Hi Stuart - Great tip to use the Resistance box to dial in resistance needed for the bias. And an excellent tip on using the coax to connect the input jack to the PC board. Here in the states, we cannot find Ambersil. So the best we can do is to find an all purpose foam cleaner.
Good job 👏 I always like seeing an amplifier returned to service rather than chucked in the landfill. I've rescued 2 amps this year from certain doom, both only had a few minor issues and were relatively easy to fix. I do have to mention that I had significant issues trying to repair a AT-100 B52 valve amp with a channel switching problem. Long story short: I happened to receive a shipment of counterfeit cd4069 opamps and that caused me to spend considerable time tracking down phantom problems when my initial diagnosis was actually correct. I bought a new batch of chips from a reputable supplier and the problems with the amp immediately went away. Be cautious of where you source components. The 1980 peavey Mark 3 was an easy fix, one leg of the (+)voltage regulator transistor corroded through and burned out the associated resistors. Simple matter of replacing the defective parts and everything came back to life. Great amp that one is. Best $30 I ever spent 😊
There is something satisfying about cleaning up an old amp. I use wd40 and a brush to get off residue from tape; it works well. I also use a foaming cleanser on dirty tolex and metal. I find that Zep 65 citrus foam works the best for me. It gets down into that old ruff tolex and losens things up. Thanks for the shoe polish trick; I'll have to try that. On chrome, I use Mother's Chrome polish and for light rust, I put it on and use crumpled up aluminum foil to scrub it. I learned this from working on chrome pipes on motorcycles. It's really surprising how well it works. It doesn't remove all the rust, but it is worth the trouble in my opinion. I have always used upholstery cleaner on grill cloth. My favorite ones are Oxiclean Total Care Carpet and Upholstery Cleaner for overall and Spot Shot for tough stains. These can clean well, but I also use a combination on vinegar, baking soda, and water to remove strong smells. I had one once that was horrible and putting this on, letting it dry then vacuuming and then using the Oxiclean did the trick. Those Blues Junior amps are sweet for a little combo. I've had a few and ended up selling the as many people love the Fender name. I still use an old Peavey Bravo for a small amp. It's alway exciting to see a new video from you and entertaining to watch. Great use of the diagrams; they are always helpful. Thanks again for the informative excursion from my day. Mike
Great stuff as always Stuart.. No mater how many BJ's I see repaired, there's always something pops up that adds to the list of "How Fender should have designed it". Hope you are well and have managed to get aloft during the very changeable summer we've had.
Well done, Stuart. I was very surprised the IC filter caps were not blistered, and leaking on the + side. Most techs I know immediately replace the IC caps in favour of F&T, or MOD caps for reliability. I believe MODs are made by F&T, but I may be mistaken. Nevertheless, you got this ancient beast resurrected without having to pull that poorly designed PC board. Cheers!
Hi Alex Most times they are ok. I usually use F&T to replace. With all the repairs I do it's totally down to the customer how much they want to spend. Also 99% of the amps I repair are not gig critical, so it doesn;t matter if (say) the caps fail in 3 years from now. Alll the best
Enjoyed watching you repair amps Stewart i’ve learned so much from you , your technique ways to test things has helped me figure out my own problems. Greetings from Minnesota always look forward to your videos.
Nice job. I like the shielded cable modification. But, when you sprayed cleaner on the grill cloth, are you concerned that the cleaner will get on the speaker cone and degrade it?
Great job,there is always something from you to learn . What does happen in the middle of the video? How do you survive this hot, hot ,summer? Anyway thank you for posting this educational video snd buy in quantity Icecream!!! Cheers Roby 👍
Thanks Roby Not sure what happened in the middle there. Unfortunately it's not easy to re-edit and re-upload a video once it's on there so I'll leave this one.
The original EL84's appear to have gotten very hot, based on the state of the ink labeling on them. Could that have cracked the glass? I have found WD40 does a good job of removing adhesive residue from tolex. I use an old toothbrush to get into the cervices of the tolex.
The IC caps (TTA series) are and were, the bottom of the line parts, cheapest axial high-voltage electrolytic available. They do offer a better grade in the brand, the TTM series. But there are much better parts out there, but this is a VERY cost-optimized amplifier. I use Kemet and Vishay-BC caps. Rated for up to 20,000 hours life, they'll outlive most of the owners of the amps. Back in the day, Sprague Atoms were great, but since around 2010, not anymore. I always replace the input jack with a metal switchcraft on insulating bushings and snip the molded 1/4 plug off the speaker wire and replace it with a metal plug. Just more reliable.
@@stuartukguitarampguy5830 Stuart, I gotta say, I've never known that to be true of ICC in the last 30 years of working on amps and stuff. Sprague Atoms used to be very good, but since about 2008, no more.
If I remember correctly, the original input jack is isolated from the chassis and if you replace it with a non isolating one you are building a nice ground loop, hence the hum.
That hum-signal (because of the non-original, non-shunting jack) will cause the output tubes to conduct more current than they normally would at idle, and so, when you put an input load on it and it's no longer humming, it will be drawing less idle current, and the EL84's will be running cooler, than your measurements indicated, perhaps with higher crossover distortion.
You can try aluminium foil dipped in water on rusted chrome, rub away. The bicycle lot use it for their vintage bikes. Of course it won't bring back the chrome plating but it does improve the appearance.
@@stuartukguitarampguy5830 That's got to be it - brains so massive it sucked all the photons right out of the camera! (Thanks for this post, by the way)
Best solution for that hum is to put isolation washer on the jack and a 2" or 3" of shilded wire, otherwise you have to cut that green wire from de PC to chassis grd. Isolation washer being the best solution.
@@stuartukguitarampguy5830 I just picked up some 6L6 bias probes for $16 each. They plug into your multimeter instead of coming with their own display like the expensive sets. They have 2 sets. One measures plate current and the other measures cathode current. I bought the plate current version since my amp is fixed bias. I couldn't find anything referring to cathode current except on cathode-biased amps? Whatever they're called. The ones where you have to replace a resistor to change the bias. I just hoping I didn't do something to my Monoprice 15w/Laney Cub 12R when I tied to install a shunted jack for an external cab. I had no sound when I tested it out so I was worried I fried something in it. When I pulled the chassis, everything looked good. So I put new EL84s in it and it had sound. Thank God. The only issue now is that I get a ringing from the amp with 1 specific guitar so I'm not sure if it's the amp or guitar. I initially thought it was bad tubes because it seemed like it went away when I put new tubes in. Nope. I used it later that same day and the ringing was back. It's around 2.1k to 2.5k hz. I don't think it's microphonic pickups as it affects both pickups and I doubt they both went microphonic at once. Anyway. I've been pretty busy lately. Now if Friday would get here so I can have my Hot Rod Deluxe 🤞. Gotta wait til my bday. Been waiting 6 weeks already and it sucks! Lol
@@J.C... Ok Good luck. On those cheaper bias meters, they're ok but they don;t measure Plate voltage so you need a separate multimeter for that. I can jutify the expense of the Eurotubes meteres because I use them a lot of course.
@@stuartukguitarampguy5830 ..that might not work for me I do a lot of camping in Upstate New York.. I have been curious about storing my extra music equipment in locations with hot summers and very cold winters.. I haven't had a issues but I always allow everything to get to room temperature before turn it on.. I live in Upstate New York and have to travel... stuff going in a out of storage.. I never store anything in a humid environment.. since it's unavoidable in your opinion genuinely speaking is heat or cold harsher on electronics ..?
@@normdurkin6425 Hi Norm. Hmmm, tbh I don't know. I don;t think either heat or cold in themselves would be a problem. But humidity is. So cold and dry, hot and dry - probably no difference. I don;t know that though. I feel a 10-year oing $20million double blind scientific study comming on...
@@stuartukguitarampguy5830 ..I really appreciate it if I ask a question to someone smart, if they says that are not sure of something.. my thought is if a pieces of equipment is in a hot dry attic that gets to a maximum of 125 degrees.. that's probably not an issue because perhaps when the same piece of gear when running warmed up might be that same temperature inside..? ..not sure freezing temperatures are a harmless..? I have stored metal tools in extremely cold dry environments and had almost zero problems with rust.. I guess it makes sense life can exist without water which is the catalyst for things to happen which obviously we are trying to avoid.. thanks for the excellent advice as always Professor..
Wow, indeed Sruart: 'hope you learned something...' = yes, every time, thank you! Your generous sharing of your experience is more than appreciated!
I'm glad you enjoyed it!
He's back, YAY!!
Just when you thought it was safe....
Hi Stuart - Great tip to use the Resistance box to dial in resistance needed for the bias. And an excellent tip on using the coax to connect the input jack to the PC board. Here in the states, we cannot find Ambersil. So the best we can do is to find an all purpose foam cleaner.
Hi Thomas, many thanks, Yes any all purpose foam cleaner is fine.
Good job 👏 I always like seeing an amplifier returned to service rather than chucked in the landfill. I've rescued 2 amps this year from certain doom, both only had a few minor issues and were relatively easy to fix.
I do have to mention that I had significant issues trying to repair a AT-100 B52 valve amp with a channel switching problem. Long story short: I happened to receive a shipment of counterfeit cd4069 opamps and that caused me to spend considerable time tracking down phantom problems when my initial diagnosis was actually correct. I bought a new batch of chips from a reputable supplier and the problems with the amp immediately went away.
Be cautious of where you source components.
The 1980 peavey Mark 3 was an easy fix, one leg of the (+)voltage regulator transistor corroded through and burned out the associated resistors. Simple matter of replacing the defective parts and everything came back to life. Great amp that one is. Best $30 I ever spent 😊
Well done! Yes I'll keep an eye out for those poor components.
There is something satisfying about cleaning up an old amp. I use wd40 and a brush to get off residue from tape; it works well. I also use a foaming cleanser on dirty tolex and metal. I find that Zep 65 citrus foam works the best for me. It gets down into that old ruff tolex and losens things up. Thanks for the shoe polish trick; I'll have to try that. On chrome, I use Mother's Chrome polish and for light rust, I put it on and use crumpled up aluminum foil to scrub it. I learned this from working on chrome pipes on motorcycles. It's really surprising how well it works. It doesn't remove all the rust, but it is worth the trouble in my opinion. I have always used upholstery cleaner on grill cloth. My favorite ones are Oxiclean Total Care Carpet and Upholstery Cleaner for overall and Spot Shot for tough stains. These can clean well, but I also use a combination on vinegar, baking soda, and water to remove strong smells. I had one once that was horrible and putting this on, letting it dry then vacuuming and then using the Oxiclean did the trick.
Those Blues Junior amps are sweet for a little combo. I've had a few and ended up selling the as many people love the Fender name. I still use an old Peavey Bravo for a small amp.
It's alway exciting to see a new video from you and entertaining to watch. Great use of the diagrams; they are always helpful.
Thanks again for the informative excursion from my day.
Mike
Thanks Mike. Odd coincidence I only heard about that aluminium foil trick yesterday, and now from you!
youre a cool dude stuart. greetings from new york city.
Great stuff as always Stuart.. No mater how many BJ's I see repaired, there's always something pops up that adds to the list of "How Fender should have designed it". Hope you are well and have managed to get aloft during the very changeable summer we've had.
Thanks. Yes all good here!
Well done, Stuart. I was very surprised the IC filter caps were not blistered, and leaking on the + side. Most techs I know immediately replace the IC caps in favour of F&T, or MOD caps for reliability. I believe MODs are made by F&T, but I may be mistaken. Nevertheless, you got this ancient beast resurrected without having to pull that poorly designed PC board. Cheers!
Hi Alex Most times they are ok. I usually use F&T to replace. With all the repairs I do it's totally down to the customer how much they want to spend. Also 99% of the amps I repair are not gig critical, so it doesn;t matter if (say) the caps fail in 3 years from now. Alll the best
Very nice one - as always !
Thanks Dirk
Enjoyed watching you repair amps Stewart i’ve learned so much from you , your technique ways to test things has helped me figure out my own problems. Greetings from Minnesota always look forward to your videos.
Thanks Alex. I also learned a lot from the other guys - Terry at D-lab and Uncle Doug etc. One of the great things about the internet.
...''I should get out more often.'''...ha, ha, good one, Mr. Stuart!
Hey Stuart, interesting rescue..! Lots of info..Great job as usual..Ed..uk.😄
Cheers Ed
Nicely done. Thank you again for sharing!
Thanks Travis
Nice one Stuart.
Fantastic mate, good one again
Thanks I'm glad you enjoyed it.
Nice job. I like the shielded cable modification.
But, when you sprayed cleaner on the grill cloth, are you concerned that the cleaner will get on the speaker cone and degrade it?
Great job,there is always something from you to learn .
What does happen in the middle of the video? How do you survive this hot, hot ,summer?
Anyway thank you for posting this educational video snd buy in quantity Icecream!!!
Cheers
Roby
👍
Thanks Roby Not sure what happened in the middle there. Unfortunately it's not easy to re-edit and re-upload a video once it's on there so I'll leave this one.
thanks for videos !
I'm glad you enjoy them!
The original EL84's appear to have gotten very hot, based on the state of the ink labeling on them. Could that have cracked the glass? I have found WD40 does a good job of removing adhesive residue from tolex. I use an old toothbrush to get into the cervices of the tolex.
Thanks for the tip. Yes could be. Fender always bias these FBJ insanely hot at about 38mA! I always rebias at a more sensible 25mA
The IC caps (TTA series) are and were, the bottom of the line parts, cheapest axial high-voltage electrolytic available. They do offer a better grade in the brand, the TTM series. But there are much better parts out there, but this is a VERY cost-optimized amplifier. I use Kemet and Vishay-BC caps. Rated for up to 20,000 hours life, they'll outlive most of the owners of the amps. Back in the day, Sprague Atoms were great, but since around 2010, not anymore. I always replace the input jack with a metal switchcraft on insulating bushings and snip the molded 1/4 plug off the speaker wire and replace it with a metal plug. Just more reliable.
Thanks. BUT... Illinois Capacitor were once THE best capacitors in the world. So what happened with this IC range? And when??
@@stuartukguitarampguy5830 Stuart, I gotta say, I've never known that to be true of ICC in the last 30 years of working on amps and stuff. Sprague Atoms used to be very good, but since about 2008, no more.
@@NinerFourWhiskey Ok I wonder what went wrong!
Stuart, Why are you using the DVM on the 20vdc SCALE when measuring 350vdc to 450vdc?
That's not what he's doing; pay attention to the detail, or you could DIE!
If I remember correctly, the original input jack is isolated from the chassis and if you replace it with a non isolating one you are building a nice ground loop, hence the hum.
Ok that makes sense. Anyway, I managed to get this one sorted.
That hum-signal (because of the non-original, non-shunting jack) will cause the output tubes to conduct more current than they normally would at idle, and so, when you put an input load on it and it's no longer humming, it will be drawing less idle current, and the EL84's will be running cooler, than your measurements indicated, perhaps with higher crossover distortion.
You can try aluminium foil dipped in water on rusted chrome, rub away. The bicycle lot use it for their vintage bikes. Of course it won't bring back the chrome plating but it does improve the appearance.
Good tip thanks I'll try it.
I wish that I had the confidence to change the filter caps in my newer 65 DRII.
I thought you only got cobwebs on Line 6 Spiders................I'll just get me coat!
Ho ho!
The screen went blank and audio/ video disappeared at about 14:36 , and stayed out for nearly a minute.
Note: video enters a black hole @14:35, resumes @15:29.
Damn the intense gravitational attraction of my massive genius striked again :) Thanks for pointing this out. Not sure what happened there.
@@stuartukguitarampguy5830 That's got to be it - brains so massive it sucked all the photons right out of the camera! (Thanks for this post, by the way)
I thought it may be an artistic interlude, like the BBC potter’s wheel of fond memory.🏺🛞😊
@@davidwilliams3274 Showing your age there David (alas I remember it too!)
I think I was abducted and probed in the middle of your video.
Best solution for that hum is to put isolation washer on the jack and a 2" or 3" of shilded wire, otherwise you have to cut that green wire from de PC to chassis grd. Isolation washer being the best solution.
The white material left on the top may be removed with Goo Gone and then the vinyl wiped down with Armor All.
Thanks for the tips Ken.
Useless Output tubes - you mean you can't re-vacuum them? 😆
I think I'll be repairing my own amp when the time comes. 👍
Ha ha!
@@stuartukguitarampguy5830 I just picked up some 6L6 bias probes for $16 each. They plug into your multimeter instead of coming with their own display like the expensive sets.
They have 2 sets. One measures plate current and the other measures cathode current. I bought the plate current version since my amp is fixed bias. I couldn't find anything referring to cathode current except on cathode-biased amps? Whatever they're called. The ones where you have to replace a resistor to change the bias.
I just hoping I didn't do something to my Monoprice 15w/Laney Cub 12R when I tied to install a shunted jack for an external cab. I had no sound when I tested it out so I was worried I fried something in it.
When I pulled the chassis, everything looked good. So I put new EL84s in it and it had sound. Thank God. The only issue now is that I get a ringing from the amp with 1 specific guitar so I'm not sure if it's the amp or guitar.
I initially thought it was bad tubes because it seemed like it went away when I put new tubes in. Nope. I used it later that same day and the ringing was back. It's around 2.1k to 2.5k hz. I don't think it's microphonic pickups as it affects both pickups and I doubt they both went microphonic at once.
Anyway. I've been pretty busy lately. Now if Friday would get here so I can have my Hot Rod Deluxe 🤞. Gotta wait til my bday. Been waiting 6 weeks already and it sucks! Lol
@@J.C... Ok Good luck. On those cheaper bias meters, they're ok but they don;t measure Plate voltage so you need a separate multimeter for that. I can jutify the expense of the Eurotubes meteres because I use them a lot of course.
hey Professor if they have to tell those hooligans to store electronics in the attic not the basement ..
Never store an amp where you wouldn;t sleep yourself!
@@stuartukguitarampguy5830 ..that might not work for me I do a lot of camping in Upstate New York.. I have been curious about storing my extra music equipment in locations with hot summers and very cold winters.. I haven't had a issues but I always allow everything to get to room temperature before turn it on.. I live in Upstate New York and have to travel... stuff going in a out of storage.. I never store anything in a humid environment.. since it's unavoidable in your opinion genuinely speaking is heat or cold harsher on electronics ..?
@@normdurkin6425 Hi Norm. Hmmm, tbh I don't know. I don;t think either heat or cold in themselves would be a problem. But humidity is. So cold and dry, hot and dry - probably no difference. I don;t know that though. I feel a 10-year oing $20million double blind scientific study comming on...
@@stuartukguitarampguy5830 ..I really appreciate it if I ask a question to someone smart, if they says that are not sure of something.. my thought is if a pieces of equipment is in a hot dry attic that gets to a maximum of 125 degrees.. that's probably not an issue because perhaps when the same piece of gear when running warmed up might be that same temperature inside..? ..not sure freezing temperatures are a harmless..?
I have stored metal tools in extremely cold dry environments and had almost zero problems with rust.. I guess it makes sense life can exist without water which is the catalyst for things to happen which obviously we are trying to avoid.. thanks for the excellent advice as always Professor..
@@normdurkin6425 Thanks Norm.