Beautiful British Amplifier 📢 Top tip: The 16 Ohm socket switches the other two via the earth terminal. Always have a look and make sure it's not looking distressed. I usually replace that socket on sight to save the output transformer failing because of a £1 socket 😋 Nice video Stu 😁
Lucky catch with that fuse holder, and nice repair. Interesting bias adjustments on that Marshall. It's a pity all amps aren't made with that feature..Thanks for sharing..Ed..Herts..uk..😀
Hi you have to change c2 on the small ac input board .they fail, 022uf 630v capacitors for a hi voltage one. Again a 2000v mkp wima will do the trick Another easy way to see if the dsl and tsl have a new board issue 20 is that on the newest board you have a relay for swithching instead of a ´´vactrol’´. Also when you put the newest version board in those amps why dont you run them with a pair of el34 or 6l6gc. It will reduce your risk of burning the new board, as you can see they didnt really change anything in the layout. And the dsl 50 was a lot more reliable for what i know. Anyway do you really need 100w and youll save on output tubes. Dont forget to adjust the bias properly. Around 37mv per sides for 50w and 75mv per sides for 100w. Thanks for sharing this video.
I seem to be experiencing this problem on the clean channel, the only temporary solution is to wiggle the volume knob which restores the volume, I just sprayed it down with electronics cleaner but from the outside and then vigorously worked the knob left and right, physically it is turning easier, give it an hour to make sure it's nice and dry, nine times out of 10 electronics cleaner it works, but I think that's more from the inside lol 🤪 if it works I'll update this comment
I feel like most marshall amps sound best with an eq shaping the sound. Even a 1979 marshall jmp sounds like a muddy mess until you throw an eq into the mix. Its actually quite easy to dial these amps especially when you balance the volume&gain controls. Volume sounds good till about 1 o clock, and gain sounds good until 12 o clock
Nice Video..Thanks for sharing..I have two of these amps..I have my bias settings at 90mv because 70 is too cold for my amps..They sound better at 90..I believe the schematic says a max of 90..It does seem kinda high because each tube is normally rated at 35 and two together makes 70..Thank you for your expertise..I learned a few things here.
Glad you enjoyed it! Yes 90 is fine. You have better ears than me. Blowed if I can hear any differemce between 20mA per tube and 40mA per tube let alone finer gradations!
Similar bias-measurement terminals are (internally) provided in some older solid-state Japanese hifi equipment such as Yamaha, Nakamichi and so on; the important difference being that if you short-circuit those solid-state bias-measurement terminals points by accident with your probes or jumper cables, you'll blow up the output stage in a fraction of a second (not only the "finals" as you British might say, but possibly the drivers, pre-drivers and differential amplifiers as well, plus a bunch of resistors). I made up some sets of various plug-in connectors (two-pin, three-pin, different spacing etc) with insulated leads and banana plugs on the other ends, to plug directly into the voltmeter, eliminating the need for fiddly "croc-clip" jumper leads. In a nutshell, this is the difference between working on tube equipment and solid state equipment: If you slip or make a mistake while working on solid state gear you'll blow up the amplifier, but if you slip and make a mistake while working on tube gear you might blow up the technician!
@@stuartukguitarampguy5830 , I try very hard to plan ahead so as to prevent the accidental release of the "magic smoke" that powers solid-state devices! I also try very hard not to let the magic smoke out of *me*. ( PS, I use a series-light-bulb current limiter as an added precaution ---- usefull while working on tube-powered devices, but absolutely essential for solid-state circuits). Some solid state amplifiers don't include test terminals for measuring bias, and therefore you have to measure the voltage drop across the emitter resistors for the output transistors. Oftentimes the emitter resistors are located in an area of the circuit board where it's almost impossible to get your meter probes in there safely without slipping and causing a disastrous short circuit.....
I sure could trigger a lot of Marshall diehard fans with a comment. One of my favorite rock guitarists who loves old Marshall’s and still has an old one he calls “the barbecue grill” (Phil X) when Marshall used to make great sounding amps (although their reliability was still an issue back then) decided to have another company make him a signature model. I’m not crazy about theirs either because I don’t trust mass produced PCB based amps for quality. All I can say is if you want a Marshall type amp that is a proper turret board, handwired amp at an unbelievably low price, call a gentleman named Nik. He’ll make you a lifetime amp.
@@SIXSTRING63 , Thank you for the link. This is extremely interesting. I would have expected the problem to occur because of the PC board absorbing moisture, and did not expect that the board would have or would develop a Negative Thermal Coefficient, which is fairly uncommon in most electronic components (with the exception of thermistors, which are specifically designed to act that way). Hygroscopy, and the conductivity it can cause, would generally be expected to decrease due to heat. I often caution people to avoid spraying contact cleaner into tube sockets, and avoid using it in such a way as to hit the PC boards with large amounts of it, for fear of causing conduction paths, or attracting dust and moisture, but most people just keep spraying away, wasting expensive products and perhaps setting themselves up for further problems down the road. (I prefer to apply contact cleaner sparingly to switches and controls using a syringe, or a squeeze bottle with extension nozzle, or a similar applicator). This has reminded me of a fancy and expensive Graaf tube hifi amp I worked on many years ago that was unstable and kept going into thermal runaway, and we never really did get it working reliably. Knowing what I know now, I would bet my bottom dollar that the board had become conductive. The output stage used 4 TV sweep tubes per channel, with all sockets mounted directly onto one big double-sided board. One side of the board wasn't accessible without complete disassembly, unsoldering numerous overly large and stiff wires, and so even if I had known about the possibility of a conductive board, fixing it by drilling holes and rewiring circuit paths would have been a nightmare. The engineers in Holland who designed it were clueless.....
Putting some high temp rated dielectric grease in ribbon connectors like that helps avoid issues with them corroding over time and getting intermittent. Doesn’t stop the wear on the solder joints from movement/vibration though.
I have a Marshall DSL 401 that started buzzing. Does it on both clean and overdrive channels and guitar plugged in or not. Are these renowned for earthing issues too, like some of the other Marshalls you've looked at? Is there a common fault?
Been having an issue with my own JCM 2000 DSL 100. One of the speaker inputs stopped working (8 ohm) so now I can't use my full stack. I have tried cleaning it with deoxit and switching cables. Also tested said cables with my other 2 amps and they work just fine.
Hi Nick Just checking you mean speaker outputs, right? Very unusual for one of those to go. It could be a dry joint on the underside of the jack socket.
So my jcm2000 just went out this weekend, I noticed recently when I was putting in standby it started making a loud popping noise usually just one pop and then Saturday when I went to try it out there was no noise coming from my guitar, it turns on and it kind of sounds like that humming noise that the amp was making when you were adjusting the bias but nothing is coming out of the speakers. All 4 tubes light up, I, need to check the fuses when I get home today from work
Hi Stuart, new to the channel 👍🏼 I have a vox ad120, I sounded like one speaker had gone bad (diminished volume) until I swapped over the wiring and the opposite speaker was "bad" (diminished volume) any ideas? I've had it returned by a couple of guys not wanting to work on it, apparently these types of amp are somewhat of a nemesis to many amp techs 🤷🏽♂️ It's too good to give up on Thanks
Hi I haven;t come across this amp before I don;t think. My guess is that it has two identical power amplifier chips in it, one for each speaker. This is why one channel is down. I hope you manage to get it sorted.
Hi Sean Hard to diagnose at a distance. Try all the preamp valves first of all. Also link FX SEND to FX RETURN with a jack-jack lead. Itherwise.. it could be quite a few things. Good luck!
@@stuartukguitarampguy5830 thanks for the reply....it actually was the number 1 pre amp valve....one half stopped working....first both channels were faint....I cleaned all the boards and put it back together and the green channel came back...but the red one didn't work....changed the number one valve and they both work....I hope nothing is causing this and it was just a faulty valve
@@SuperSeanXXX Great well done. Yes probably just a fauty vakve. Just had one this morning in a Marshall. Totally dead phase splitter valve. Changed it .. bingo!
I would love to do a totally blind rest on this, also on other things like this or that preamp valve has a 'warmer' tone or whatever. These tests are never done. Not saying you're wrong of course, it would just be interesting. I've got a pretty good ear and I can't really hear much difference between a warm and a cool bias.
@@stuartukguitarampguy5830 For example; the Thrash Metal guys I serviced liked the bias setting around 15-20mA per tube in their JCM800's with 6550's for a really crunchy albeit slightly thinner tone. On the other hand, the blues guys liked the bias running a little hotter around 35-40mA per tube in their 6L6 Fenders for a thicker tone and quicker breakup. Might I suggest; The Trainwreck Pages by legendary amp guru Ken Fischer... you can find it on Google, and it's a wealth of information on bias, etc. 👍
@@scottdunn2178 Yes I know the train wreck pages. I would still love to do a proper test as these things are SO subjective. Trouble is, such a test is almost impossible to carry out. Youi'd need two identical (!) amps, one biased cold, one hot and do a proper blind A/B comparison. Same with different makes of preamp and power tubes. Very, very tricky experiment to carry out and you'd need 100+ guitarists to do the test, double blind, to get statistically meaningful results. Again, please don't think I'm sayoing there's no detecatble difference or that people ar wrong. I'd just like to do the test. There's such a lot of smoke and mirrors in audio.
@@stuartukguitarampguy5830 And its very subjective from amp to amp... I would have the player play through the amp with their guitar, pickups, speakers, etc. and adjust.
@@scottdunn2178 Yes but hard to get meaningful info due to the time delay between playing with bias 'A' then adjusting, and some times later (even a couple of minutes) playing with bias 'B'. There are statistical methods for handling this sort of thing but it complicates the experiment. E.g. you would sometimes pretend to adjust the bias, when I fact you hadn't etc. But an A/B switch is a preferable solution when doing tests like this. You don't want a time delay between condition A and condition B. It also needs to be double blind so that neither the experimenter nor the player knows which bias setting they are listening to.
Beautiful British Amplifier 📢
Top tip: The 16 Ohm socket switches the other two via the earth terminal.
Always have a look and make sure it's not looking distressed.
I usually replace that socket on sight to save the output transformer failing because of a £1 socket 😋
Nice video Stu 😁
Good tip thanks.
Lucky catch with that fuse holder, and nice repair. Interesting bias adjustments on that Marshall. It's a pity all amps aren't made with that feature..Thanks for sharing..Ed..Herts..uk..😀
Hi you have to change c2 on the small ac input board .they fail, 022uf 630v capacitors for a hi voltage one. Again a 2000v mkp wima will do the trick
Another easy way to see if the dsl and tsl have a new board issue 20 is that on the newest board you have a relay for swithching instead of a ´´vactrol’´.
Also when you put the newest version board in those amps why dont you run them with a pair of el34 or 6l6gc. It will reduce your risk of burning the new board, as you can see they didnt really change anything in the layout. And the dsl 50 was a lot more reliable for what i know. Anyway do you really need 100w and youll save on output tubes. Dont forget to adjust the bias properly. Around 37mv per sides for 50w and 75mv per sides for 100w.
Thanks for sharing this video.
Awesome, I love these videos, greetings from Colombia!
Thanks Santiago!
Nice one Young Stuart!!
I seem to be experiencing this problem on the clean channel, the only temporary solution is to wiggle the volume knob which restores the volume, I just sprayed it down with electronics cleaner but from the outside and then vigorously worked the knob left and right, physically it is turning easier, give it an hour to make sure it's nice and dry, nine times out of 10 electronics cleaner it works, but I think that's more from the inside lol 🤪
if it works I'll update this comment
I bought one of these once. Returned it. The clean was great but the over drive was BAD! Thanks for the video.
I feel like most marshall amps sound best with an eq shaping the sound. Even a 1979 marshall jmp sounds like a muddy mess until you throw an eq into the mix. Its actually quite easy to dial these amps especially when you balance the volume&gain controls. Volume sounds good till about 1 o clock, and gain sounds good until 12 o clock
Nice Video..Thanks for sharing..I have two of these amps..I have my bias settings at 90mv because 70 is too cold for my amps..They sound better at 90..I believe the schematic says a max of 90..It does seem kinda high because each tube is normally rated at 35 and two together makes 70..Thank you for your expertise..I learned a few things here.
Glad you enjoyed it! Yes 90 is fine. You have better ears than me. Blowed if I can hear any differemce between 20mA per tube and 40mA per tube let alone finer gradations!
Good job!
Similar bias-measurement terminals are (internally) provided in some older solid-state Japanese hifi equipment such as Yamaha, Nakamichi and so on; the important difference being that if you short-circuit those solid-state bias-measurement terminals points by accident with your probes or jumper cables, you'll blow up the output stage in a fraction of a second (not only the "finals" as you British might say, but possibly the drivers, pre-drivers and differential amplifiers as well, plus a bunch of resistors). I made up some sets of various plug-in connectors (two-pin, three-pin, different spacing etc) with insulated leads and banana plugs on the other ends, to plug directly into the voltmeter, eliminating the need for fiddly "croc-clip" jumper leads.
In a nutshell, this is the difference between working on tube equipment and solid state equipment: If you slip or make a mistake while working on solid state gear you'll blow up the amplifier, but if you slip and make a mistake while working on tube gear you might blow up the technician!
Wow! Great design!!!
@@stuartukguitarampguy5830 , I try very hard to plan ahead so as to prevent the accidental release of the "magic smoke" that powers solid-state devices! I also try very hard not to let the magic smoke out of *me*. ( PS, I use a series-light-bulb current limiter as an added precaution ---- usefull while working on tube-powered devices, but absolutely essential for solid-state circuits).
Some solid state amplifiers don't include test terminals for measuring bias, and therefore you have to measure the voltage drop across the emitter resistors for the output transistors. Oftentimes the emitter resistors are located in an area of the circuit board where it's almost impossible to get your meter probes in there safely without slipping and causing a disastrous short circuit.....
I sure could trigger a lot of Marshall diehard fans with a comment. One of my favorite rock guitarists who loves old Marshall’s and still has an old one he calls “the barbecue grill” (Phil X) when Marshall used to make great sounding amps (although their reliability was still an issue back then) decided to have another company make him a signature model. I’m not crazy about theirs either because I don’t trust mass produced PCB based amps for quality. All I can say is if you want a Marshall type amp that is a proper turret board, handwired amp at an unbelievably low price, call a gentleman named Nik. He’ll make you a lifetime amp.
What’s Nick’s contact details…?
I found a really good fix for those conductive PCB's. I'll send you the link later. Building a Fender Champ from junk parts at the bench right now LOL
I'd like to see that as I usually end up changing the whole board.
@@stuartukguitarampguy5830 www.hullerum.de/Marshall/TSL122repair.html
This works great. I've done 10 or 12 TSL's with runaway bias and it cured everyone I did it too.
@@SIXSTRING63 , Thank you for the link. This is extremely interesting. I would have expected the problem to occur because of the PC board absorbing moisture, and did not expect that the board would have or would develop a Negative Thermal Coefficient, which is fairly uncommon in most electronic components (with the exception of thermistors, which are specifically designed to act that way).
Hygroscopy, and the conductivity it can cause, would generally be expected to decrease due to heat.
I often caution people to avoid spraying contact cleaner into tube sockets, and avoid using it in such a way as to hit the PC boards with large amounts of it, for fear of causing conduction paths, or attracting dust and moisture, but most people just keep spraying away, wasting expensive products and perhaps setting themselves up for further problems down the road. (I prefer to apply contact cleaner sparingly to switches and controls using a syringe, or a squeeze bottle with extension nozzle, or a similar applicator).
This has reminded me of a fancy and expensive Graaf tube hifi amp I worked on many years ago that was unstable and kept going into thermal runaway, and we never really did get it working reliably. Knowing what I know now, I would bet my bottom dollar that the board had become conductive. The output stage used 4 TV sweep tubes per channel, with all sockets mounted directly onto one big double-sided board. One side of the board wasn't accessible without complete disassembly, unsoldering numerous overly large and stiff wires, and so even if I had known about the possibility of a conductive board, fixing it by drilling holes and rewiring circuit paths would have been a nightmare. The engineers in Holland who designed it were clueless.....
@@SIXSTRING63 REALLY useful thanks! I'll give that a go next time.
Putting some high temp rated dielectric grease in ribbon connectors like that helps avoid issues with them corroding over time and getting intermittent. Doesn’t stop the wear on the solder joints from movement/vibration though.
Thanks Jonathan
Nice one. Know what I like about this amp? It's not a Peavey Classic 30 or a Fender Bassbreaker. :p
I have a Marshall DSL 401 that started buzzing. Does it on both clean and overdrive channels and guitar plugged in or not. Are these renowned for earthing issues too, like some of the other Marshalls you've looked at? Is there a common fault?
Been having an issue with my own JCM 2000 DSL 100. One of the speaker inputs stopped working (8 ohm) so now I can't use my full stack. I have tried cleaning it with deoxit and switching cables. Also tested said cables with my other 2 amps and they work just fine.
Hi Nick Just checking you mean speaker outputs, right? Very unusual for one of those to go. It could be a dry joint on the underside of the jack socket.
Yes that is what I meant. I appreciate your response and I'll definitely be looking into that.
So my jcm2000 just went out this weekend, I noticed recently when I was putting in standby it started making a loud popping noise usually just one pop and then Saturday when I went to try it out there was no noise coming from my guitar, it turns on and it kind of sounds like that humming noise that the amp was making when you were adjusting the bias but nothing is coming out of the speakers. All 4 tubes light up, I, need to check the fuses when I get home today from work
Ok could be the HT fuse.
Nice one. Just curious... what kind of glue did you use?
From memory it was a 2-part epoxy.
Hi Stuart, new to the channel 👍🏼
I have a vox ad120, I sounded like one speaker had gone bad (diminished volume) until I swapped over the wiring and the opposite speaker was "bad" (diminished volume) any ideas?
I've had it returned by a couple of guys not wanting to work on it, apparently these types of amp are somewhat of a nemesis to many amp techs 🤷🏽♂️
It's too good to give up on
Thanks
Hi I haven;t come across this amp before I don;t think. My guess is that it has two identical power amplifier chips in it, one for each speaker. This is why one channel is down.
I hope you manage to get it sorted.
@@stuartukguitarampguy5830 Thank you for the reply, i'll take a gander 👍🏼 great channel by the way, so much to learn!
what did you turn your meter to when you checked the HT Fuse? Great video.
Hi Ktch
Continuity - makes a beep when short circuit
@@stuartukguitarampguy5830 I think I have the exact problem with the exact same amp mine is the 50w
@@NorthernProductions886 Aha! Okay I hope you manage to resolve it.
@@stuartukguitarampguy5830 what type of fuse is the HT fuse Stu?
@@NorthernProductions886 It's usually a T1A (time delay 1 amp) but try and get confirmation. It should be written on the fuse end cap.
Hey there...I'm having a similar problem but I'm getting sound but it's very faint....I'm getting voltages and bias is holding steady
Output transformer? I have the same symptoms and mine is shorted. Damn
Hi mate I have a tsl 100 with a blown tube that cut out after playing could it be the same issue or could it be the main board?
Hi Paul. Hard to say. Tubes do go. I would just replace that tube and keep an eye on it. If it blows again, there's an obvious issue there.
Should have used the wifes.
I'm thinking boss katana are much better lighter and simpler to play
Stuart did you go to school electric's
Hi Paul I did a degree in electronics.
How do we know for certain that the toothbrush was invented in England? Because otherwise it would have been called a "teethbrush" :) :) :)
True, true...
Ouch! That's brutal. Lol
It's the dsl jcm2000
Hi Sean Hard to diagnose at a distance. Try all the preamp valves first of all. Also link FX SEND to FX RETURN with a jack-jack lead. Itherwise.. it could be quite a few things. Good luck!
@@stuartukguitarampguy5830 thanks for the reply....it actually was the number 1 pre amp valve....one half stopped working....first both channels were faint....I cleaned all the boards and put it back together and the green channel came back...but the red one didn't work....changed the number one valve and they both work....I hope nothing is causing this and it was just a faulty valve
@@SuperSeanXXX Great well done. Yes probably just a fauty vakve. Just had one this morning in a Marshall. Totally dead phase splitter valve. Changed it .. bingo!
I would disagree... bias current adjustment has a huge effect on the tone of the amplifier.
I would love to do a totally blind rest on this, also on other things like this or that preamp valve has a 'warmer' tone or whatever. These tests are never done. Not saying you're wrong of course, it would just be interesting. I've got a pretty good ear and I can't really hear much difference between a warm and a cool bias.
@@stuartukguitarampguy5830 For example; the Thrash Metal guys I serviced liked the bias setting around 15-20mA per tube in their JCM800's with 6550's for a really crunchy albeit slightly thinner tone. On the other hand, the blues guys liked the bias running a little hotter around 35-40mA per tube in their 6L6 Fenders for a thicker tone and quicker breakup. Might I suggest; The Trainwreck Pages by legendary amp guru Ken Fischer... you can find it on Google, and it's a wealth of information on bias, etc. 👍
@@scottdunn2178 Yes I know the train wreck pages. I would still love to do a proper test as these things are SO subjective. Trouble is, such a test is almost impossible to carry out. Youi'd need two identical (!) amps, one biased cold, one hot and do a proper blind A/B comparison. Same with different makes of preamp and power tubes. Very, very tricky experiment to carry out and you'd need 100+ guitarists to do the test, double blind, to get statistically meaningful results. Again, please don't think I'm sayoing there's no detecatble difference or that people ar wrong. I'd just like to do the test. There's such a lot of smoke and mirrors in audio.
@@stuartukguitarampguy5830 And its very subjective from amp to amp...
I would have the player play through the amp with their guitar, pickups, speakers, etc. and adjust.
@@scottdunn2178 Yes but hard to get meaningful info due to the time delay between playing with bias 'A' then adjusting, and some times later (even a couple of minutes) playing with bias 'B'. There are statistical methods for handling this sort of thing but it complicates the experiment. E.g. you would sometimes pretend to adjust the bias, when I fact you hadn't etc. But an A/B switch is a preferable solution when doing tests like this. You don't want a time delay between condition A and condition B. It also needs to be double blind so that neither the experimenter nor the player knows which bias setting they are listening to.
Toasty....
Indeed!
Hi Stuart. It was an accedent that I hit dislike. My mistake. Sorry
No worries!
Go back to 60’s for a Marshall spl. 🎸🎛🔈