British uncle doug!! If you guys don't know uncle doug,, he's our , yank, vintage amp guru and teacher. He's on you tube and one of the best in class!!!
Great amp. Great repair and restoration. Very interesting detective work. These old Marshall 20-40 watt amp circuits are all the rage with two valves. Its fascinating the use of TWO EL 34 or even KT 66 or KT 88 tubes. And even their American mother 6 L6 versions here in the States. Where the original Fender Bassman curcuits still began and rule all the Boutique amplifier two valve high gain guitar amplifiers. My friend here in California played two 50 Watt JCM 800 marshalls in stereo In the 1980's I must say of all the great Classic Rock guitar amplifiers I ever heard live the 50 Marshals were by far the best sounding amplifiers ever. A unique quality of upper mid range punch and gain that many otheramps have tried to emulate, but never quite attained. This one you worked on was beyond interesting. I felt like I was watching a classic Morse episode of who dunn it. Oxford and all. Every tech and sound engineer knows all of this began in the UK. I still remember Ginger Baker say it only went Tropo when Mr Marshall went to 100 watts instead of leaving well enough alone at these 50 Watt -/+ amps.
I dont often get excited about amps , but good God ! What a peice of history. I would absolutely love to put that through its paces. I do t think I'm worthy of working on it but.id looove to service it too. Wow ... just.wow
The introduction to this amp sounds about like my twenties... I found your channel yesterday, I think you're more fun than Netflix. Thanks for sharing your adventures in amplitude..
Sir I really enjoy watching you work. I am a radio and rf amp repair tech.for many many years. Not much audio work. A little on amy own guitar amps. I have learn alot from you and Uncle Doug. Thanks a million.
Thanks Monty. Wow I envy you your skills! I can;t do RF stuff. My father was a very well known radio amateur G3HSR and VK9NS. Never taught me a damn thing though!!
@@stuartukguitarampguy5830 You could do it Stuart, Just a little different. I have been an amateur many years. It is possible I ran into him at sometime. God Bless..Monty
Ove gotten into the habit of soldering everything on top of the board . And anything that has to go on the bottom gets a dab or super glue. I've also set amps aside for weeks out of frustration!!. Amazing job on that old beast!!
Enjoying your videos very much Stuart! Thanks for sharing. On the seemingly random component value 47uF: my understanding is that the values are chosen so that they cover all possible values if you factor in the tolerance. For example, if you start with a value of 1 (ohm or nanofarad or whatever), considering a tolerance +/- 10%, that 1.0 is really just somewhere between 0.9 and 1.1. The next value is 1.2 covering 1.08 to 1.32 and so one, giving "preferred values" of 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.1 and 10, at which point you start all over. 5% series will have more values to cover the range (and 1% range will have _many_ more values.) Hope that makes sense! Cheers from Sydney AU
Beautiful amp and I admire your tenacity on doing it right! I built one of these with an aluminium chassis about 15 years ago! One of the best sounding amps I own. Cheers Stuart!
What I get to repair in Brazil is worse! Messed around by customers of other service centres! People here now are learning to always bring to the honest and experienced English guy!
Hi Stuart another great video on what must be one of the greatest amps Jim Marshall ever made, a huge part of Rock & Roll history and used by many great players back in the day
Hi Stuart, when I repair an amplifier or other type of device and I have to unsolder components, I take a picture with the phone and also write down in a notebook the description of what I have done, because sometimes I am wrong and then I have gone crazy looking the problem. Thus, before turning on the amplifier I review all the notes and the photographs and make sure that everything is correct. The Bluesbreaker is a legendary amp, a gem. The video is great and your work has been excellent. Cheers
Thanls fpr the link to the tubestore schematics, I did know about that. You'll notice that your posting didn;t make it here. That's because anything with a URL in it is automatically considered spam and chucked out by RUclips!
Hi Stuart. I was watching a video on youtube a guy I don't really care for. I noticed right off he was tiring to parrot you and uncle doug. Keep up the great work and maybe he will pick up you personality.
Hi Stuart, that old JTM 45 amp you're working on sounds like it's getting a bit cranky, judging by all the funny sounds it's producing, I had a bit of a laugh when I first heard them, cheers for uploading the video and please keep them coming.
Oh my! Nice job! Some people see a thing like that as a challenge. personally I see it as something I should throw as far away as I can AND run the other direction...nice little amp though :)
Ha ha. You should watch some of the 'restoration videos' on RUclips where they drag a rusty old engine out of the bushes and spend 30 hours getting it back to near perfect!
@@stuartukguitarampguy5830 hi could I just ask where is the best place to buy amp parts from, I have striped down a fender stage 100. As you said in another video on the Cora’s I think the smoothing is done by the large capacitors , I taped everything no laud hum that you can’t turn off then taped and put slight pressure on the nichicon CE 105c G Q (M) and there’s the loud buzz you can’t turn off . Are these any good as a make , also on the solder side there are two , IN 535’s the solder also showed as if they have had rust on and around so I will change those , I tried all sorts of repair company’s but they want £300 just to look at it ,so watching you and having been a mechanic all my working life I thought I’d have a go as that buzz you showed was exactly the same. A crazy set up in the cab as I literally had to remove every thing to get the PCB out . Thanks for showing your skills great to see Regards Craig Macdonald.
Hi thanks as I don’t buy components like these , is the CE 105 c GQ(M) the legend identification and the IN 535 the legend of the smaller part, I was going to ask you to repair this but you aren’t taking work on and it’s a good challenge now iv just retired and have the time. So I hope you don’t mind me asking . I was watching your videos on how a valve amp works great stuff.
Now that you have had your AHA! moment, I want to know if the turrets on this Marshall are hollow. I recently read a kit-building article I online which said that if the turrets are hollow and you have wires connecting to them from under the board, the thing to do is push the wire from under the board all the way up through the top of the hollow turret and bend it over into a little hook so that it cannot drop back down when you unsolder or solder other components to the top side of that turret. Admittedly this is only practical if you are either building an amp from scratch, or if you absolutely have to pull up the turret board to get to the underside of it while servicing, but anyway it's a good technique to keep in mind.
I've restored a number of AA5 tube radios and most of them have been in storage for 50 years or more. The last thing you want to do is plug it in and turn it on! I like to say that these old devices have been "asleep" for a long time, so you have to "wake them up" slowly. Very slow, methodical checks on each leg of the circuit, and always replace the electrolytic caps as a matter of course. Even the resistors can lose their potency after such a long time- trust nothing.
Although I sometimes do use a dab of extra rosin flux when soldering, my preference is to polish the metal terminals first, with a pencil eraser, ink eraser (better), or a glass-bristle "scratch brush" (best). This cleans the metal better than flux could ever do and assures an electrically and mechanically sound connection. If installing a resistor or film cap that has been sitting in the parts drawer for a decade or more, I'll clean the component leads with steel wool first. Cleaning/ polishing the metal parts allows the solder to wet and flow into the joint so quickly that there is absolutely no chance of damaging a component from overheating.
@@stuartukguitarampguy5830 , the pencil eraser trick is something I learned from old ham radio operators, many of whom were Signal Corps radiomen in WWII, Korea and Vietnam. An ink eraser works better because it has silica in it and is more abrasive. At the audio repair shop I work for, we've gone one better ---- we have AC- powered draftsman's erasers (aka draughtman's erasers on your side of the pond!), sort of like a die grinder that's hollow in the middle and spins an 8" rubber eraser (1/4" diameter) rod that runs up through the middle of the tool. These work great for polishing and buffing prior to soldering, although getting old-stock eraser rods that aren't dried up and brittle is becoming difficult. The gray erasers work best. You can also find miniature battery-powered erasers online, which are used by artists, and only cost $10 or so. The 4 mm white vinyl eraser rods that come with these are a bit too soft to be of much use on metal, but SunSeed Dolphin (weird name) makes a "silica" eraser, grey or beige color, that works well. Those are 3.5 mm but will fit a 4 mm battery-powered device if you put. A wrap of electrical tape, or heatshrink tubing, on the end of the eraser rod so it'll fit the 4 mm chuck. Also get yourself a glass-bristle scratch brush! Some of the scratch brush kits come with brass and steel brushes, but the glass bristles work best for our purposes.
Pardon for asking a question. I seemed like, you didn't use a dummy load on the speaker channel. I am not a professional and have only built one amp a JTM45 1964 clone and repaired another Marshall.
Stayed to the end to see it used as God intended, this needs a follow up with some lead tones please, great amp indeed. Not sure about the originality of the cab though, looks far too new. Good job.
"Check your DC conditions". Your former instructor was a very smart man.. However, I would suggest starting at the output stage and working backwards as you check the DC voltages, turning up the volume control slightly as you take each measurement. This will more easily allow you to find the stage where the voltage is falling away significantly because of the current draw conditions created by the oscillation. The same can be said for signal injection techniques: if you are injecting signal with a handheld probe, start at the output stage and work backwards, from one tube grid amplification stage to the next, and the signal from the amps' own speaker-load should get louder with each stage, until suddenly it doesn't, helping you to find a stage with low or no output. If injecting a signal at the amp's input jacks, however, and checking gain stages at the tube plates with a takeoff probe (feeding a separaye small amp and speaker), best to start at the first gain stage and work towards the output stage and your test-rig speaker will get successively louder until you reach a non-functioning gain stage.....
@@stuartukguitarampguy5830, weirdly, I don't see my original comment wherein I recommended that tropicalfishvintage site. Did YT remove my comment? (I had specifically *not* written the full link with the usual punctuation and the abbreviation for "communicate", and yet they pulled it anyway?). Anyway, for other viewers who don't know what we are referring to, its about tube amps, not aquarium fish, and there's a lot of excellent info on the site.
@@goodun2974 Ah that's interesting. I always get an email when someone has commented. I click on the link and it takes me to the comment. From time to time, when I click there is no comment there. Until now I've had no idea why some comments didn't show and it's been really annoying not to be able to reply to the person. This may be the reason, if they contain a URL.
@@stuartukguitarampguy5830 , i only alluded to the URL, I didn't actually type it in full or post a hyperlink. And yet, when I watch politically themed RUclips channels, people post links all the time, including context-free links posted by trolls, spammers and phishers, yet RUclips rarely removes them even when you report them. ( Hint: if the link doesn't come with a sentence or two providing context related to the subject of the main video or explaining what you're about to see, don't click on it!).
@@goodun2974 Okay maybe it's not that then. It's a real mystery why some comments simply vanish. Try posting exactly the same comment again and see what happens.
@@stuartukguitarampguy5830 hey man check out Lyle at Psionic channel. He's a great amp tech. Bit of sniffing his own cork but interesting and informative.
@@stuartukguitarampguy5830 yeah,, he doing a bit of looking at clone builds and generally no holds barred critiquies. His latest on a clone blonde bassman build is great. He shares his secrets! He's very knowledable about AC 30'S! Most of those had bad ground schemes especially after the late 60's. After that full of ground loops. He thinks Marshall ground schemes are lacking too. He says ground them like Fender does.
I paint for a living. And I build amps as a hobby. I make more painting walls than I would selling my amps. That's quite depressing. It all boils down to the fact that people don't appreciate art. ( musicians who need these amps) I remember an art teach saying something like this 40 years ago. Yet people will spend 2000 bucks on a mass produced POS from a massive corporation like marshall or fender. They'll only receive a garbage pcb ... People need to think for themselves
You can't fight it I'm afraid. Twas ever thus and will always be. Actually, you can extend this much further. In general people don;t apreciate ANYTHING because they have close to zero idea what goes into it. Do people truly appreciate your decorating skills or do they just go 'that's nice' after you've put in 20 hours? Basically we all know a little bit about our own area of expertise and f-all about 99% of everything else, so we just take it for granted.
@stuartukguitarampguy5830 Yeah, that makes sense. People generally are excited to see the. Finished product of a painted room, but with amps, a lot of people think it's a diy amp vs. a professional amp from a Corp, hahah. Usually, they have a hot rod deluxe slowly burning its board and self destructing caps .. In any case, I have a hard time parting with my amps anyway . Feels like I'm selling my dog .
I Can;t remember tbh, but it's not necesary to have a load connected as long as you don't pass a signal through the amp. Even then, it's VERY rare for that to cause a problem.
That amp in as-found condition would be best represented by feline hindquarters mounted on the wall: a "cat ass trophy"! Say it three times really fast.....
British uncle doug!! If you guys don't know uncle doug,, he's our , yank, vintage amp guru and teacher. He's on you tube and one of the best in class!!!
Oh yes, we all know Uncle Doug! Where do you think I stole the idea from??!! :)
Another brilliant repair. My JMP is available to be worked on.
Thanks Darell. Did you want me to work on yours?
Great amp. Great repair and restoration.
Very interesting detective work.
These old Marshall 20-40 watt amp circuits are all the rage with two valves.
Its fascinating the use of TWO EL 34 or
even KT 66 or KT 88 tubes.
And even their American mother 6 L6 versions here in the States.
Where the original Fender Bassman curcuits still began and rule all the Boutique amplifier two valve high gain guitar amplifiers.
My friend here in California
played two 50 Watt
JCM 800 marshalls in stereo
In the 1980's
I must say of all the great Classic Rock guitar amplifiers I ever heard live
the 50 Marshals were by far the best sounding amplifiers ever.
A unique quality of upper mid range
punch and gain that many otheramps have tried to emulate, but never quite attained.
This one you worked on was beyond
interesting. I felt like I was watching a classic Morse episode of who dunn it.
Oxford and all. Every tech and sound engineer knows all of this began in the
UK.
I still remember Ginger Baker say it only went Tropo when Mr Marshall went to
100 watts instead of leaving well enough alone at these 50 Watt -/+ amps.
Thanks for sharing your experience.
I dont often get excited about amps , but good God ! What a peice of history. I would absolutely love to put that through its paces. I do t think I'm worthy of working on it but.id looove to service it too.
Wow ... just.wow
Love seeing these old Marshall’s being preserved for future generations.
Yes it's probably why I do it. It certainly isn;t the money, drugs and girls...
Love tube Amps i use to watch my pop fix them in the 70s and i see you have the passion and skill to fix these awesome vintage treasures.
Cheers Brian
Great job Stuart, I appreciate that you refused to drill larger holes in that vintage chassis.
Yes that would have been a shame
The introduction to this amp sounds about like my twenties...
I found your channel yesterday, I think you're more fun than Netflix. Thanks for sharing your adventures in amplitude..
Thanks!
Sir I really enjoy watching you work. I am a radio and rf amp repair tech.for many many years. Not much audio work. A little on amy own guitar amps. I have learn alot from you and Uncle Doug. Thanks a million.
Thanks Monty. Wow I envy you your skills! I can;t do RF stuff. My father was a very well known radio amateur G3HSR and VK9NS. Never taught me a damn thing though!!
@@stuartukguitarampguy5830 You could do it Stuart, Just a little different. I have been an amateur many years. It is possible I ran into him at sometime. God Bless..Monty
Ove gotten into the habit of soldering everything on top of the board . And anything that has to go on the bottom gets a dab or super glue. I've also set amps aside for weeks out of frustration!!.
Amazing job on that old beast!!
Ah, spokem like a true real-world amp tech!!
Enjoying your videos very much Stuart! Thanks for sharing.
On the seemingly random component value 47uF: my understanding is that the values are chosen so that they cover all possible values if you factor in the tolerance.
For example, if you start with a value of 1 (ohm or nanofarad or whatever), considering a tolerance +/- 10%, that 1.0 is really just somewhere between 0.9 and 1.1. The next value is 1.2 covering 1.08 to 1.32 and so one, giving "preferred values" of 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.1 and 10, at which point you start all over.
5% series will have more values to cover the range (and 1% range will have _many_ more values.) Hope that makes sense! Cheers from Sydney AU
well done Stu. Glad you chased all those rats out of there. One of my favorite amps.
Excellent vid Stuart, many thanks
Glad you enjoyed it Peter.
That was so cool to watch you go thru that entire amp vlog. Thank you for sharing your thoughts & experience & wisdom. Just wonderful to watch.
Thanks Matthew
Fantastic detailed video. I loved it and subscribed
Thanks Richard!
Beautiful amp and I admire your tenacity on doing it right! I built one of these with an aluminium chassis about 15 years ago! One of the best sounding amps I own. Cheers Stuart!
Nice!
Nice one Stuart 👍
Thanks Spencer!
I got really involved in this fix, talking to the screen at times! Thankyou for sharing this content with us Stuart. Great to hear you play too.
First sign of madness!
Great video and so many little issues...Super interesting and repair..Great job..Ed..uk..😀
Thanks Ed!
What I get to repair in Brazil is worse! Messed around by customers of other service centres! People here now are learning to always bring to the honest and experienced English guy!
I can imagine! Well done.
Excellent job!
Thanks Zack!
Great video, really interesting. I felt your pain when it oscillated - I’ve been there!
Thanks Steve
Hi Stuart another great video on what must be one of the greatest amps Jim Marshall ever made, a huge part of Rock & Roll history
and used by many great players back in the day
It's a fender tweed bassman made to work withbritish components and valves. Some changes to the inputs and tone stack. Great amp definitely!
Very well done!!
Thanks John.
Nice Job! Very cool to get to work on that. I know the 2 week layaway feeling.
Yes... "have I ever seen this amp before in my life...? I'm sure I did WOMETHING to it a few weeks ago..."
Good work! Very enjoyable 😀
Many thanks!
Hi. Good video. Glad to find your channel.
Thanks Monty
Fascinating video. Thanks!
Cheers Greg.
Not bad guitar playing for someone who claims to 'not be a guitarist
Great restoration.
I'm in the field too as a hobby.
Thanks very much. My repertoire is a bit limited though!
Good job Stuman!
Thanks Neville.
Hi Stuart, when I repair an amplifier or other type of device and I have to unsolder components, I take a picture with the phone and also write down in a notebook the description of what I have done, because sometimes I am wrong and then I have gone crazy looking the problem. Thus, before turning on the amplifier I review all the notes and the photographs and make sure that everything is correct.
The Bluesbreaker is a legendary amp, a gem. The video is great and your work has been excellent.
Cheers
Hi yes I also take a photo on my phone. Saved me many a time!
Thanls fpr the link to the tubestore schematics, I did know about that. You'll notice that your posting didn;t make it here. That's because anything with a URL in it is automatically considered spam and chucked out by RUclips!
@@stuartukguitarampguy5830 Ohh, thanks, I didn't know.
Hi Stuart. I was watching a video on youtube a guy I don't really care for. I noticed right off he was tiring to parrot you and uncle doug. Keep up the great work and maybe he will pick up you personality.
Hi Stuart, that old JTM 45 amp you're working on sounds like it's getting a bit cranky, judging by all the funny sounds it's producing, I had a bit of a laugh when I first heard them, cheers for uploading the video and please keep them coming.
Will do. Thanks Simon.
You’re Awesome, I love watching you trouble shoot then repair amps!
Thanks Barndon!
Oh my! Nice job! Some people see a thing like that as a challenge. personally I see it as something I should throw as far away as I can AND run the other direction...nice little amp though :)
Ha ha. You should watch some of the 'restoration videos' on RUclips where they drag a rusty old engine out of the bushes and spend 30 hours getting it back to near perfect!
Excellent Video so interesting thanks
Thanks very much.
@@stuartukguitarampguy5830 hi could I just ask where is the best place to buy amp parts from, I have striped down a fender stage 100.
As you said in another video on the Cora’s I think the smoothing is done by the large capacitors , I taped everything no laud hum that you can’t turn off then taped and put slight pressure on the nichicon CE 105c G Q (M) and there’s the loud buzz you can’t turn off .
Are these any good as a make , also on the solder side there are two , IN 535’s the solder also showed as if they have had rust on and around so I will change those ,
I tried all sorts of repair company’s but they want £300 just to look at it ,so watching you and having been a mechanic all my working life I thought I’d have a go as that buzz you showed was exactly the same.
A crazy set up in the cab as I literally had to remove every thing to get the PCB out .
Thanks for showing your skills great to see
Regards Craig Macdonald.
Hi. I usually just get my bits on eBay you can almost always find them there and I like to support people who have a little eBay business going on.
Hi thanks as I don’t buy components like these , is the CE 105 c GQ(M) the legend identification and the IN 535 the legend of the smaller part, I was going to ask you to repair this but you aren’t taking work on and it’s a good challenge now iv just retired and have the time.
So I hope you don’t mind me asking . I was watching your videos on how a valve amp works great stuff.
Hi the 1N535 is a diode. I have no idea what CE 105 c GQ(M is.
Now that you have had your AHA! moment, I want to know if the turrets on this Marshall are hollow. I recently read a kit-building article I online which said that if the turrets are hollow and you have wires connecting to them from under the board, the thing to do is push the wire from under the board all the way up through the top of the hollow turret and bend it over into a little hook so that it cannot drop back down when you unsolder or solder other components to the top side of that turret. Admittedly this is only practical if you are either building an amp from scratch, or if you absolutely have to pull up the turret board to get to the underside of it while servicing, but anyway it's a good technique to keep in mind.
Sometimes the high voltage was wired under the board.
GLORIOUS WORK STU HAVE 2 PINTS WAS RIGHT THERE WITH YOU IN STRUGGLE AND TRIUMPH BE WELL
Thanks Freddy
I've restored a number of AA5 tube radios and most of them have been in storage for 50 years or more. The last thing you want to do is plug it in and turn it on! I like to say that these old devices have been "asleep" for a long time, so you have to "wake them up" slowly. Very slow, methodical checks on each leg of the circuit, and always replace the electrolytic caps as a matter of course. Even the resistors can lose their potency after such a long time- trust nothing.
Hey Stu, why didn`t you renew the cap can (between the rectifier and the trem valve)?
Although I sometimes do use a dab of extra rosin flux when soldering, my preference is to polish the metal terminals first, with a pencil eraser, ink eraser (better), or a glass-bristle "scratch brush" (best). This cleans the metal better than flux could ever do and assures an electrically and mechanically sound connection. If installing a resistor or film cap that has been sitting in the parts drawer for a decade or more, I'll clean the component leads with steel wool first. Cleaning/ polishing the metal parts allows the solder to wet and flow into the joint so quickly that there is absolutely no chance of damaging a component from overheating.
I'll give the pencil eraser a go! Yes, I def use the wire wool on older parts.
@@stuartukguitarampguy5830 , the pencil eraser trick is something I learned from old ham radio operators, many of whom were Signal Corps radiomen in WWII, Korea and Vietnam. An ink eraser works better because it has silica in it and is more abrasive. At the audio repair shop I work for, we've gone one better ---- we have AC- powered draftsman's erasers (aka draughtman's erasers on your side of the pond!), sort of like a die grinder that's hollow in the middle and spins an 8" rubber eraser (1/4" diameter) rod that runs up through the middle of the tool. These work great for polishing and buffing prior to soldering, although getting old-stock eraser rods that aren't dried up and brittle is becoming difficult. The gray erasers work best.
You can also find miniature battery-powered erasers online, which are used by artists, and only cost $10 or so. The 4 mm white vinyl eraser rods that come with these are a bit too soft to be of much use on metal, but SunSeed Dolphin (weird name) makes a "silica" eraser, grey or beige color, that works well. Those are 3.5 mm but will fit a 4 mm battery-powered device if you put. A wrap of electrical tape, or heatshrink tubing, on the end of the eraser rod so it'll fit the 4 mm chuck.
Also get yourself a glass-bristle scratch brush! Some of the scratch brush kits come with brass and steel brushes, but the glass bristles work best for our purposes.
@@goodun2974 Interesting thanks.
EROICO!!!!
There's a saying in electronics that goes like this "Amplifiers only oscillate, and oscillators only amplify".
Now we know how the Moog was invented :-)
Ha ha!
Washing-up liquid is great for getting grommets back in!
Ah I'd forgotten that. Thanks for the reminder.
@grahambambrook313 Yeah & sometimes even just a bit of plain water works too!
Pardon for asking a question. I seemed like, you didn't use a dummy load on the speaker channel. I am not a professional and have only built one amp a JTM45 1964 clone and repaired another Marshall.
You don;t need a dummy load as long as you don't put a large signal through the amp. All the best
Stayed to the end to see it used as God intended, this needs a follow up with some lead tones please, great amp indeed. Not sure about the originality of the cab though, looks far too new. Good job.
Glad you enjoyed it! Nope, the cabinet is original as is the grill cloth! The amp is worth a small fortune.
"Check your DC conditions". Your former instructor was a very smart man.. However, I would suggest starting at the output stage and working backwards as you check the DC voltages, turning up the volume control slightly as you take each measurement. This will more easily allow you to find the stage where the voltage is falling away significantly because of the current draw conditions created by the oscillation.
The same can be said for signal injection techniques: if you are injecting signal with a handheld probe, start at the output stage and work backwards, from one tube grid amplification stage to the next, and the signal from the amps' own speaker-load should get louder with each stage, until suddenly it doesn't, helping you to find a stage with low or no output. If injecting a signal at the amp's input jacks, however, and checking gain stages at the tube plates with a takeoff probe (feeding a separaye small amp and speaker), best to start at the first gain stage and work towards the output stage and your test-rig speaker will get successively louder until you reach a non-functioning gain stage.....
Thanks for the lead to the tropicalfishvintage site. I'll check it out.
@@stuartukguitarampguy5830, weirdly, I don't see my original comment wherein I recommended that tropicalfishvintage site. Did YT remove my comment? (I had specifically *not* written the full link with the usual punctuation and the abbreviation for "communicate", and yet they pulled it anyway?). Anyway, for other viewers who don't know what we are referring to, its about tube amps, not aquarium fish, and there's a lot of excellent info on the site.
@@goodun2974 Ah that's interesting. I always get an email when someone has commented. I click on the link and it takes me to the comment. From time to time, when I click there is no comment there. Until now I've had no idea why some comments didn't show and it's been really annoying not to be able to reply to the person. This may be the reason, if they contain a URL.
@@stuartukguitarampguy5830 , i only alluded to the URL, I didn't actually type it in full or post a hyperlink. And yet, when I watch politically themed RUclips channels, people post links all the time, including context-free links posted by trolls, spammers and phishers, yet RUclips rarely removes them even when you report them. ( Hint: if the link doesn't come with a sentence or two providing context related to the subject of the main video or explaining what you're about to see, don't click on it!).
@@goodun2974 Okay maybe it's not that then. It's a real mystery why some comments simply vanish. Try posting exactly the same comment again and see what happens.
Vintage lovers need to rationalize a safe reliable amp that you can play or put the thing in a museum!!
Well said!
@@stuartukguitarampguy5830 hey man check out Lyle at Psionic channel. He's a great amp tech. Bit of sniffing his own cork but interesting and informative.
@@russellesimonetta3835 Thanks Russell, yes I watch that channel. Very good.
@@stuartukguitarampguy5830 yeah,, he doing a bit of looking at clone builds and generally no holds barred critiquies. His latest on a clone blonde bassman build is great. He shares his secrets! He's very knowledable about AC 30'S! Most of those had bad ground schemes especially after the late 60's. After that full of ground loops. He thinks Marshall ground schemes are lacking too. He says ground them like Fender does.
Am I the only one who watched this video from begining to end? :)
Hi Pedro. Ni I did - several times! :)
Nope 🙂
I paint for a living. And I build amps as a hobby. I make more painting walls than I would selling my amps. That's quite depressing. It all boils down to the fact that people don't appreciate art. ( musicians who need these amps)
I remember an art teach saying something like this 40 years ago.
Yet people will spend 2000 bucks on a mass produced POS from a massive corporation like marshall or fender. They'll only receive a garbage pcb ...
People need to think for themselves
You can't fight it I'm afraid. Twas ever thus and will always be. Actually, you can extend this much further. In general people don;t apreciate ANYTHING because they have close to zero idea what goes into it. Do people truly appreciate your decorating skills or do they just go 'that's nice' after you've put in 20 hours? Basically we all know a little bit about our own area of expertise and f-all about 99% of everything else, so we just take it for granted.
@stuartukguitarampguy5830 Yeah, that makes sense. People generally are excited to see the. Finished product of a painted room, but with amps, a lot of people think it's a diy amp vs. a professional amp from a Corp, hahah. Usually, they have a hot rod deluxe slowly burning its board and self destructing caps ..
In any case, I have a hard time parting with my amps anyway . Feels like I'm selling my dog .
you were having no load or speaker connected? why's that..
I Can;t remember tbh, but it's not necesary to have a load connected as long as you don't pass a signal through the amp. Even then, it's VERY rare for that to cause a problem.
Looks as if someone did some "blindfold" modding...
a schematic can be obtained on line in less than a minute and no; a transistor is not part of a 1962 JTM 45 ...
George Whitfield would be very proud :-)
Thanks!
a matched pair of kt66 would be much better
Giid Idea. When I win the lottery I'll pop a pair in!!
That amp in as-found condition would be best represented by feline hindquarters mounted on the wall: a "cat ass trophy"! Say it three times really fast.....
Very good!
looks like we are all using theses cheapo soldering irons from china : )
Waddya mean??? That's an expensive iron, that! My Weller KEEPS failing however. Very annoying.
BS never saw a thing …., click bait
??? not sure what you meant by that comment.