------------------------------------------
SHOW YOUR SUPPORT
1: Donate via Paypal: paypal.me/guitologist?locale....
2: Send in Viewer Mail. (Contact Me for details at bradlinzy@gmail.com )
3: Purchase an ad! (Rate sheets available upon request at email above.)
4: Buy something from a sponsor and tell them I sent you.
5: Stand in the middle of the street naked screaming "LONG LIVE THE GUITOLOGIST!" Then when the cops arrive, tell them about my channel.
------------------------------------------------------------
♠STUFF I USE
-5A Variac: amzn.to/2FNWthU
-Jameco Isolation Transformer: amzn.to/2PRv1Fa
-Fluke 87: amzn.to/2DwHjvr
-Yotec 936 Soldering Station: bit.ly/2JqB1Vw
-Sealody SSA51 soldering station: amzn.to/2DJTS7P
-Black and Decker Heat Gun: amzn.to/2DWpDhr
-Geekcreit® LCR-T4 Mega328 Transistor Tester bit.ly/2J9uLSA
-HT02 Handheld Infrared Thermal Camera bit.ly/2LXfLoD
-Solderless Breadboard: bit.ly/2stkVAq
-Breadboard Jumper Wires: bit.ly/2JowaEh
-Geekcreit® XR2206 Function Signal Generator DIY Kit bit.ly/2LYBvkb
-Contact Cleaner: amzn.to/2FVitro
-Max Professional Cleaner and Lubricant: amzn.to/37R3JY8
-Deoxit Fader Cleaner: amzn.to/2LPwtsE
♠RECORDING
-JVC Everio Camcorder amzn.to/2RLIleU
-Andonstar USB Microscope: bit.ly/2q8QIWz
-Articulated Boom Arm with Cam Mount: amzn.to/2Hlo2AX
-Shure Beta 87A amzn.to/2rNPnoW
-EV 635A Omnidirectional Dynamic Mic amzn.to/2pR8HQT
♠RECOMMENDED BOOKS
-RCA TUBE MANUAL amzn.to/2GOBVqS
-DESIGN AND CONSTRUCTION OF TUBE AMPLIFIERS: amzn.to/2HSNMne
-Designing Tube Preamps for Guitar and Bass: amzn.to/2DK5tmt
♠2006 FENDER AMERICAN STD TELECASTER PICKUPS
-TV Jones Magnatron Neck: amzn.to/2q1zQjD
-Seymour Duncan Vintage Stacked Bridge: amzn.to/2GyZjrK - Наука та технологія
As the person who owned this amp at one time, and the person who had it modded the first time, this amp has changed so much since I had it. First off P.A.T. stands for Precision Audio Tailoring. The JB stands for Jeff Bober. Yes, THAT Jeff Bober. The amp originally was modded using KT88 tubes. When I talked to Jeff to have it modded I wanted basically the same mod he did on Brian Forsythe's (KIX) Mesa amp. The amp sounded amazing when I had it.
It would be interesting to figure out the original mods he did versus any that came later.
Funny thing is I sold it to finance another one of his amps, a Budda Twin Master head and 4X10 cabinet. It was the first run with the purple faceplate but was wired like the original black faceplate ones.
Man this is a cool story! This is why I watch this channel. I am obsessed with different personal mods artists do to their equipment, I would (almost) kill to see some clips of this amp with the P.A.T. Mods working properly!
@@TheGuitologistHere is Jeff's webpage and it has all his contact info. www.jeffbober.com/#2707
Awesome to get a back story on things like this and hear about some of its travels thru its life
Oh how I've missed these amp repairs...
Tele looks killer too Brad good job
Tech vids coming back in 2020.
The Guitologist yeah it seemed you are very busy opening cool stuff people send you. Must be like your birthday every time the postman brings you something. But good to see some more tech stuff like in your earlier posts. I don't know know half the stuff you explain but before watching your videos I understood nothing. So I'm learning something!
@@TheGuitologist I'm in no hurry, but still have a JCM 2000 DSL100 that blew a mains fuse about 12 years ago, and I just put it in storage rather than have it fixed. From your vid from last year, I suspect it needs the motherboard replaced, a cap job, and I'd like to put a (Classic Tone) choke in it. Can I get on a waiting list to have it fixed sometime in the future? You are familiar with this issue on these amps, and I'd certainly trust you to fix it. It's been down a long time and deserves to get working again.
Regards, Brad.
My favorite part about your amp videos is always at the end when you are testing them out. You have some serious chops my friend. Always look forward to hearing your playing.
Thanks man. I appreciate you watching.
It’s fascinating to me to hear the playing of someone who really understands the vibration.. ⚡️
I’ve worked in electronics for 42 years. I watch you because the shit you do is way out of my experience. I understand the editing and other stuff but I could watch you solder all day long. I also love your commentary while you work. I’m an expert but not in tube amps so I have no criticism. You keep doing your thing because that’s why I subscribed. Just don’t think that anything you do is boring to us.
Thanks for watching, Bruce!
Really psyched to see another amp video. Keep ‘em coming!
Yes. Your best content.
I agree with bbmade Brad CRANK em out
YES!!! Thank you Brad, I love the commentary vids, they are really quite good. For me though, nothing beats a sweet repair vid! Thank you!
came to say the same :)
I echo liteabong!!!
Me too, the repair videos are the gold IMO
You have one of the best down to earth channels on here!
So watchable, love your commentary, "Fuck off man" ha ha ha…
Don't ever change
This kind of stuff is how and why I started watching your channel. Always great info.
Suggestion: (if I may) would have been nice to see what it sounded like beforehand. Great video. Thank your for your time and effort. 🤘
Understandable. In cases where I’m unsure what the problem is, I don’t like firing one up without looking inside. You just never know how hacked up something is going to be.
David Helmuth agreed
I like to test the power transformer on really old amps before I begin the overhaul. At least bring up amp with variac & light bulb limiter in tandem. Just make sure light bulb not shining bright. If it lights up bright I float HV secondaries and check bulb limiter again. If I can find out the health of the transformer first it makes my repair run smoothly. If the client says he was running the amp prior to sending it to me then it also makes me feel more at ease about jumping right in to replacing caps. Bravo Brad on another great repair.
I agree, sort of skipped over “Step #1”, verifying the customer’s initial complaint of sound quality...
Brad I could listen to you for hours man. You seem like such a genuine dude. Cheers From this happy Okie. 😁
The silent majority loves your technical stuff. You have guitar chops and tech chops. That puts you in the 100th percentile. Don’t let the haters bring you down.
I'm from ex-Yugoslavia. Like that tube :) and fun fact...just 60km from the factory that tube was made in :) BTW, excellent YT channel! Cheers ;)
I’m looking for a new set of tubes - you can grab the best!!
Unfortunately EI did run in financial problems a few years ago, didn't it. Sorry about that. So tubes are manufactured in Europe only by JJ in Slovakia.
Many years ago my old lab boss gave me some very useful advice that has served me well when dealing with so called experts, that advice was:-
1) Ex means "somebody who used to do a job" & a spert from a tap is "a drip"
2) "Everyone has an opinion but I'd doesn't make it right"
3) "The right way is the way that works for you and achieves the desired result"
Brad Rocks
👍👍👍👍👍
That rant... I'm laughing so hard over here.
I'm a photographer and that community has a good sized element of "elitist" attitude as well.
Be you and do your thing.
photog elitists are the worst of them all, if you don't have bokah you're a point n shoot noob, if you have bokah you're a noob that used too much bokah, if you have soft bokah you're too poor for a lens with crisp bokah, if you have crisp bokah you're a noob thats drawing to much attention to your bokah.
I don't think there exists a community devoid of know it all blowhards absolutely CONVINCED that they're the only demi-god on earth doing it the right way and everyone else is just retarded.
That rant owns the Internet. 😂
Oh god, the photography community is literally violatile.
A bit late to this comment, but you ain't kidding! This is an example I can relate to as I'm a photographer also, and I've bailed on more photography related forums because of that very reason.
I've never gotten into it hard and heavy with anyone, because you just aren't going to change minds generally, but just the hypocrisy of some of the "snobs", as with any gear driven hobby, or profession gets really irritating.
On one hand, you'll get these guys going on about shelling out big bucks, and having the absolute latest feature rich camera body with fantastic high ISO performance, and mega multipoint focus capability, incredibly fast burst rates, touch screen advances, processor speeds...the list goes on, but these same "Elites" will look at EXIF data posted along side, and are the first to come down hard on people "under them" that dare go outside the confines of near native ISO (usually because of lens/cost constraints), and full manual mode, and relied on these amazing features to their maximum potential in the posted photos areas on the forum. It's such a contradiction, and does nothing to embrace people coming into their own in the realm of their chosen hobby/field.
At the end of the day...to many hobbyists, and pros alike, a good photo is a good photo no matter how you got there, just like here..a good repair, is a good repair.
It gets real old and silly. Just like anything, there's always detractors, know it alls, and "Elites" who generally shit on anything, and anyone simply because it makes them feel better about themselves for whatever the reason.
Brad's had more than his share of the same shit, and again...at the end of the day...who cares how he got there?
It may not be "by the book" in some tech's eyes, but there's also a lot to be said for hands-on experience, and a hard knocks approach to dealing with certain repair challenges.
I for one really value his approach. It's saved me some serious time and bucks.
“I’m a hack and an asshole now fuck off” 😂😂😂 couldn’t have said it better myself! I love both of your channels. Subscribed to both and binge watching during quarantine.
I just want to thank you for introducing your head phones to us. I recently bought the same set you have the EX29's. The bass response of these are outstanding. Thanks again as I haven't been able to try a lot out but I took your word for it and I am super happy.
Mate i have been watching for a long time , been playing for over 30yrs , you are a champion i wish you where in Australia to service my 30 + 100 watt heads , mate you are a great person and i truly love your content great job mate !!!!!!!!!!!!!!
I learned this from an old audio electronics tech from Switzerland named Rudy who worked for my father's TV and Stereo repair. The tech who preceded him Bud now an electronics engineer uses this too. For protection from a hi current draw from the power supply to prevent burning up stuff more for solid state but also tubes. You get a light bulb socket with 100 watt light bulb in series with the hot line with the AC Power plug also can help along with the Variac. If you get excessive current draw the light bulb will light up and it will current limit the AC Power and save unnecessarily burning up of new parts. I love your Channel I'm learning a lot. Thank You
Great to see another amp repair video Brad. I'm still pretty new to the amp building and repair scene and find these inspirational. Thanks a bunch.
You always show cleaning and or pin alignment on tube sockets!! Your service videos are NEVER boring! Let's just get that straight! We are so lucky to have you post this kind of projects! I am excite about this amp, can you Tell? Huh? Huh? I have a 50 watt version of this amp combo and I need to do what you have done on this one, so now I have a roadmap on how to do mine! Do the voodo you do so well! This one really hit home for me! It sounds the way it was supposed to! I was debating on which 6550s to put in mine, so now I know. Thanxz, brother!
Nice work... Keep the repair videos coming. I don't think they will ever get boring!!!!!
Brad, video's like this is what sucked me in a year ago and got me working on amps and to become a member of this channel. In the past year I've built a few amps, modded a few more, even done a few repairs. I've learned a lot between your backlog of video's and some of the other UA-camr's, most notably Uncle Doug (which you recommended). Keep up the great work, and I'll keep watching, and supporting the channel! Thanks again Brad!
You're amazing, David. If it wasn't for dudes like you and the encouragement and support you provide, I'd probably have found another vocation long ago.
Hi Brad. The tone and playing is exemplary. Please keep the repair vids coming. Cheers from Western Australia.
Just started watching this channel. LOVE IT. Brad is hilarious!! No idea what he’s doing but I’m addicted.
When I built my jtm-45 clone; I omitted 3 of the input jacks and wired both channels together. The high/low input resistors are on a toggle switch. I also did independant bias adjustments so I can mix output tubes and dial in the bias on each tube. I put the measurement and adjustment hardware on the back of the chassis so the amp doesn't need disassembled. You brought back memories with using that decade resistance box to dial in which potentiometer was best . I ended up using 3 pots (one for each tube and one in series to tweak both in tandem).
Hell yeah, love the amp vids, keep ‘em coming Brad. And i love the sound of the Tele. Awesome stuff
always entertaining ,and amusing, but the priceless ability to fathom out
and repair a jigsaw puzzle from a maze of lost connections like that, ,,and then
play whats coursing through your veins, ,,those who can,,DO!
I enjoyed the play through at the end just as much as I enjoyed the amp repair. Thanks for bringing us along Brad!
I had that pcb in my 1980 I finally couldn’t take it any more and put in a turret board like the earlier models. It is now a dream to work on. I feel your pain working underneath.
Hi Brad....Having owned a JCM 800 2204 which I basically learned on and modded,and now owning a JMP 50 watter for many years,love watching the Marshall videos...Enjoying all your videos..Great stuff! Always enjoy your playing at the end of the repair videos!
Definitely missed the amp repair videos and loved this one 🙂 excellent work!
The best way to clean electrical contacts is to use an eraser. I use pencil erasers for typical oxidation, and ink style erasers for lightly arced / pitted contacts as they are a little more abrasive. For heavier damage, diamond contact files would be preferred (McMaster-Carr carries them). Many contacts are plated with ??? to lower contact resistance and resist arcing. Using any sort of abrasives will reduce/remove the plating causing premature failure so you always want to use the least abrasive methods first. Also, the smoother you can keep the surface of the contact the better. Arcs tend to initiate on pointy things and edges therefore you always want to minimize any scratches. Usually by the time you get to the point of needing contact files, the switch/relay is screwed and should be replaced anyway but it will buy a bit of time. Everything else you did was absolutely spot-on. You're one of the few techs I've seen that use the cheap wire strippers that fit any size of wire rather than the ones with half a dozen fixed sized holes - right on! Of course, I'm not a triple platinum certified super duper golden screwdriver award winning tech, just a guy that's been repairing electronic crap in my basement for over 40 years now, and an industrial tech working on CNC machines when I crawl out of my hole.
Yay, an amp restore video! This is what brought me here. "Well fucking congratulations!" -These are the comments that keep me coming back.
Awe man, was so excited to watch a new amp repair and get hit by an emergency. Great upload Brad! Thank you very much!!!
Hey Brad. Thanks for the Amp Repair video after a short drought of such! I know you put a huge amount of production time into your videos outside of the actual subject matter, so understand this is not a gripe. Love your channel. I always learn something.
Great video! I have been learning amp repair and building on my own and I get so much info watching you do these videos! Thanks!
You fixed the switch!! Most repair-shops would just replace it, but you did not even if it is very time consuming and by that a economical disaster.. at least for the growth of capitalism.hehe
That is just awesome!!!! Demonstrating that it is easy to do for all diy folks is worth a lot more than the value of the time used to do it.
You are a honest man that keep your mistakes in the videos, just so the audience can learn even more..that is something to applaud !!! Also, you are a brilliant guitarist, seriously!! Thanx!!
I appreciate that.
Fantastic job restoring back to nearly original condition (original tone). Sounded great at the end.
That amp has some nice tone at the end. Great work Brad!
To my ears, this is the best sounding amp you've played on this channel (that I've heard). Also reading the comments, to my mind, this is the most interesting amp with the back story thats been given up to this point.
My Dad was an ETN in the Navy, and he taught me to clean contacts like on an old auto ignition with a dollar bill.
Curtis Lee, I haven't heard that one before; the old military techs and ham radio guys I learned from cleaned electrical contacts using a pencil eraser or ink eraser.
Nice Job Brad, it is great to see you get back to repair...great clean sound on a Marshall, Versile...
This is so good. Love this channel. So satisfying to find the issues and overcome them!
Ah cool a repair video.. thanks dude. You can keep those coming man.. I don't get bored of it and since I learn from it it is much appreciated.
I have also noticed every Hamsterhead that knows better. I've been doing tech work for 40 years and I consider myself plenty above average. But everyone is an expert. LOL. Keep on doing what you do I enjoy the videos. They are a fun romp and you have a great selection of all these different amps which makes it much less boring. I have never worked on Mesa amps, and after watching your vids, I never will. Thanks for that.
YYYAYYY!!! Another fantastic amp tech video! This made my night! Keep these coming PLEASE!
😊😊😊 ... And just for my 2 cents worth, I LLLOVE the long videos. Show EVERYTHING as far as I’m concerned, even cleaning pots. I like seeing it all, and even if it’s not always “entertaining”, the things you have to SAY, ARE entertaining, so yeah, keep ‘em coming like this, man! Awesome!
😊😊😊
Thanks for watching, Steve.
Great video Brad and the amp sounds awesome! Thanks for all of the free technical information!
i think you are great man,thank u so much learn so much everytime,,and i like the way you present things interesting,,your humor is great..its like a spoon full of sugar with the medicine
Fantastic video again! We learn so much from you. Thanks for sharing your knowledge. Superb playing at the end of the video. A happy ending to a sad tale! Cheers!
Damn that is a great Nirvana cover! And its really good see another amp video, seems like years since the last one!!!! Thanks Brad!
i watched this at 1.5 speed just to get throw it a little faster. Then when you started doing the sound demo I was like "damn Brad can shred" then i realized you weren't rely playing that fast.. Love the leather pick guard .
Wow! Great video and amazing ending! Jam on, Brad!
Love your tech videos. I really enjoy learning what makes the amps do what they do.
Man, I have that exact model amp from '79! Great to see this on here. I had mine professionally set up and rebiased for EL34s when I got it in '96- I got the good original factory Svetlanas with the test-tube logo. Sounds amazing still!! Thanks for a great video Brad
A return to familiar ground my man. Excellent vid. I watch these in awe, and with a distant hope that it'll give me inspiration to refurb my 80s AC15myself.... Just got a work out which end of a soldering iron is the hot bit and I'm golden..! Happy New Year to you and yours btw, keep these coming! Cheers from the UK.
I really respect your willingness to show your mishaps while repairing amps. These things happen in real life.
Honestly I have no interest in learning how amps work but I made it all the way through the vid. Very entertaining. Beast playing at the end 💪🏼.
i def. have learned more about amps watching you Brad ... thanks
Hey brad, I'm a truck driver and that guy you talked about bitching, in my industry we call a Super Trucker. A guy that thinks they know everything but in reality is a half-ass driver. Love your channel Brad
Do you still use CB at all in trucking?
Great vid Brad u always nail the tone outve these amps u victoriously work on !!!!!🤘🤘
Great work Brad! Best wishes from Cambridge, UK!
You have reawakened the Marshall BEAST!! ...nice.
Liked that sound. Good work and playing Brad.
The commentary on techs was priceless. Too funny.
Been waiting for a amp video lile this for a long time. Thanks. Great job!
Typically the losers that trash my videos have no videos on their own channel and I have to remind that THEY are watching MY videos and their videos, if they have any, aren't anything I would watch. I might not have the knowledge you have, but I enjoy watching your stuff. Thank you for putting in the effort.
great learning video. cleared up some issues that I was dealing with. Thanks!!!! Amp sounds rockin.
PAT test, can't imagine I'm the first to suggest this but I don't want to leave your wonderful content to read the comments yet. I realise you're resculpting you're algorithm but it's nice to see you're tech work again, much as SPF is a solid part of my week.
Several others did suggest that, but that's not what it is. See pinned comment.
Arm chair quarter backs. I love it. Hi brad just wanted to say i love watching your videos they are always entertaining & I learned about cleaning pots & tube sockets from watching your videos uno plus a bunch of other useful information. So thanks for that.
Thank Christ, an amp repair video. I might even resubscribe if this keeps up.
Great to see an amp video Brad. Hope you’re well mate.
Hey Dan! How are things? I hope you're escaping the fires! You ok? Family all ok?
Clearly you do things very well Brad. Your attitude is perfect. Flex and move on.
Thanks Robert. That's about all you can do. I don't even hold a grudge against the dude. We all say shit online we probably would say differently in person.
Hi Brad, Love the videos, thank you for teaching us, don't mind the begrudgers. Your work is impressive.
Oh I need this amp!
Learned a lot. Great episode!
Wow. I really enjoyed this video !! I am a guitar player but I would love to know more about how my amps work so I've been watching a number of "repair" videos on UA-cam. The more videos I watch, the more I realize how much I don't know. Not sure if I ever will. I absolutely respect the amount of voltage inside the tube amps and frankly it scares me to think that one mistake could be your last. Great to see your process of troubleshooting and willingness to show that on your video. I look forward to watching more of your videos. Thanks so much for sharing !!
Awesome video dude. You’re even adding suspense music for when shit starts getting real. Love it.
Back to the good old times thanks for the video
Nice! Looking forward to watching this video tonight.
A very welcome return to the type of video content that I sub’d your channel for. Keep it up!
Thanks for making videos like this man! I want to get into amp repairs and building
Amp repair video !!!
sweet , I love these.
My very limited knowledge of amps has been learned from you Brad. I don't understand most of it but i certainly know more than i did about 200 videos ago 👍🏻
so I guess that makes me an "Arse Hole Hack" lover !
Which is fine by me 👍🏻peace and love brother 👍🏻☮❤
I don’t know anything you say when you talk about voltages and bust out your calculations....BUT....they are satisfying to watch. 🇺🇸🇺🇸🇺🇸👍👍👍😁😁😁 AND that Marshall sounds sweet also. Classic sound.
For some silly reason while you were doing this restoration back to "stock" I had the thought in my techo brain that someone had made a bastard 100W Marshall bass amp out of it before it got to your bench. Way back in the late '80's I heard of many stories where this bass modification was done on numerous brands of amps but this for me is the first time I have seen the sorts of things that might/could be done to turn a guitar amp into a bass amp ... Good job on getting it back to its stock goodness...
Welcome back to the way you normally do stuff/ this is exactly what a guitologist does ( I think).
Amp sounds great!
Wow this 2203 sounds very good! Just watched this for the second time😁
The best place to draw the dc voltage for the effects loop is the cathode follower stage in my opinion. The 2nd gain stage is so hot for a 2203 style circuit, I can see why the bright caps before it were removed and 2nd pre gain pot added. The stock cold 10k cathode resistor on that stage is necessary between the 1st and 3rd hot stages. Great video by the way! You're a very good troubleshooter.
Good point about the stock 10k and pot.
Love your videos, I've learned so much. Thanks Brad
Awesome video! More like this please
That Marshall sounds awesome and you're playing is great to I'd love to hear you play some more bro Rock on
Brad, I enjoy your videos. I am a EE, guitar player( not as profficient as you), and have worked on tube amps for years. It appears that Jeff Bober was attempting to transform this Marshall into more of a Mesa type amp. Anyway, from my observations, you have some very sound methodology, and technique for servicing and modding amps. I may do some things differently, but remember, electronics is not only a science, but an artform. Be assured, the naysayer, know it all experts have a lot to learn yet.
I love what u said at 29 minutes. So true about ppl and the internet. 👍
Thanks,another good one ,cleaning up another mess.
"Lets flip this around and get a better look at the rear". Now we're talking... :)
Another great vid, Brad, thanks man!! Getting towards 100K subs, we'll have to throw ya a plaque party!!
Nice playing at the end dude.
Impressive tele playing Brad!!
The Ampologist,,,great video
Brad👍👍🎸
I loved the tech beat down 😭😭😭😭😭😭😭😭😭
😂🤣😂🤣😂🤣😂🤣😂
very cool, I have an early JCM 800 2203 with similar mods that's being restored by a tech as we speak, thanks for the insight on what goes into that project.
Thanks for the videos man!