To those asking why didn't I swap or pull tubes to diagnose first, it's a good question... That's where I'd begin too if the amp was not open on my bench. I'd pull V1 and look for noise to persist. If it persisted, pull V2. If noise disappears, you've found the stage, but not necessarily the source. If you're LUCKY, you've got a tube issue, but not always. Since the amp was already open, this made a better video than just pull V1...still noise...pull V2...noise gone...maybe it's the tube...swap tube...get lucky. I'm not recommending everyone open their amp and trace the problem in this manner for the word "go". Sorry if I gave that impression. But this would have caught the issue whether it was a bad tube (which was the case here) or a bad something else. Hope this helps someone.
The Guitologist i have an Deluxe Reverb 68 reissue that had exactly that noise, i was lucky it was just a bad preamp tube, dont know which cus i got a set of quality replacements for all of the preamps. Love your videos Brad, keep up the good work 👍🏻
The Guitologist hi, if you are interest I’ve encountered the standard bias trouble with my 1997 DSL100 (red plating the power tubes) and I used an extra little board (5cmx8cm) connect to the power tubes which redesign and solve the bias problem on these earlier versions!! And that solved my trouble like a dream!! So if you want I send you all the infos, pcb, part list and layout in PM!? By the way your videos are AWESOME!!! Thank you so much!
Good Job Brad..!! I wonder how much noise this amp has due to the fact that many of the harnesses are NOT twisted?? Having a good tube tester is always simpler. I usually use Amperex on the pre amp side.
This and your last video, show exactly why I like this channel so much. You are not afraid to show you are human and leave in mistakes, which you could have easily edited out
Old EL 34s ('60s) were never a problem. The only time I lost one was when someone tipped a pint of beer into my mesh-boxed amp. That cleared everything out with a bang. You should get a tester. :)
I'm glad I set my mind to never going with first impressions. My first viewing of your channel was a S*** Friday vid and I found myself coming away from it with the wrong impression. Car guys can argue all day about different makes and models. Both sides are right on some of the particulars. It is most often just a matter of personal tastes. Your channel has become a favorite. I get a bit nostalgic looking over your shoulder. Back in '71 I had completed the first six months with U.E.I. (University of Electronics Institute) in Louisville, KY. (Done through the mail) with perfect grades. When it came time for the year and a half in L'ville, our dad told me, "Nobody paid to send me to college so I don't see why I should for you..." I had paid for the first semester with my savings from working on other farms. Since I'd graduated from school at 17, I had no chance at financing without a co-signer. So that put the brakes on that. I also did some time in IT as service manager for my professor/employer at the local community college twenty years later. I once had a Wyse keyboard computer (don't remember the model number but the entire system was in the keyboard and just had the power chord and monitor cord externally) waiting on my desk when I came in to work. Some sadist at Wyse had designed the thing with the 3-pin (soldered to the bottom of the motherboard) battery at the bottom of everything. I was given the task of replacing the battery with *NO* documentation, going to the customer's home and setting it back up (they were at work) and then being out at the college for mid-terms at 1pm. (You wouldn't have wanted to look over my shoulder and listen in on that one... [Grin] ) I had a blast building kits and was fascinated by electronics. The advent of calculators would have helped with my dislike of mathematics. Getting to follow along on your projects is very enjoyable. It is a gift as well as a sign of your comfort with what you've learned along the way that you are able to talk through your thought processes while troubleshooting a project. If only I had your experience maybe I could get my old 10 channel, powered Carvin mixer working again... :( This was one of the 1970s models made back when they still did military style wiring. I look at the schematic and compare it to the guts of the mixer and just can't get the feeling that they are both the same thing.
Thanks for watching. Shame your dad wouldn't help you out with college. You can learn all you need to know these days from books, TH-cam, and diving in.
friend of mine had one of these 2000s for 6 months & 4 months of that was spent at a shop ,, nothing but trouble ,, getting hot beyond normal ,, on the other hand I've been using a JCM 800 100w 2ch for almost 25 years & NOT ONCE its been to a shop,, still has the same tubes I bought it with 25 years ago,, same caps & everything,, OK cheers !!
Having some of the same issues with my TSL 100. First time seeing the shields inside the EL34s (v7 and v8) glowing red! I've watched Tony McKenzie's video about changing the motherboard to issue 20, and decided to bite the bullet and change it out (it is currently shipping my way). One of the things he suggested was to solder electrically close the ground "switch" of the 16 ohm speaker jack closed to prevent putting an excessive load on capacitor C46 by the edge of the board. Something to consider... great video! Thank you so much!
As you adjust the bias between each pair of tubes it is definitely a balancing act. It is also beneficial to have a four probe bias socket tester for beast amps like these. The last TSL100 I worked on had one single tube pulling a butt load of current. Using the bias probes allows me to swap tubes around to see bias shifts quickly. My problem was that there was just one tube cooking at 85-95% dissipation. Point is that setting the bias the way Marshall intended would never reveal that issue with one of the tubes. Perhaps this is what was going on with that one tube in this video that looked like it had taken some heat.
Hi Brad, another informative video. Always worth remembering that the only ‘bias’ is actually the voltage on pin 5 of the output tubes. Before looking for faults in the bias circuit just pull the EL34s and check that you can get the same voltage on all pin 5s. Also, if one side bias current is around half of the other side then you know you have lost one of the two valves in that pair. Cool playing as always.
Very interesting I had the same problem with my TSL 122 and in the end after having alot of problems Marshall rebuilt one main board and changed the tubes and the I started to get the same noise as you had in my other cab and I sent them both back to get sorted even though they were brand new at the time and under warranty it still makes you wonder and from what I know they have done a major board update to fix the bias problem once and for all but I am having a problem with forking out an extra £400 plus just to fix a problem that should not have been there in the first place. If I had known at the time I think I would have gone with the JSX which were going for about £1200 at the time but since I was building a stereo set-up it means two of everything. I still have the amps but I use my Bandit 112 for home use most of the time. Keep up the good work very interesting vids.
I had TSL 100...I love it.....at first ...started making screeching noises,replaced the tubes...matched set!....noise came back everytime they heated up! Brought it to my friend...you might have heard of him TONY BRUNO...BRUNO AMPS! He worked on it for hours still kept running crazy.. The Bias kept going a drift,and still crackeld! The cheap ass design that Marshall uses allows the heat to breakdown the board overtime! Tony worked for Korg/Vox/Marshall,and said the amps are junk compared to the earlier models...took his advice...got rid of it!
I had one these set on fire while playing on stage, completely burned out. The shop said it was due to tracking under the output valves. The vales used to really glow too hot.
Hello Mate, thanks for the video!!! I got TSL 100 JCM 2000, and gain is so weak, gain is almost 9 on the crucnh channel but there is no gain at least, preamp tubes also new.. but result is same i wonder that have you any video that kind of problem? By the way i faced same issue with all channels , clean-crunch and lead😢
Love this video of you working on this particular amp. I just bought one for around $700 and have not received it yet. I can only hope that it's a good one but I may be sending it to you to fix if needed. I suppose they may not be actually possible since you may be a very guy. But seriously, I would rather have you fix it since I trust you. Anyway guy, your skills are awesome with fixing amps. If your amp fixing skills match your guy playing skills then you are a fantastic amp fixer. I love your playing. Man can you move those fingers around fast. Great playing dude. Thanks for having your channel. I really enjoy watching you work. Take care man.
I bought one off the first tsl122 combos , I had my own lightshow , it burnt out valves at an alarming rate ,literally as soon as it warmed up .The bias drift was unbelievable , it would go up to 20 v !!!!!!! I retired it ,and by chance read about this bias drift on the internet ,people where changing lots of components and still no joy !!!! then someone found out that the material the board was conducting voltage through the board !!!! the only cure is to replace the board ,I replaced mine and it has been perfect ever since !!!!
I've heard the odd report of a new board doing the same thing, but I'm aware of the fix for the old boards. I'll do another video showing how that's done.
After watching part 1 and 2 of this "saga", I'm so glad I bought a Bugera 6262 Infinium head instead. : ) 3:48 AM? I guess you can't sleep when you're having fun. XD
Looked at a TSL100, that was hissing, rustling, and popping. New tubes cleared up the noise floor, but the amp would continue to sporadically pop and rustle. It was angry inside lol. These issues followed the volume. I think all channels were affected. As the amp belonged to a friend of a friend, I didn't feel comfortable with more intrusive testing. Bias was solid and visually everything looked healthy. Not sure if there is a common culprit for these symptoms (?)
Whatever it was, it was likely toward the output of the amp, after the channels get mixed back together.. You can start at V1 and pull tubes while it's on and whichever one stops the noise, you've found the stage.
I purchased a TSL 100 for about $400 and it was red-plating a power tube. I replaced the mainboard and tubes and it rages. The only gripe I have about this head is that it runs at about 6.2 million degrees and I always run a fan at the power tubes. I have a JCM 900 and it just gets warm while playing for hours.
Hi Brad, you Tube Stuff Nerd (such a non sense in these two words, tube and nerd lol) These few words to say I'm really fond of your amp surgeries, modding and so on. I learn so much, and reminds me some memories (trying to fix Marshall DSL or my Mesa Roadster nightmare) Greetings from France :)
This right here is one good reason that I will probably not ever buy another tube amp with circuit boards in them.I have also built one tube amp and learned a little more. There is just too much that can go wrong in a circuit board to suit me. In 2012 I bought a blues jr, and a hot rod deluxe,brand new. Within one week the blues jr., blew up got another and it messed up and within about a month one of the buttons on the hrd messed up.I still have an older blues jr. that I bought used.Had I known what I know now about tube amps, I probably would have kept them but at the time, I knew nothing about tube amps.I just don't have the money I used to have to buy gear that does not hold up. I have gone back to solid state for playing around the house.
It seems the first benefit of circuit boards is that amp designers can fit all these overly complicated circuits into a chassis. Many guitar players will see all these switches, extra jacks and buttons and get all excited. Not only is it nightmare to repair but as a player it is just overkill. It begs the question just because you can do something does it mean you should.
Some pretty tasty licks at the end there! Wasn't expecting to be more interested in trying to figure out what you were doing there than the fix! =) I just had the same issue on my JCM2000 50w with the noise. It was just a preamp tube (brand new ones). Thank God! I think I messed it up trying to bias the power tubes. Can you mess up pre-amp tubes by playing around to much with the bias pots? Going down to 20mA and back up to 60mA etc..? Tube Depot also gave me some bad power Tubes. Got some matched JJ EL34L and they sounded horrible, thought my amp was broken. Sounded good again when I just put the old regular Sylvania EL34's. Not sure if it was because the type of tube "EL34L" or if they were just bad tubes.
i have the combo version of the tsl 122. new tubes, i have NO output to speakers and NO voltage on the bias adjuster. Do you have a video that adresses this problem. It's not low it's zero thanks
So I have a TSL602 that has been driving me crazy and I can't track down the issue on. I'm by no means an amp repair pro, but I can handle most amp jobs I get. This one ended up having a power filter cap installed BACKWARDS by the nucklehead who got his hands on it before me. There were several blown caps. I replaced them and most of the crappy stock electrolytic caps with Nichicon and TDK caps. Replaced a few burnt up diodes and ceramic caps as well. This got the amp up and running, but there was no output and no power to the tubes. Turns out the internal fuse was blowing. Starting it with either one of the power tubes removed allowed the amp to start without blowing the fuse. But one of the Pre tubes (V4) hardly glows compared to the others. Low heater voltage if I remember correctly. The filament in the fuse also warps like it's on the brink of blowing. Tubes are new and seem to check out. I end up figuring it's the Bridge Rectifier. Replace that, same problem! Anyone have any advice or similar experiences? This is the one amp I just can't get working and it's driving me crazy.
Also, I forgot to mention, the guy who had it before me ended up making a solder bridge to compensate for where I assume he damaged the pcb. I forget exactly what circuit it's on (don't have the amp handy), but it was right beneath/next to one of the power filter caps. It was gobbed with silicon to insulate it and the cap had to be installed in a raised position. I made a small rubber platform to isolate and support the leads of the cap. It's been so long that I forget the exact details, but the circuit did seem to be functioning properly with no shorting caused by the solder bridge.
that rustling to me sounds like radio noise, like something is working as an antenna when it shouldnt be, now im not an expert on how tubes work, but if the tubes been cooked and the coatings burned off inside, would this be the cause of said noise ? electrons unable to be captured by the plate need to go somewhere...
Hello... Awesome video... I have a JCM 2000 DSL100 and have a lot of hum when I am not playing. I also get a lot of crackle with the pots and even push buttons. I had a tech tell me that he doesn't think the pots are dirty and that its probably voltage from the MB? Does that even sound right? I was going to order a new MB and dont know if that will fix my problems. Any help is greatly appreciated :) Paul
Another great mod to do on these is to remove that 7W 270 ohm resistor and replace it with a filter choke. Do that to all these modern Marshall's. Just did my little DSL40 with a choke and a new output tranny. Night and day difference. Just put a filter choke in a friends JVM210 with a new set of 6CA7 tubes. Plus removed the C83( I think that's the number) cap on the input. Much more old school sounding with out all the fizz. He loves it now.
Those are notorious for bias drift. I had a TSL-100 and it required me to replace the entire board. I found one cheap from a UK supplier for < $100 brand new. Once it was replaced, the amp sounded like poop so I sold it. Too bad.
I had one of these TSL's before but I sold after going the shop so much. Here I picked another one up recently that's a bit on the noisy side and the reverb only works on the clean channel. Any one ever run into that before and if so how did you fix it?
Nice Vid ! Dig the hunt ! Don't know why JJ Tubes are so popular. I've got so many Microphonic 12AX7 and 6L6's. These Marshall High gains will find any weakness in the preamp section. Since I worked on many Mesa's I have a stock pile of Mesa Tested 12AX7"s, never had a Microphonic Mesa 12AX7. Not that their the best , they can be low gain or output in some amps ,but they are consistent . My fave 12AX7 has to be the NOS EI long Smooth Plate . Back over a decade ago I got mega gross for cheap . Now there not cheap everyone knows they were made the same as the German Telefunken's. So if you see someone selling old Boogie preamp tubes for cheap , get them !
Nice job on finding the faulty tube...and showing the process of elimination to get there. This shows how to eliminate 100's of components in a matter of minutes, leaving only a few to troubleshoot. P.S. I happened to notice the time on your laptop...late night or early morning?!
Very cool video Brad. Once again I’ve learned a lot and you have reminded me of things I’ve forgotten over the last thirty-five years or so since I did much of this. I’m also curious, would you call this a regular or hybrid tube amp? It sure is one hell of a pain in the arse bouncing from one board to another to test components.
regular,hybrid is tube power section and solid state pre amp or solid state power section and tube pre amp, that's what makes it a hybrid.this is just a complicated three channel tube amp.
I have the tsl122 combo ,, replaced the board to rev20 and seems ok ,, bias holding steady at 91mv which is stock ,, I tried setting it lower but sounds terrible , 90 91 is the sweet spot on the combo and runs really cool no issues so far ,, I would not fool with this amp if it did not sound so good up loud ,, I have had the mesa boogie rectifier and the carvin ,, and the jcm2000 live sounded the best for me ,, the clean is really punchy and super , loud this Marshall is meant for a strat
Nice shirt, I have that one and the Taylor Swift one as well. Have you ever worked on the old marshall vs100 amps? I picked one up last week and it's a bit noisy. Not sure of that's just the nature of the beast or not. It was supposedly service at a guitar center last year.
the ring you are wearing. my late grandfather left one almost exactly like that to me. its called a kentucky cluster and no we dont live in ky lol.. is that what yours is
It was going to be a Christmas gift from my Grandma to my Granddad in 1980. He died on her birthday, December 8, 1980, which was also the same day John Lennon was shot, and never received it. Years later, my Grandma gave it to me. I've worn it ever since My finger was large enough to wear it. Yes, I think they call it a Kentucky Cluster Ring. I've lost one of the diamonds from it along the line. I need to get another one set.
JJ el84s and the 5751 is the only tubes I would use from them..pre amp tubes and 6l6 always gave me trouble..and they sound sterile..btw had a old fender twin lying up..wouldnt power up..always thought the transformers were bogey..thanks to your vids I got it going perfect..you gave me somewhere to look..keep up the good work...SLAN.
Their 6V6 is pretty good too. It can withstand some crazy high voltage levels that turn certain modern valves into redplating messes. They don't sound half bad either.They work very well in Fender amps that run very high voltages. I've got a pair in a Cub, but that's quite a low voltage amp. They've run happily for a couple of years now and sound great when cranked. Biasing is important!That amp has a JJ 5751 as V1. Their 12AX7 didn't sound good. Their 12AY7 was mud incarnate. Yuk.I tried JJ in my home made Champ-a-like, largely because I've got a few of various types knocking around. The 6V6 wasn't a good match in it and the 12AX7 made it flaccid. Oddly, that amp sounds its best ( to my ears ) with either an EHX 12AY7 or a Ruby 12AX7HG5+ and an old Reflektor 6n6p ( Russian 6V6 clone )
Although I am not a guitar amp tech, furthest from it, I really enjoy your videos. I think I have heard you say you"re in N.C.? If so, I have a few projects that I would like discuss with you. 1. 1971 Univox U-1011 Lead 2. 1971 Univox U-1226 Lead. I just don't know if it would worth restoring but the old "KOOL" factor. I would value your opinion if you could. This is info I have found so far; "1010/1011 (1) ($605) - separate w/ 10 tubes, 105 W, 2 channels, 4 inputs, bright and normal for eah channel, volume for each channel , bass, middle and treble shared on both. presence, reverb, tremolo speed and intensity, variable impedence (8/16ohm) and a cabinet w/ 8 10" Univox Special Design speakers. Volume for channel one also had "Pull HB", a brightness/boost selector. Also has a 2-4-6 ohm switch on the back, as well as 4 separate speaker outputs, and two foot switch inputs. The handles are located on top of the head. The 1010 came with the 1011 (amp) and the 2080 (cab)." "1225/1226 ($435) - 60W head(1,2), same controls as 1010 ( 2 channels, 4 inputs, volume, bass, middle and treble for each channel, presence, reverb, tremolo, pull bright on ch 1), variable impedence(8 or 16 ohms), jack for reverb and tembolo switch, 8 tubes (6L6GC), and metal handles. Note the 1225 is the Amp and Cab, the 1226 just the amp., the 1205 is the cab"
These kind of videos I like, I need to do my JCM2000 DSL,so this is great.Thanks man.A lot of folks are changing out these motherboards ,easy enough ,but why not do a little more long term testing at the factory,so you don't have to change a large item such as this.Everyone needs a buck I guess.Thanks 👍🎸🎸😎😎🎶🎶🎶 Rock on!!!
ten littleindians there's a guy on Facebook that makes t shirts of pop stars but if they were metal bands. The Celine Dion on is a paradoy of a cannibal corpse albulm cover. I have that one and the Taylor Swift one, which is a darkthrone paraody.
This constant battle between tube vs solid state/digital amp technology is reminding me of the battle between film and digital cameras. And we all know how that ended don't we?!😂
i have this amp, it died, i left it for 2 years, took it to a tech, he said the transformer was blown, it was sent away, rewound, and he charged me $200, i took it home, sounded great, then an hour later i got a buzzing noise, and i remembered it from before it died the first time, the distortion also got a fuzz on it, so i let it cool and turned it off, and returned it to the tech, he looked at it told me it was sweet and gave it back to me, it started buzzing then it shut off, 90 mins later i took it to him and we opened it up, the transformer was SOOO hot!! it was stuffed again, hes had it rewound, says its over heating and he does not what to do, all this time i thought he was fixing it, but he just put it to the side, its been 4 to 5 months..... would you know what would be causing this?
Did you try turning it up to 11? Lol. But seriously I love your video’s. Always look forward to new ones....even the non guitar/amp ones. Better than any reality show. Shit post Friday’s are awesome! 🤘🏼
My tsl reverb hummed like it had forgotten the words after changing the board, turned out I'd connected it up in reverse durrr!! I convinced my self it was a bad connection...,.. which I suppose it was!!
JJs aren't always good as cathode followers and input tubes (even though they are low microphonics) depending on amp design and luck of the draw on the tube itself. They don't like low plate voltages and become "scratchy" and they're known to pull more current and in turn lower the plate voltage, they don't like high cathode to filament voltages either. JJs can be really a pain depending on the amp.
Yeah in theory that is true, but a lot of internet feedback (and personal experience) leads me to believe that that is no longer the case. My belief is that today's production can't really handle the 180v Uk/f as well as know tubes that can (Chinese) meaning they are generously rated, or play with words like saying yeah that's the limiting value, you shouldn't really run them at that all the time. I think they might have changed something down the line regarding raw materials or something to reduce production costs, coz now (in Europe anyways) they are the cheapest tube you can buy (not talking OEM), even cheaper than Shuguang branded tubes (except when you go in to gold pin BS and balanced and all that). JJ by the looks of it has been going a bit down hill for the past decade, they just have a tendency of just crapping out for no real reason or half of the tube going, the cathode shorting or some stupid thing that doesn't normally happen. They don't like the low input grid voltages either and draw more current than they should, just an overall problematic tube good for low noise. Don't know how the 803 JJs hold up though (rated for 200v). But really they've been tubes that have been advised for such a long time now that they can probably get away with it easier. And frankly I hate the sound of JJ preamp tubes (but that's just me), they suck all the highs and mids, sound dull and "too" smooth a bit like if you'd use an excessively long guitar cable without a buffer, even in bright amps they don't do it for me. And on the other hand the new sensor tubes that shouldn't be able to handle high Uk/f voltages never give me any trouble at all in the CF position so go figure...
I think you'll find that the "too smooth" thing is really just their short plate tubes. In my Jet City JCA100HDM, I run a long plate (803) in V1 and V2-4 are the medium plates (83MG).
Confused these are dl34 tubes which are 25 watt tubes with 70% is 17.5 watts that should have a bias of around 36 to 40 mv not 70 varies of course on plate voltage
Appreciate the schematic and tech fault find lesson but wouldn't you just start swapping existing tubes with known to be good tubes as that would always be the most suspect origin to pinpoint the fault ..?? I'm not a pro tech but that would always be where I would think to begin the process. Thanks as I always learn something re: trouble shooting from your channel
Those JCM 2000 were infamous tube killer, with errant bias, unlocatable noises etc. When those was sent back for repair under warranty, Marshall often return a brand new one, pretending the original one was lost or destroyed by the transporter.. To bad as the jcm2000 are sounding quite good, but the serie earned a reputation of bad amps overall. This also damaged Marshalls reputation , and opened the way for smaller makes.. Apparently there was a defecti on the first iterations up to the 7 (as written on the board) revision. Was fixed, but to late and the damage already done.
JJ's 7591 is to be avoided, as it does NOT meet the required specs of the stuff that take that tube. (scott receivers, some Ampegs, Cordovox). I wonder if JJ's EL34 has some issues......... I know Tung-Sol's first 5881 reproduction was NOT as robust as the old school ones, and a number of them went poof. If I don't have a go-to for a tube model/maker, I usually default to EH, since I've NEVER gotten a stinker with their brand on it.... their 6V6 is super.
I have nothing bad to say about JJ's 12AX7, or EL84 (6bq5)... They've fixed a number of their issues.... I have a Quad of 6L6 that are doing well. My fav 6l6 is the Tung-Sol. JJ isn't an end-all tube supplier for us at Mr. V Amps.
Sovtek is pretty durable... for "function" tubes they are a go-to. The Same plant that makes Sovtek also makes EH, TungSol, Genalex, Mullard, and Svetlana brands (current production versions) Sovtek's 12AX7's were gritty until they released the LPS... that's a good improvement.
I have installed a quad of JJ 6L6gc in V4 amp running 585vdc on the plates successfully. How long they lasted I am not certain but they held up to the high voltage. However it is the current that is the tube killer so yes bias those cold of course. If I had a V4 on the bench today I think I would go with some Sovtek 6L6Wxt tubes.
how much do these heads cost? wouldnt it be nice if marhsall used some better caps? those sanwa electrolytics are pieces of total shit. I do alot of crt television repair for arcade games and those things are piles of junk.
Marshall just replace the motherboards on DSL's and TSL's - the original boards were crap quality and break down internally over time. They had new ones made that "should" last. I dont even attempt to repair them any more if customer isn't prepared to pay for new boards.
Gday brad! I find it hard to watch anything Marshall related... my wallet seems draw stay current and heat up, often followed by red plating on my face. I've only known somewhat dissatisfied owners of Marshall tube amps. The valvestate 2000 series were, are somewhat well liked in my neck of the woods. Batches of entire amp models seem to be hit and miss from old Jim C Marshall. The last 15 yrs anyway...thanx for making this video.
To those asking why didn't I swap or pull tubes to diagnose first, it's a good question... That's where I'd begin too if the amp was not open on my bench. I'd pull V1 and look for noise to persist. If it persisted, pull V2. If noise disappears, you've found the stage, but not necessarily the source. If you're LUCKY, you've got a tube issue, but not always. Since the amp was already open, this made a better video than just pull V1...still noise...pull V2...noise gone...maybe it's the tube...swap tube...get lucky. I'm not recommending everyone open their amp and trace the problem in this manner for the word "go". Sorry if I gave that impression. But this would have caught the issue whether it was a bad tube (which was the case here) or a bad something else. Hope this helps someone.
The Guitologist i have an Deluxe Reverb 68 reissue that had exactly that noise, i was lucky it was just a bad preamp tube, dont know which cus i got a set of quality replacements for all of the preamps. Love your videos Brad, keep up the good work 👍🏻
Thanks, Thomas.
The Guitologist hi, if you are interest I’ve encountered the standard bias trouble with my 1997 DSL100 (red plating the power tubes) and I used an extra little board (5cmx8cm) connect to the power tubes which redesign and solve the bias problem on these earlier versions!! And that solved my trouble like a dream!! So if you want I send you all the infos, pcb, part list and layout in PM!? By the way your videos are AWESOME!!! Thank you so much!
Good Job Brad..!! I wonder how much noise this amp has due to the fact that many of the harnesses are NOT twisted?? Having a good tube tester is always simpler. I usually use Amperex on the pre amp side.
any chance you could send that my direction? Having a nightmare with a JVM 410H
This and your last video, show exactly why I like this channel so much.
You are not afraid to show you are human and leave in mistakes, which you could have easily edited out
Old EL 34s ('60s) were never a problem. The only time I lost one was when someone tipped a pint of beer into my mesh-boxed amp. That cleared everything out with a bang.
You should get a tester. :)
I'm glad I set my mind to never going with first impressions. My first viewing of your channel was a S*** Friday vid and I found myself coming away from it with the wrong impression. Car guys can argue all day about different makes and models. Both sides are right on some of the particulars. It is most often just a matter of personal tastes.
Your channel has become a favorite. I get a bit nostalgic looking over your shoulder. Back in '71 I had completed the first six months with U.E.I. (University of Electronics Institute) in Louisville, KY. (Done through the mail) with perfect grades. When it came time for the year and a half in L'ville, our dad told me, "Nobody paid to send me to college so I don't see why I should for you..." I had paid for the first semester with my savings from working on other farms. Since I'd graduated from school at 17, I had no chance at financing without a co-signer. So that put the brakes on that. I also did some time in IT as service manager for my professor/employer at the local community college twenty years later. I once had a Wyse keyboard computer (don't remember the model number but the entire system was in the keyboard and just had the power chord and monitor cord externally) waiting on my desk when I came in to work. Some sadist at Wyse had designed the thing with the 3-pin (soldered to the bottom of the motherboard) battery at the bottom of everything. I was given the task of replacing the battery with *NO* documentation, going to the customer's home and setting it back up (they were at work) and then being out at the college for mid-terms at 1pm. (You wouldn't have wanted to look over my shoulder and listen in on that one... [Grin] )
I had a blast building kits and was fascinated by electronics. The advent of calculators would have helped with my dislike of mathematics.
Getting to follow along on your projects is very enjoyable. It is a gift as well as a sign of your comfort with what you've learned along the way that you are able to talk through your thought processes while troubleshooting a project. If only I had your experience maybe I could get my old 10 channel, powered Carvin mixer working again... :( This was one of the 1970s models made back when they still did military style wiring. I look at the schematic and compare it to the guts of the mixer and just can't get the feeling that they are both the same thing.
Thanks for watching. Shame your dad wouldn't help you out with college. You can learn all you need to know these days from books, TH-cam, and diving in.
Brad.
Your playing rocks!
Thank you for putting out great content and sound values.
Have a good one.
friend of mine had one of these 2000s for 6 months & 4 months of that was spent at a shop ,, nothing but trouble ,, getting hot beyond normal ,, on the other hand I've been using a JCM 800 100w 2ch for almost 25 years & NOT ONCE its been to a shop,, still has the same tubes I bought it with 25 years ago,, same caps & everything,, OK cheers !!
Having some of the same issues with my TSL 100. First time seeing the shields inside the EL34s (v7 and v8) glowing red! I've watched Tony McKenzie's video about changing the motherboard to issue 20, and decided to bite the bullet and change it out (it is currently shipping my way). One of the things he suggested was to solder electrically close the ground "switch" of the 16 ohm speaker jack closed to prevent putting an excessive load on capacitor C46 by the edge of the board. Something to consider... great video! Thank you so much!
As you adjust the bias between each pair of tubes it is definitely a balancing act. It is also beneficial to have a four probe bias socket tester for beast amps like these. The last TSL100 I worked on had one single tube pulling a butt load of current. Using the bias probes allows me to swap tubes around to see bias shifts quickly. My problem was that there was just one tube cooking at 85-95% dissipation. Point is that setting the bias the way Marshall intended would never reveal that issue with one of the tubes. Perhaps this is what was going on with that one tube in this video that looked like it had taken some heat.
I have a thermal imaging camera that would tell me that too.
Hi Brad, another informative video. Always worth remembering that the only ‘bias’ is actually the voltage on pin 5 of the output tubes. Before looking for faults in the bias circuit just pull the EL34s and check that you can get the same voltage on all pin 5s. Also, if one side bias current is around half of the other side then you know you have lost one of the two valves in that pair. Cool playing as always.
Very interesting I had the same problem with my TSL 122 and in the end after having alot of problems Marshall rebuilt one main board and changed the tubes and the I started to get the same noise as you had in my other cab and I sent them both back to get sorted even though they were brand new at the time and under warranty it still makes you wonder and from what I know they have done a major board update to fix the bias problem once and for all but I am having a problem with forking out an extra £400 plus just to fix a problem that should not have been there in the first place. If I had known at the time I think I would have gone with the JSX which were going for about £1200 at the time but since I was building a stereo set-up it means two of everything. I still have the amps but I use my Bandit 112 for home use most of the time. Keep up the good work very interesting vids.
I had TSL 100...I love it.....at first ...started making screeching noises,replaced the tubes...matched set!....noise came back everytime they heated up! Brought it to my friend...you might have heard of him TONY BRUNO...BRUNO AMPS! He worked on it for hours still kept running crazy.. The Bias kept going a drift,and still crackeld! The cheap ass design that Marshall uses allows the heat to breakdown the board overtime! Tony worked for Korg/Vox/Marshall,and said the amps are junk compared to the earlier models...took his advice...got rid of it!
I'm in Santa Fe and just acquired a DSL 100, locally, that has the same problem. Amazing. I believe this will help me. Thanks.
I must have got lucky, I've had a TSL60 head and cab for decades and not a spot of trouble, still got the same valves and sounds great.
I had one these set on fire while playing on stage, completely burned out. The shop said it was due to tracking under the output valves. The vales used to really glow too hot.
Had exactly the same problem and this helped a lot in troubleshooting it! Thank you!
Hello Mate, thanks for the video!!! I got TSL 100 JCM 2000, and gain is so weak, gain is almost 9 on the crucnh channel but there is no gain at least, preamp tubes also new.. but result is same i wonder that have you any video that kind of problem? By the way i faced same issue with all channels , clean-crunch and lead😢
Love this video of you working on this particular amp. I just bought one for around $700 and have not received it yet. I can only hope that it's a good one but I may be sending it to you to fix if needed. I suppose they may not be actually possible since you may be a very guy. But seriously, I would rather have you fix it since I trust you. Anyway guy, your skills are awesome with fixing amps. If your amp fixing skills match your guy playing skills then you are a fantastic amp fixer. I love your playing. Man can you move those fingers around fast. Great playing dude. Thanks for having your channel. I really enjoy watching you work. Take care man.
Or...... guitar playing skills.....not guy playing skills..... sorry about that man.
The only Channel I don't fast forward thought the sponsor portion of the video.
Those Native Sons straps are really cool - wish I had the money to buy one!
Get the organic hemp backing if you get one. Best woven strap I own! And I own a LOT of woven straps.
Damn Brad I like the way you play, your phrasing is killer!
I bought one off the first tsl122 combos , I had my own lightshow , it burnt out valves at an alarming rate ,literally as soon as it warmed up .The bias drift was unbelievable , it would go up to 20 v !!!!!!! I retired it ,and by chance read about this bias drift on the internet ,people where changing lots of components and still no joy !!!! then someone found out that the material the board was conducting voltage through the board !!!! the only cure is to replace the board ,I replaced mine and it has been perfect ever since !!!!
I've heard the odd report of a new board doing the same thing, but I'm aware of the fix for the old boards. I'll do another video showing how that's done.
After watching part 1 and 2 of this "saga", I'm so glad I bought a Bugera 6262 Infinium head instead. : )
3:48 AM? I guess you can't sleep when you're having fun. XD
Looked at a TSL100, that was hissing, rustling, and popping. New tubes cleared up the noise floor, but the amp would continue to sporadically pop and rustle. It was angry inside lol. These issues followed the volume. I think all channels were affected. As the amp belonged to a friend of a friend, I didn't feel comfortable with more intrusive testing. Bias was solid and visually everything looked healthy. Not sure if there is a common culprit for these symptoms (?)
Whatever it was, it was likely toward the output of the amp, after the channels get mixed back together.. You can start at V1 and pull tubes while it's on and whichever one stops the noise, you've found the stage.
I purchased a TSL 100 for about $400 and it was red-plating a power tube. I replaced the mainboard and tubes and it rages. The only gripe I have about this head is that it runs at about 6.2 million degrees and I always run a fan at the power tubes. I have a JCM 900 and it just gets warm while playing for hours.
Hi Brad, you Tube Stuff Nerd (such a non sense in these two words, tube and nerd lol)
These few words to say I'm really fond of your amp surgeries, modding and so on. I learn so much, and reminds me some memories (trying to fix Marshall DSL or my Mesa Roadster nightmare)
Greetings from France :)
Thanks for watching.
Is the demo at the end through the test speaker? Sounds a bit thin, but excellent playing- I would love to see more Marshall vids.
Yeah that's just the test speaker sitting face down on the bench. :)
Doesn't the Marshall 2000 have a bias drift problem? And there's a klit from "Dr. Tube" to fix this problem? The kit may be cheaper?
This right here is one good reason that I will probably not ever buy another tube amp with circuit boards in them.I have also built one tube amp and learned a little more. There is just too much that can go wrong in a circuit board to suit me. In 2012 I bought a blues jr, and a hot rod deluxe,brand new. Within one week the blues jr., blew up got another and it messed up and within about a month one of the buttons on the hrd messed up.I still have an older blues jr. that I bought used.Had I known what I know now about tube amps, I probably would have kept them but at the time, I knew nothing about tube amps.I just don't have the money I used to have to buy gear that does not hold up. I have gone back to solid state for playing around the house.
It seems the first benefit of circuit boards is that amp designers can fit all these overly complicated circuits into a chassis. Many guitar players will see all these switches, extra jacks and buttons and get all excited. Not only is it nightmare to repair but as a player it is just overkill. It begs the question just because you can do something does it mean you should.
Some pretty tasty licks at the end there! Wasn't expecting to be more interested in trying to figure out what you were doing there than the fix! =) I just had the same issue on my JCM2000 50w with the noise. It was just a preamp tube (brand new ones). Thank God! I think I messed it up trying to bias the power tubes. Can you mess up pre-amp tubes by playing around to much with the bias pots? Going down to 20mA and back up to 60mA etc..? Tube Depot also gave me some bad power Tubes. Got some matched JJ EL34L and they sounded horrible, thought my amp was broken. Sounded good again when I just put the old regular Sylvania EL34's. Not sure if it was because the type of tube "EL34L" or if they were just bad tubes.
Great tutorial on the TSL-100. May I ask where I can get schematics for the TSL-100. Thanks. All the best & stay well !!!
i have the combo version of the tsl 122. new tubes, i have NO output to speakers and NO voltage on the bias adjuster. Do you have a video that adresses this problem. It's not low it's zero
thanks
So I have a TSL602 that has been driving me crazy and I can't track down the issue on. I'm by no means an amp repair pro, but I can handle most amp jobs I get. This one ended up having a power filter cap installed BACKWARDS by the nucklehead who got his hands on it before me. There were several blown caps. I replaced them and most of the crappy stock electrolytic caps with Nichicon and TDK caps. Replaced a few burnt up diodes and ceramic caps as well. This got the amp up and running, but there was no output and no power to the tubes.
Turns out the internal fuse was blowing. Starting it with either one of the power tubes removed allowed the amp to start without blowing the fuse. But one of the Pre tubes (V4) hardly glows compared to the others. Low heater voltage if I remember correctly. The filament in the fuse also warps like it's on the brink of blowing. Tubes are new and seem to check out. I end up figuring it's the Bridge Rectifier. Replace that, same problem!
Anyone have any advice or similar experiences? This is the one amp I just can't get working and it's driving me crazy.
Also, I forgot to mention, the guy who had it before me ended up making a solder bridge to compensate for where I assume he damaged the pcb. I forget exactly what circuit it's on (don't have the amp handy), but it was right beneath/next to one of the power filter caps. It was gobbed with silicon to insulate it and the cap had to be installed in a raised position. I made a small rubber platform to isolate and support the leads of the cap. It's been so long that I forget the exact details, but the circuit did seem to be functioning properly with no shorting caused by the solder bridge.
Dang man you can shred a little bit! And with finger picken too... good work.
Brad what power tubes do you recommend for Marshalls ?
Please. I need to replace the registor R21 on the rear jack board. Can You tel me what is the exactly resistor? A link, please.
Great video as always brad, awesome to see uncle Doug back making videos too . And wills easy guitar is back up . Happy days 😁
that rustling to me sounds like radio noise, like something is working as an antenna when it shouldnt be, now im not an expert on how tubes work, but if the tubes been cooked and the coatings burned off inside, would this be the cause of said noise ? electrons unable to be captured by the plate need to go somewhere...
Hello... Awesome video...
I have a JCM 2000 DSL100 and have a lot of hum when I am not playing. I also get a lot of crackle with the pots and even push buttons. I had a tech tell me that he doesn't think the pots are dirty and that its probably voltage from the MB? Does that even sound right? I was going to order a new MB and dont know if that will fix my problems. Any help is greatly appreciated :)
Paul
Brad when are you going to do more amp repais. My favorite .
does the Marshall JCM2000 TSL100, break easily? is the jvm 210 H better? please advise me thank you. because i dont know which one to buy.
What are your thoughts about the (PPIMV) Post Phase Inverter Master Volume kit from Triode USA?
Jesus dude you were amazing at the end there
Another great mod to do on these is to remove that 7W 270 ohm resistor and replace it with a filter choke. Do that to all these modern Marshall's. Just did my little DSL40 with a choke and a new output tranny. Night and day difference. Just put a filter choke in a friends JVM210 with a new set of 6CA7 tubes. Plus removed the C83( I think that's the number) cap on the input. Much more old school sounding with out all the fizz. He loves it now.
Guitar playing and amp sound great! 26:00
yea for some reason the reverb doesn’t work on mine ,anyone have any ideas why?
Hi mate. My tsl 100 head sounds like paper being scrunched or a static sound. Please help. Board changed, new tubes. Leaking capacitor perhaps?
I Have A TSL 100 Marshall Head & No Sound. How Can I Send It To You For Repair ?
Question... I just Bought a TSL 100.Do they have a lot of problems or should I buy something else !Tad.
I wouldn't want to rely on one without backup.
Buy a Mesa or Rivera be Happy!
Those are notorious for bias drift. I had a TSL-100 and it required me to replace the entire board. I found one cheap from a UK supplier for < $100 brand new. Once it was replaced, the amp sounded like poop so I sold it. Too bad.
Brad,
Thanks for the new video! Very interesting. Have you ever made a video featuring your tube tester? I'd like to see that.
I had one of these TSL's before but I sold after going the shop so much. Here I picked another one up recently that's a bit on the noisy side and the reverb only works on the clean channel. Any one ever run into that before and if so how did you fix it?
lots and lots of diagnostics,there's no quick,cheap easy answer to these questions
Same for me but just in 25 watts !?!? Any solution ? Thanks :)
It does seem to be the pattern with most of these amps that the faults are most likely to be in the capacitors, the valves or diodes.
Nice Vid ! Dig the hunt ! Don't know why JJ Tubes are so popular. I've got so many Microphonic 12AX7 and 6L6's. These Marshall High gains will find any weakness in the preamp section. Since I worked on many Mesa's I have a stock pile of Mesa Tested 12AX7"s, never had a Microphonic Mesa 12AX7. Not that their the best , they can be low gain or output in some amps ,but they are consistent . My fave 12AX7 has to be the NOS EI long Smooth Plate . Back over a decade ago I got mega gross for cheap . Now there not cheap everyone knows they were made the same as the German Telefunken's. So if you see someone selling old Boogie preamp tubes for cheap , get them !
Thanks for posting this ,.........I've watch both videos and not sure about JJ tubes anymore !!...haha!
Id like to know how much u charged for this?. All that work just for a bad tube. Plz be honest. Thx
Nice job on finding the faulty tube...and showing the process of elimination to get there. This shows how to eliminate 100's of components in a matter of minutes, leaving only a few to troubleshoot.
P.S. I happened to notice the time on your laptop...late night or early morning?!
Congrats on the use of the capacitor-blocked signal tracer probe. Those babies usually tell ya what you need to know.
I get this very light crackling in my tubes I believe it is in my Marshall DSLHR100 head.
Very cool video Brad. Once again I’ve learned a lot and you have reminded me of things I’ve forgotten over the last thirty-five years or so since I did much of this. I’m also curious, would you call this a regular or hybrid tube amp? It sure is one hell of a pain in the arse bouncing from one board to another to test components.
regular,hybrid is tube power section and solid state pre amp or solid state power section and tube pre amp,
that's what makes it a hybrid.this is just a complicated three channel tube amp.
I have the tsl122 combo ,, replaced the board to rev20 and seems ok ,, bias holding steady at 91mv which is stock ,, I tried setting it lower but sounds terrible , 90 91 is the sweet spot on the combo and runs really cool no issues so far ,, I would not fool with this amp if it did not sound so good up loud ,, I have had the mesa boogie rectifier and the carvin ,, and the jcm2000 live sounded the best for me ,, the clean is really punchy and super , loud this Marshall is meant for a strat
Nice shirt, I have that one and the Taylor Swift one as well.
Have you ever worked on the old marshall vs100 amps? I picked one up last week and it's a bit noisy. Not sure of that's just the nature of the beast or not. It was supposedly service at a guitar center last year.
the ring you are wearing. my late grandfather left one almost exactly like that to me. its called a kentucky cluster and no we dont live in ky lol.. is that what yours is
It was going to be a Christmas gift from my Grandma to my Granddad in 1980. He died on her birthday, December 8, 1980, which was also the same day John Lennon was shot, and never received it. Years later, my Grandma gave it to me. I've worn it ever since My finger was large enough to wear it. Yes, I think they call it a Kentucky Cluster Ring. I've lost one of the diamonds from it along the line. I need to get another one set.
JJ el84s and the 5751 is the only tubes I would use from them..pre amp tubes and 6l6 always gave me trouble..and they sound sterile..btw had a old fender twin lying up..wouldnt power up..always thought the transformers were bogey..thanks to your vids I got it going perfect..you gave me somewhere to look..keep up the good work...SLAN.
Their 6V6 is pretty good too. It can withstand some crazy high voltage levels that turn certain modern valves into redplating messes. They don't sound half bad either.They work very well in Fender amps that run very high voltages. I've got a pair in a Cub, but that's quite a low voltage amp. They've run happily for a couple of years now and sound great when cranked. Biasing is important!That amp has a JJ 5751 as V1. Their 12AX7 didn't sound good. Their 12AY7 was mud incarnate. Yuk.I tried JJ in my home made Champ-a-like, largely because I've got a few of various types knocking around. The 6V6 wasn't a good match in it and the 12AX7 made it flaccid. Oddly, that amp sounds its best ( to my ears ) with either an EHX 12AY7 or a Ruby 12AX7HG5+ and an old Reflektor 6n6p ( Russian 6V6 clone )
Hey Brad. Love the elevator musak. Great show I enjoy the content..
In a round about way I liked both videos on this bro. ATB
That bad preamp tube needs to make a bee line to the trash can. Good video! I have two Marshall TSL60 amps. I love how they sound.
Although I am not a guitar amp tech, furthest from it, I really enjoy your videos.
I think I have heard you say you"re in N.C.? If so, I have a few projects that I would like discuss with you. 1. 1971 Univox U-1011 Lead 2. 1971 Univox U-1226 Lead. I just don't know if it would worth restoring but the old "KOOL" factor. I would value your opinion if you could. This is info I have found so far;
"1010/1011 (1) ($605) - separate w/ 10 tubes, 105 W, 2 channels, 4 inputs, bright and normal for eah channel, volume for each channel , bass, middle and treble shared on both. presence, reverb, tremolo speed and intensity, variable impedence (8/16ohm) and a cabinet w/ 8 10" Univox Special Design speakers. Volume for channel one also had "Pull HB", a brightness/boost selector. Also has a 2-4-6 ohm switch on the back, as well as 4 separate speaker outputs, and two foot switch inputs. The handles are located on top of the head. The 1010 came with the 1011 (amp) and the 2080 (cab)."
"1225/1226 ($435) - 60W head(1,2), same controls as 1010 ( 2 channels, 4 inputs, volume, bass, middle and treble for each channel, presence, reverb, tremolo, pull bright on ch 1), variable impedence(8 or 16 ohms), jack for reverb and tembolo switch, 8 tubes (6L6GC), and metal handles. Note the 1225 is the Amp and Cab, the 1226 just the amp., the 1205 is the cab"
?
Nice work and great playing...
I've taken off and gone stupid many times. I always seem to be biased though, especially when I'm properly wired.
What year is that tele?
GriffinGTR Goodyear
These kind of videos I like, I need to do my JCM2000 DSL,so this is great.Thanks man.A lot of folks are changing out these motherboards ,easy enough ,but why not do a little more long term testing at the factory,so you don't have to change a large item such as this.Everyone needs a buck I guess.Thanks 👍🎸🎸😎😎🎶🎶🎶 Rock on!!!
Same problem, same solution on a Randall RG50 here :)
nice troubleshooting. BTW, I want a guitar duet between you and Richie castellano. the analogic world meets cpu. :)
KISS. All techs get reminded of it occasionally. Anyway, BTG is the best guitar player/ amp tinkerer that I watch on YT.
Nice video but? What's the story behind that tee shirt?
ten littleindians there's a guy on Facebook that makes t shirts of pop stars but if they were metal bands. The Celine Dion on is a paradoy of a cannibal corpse albulm cover. I have that one and the Taylor Swift one, which is a darkthrone paraody.
So, a power tube shorting afternoon heating up and a noisy pre amp tube. Nothing much to it other than figuring it out :-)
This constant battle between tube vs solid state/digital amp technology is reminding me of the battle between film and digital cameras. And we all know how that ended don't we?!😂
tube amps will exist indefinitely as they are what "solid state/modelling amps" are essentially emulating
i have this amp, it died, i left it for 2 years, took it to a tech, he said the transformer was blown, it was sent away, rewound, and he charged me $200, i took it home, sounded great, then an hour later i got a buzzing noise, and i remembered it from before it died the first time, the distortion also got a fuzz on it, so i let it cool and turned it off, and returned it to the tech, he looked at it told me it was sweet and gave it back to me, it started buzzing then it shut off, 90 mins later i took it to him and we opened it up, the transformer was SOOO hot!! it was stuffed again, hes had it rewound, says its over heating and he does not what to do, all this time i thought he was fixing it, but he just put it to the side, its been 4 to 5 months..... would you know what would be causing this?
Did you try turning it up to 11? Lol. But seriously I love your video’s. Always look forward to new ones....even the non guitar/amp ones. Better than any reality show. Shit post Friday’s are awesome! 🤘🏼
Nice job man 👍
Those proprietary Marshall stand-offs are (M-SPCR-00045) and $5.95 each. Sharing in case anyone else is in the same boat I am.
My tsl reverb hummed like it had forgotten the words after changing the board, turned out I'd connected it up in reverse durrr!! I convinced my self it was a bad connection...,.. which I suppose it was!!
gostei muito thanks
JJs aren't always good as cathode followers and input tubes (even though they are low microphonics) depending on amp design and luck of the draw on the tube itself. They don't like low plate voltages and become "scratchy" and they're known to pull more current and in turn lower the plate voltage, they don't like high cathode to filament voltages either. JJs can be really a pain depending on the amp.
Interesting, my understanding was they could handle high cathode to filament voltage about as well as Chinese tubes.
Yeah in theory that is true, but a lot of internet feedback (and personal experience) leads me to believe that that is no longer the case.
My belief is that today's production can't really handle the 180v Uk/f as well as know tubes that can (Chinese) meaning they are generously rated, or play with words like saying yeah that's the limiting value, you shouldn't really run them at that all the time.
I think they might have changed something down the line regarding raw materials or something to reduce production costs, coz now (in Europe anyways) they are the cheapest tube you can buy (not talking OEM), even cheaper than Shuguang branded tubes (except when you go in to gold pin BS and balanced and all that).
JJ by the looks of it has been going a bit down hill for the past decade, they just have a tendency of just crapping out for no real reason or half of the tube going, the cathode shorting or some stupid thing that doesn't normally happen.
They don't like the low input grid voltages either and draw more current than they should, just an overall problematic tube good for low noise. Don't know how the 803 JJs hold up though (rated for 200v).
But really they've been tubes that have been advised for such a long time now that they can probably get away with it easier.
And frankly I hate the sound of JJ preamp tubes (but that's just me), they suck all the highs and mids, sound dull and "too" smooth a bit like if you'd use an excessively long guitar cable without a buffer, even in bright amps they don't do it for me.
And on the other hand the new sensor tubes that shouldn't be able to handle high Uk/f voltages never give me any trouble at all in the CF position so go figure...
I think you'll find that the "too smooth" thing is really just their short plate tubes. In my Jet City JCA100HDM, I run a long plate (803) in V1 and V2-4 are the medium plates (83MG).
Confused these are dl34 tubes which are 25 watt tubes with 70% is 17.5 watts that should have a bias of around 36 to 40 mv not 70 varies of course on plate voltage
Appreciate the schematic and tech fault find lesson but wouldn't you just start swapping existing tubes with known to be good tubes as that would always be the most suspect origin to pinpoint the fault ..?? I'm not a pro tech but that would always be where I would think to begin the process.
Thanks as I always learn something re: trouble shooting from your channel
amp was already apart,next question?
Those JCM 2000 were infamous tube killer, with errant bias, unlocatable noises etc. When those was sent back for repair under warranty, Marshall often return a brand new one, pretending the original one was lost or destroyed by the transporter..
To bad as the jcm2000 are sounding quite good, but the serie earned a reputation of bad amps overall.
This also damaged Marshalls reputation , and opened the way for smaller makes..
Apparently there was a defecti on the first iterations up to the 7 (as written on the board) revision. Was fixed, but to late and the damage already done.
I like the Ampeg VL502 more than a Marshall.
JJ's 7591 is to be avoided, as it does NOT meet the required specs of the stuff that take that tube. (scott receivers, some Ampegs, Cordovox). I wonder if JJ's EL34 has some issues......... I know Tung-Sol's first 5881 reproduction was NOT as robust as the old school ones, and a number of them went poof. If I don't have a go-to for a tube model/maker, I usually default to EH, since I've NEVER gotten a stinker with their brand on it.... their 6V6 is super.
I tend to err away from JJ too. I have a quad of 6 month old 6L6GCs in my Peavey that are already showing signs of premature wear.
I have nothing bad to say about JJ's 12AX7, or EL84 (6bq5)... They've fixed a number of their issues.... I have a Quad of 6L6 that are doing well. My fav 6l6 is the Tung-Sol. JJ isn't an end-all tube supplier for us at Mr. V Amps.
DeadKoby I've had really good luck so far with sovtek and and old surplus Phillips tubes.
Sovtek is pretty durable... for "function" tubes they are a go-to. The Same plant that makes Sovtek also makes EH, TungSol, Genalex, Mullard, and Svetlana brands (current production versions) Sovtek's 12AX7's were gritty until they released the LPS... that's a good improvement.
I have installed a quad of JJ 6L6gc in V4 amp running 585vdc on the plates successfully. How long they lasted I am not certain but they held up to the high voltage. However it is the current that is the tube killer so yes bias those cold of course. If I had a V4 on the bench today I think I would go with some Sovtek 6L6Wxt tubes.
Test the tubes ---- 6CA7 will do it!
always always put a fresh set of tubes.
how much do these heads cost? wouldnt it be nice if marhsall used some better caps? those sanwa electrolytics are pieces of total shit. I do alot of crt television repair for arcade games and those things are piles of junk.
LOL I wish i had a dollar for every time I was repairing and amp and said "Man I hope that's all that was!"
Marshall just replace the motherboards on DSL's and TSL's - the original boards were crap quality and break down internally over time. They had new ones made that "should" last. I dont even attempt to repair them any more if customer isn't prepared to pay for new boards.
Thanks Brad..... God Damn Marshall's
Right!! I finally worked out who Bradley Govan is, LOL!
Celine Dion?.... on your shirt :)
Gday brad! I find it hard to watch anything Marshall related... my wallet seems draw stay current and heat up, often followed by red plating on my face. I've only known somewhat dissatisfied owners of Marshall tube amps. The valvestate 2000 series were, are somewhat well liked in my neck of the woods. Batches of entire amp models seem to be hit and miss from old Jim C Marshall. The last 15 yrs anyway...thanx for making this video.
@28:00 great playing, now, PUT A TORTOISE SHELL PICK-GUARD ON THAT TELE FOR THE LOVE OF MIKE !!