Love this format. And the way it was presented I made it easy to learn. I watched mini repairs by yourself and several other technicians but have trouble understanding. This presented in this manner one issue at a time really hits it on the head for me
I would not have thought .3 or .8 of a volt would cause that much of an issue on the other side of the Cap. Thanks Terry for the 'awakening' of such things.
Now this is a great idea and doing it in this manner will be invaluable to so many people who just want to learn and have an interest in this. Forums are great but seeing and watching makes all the difference. I'll be tuning in
It’s always such a joy to work on old hand wired boards and chassis mounted sockets and pots. Today’s typical tube amps are ugly multiple double sided circuit boards with surface mount components and a rats nests of ribbon cables. You’ve got to have an electron tunneling microscope to see what you’re doing. You literally have to rebuild an amp just to change a blown hissing resistor. Good look on your new full time work. Always enjoy your videos!
When I heard the sound I knew what it was, DC across the pot. Once you have heard that sound you know. Then you need to track down the source of the DC and how it is getting there. I had a stepped type treble and bass controls on a Magnavox console that would pop with every step change due to leaking caps. Replaced the coupling electrolytic caps in the preamp and amp and no more pops.
Love your videos and very happy that your granddaughter is already into electronics like me at age 8 or so, I built all the RadioShack pbox kits,had the lab spring board, awesome for teaching children basic electronics!!!! There is hope for the youth of America!!! Hooray! Thanks keep it going T
I think I should urgently replace my capacitors on the Orange OR120. That's probably where my problems are. Many thanks, and best regards from Germany, Kay
I think what you are doing is a great idea! Reminds me of what Marlin Perkins did with Mutual of Omaha's Wild Kingdom show back in the 60's through the 80's. There was a disclaimer at the beginning of the show that all events may be staged, but depict actual animal behavior in the wild. A great learning tool that recreates events which would be hard to come across by chance in the wild and catch on film.
There can be leakage on the board itself too, and changing the caps is just a temp fix and they aren't really leaky. Should desolder one end first and check if there is any voltage to confirm suspicions. If there is none, start measuring the board, they attract crap from smokers and moisture, also that wax that CBS started adding later can become conductive and it needs to be removed in some cases.
WTG Terry, thanks again for sharing your valuable knoeledge. Those dang leaky caps strikes again! Knowing which stage or section of the amplifier to troubleshoot comes from understsnding the circuits of each staage, power supply, preamp, amp, or speaker. The preamp cam be devided into sections, tone, fx, or controls and their tubes. I've learned from you a lot aboit tubes and their purposes or multipurposes, how to break down each stage by their tubes, PS, preamp, and PA. One thing that I do first is troubleshoot for bad connections, then old caps. Way back, we tested tubes first at the Rad Shak becsuse the caps and pots were not old yet. Then maybe a blown speaker from abuse? Sometimes we got lucky, and bought a ""Lifetime"" tube or cheapo speaker from Radidio Shak!
PS: btw, way back, I had a Rad Shak MIJ guitar amplifier that had two twelves as I recall. It had four tubes, I guess, since it had reverb and tremolo. It was either a 6aq5oir 6bq5 amp. Lafayette sold a simular guitar amp that was supposedly a rebadged Univox. It serms that you favor "made in the usa" amps. The MIJ copy cat amps were built cheap, and at best were good for home practice. I'd like to see you do a vid about an old cheapo made in Japan copy cat amp, to see a diagnostic 50+ years later. . Rad Shak amps are quite rare, but you might find a tubie Univox for funage.
For future videos perhaps include a method for comparing the bad component with the replacement, say using ESR / LCR meter etc. Many viewers may not have such a meter but it's the diagnosis / confirmation procedure which should be of interest.
Congrats on the new series, Terry! xraytonyb is doing a similar series on his channel. Building an integrated stereo tube amp kit and walking though EVERY aspect of it. Tony even tossed the circus board in favor of point-to-point wiring! The circuit is SO simple, it's comical seeing it laid out on a PC board!
David Perkins, I love Terry and Tony, both great teachers of how to do point to point wiring, and do it right. It is an art, and takes that old school knowledge which is becoming a lost art. I tip my hat to a couple of great teachers here on the tube.
nice idea for the series Terry - thanks for all the great content. you mention the problem here being a leaky "tone cap" rather than identifying it as a leaky "coupling cap" feeding the tone stack. thought it might be helpful to point that out since "tone cap" is the standard term referring to a cap between a tone pot and ground responsible for altering tone and using that term to describe these frequency tuned DC-filtering couple caps could be a little confusing for some audience members. cheers.
Hi Love all your videos. Maybe my hearing is not so good, but I could not hear the rumble. I think a seperate mic for the amps speaker would help. Dub in the audio track. Various sounds amps make when sick are important for diagnostics. Looking forward for more Dlab videos. Bob
Thanks Terry! Does the signal ride on the DC and that is why you’re blocking DC…can you provide a little more explanation there ? Also, it would be helpful to know how to wire jacks and pots and provide explanation on how the signal passes ..
So simple ,with just using a voltmeter to find the errant culprit or culprits. After hearing the pot was replaced and had the same issue one must go a little deeper to find the problem. Thanks Terry.
This video and the next ones are a vital look at how to repair your own amp. Many of us, your loyal subscribers would have known the answer to the 3 choices you presented because you have explained it before. I knew. By the by, I normally watch UA-cam videos on the iPad speakers but on this one I used headphones and the opening music was great! I found out what I’ve been missing! Love from spring in the Rocky Mnts. Thanxz
I just finished building a Fender Champ 5C1 and love it! It is basic, just a volume control, five watt practice amp. I plugged in a 12 inch speaker Vintage Classic from Mojotone... sounds great with just enough low end. Next is a cabinet to protect the speaker... my thoughts the Mojotone Tweed Deluxe 1x12 ...
Great idea Terry. I always look forward to your videos. I don't know if you would want to give away your parts supplier information, but if you do, showing where and how to find good parts would be a good video too. Of course, that may overload and deplete those vendors' supplies!
Terry Nice video when I was in high school our Electronics teacher had us built this RCA AA5 chassis but he did not tell us he included either wrong value parts or defect parts !
Howdy. Great. I had a persistent problem with my DIY amp. The driver stage of one channel sounded awful and the DC levels were nuts. I disconnected the input cap. No change in levels. Then disconnected the stage neg. feedback cap. Still no change. Finally I disconnected the global neg. feedback cap. Voila ! Unmounted the cap showed a resistance of about 800 ohm. Brand new cap and faulty ! After replacing and reconnecting everything the stage worked fine. Since then I have encountered another leaky cap in the bag of 50 items I bought. Lesson. Sacrifice the time to resistance check caps before soldering them in. Will save one a lot of headache in the long run. Regards.
Thank you for the fantastic hands on sharing approach in this vid. If I ever make money repairing an amp, I will keep you in mind. Currently it is just a hobby to build amps.
just started fixing amps love this and i have seen the resistor thing years ago when i first got into tube amps as a young teen tried to help him but told him you have messed with this thing to much
I sent my Champ in to have it serviced, the volume pot was noisy and it started popping and making static. It came back with a new rectifier tube and was still noisy at the volume pot. I replaced the pot myself and the popping came back. Grrrr..the original Fender tube was probably still good. I noticed the power tube and rectifier tube were kinda loose. I replaced the tube sockets myself. All is good. I will be watching the videos.
Yeah... Longtime subscriber and I do enjoy seeing these type of issues and the solution. Perhaps slightly more explanation. Okay DC on a pot but why does that make it scratchy? My guess is DC discharge causing tiny sparks, almost microscopic but enough to change the audio signal from flat nothing to a series of point discharges as the pot surface is rotated. Oscillations, hum loops, conductive boards, NFB resistor sizes verses the tap on size of NFB added or removed, Hum in general, plate and cathode wires to close to grid, raised heater...why? and How do you make one? Wrong size pot what happens...symptom, Linear when should be audio tapered, X-Cap bias feed circuit, crackle from carbon comp resistor fail, why dual bias circuit could be useful in these times with hard to find tubes. Some ideas. Love the format, induce a problem guess the issue and why the fix is the fix. Great info channel, keep up the great work.🙂
Love this format. And the way it was presented I made it easy to learn. I watched mini repairs by yourself and several other technicians but have trouble understanding. This presented in this manner one issue at a time really hits it on the head for me
Thank you for sharing your knowledge and expertise with us, who are wanting to learn and understand these issues ! Very Informative.
I would not have thought .3 or .8 of a volt would cause that much of an issue on the other side of the Cap.
Thanks Terry for the 'awakening' of such things.
Awesome!! As someone new to electronics and building amplifiers, this series will be very helpful. Thanks Terry!
Now this is a great idea and doing it in this manner will be invaluable to so many people who just want to learn and have an interest in this. Forums are great but seeing and watching makes all the difference. I'll be tuning in
Thank you Steve, I am trying to up the game
yes!
Appreciate this series; looking forward, to more!
fAMPtastic! Great content, Terry! Been subscribing for years... this kind of stuff is icing on the D-Labs cake. Appreciated!
2:30 - My guess is a leaky coupling cap leaking DC onto the pot. This is one of those SNEAKY not-at-all-obvious problems.
This is wonderful to know! This going to be a great series! Excited for more!
I know he likes red wine, but which one ?
Robert Mondavi Cab
I love the look of "Orange-Drop" Capacitors!
Definitely prettier than those crappy green chiclets
Thanks Terry. Looking forward to learning from an excellent Technician!
Thank you Terry , for this new series of video's . The testing with is what I am always looking for . Please keep releasing your great video's .
Any idea what wine he likes ?
Great job on walking us through the process!
It’s always such a joy to work on old hand wired boards and chassis mounted sockets and pots.
Today’s typical tube amps are ugly multiple double sided circuit boards with surface mount components and a rats nests of ribbon cables. You’ve got to have an electron tunneling microscope to see what you’re doing.
You literally have to rebuild an amp just to change a blown hissing resistor.
Good look on your new full time work. Always enjoy your videos!
Excellent approach to a new beginning, especially if it is often running !
When I heard the sound I knew what it was, DC across the pot. Once you have heard that sound you know. Then you need to track down the source of the DC and how it is getting there. I had a stepped type treble and bass controls on a Magnavox console that would pop with every step change due to leaking caps. Replaced the coupling electrolytic caps in the preamp and amp and no more pops.
Great video Terry, the troubleshooting was presented very well and easy to follow. You rock!
Looking forward to seeing this new series...I'm sure I will learn a lot.
Thanks!
What a great idea to put out there Terry. Gonna help a lot of people.
Keep 'em coming! Great time and money saving tips are always appreciated.
Love your videos and very happy that your granddaughter is already into electronics like me at age 8 or so, I built all the RadioShack pbox kits,had the lab spring board, awesome for teaching children basic electronics!!!! There is hope for the youth of America!!! Hooray! Thanks keep it going T
I think I should urgently replace my capacitors on the Orange OR120. That's probably where my problems are. Many thanks, and best regards from Germany, Kay
Topic suggestion. Troubleshoot a conductive board.
I think what you are doing is a great idea!
Reminds me of what Marlin Perkins did with Mutual of Omaha's Wild Kingdom show back in the 60's through the 80's. There was a disclaimer at the beginning of the show that all events may be staged, but depict actual animal behavior in the wild. A great learning tool that recreates events which would be hard to come across by chance in the wild and catch on film.
I really enjoyed the video. When you verbally reference the schematic diagram, could you show us on the actual schematic if you have one on hand?
In really looking forward to this series. Great idea! Thanks, Terry!
Very good, Terry. I like this new series!
There can be leakage on the board itself too, and changing the caps is just a temp fix and they aren't really leaky. Should desolder one end first and check if there is any voltage to confirm suspicions. If there is none, start measuring the board, they attract crap from smokers and moisture, also that wax that CBS started adding later can become conductive and it needs to be removed in some cases.
Howdy D-Lab! This was a great lesson!
WTG Terry, thanks again for sharing your valuable knoeledge. Those dang leaky caps strikes again! Knowing which stage or section of the amplifier to troubleshoot comes from understsnding the circuits of each staage, power supply, preamp, amp, or speaker. The preamp cam be devided into sections, tone, fx, or controls and their tubes. I've learned from you a lot aboit tubes and their purposes or multipurposes, how to break down each stage by their tubes, PS, preamp, and PA. One thing that I do first is troubleshoot for bad connections, then old caps. Way back, we tested tubes first at the Rad Shak becsuse the caps and pots were not old yet. Then maybe a blown speaker from abuse? Sometimes we got lucky, and bought a ""Lifetime"" tube or cheapo speaker from Radidio Shak!
PS: btw, way back, I had a Rad Shak MIJ guitar amplifier that had two twelves as I recall. It had four tubes, I guess, since it had reverb and tremolo. It was either a 6aq5oir 6bq5 amp. Lafayette sold a simular guitar amp that was supposedly a rebadged Univox. It serms that you favor "made in the usa" amps. The MIJ copy cat amps were built cheap, and at best were good for home practice. I'd like to see you do a vid about an old cheapo made in Japan copy cat amp, to see a diagnostic 50+ years later. . Rad Shak amps are quite rare, but you might find a tubie Univox for funage.
For future videos perhaps include a method for comparing the bad component with the replacement, say using ESR / LCR meter etc. Many viewers may not have such a meter but it's the diagnosis / confirmation procedure which should be of interest.
Thanks Terry for giving us access to the D-Lab Team!
Congrats on the new series, Terry! xraytonyb is doing a similar series on his channel. Building an integrated stereo tube amp kit and walking though EVERY aspect of it.
Tony even tossed the circus board in favor of point-to-point wiring! The circuit is SO simple, it's comical seeing it laid out on a PC board!
David Perkins, I love Terry and Tony, both great teachers of how to do point to point wiring, and do it right. It is an art, and takes that old school knowledge which is becoming a lost art. I tip my hat to a couple of great teachers here on the tube.
Bravo!
nice idea for the series Terry - thanks for all the great content. you mention the problem here being a leaky "tone cap" rather than identifying it as a leaky "coupling cap" feeding the tone stack. thought it might be helpful to point that out since "tone cap" is the standard term referring to a cap between a tone pot and ground responsible for altering tone and using that term to describe these frequency tuned DC-filtering couple caps could be a little confusing for some audience members. cheers.
WOW! Could be awesome if you could start explain from the very basics and schematics 😮
Lots of guys on line. I like Terry.
Great idea! I'm down to watch the entire series.
Hi
Love all your videos. Maybe my hearing is not so good, but I could not hear the rumble. I think a seperate mic for the amps speaker would help. Dub in the audio track. Various sounds amps make when sick are important for diagnostics. Looking forward for more Dlab videos.
Bob
Thanks Terry! Does the signal ride on the DC and that is why you’re blocking DC…can you provide a little more explanation there ? Also, it would be helpful to know how to wire jacks and pots and provide explanation on how the signal passes ..
I love this! This is information you don't ever get from a repair center.
wow! MY LAPTOPS speakers wouldnt play the rumble but when I hooked up a mega boom to it, I heard the rumble.
Terry,Awesome video as always wish you were closer to my home town! Thanks Dan Penticton BC
Really looking forward to this series.
So simple ,with just using a voltmeter to find the errant culprit or culprits. After hearing the pot was replaced and had
the same issue one must go a little deeper to find the problem. Thanks Terry.
Great ideal Terry keep him coming please, Thank you so much for thinking of us.😁
I wouldn’t be surprised if this guy had the skills to build his own amp.
Terry you’re amazing and we so much appreciate the help given HAM Radio
I measured 1V on C5, C6 and C7 on my Marshall JTM30. It has a slight rumble on the tone pots. Thanks for this vid.
Great presentation. Well explained and clear tests/ results! Looking forward to the next episode. You could charge for this stuff
This video and the next ones are a vital look at how to repair your own amp. Many of us, your loyal subscribers would have known the answer to the 3 choices you presented because you have explained it before. I knew. By the by, I normally watch UA-cam videos on the iPad speakers but on this one I used headphones and the opening music was great! I found out what I’ve been missing! Love from spring in the Rocky Mnts. Thanxz
thank you, I've been looking for a truly beginners video series on how to troubleshoot power amplifiers
I just finished building a Fender Champ 5C1 and love it! It is basic, just a volume control, five watt practice amp. I plugged in a 12 inch speaker Vintage Classic from Mojotone... sounds great with just enough low end. Next is a cabinet to protect the speaker... my thoughts the Mojotone Tweed Deluxe 1x12 ...
Great idea Terry. I always look forward to your videos. I don't know if you would want to give away your parts supplier information, but if you do, showing where and how to find good parts would be a good video too. Of course, that may overload and deplete those vendors' supplies!
Great job Terry, I could even understand it.😁
Keep ‘em coming Terry!
Great video Terry, love the new series
Nice video, Terry. Please keep ‘em coming.
Terry Nice video when I was in high school our Electronics teacher had us built this RCA AA5 chassis but he did not tell us he included either wrong value parts or defect parts !
Excellent series !! I was surprised that a small leakage DC voltage (under 1 volt) could cause that kind of problem !! Thanks for the series !!
Very good approach, Terry 👍
Howdy. Great.
I had a persistent problem with my DIY amp. The driver stage of one channel sounded awful and the DC levels were nuts. I disconnected the input cap. No change in levels. Then disconnected the stage neg. feedback cap. Still no change. Finally I disconnected the global neg. feedback cap. Voila ! Unmounted the cap showed a resistance of about 800 ohm. Brand new cap and faulty ! After replacing and reconnecting everything the stage worked fine. Since then I have encountered another leaky cap in the bag of 50 items I bought.
Lesson. Sacrifice the time to resistance check caps before soldering them in. Will save one a lot of headache in the long run.
Regards.
Thanks! Well spoken, concise - just what I needed to know. 👍👍 ...
Fantastic news Terry
You are the wizard
I'm always glad to see a new DLab video on my UA-cam feed
terry, wonderful! anxiously awaiting next clip.... thanks
Keep 'm coming, Terry!
very nice Terry. 73 from ON6VL in Belgium
Good video terry, I’m looking forward to seeing the next one
Great video! Looking forward to the next video in the series!
That was a great video!! Short and to the point w theory and repair. Much needed series here in UA-cam land.
Terry, great idea for the series. Can’t wait to see more.
Quite helpful, Terry! Keep em coming please
Looking forward to all of this series! Excellent Terry
Thank you! Really looking forward to this insight and knowledge. Please continue!
Thank you for the fantastic hands on sharing approach in this vid. If I ever make money repairing an amp, I will keep you in mind. Currently it is just a hobby to build amps.
Enjoy it very much. More tutorials please. Best regards
I'm relatively new to your channel and to amp repair in general. I am so glad you are going to produce these Basic Training videos. Thanks!.
Short.sweet.and to the point.
Helps me to learn how circuitry is supposed to work...
Had the same leakage issue even with a new old stock vintage coupling cap in front of a volume pot when building a guitar amp.
Yep....Im with ya Terry. More please.....
Thanks Terry. Looking forward to more in this series.
Love this new series. Please continue.
your expertise in these matters is always greatly appreciated. Thank you!
I personally enjoy every one of d labs videos..great job terry
I really didn't hear the rumble before or after the changes. I did enjoy the video!
just started fixing amps love this and i have seen the resistor thing years ago when i first got into tube amps as a young teen tried to help him but told him you have messed with this thing to much
Wow Terry, great new series...! Can't wait for more info, just love it..Ed..UK..😀
Thank you for your continuing support my friend
@@d-labelectronics You're just the best Terry..😀
I sent my Champ in to have it serviced, the volume pot was noisy and it started popping and making static. It came back with a new rectifier tube and was still noisy at the volume pot. I replaced the pot myself and the popping came back. Grrrr..the original Fender tube was probably still good. I noticed the power tube and rectifier tube were kinda loose. I replaced the tube sockets myself. All is good. I will be watching the videos.
Yeah... Longtime subscriber and I do enjoy seeing these type of issues and the solution. Perhaps slightly more explanation. Okay DC on a pot but why does that make it scratchy? My guess is DC discharge causing tiny sparks, almost microscopic but enough to change the audio signal from flat nothing to a series of point discharges as the pot surface is rotated.
Oscillations, hum loops, conductive boards, NFB resistor sizes verses the tap on size of NFB added or removed, Hum in general, plate and cathode wires to close to grid, raised heater...why? and How do you make one? Wrong size pot what happens...symptom, Linear when should be audio tapered, X-Cap bias feed circuit, crackle from carbon comp resistor fail, why dual bias circuit could be useful in these times with hard to find tubes. Some ideas. Love the format, induce a problem guess the issue and why the fix is the fix. Great info channel, keep up the great work.🙂
Love this Format as a series. Thanks.
You are the best Terry.
Thank you for these. I have learned very useful information from these.
Absolutely a legend teacher to all us audio wannabe amp techs
Excellent! Please more videos like this.
Terry - great idea for a series and you've explained it very very well. Great job brother
GREAT WORK THANK FOR ALL YOU DO / YOU ALREADY HAVE HELPED SO MUCH LOKKING FORWARD TO SERIES
Thanks Terry Good Stuff...Jolten Jay Aka Jeff 👍
Two knobs up… Good job Terry!!!
Love this Terry. Looking forward to to get into tube amp repair as there ain’t many in my area. Thanks
Excellent Video. Short and to the point.