Love these basic trainings. The way you present them makes it so understandable and rememberable as well. Thank you for clearing things up. Seeing a whole build or even repair jobs in total are fun to watch but I don't get the expertise that I pick up from this. Thank you
Excellent. It is hard to find a Fender circuit board amp WITHOUT those IC filter caps. A full cap replacement can get expensive, but for a musician who loves the amp and plans on keeping it, it is worth the investment.
Honestly Sir. A master class. Simple. Logical. Obvious expertise born from years of experience. By Voltaires Bastards I’ll keep enjoying watching D-Lab for years to come … there’s something so satisfying about watching a master at his craft. Carry on sir.
Love the basic training videos Terry..So much info and tech tips..Look forward to the next, and I am always singing your praises to friends etc. in the hope they take a look and subscribe..! Take care..Ed..uk..😁
Stumbled on your channel with that Proco Rat video and ended up watching a few vids about amp repair and I love it. I've been trying to debug and fix my amps and my pedals myself over the years and while I'm not a pro, I'm definitely getting better at it. These kind of videos are very insightful, and I thank you for that.
Great video, Mr. D-lab! I have a friend who just bought a new Blue's Jr, and its already complaining about burning smells and weird sounds. I'm going to have him bring it over so I can take a look at those caps. I wouldn't be surprised to see them fail almost right away. The amp is probably severely over-biased too.
Great stuff! I'm not into guitar amps per-se, but this is helping me with troubleshooting ideas for some stubborn radio & TV problems I have sitting up on shelfs collecting dust.
Nice explanation and demonstration Terry! I’ve run into the motorboating problem several times. You hate to see folks shotgunning new tubes and reverb tanks when they’re chasing something like this. Thanks for the great video.
Well, I stumbled upon this video and had the identical problem with my SS 60. I found C82 and C 83 both reading open. The remainder of the PS caps checked good but I replaced them along with an overheated resistor and bypass cap(out of tolerance) in the reverb circuit. No more oscillations! Thank you for your videos. My SS is sounding awesome again.
I'm a new watcher and I'm really enjoying your work sir. All the amp repairs are great. Maybe walk us through one sometime without time lapsing. Very Into it brother. Rock on.
I've been a player for over 40 Years. It's time to add amp build and repair knowledge. Your videos are great! I haven't seen them all but have you created a video on how to create a "dummy load resistor" yet?
Tks for this video . . . have similar issue with my '65 Fender Princeton RI. . . replaced tubes and tank . . . I was going to change out the filter caps anyway which I should have done in the first place as the amp prolly had those IEC caps . . . will use F&T which I use all the time anyway 😎👍
USA Made! Must be good...Why don't shut the Illinois capacitor factory down? If they can't produce decent caps? Well then there be much less easy repairs to be done! Earning easy money with replacing them with F&T caps.....Of course the abominal amplifier constructions of these years will provide more income.....Keep up the very good work Uncle D.
Great tip! I had a small combo amp (can't remember which, sorry) in my shop that had a feedback issue in reverb on only one guitar string. In this amp, the tank was mounted to the chassis. The fix ended up being isolating the tank with rubber grommets like Fender does.
Really good video EXCEPT you did not show how to connect the oscilloscope to the amp. You verbally mentioned it but I am new and it did not mean anything to me. Can you do a video on connecting the scope to the amp for various kinds of measurements that might be taken. Thanks.
Hum is a lower frequency - typically from the AC mains. What's happening here is the power draw of finals or later stage driver is imposing a signal on the B+ due to the changing current draw. Without good caps, that "signal" gets back into the sensitive front end stage though the B+. This kind of feedback is high frequency. I'm actually a little surprised it's audible and not out at ultrasonic frequencies. The main filter caps take care of the hum from rectifying the AC power to DC (for the most part), but the later caps help keep the stages isolated from each other.
@@russellhltn1396 yes, I was surprised it was audible. I couldn't think how a cap in power supply would make an audible squeal. But I understood it wasn't the usual simple AC hum. As you say other oscillation issues are usually ultrasonic.
Listening in the car, as soon as you said all controls have some affect in it, I said power supply. Couldn't see the scope at that point, so no clue what it looked like. What was it, 60 or 120 Hz?
i have a crackling sound just on my clean channel, when i turn on the FAT switch or BURN channel everything is ok,and it is not connected to a volume, it`s just a crakling sound on clean and it is not loud but wierd
I ordered a late 70's early 80's Fender Pro Reverb, I'm waiting for it in the mail. Right around that time the amps went from a tube rectifier to a solid state rectifier. I called the guy at the guitar center and asked him to look and see what rectifier it had. He said that it had the tube slot but no tube. They played the amp and it worked. I'm wondering if this could be a transition amp. If it indeed does have the slot could I go back to a tube rectifier?
I was wondering about meter calibration on the old beckman, I have one but the dc isn’t accurate, is this something for a specialist to undertake or can I do it myself?
Awesome, I have the exact same issue, just got the SS 22.. I noticed the squeal when tilting the combo back slightly, also noticed it bleeding through to the other pots/EQ.. then found this video boom! Awesome I'll be opening it up later & take ur advice & replace those poor quality caps.. What manufacturer/Brand would you suggest?
Hey Terry, Great job! Quick question, to change the caps would you use your Jhook method or would you pull the pc board out to solder the caps in. I can really see why many engineers prefer point to point wiring vs pc board. Thanks Terry.
this would depend on what the situation is. if you have to spend more time that should be charged but the customer is on a budget, then it may be ok to j hook. But, it is always better to solder the caps to the board. Pc board components are a pain. Especially with a bunch of wires connected to the board. other times you have to do it.
Beware of those crocodile clip cables people! Remember you are taking several hundred volts of DC outside of the chassis. Even after the amp is powered down until you discharge the HV caps.
I've seen another video that says that IC has different lines for different price points. The better ones are good. But their cheap ones turn to garbage pretty quickly.
I suppose Fender doesn't care? or ever see these repetitive failures/repairs from their side? as the amps make through the warranty period. So much for caring about your customers, and Fender's new amps aren't cheap at this point, with new prices on par with the low end boutique amp offerings. :(
Love these basic trainings. The way you present them makes it so understandable and rememberable as well. Thank you for clearing things up. Seeing a whole build or even repair jobs in total are fun to watch but I don't get the expertise that I pick up from this. Thank you
I went to Army Basic Training over 30 years ago. Your new series of videos are triggering my PTSD. LOL
Excellent. It is hard to find a Fender circuit board amp WITHOUT those IC filter caps. A full cap replacement can get expensive, but for a musician who loves the amp and plans on keeping it, it is worth the investment.
Terry, we love all the educational videos on your channel:)
God Bless and protect you and your family:)
Keep them coming Terry and the subscribers will cone rolling in , if they want amp Knowledge this is the place to get it ,
Thank you
Honestly Sir. A master class. Simple. Logical. Obvious expertise born from years of experience.
By Voltaires Bastards I’ll keep enjoying watching D-Lab for years to come … there’s something so satisfying about watching a master at his craft.
Carry on sir.
Thank you my friend, Lots more in the Q
More of these basic training videos lease :)
Much appreciated, cheers Louis
Terry, can you describe the dummy load used for the scope in this scenario?
Love the basic training videos Terry..So much info and tech tips..Look forward to the next, and I am always singing your praises to friends etc. in the hope they take a look and subscribe..! Take care..Ed..uk..😁
Hiya Ed! Terry is a cool guy.
Just when mine started squealing, thanks Terry, appreciated 👍
Stumbled on your channel with that Proco Rat video and ended up watching a few vids about amp repair and I love it. I've been trying to debug and fix my amps and my pedals myself over the years and while I'm not a pro, I'm definitely getting better at it. These kind of videos are very insightful, and I thank you for that.
Great lesson and very interesting. Love the new direction and seeing D labs going full time.
what Hz was that oscillation at
Great video, Mr. D-lab!
I have a friend who just bought a new Blue's Jr, and its already complaining about burning smells and weird sounds. I'm going to have him bring it over so I can take a look at those caps. I wouldn't be surprised to see them fail almost right away. The amp is probably severely over-biased too.
Great stuff! I'm not into guitar amps per-se, but this is helping me with troubleshooting ideas for some stubborn radio & TV problems I have sitting up on shelfs collecting dust.
Nice explanation and demonstration Terry! I’ve run into the motorboating problem several times. You hate to see folks shotgunning new tubes and reverb tanks when they’re chasing something like this. Thanks for the great video.
Excellent presentation once again, Terry. Keep up the good work!
Well, I stumbled upon this video and had the identical problem with my SS 60. I found C82 and C 83 both reading open. The remainder of the PS caps checked good but I replaced them along with an overheated resistor and bypass cap(out of tolerance) in the reverb circuit. No more oscillations! Thank you for your videos. My SS is sounding awesome again.
I'm a new watcher and I'm really enjoying your work sir. All the amp repairs are great. Maybe walk us through one sometime without time lapsing. Very Into it brother. Rock on.
Hmm, taught me something I didn't know. Thanks Terry for sharing 😀
Awesome job and presentation! Thank you very much for sharing your knowledge ! You are a great technician.
A most excellent tutorial. Thank you.
I've been a player for over 40 Years. It's time to add amp build and repair knowledge. Your videos are great! I haven't seen them all but have you created a video on how to create a "dummy load resistor" yet?
Tks for this video . . . have similar issue with my '65 Fender Princeton RI. . . replaced tubes and tank . . . I was going to change out the filter caps anyway which I should have done in the first place as the amp prolly had those IEC caps . . . will use F&T which I use all the time anyway 😎👍
Another excellent video 💪😎. God bless 🙏
Great video as usual Terry! ☺
USA Made! Must be good...Why don't shut the Illinois capacitor factory down? If they can't produce decent caps? Well then there be much less easy repairs to be done! Earning easy money with replacing them with F&T caps.....Of course the abominal amplifier constructions of these years will provide more income.....Keep up the very good work Uncle D.
Great tip! I had a small combo amp (can't remember which, sorry) in my shop that had a feedback issue in reverb on only one guitar string. In this amp, the tank was mounted to the chassis. The fix ended up being isolating the tank with rubber grommets like Fender does.
appreciate the info. this has helped greatly with my repairs. Thank you and I will tell other techs about your channel.
Thanks Terry!
Yes, I certainly could use more stuff like this. Look forward to what else Fink will drag in. 😀
Great training, hi from Sweden 👌
Another great video. Thanks
Great video! Learned a ton!
Excellent training video.. Thank You have the same problem in a fender amp.
Very helpful. Thanks
Very interesting! Thank you for going through this tutorial. Very clear and informative. Thank you, Terry!
Great explanations, enjoying your teaching vids
Great explanation. Truly enjoyed this.
Another great one. Really useful tips. Thank you
Nice job Fred another great one!!
Good work mate.
I like these new Fred videos
Really good video EXCEPT you did not show how to connect the oscilloscope to the amp. You verbally mentioned it but I am new and it did not mean anything to me. Can you do a video on connecting the scope to the amp for various kinds of measurements that might be taken. Thanks.
Fantastic!
Yes buddy... great video
I have the same issue with my mesa f-30.
Good bit of fault finding. Though I am not sure why the noise was a “squeal” rather than a “hum”.
Hum is a lower frequency - typically from the AC mains. What's happening here is the power draw of finals or later stage driver is imposing a signal on the B+ due to the changing current draw. Without good caps, that "signal" gets back into the sensitive front end stage though the B+. This kind of feedback is high frequency. I'm actually a little surprised it's audible and not out at ultrasonic frequencies. The main filter caps take care of the hum from rectifying the AC power to DC (for the most part), but the later caps help keep the stages isolated from each other.
@@russellhltn1396 yes, I was surprised it was audible. I couldn't think how a cap in power supply would make an audible squeal. But I understood it wasn't the usual simple AC hum. As you say other oscillation issues are usually ultrasonic.
Listening in the car, as soon as you said all controls have some affect in it, I said power supply. Couldn't see the scope at that point, so no clue what it looked like. What was it, 60 or 120 Hz?
Same question here. Though I doubt it would be 60 or 120 Hz, because at some point, you can see the frequency shifting on the scope.
Thank you again, and tell me about that super cool amp head cradle you have there. That is very nice. Did you build it? Plans?
The feedback starts with the DC riding on the B+ from a leaky filter cap, correct?
Great troubleshooting Terry! How is Bob Mondavi handling the demotion now that Fred is here?
Terry & Fred, which soldering cartridge & tip do you use with your Unger Snawsosaurus ?
My super sonic 22 has a loud Hum with the reverb.. also when i rested my forearm in the top metal strip i got slightly zapped
Another great video, Terry
i have a crackling sound just on my clean channel, when i turn on the FAT switch or BURN channel everything is ok,and it is not connected to a volume, it`s just a crakling sound on clean and it is not loud but wierd
Can polypropylene capacitors replace electrolytic capacitors with advantages?
Thank you very much for sharing your experience with us.
How nice of Fender to put those IC caps into their amps making sure that amp techs can pay rent!
I ordered a late 70's early 80's Fender Pro Reverb, I'm waiting for it in the mail.
Right around that time the amps went from a tube rectifier to a solid state rectifier.
I called the guy at the guitar center and asked him to look and see what rectifier it had.
He said that it had the tube slot but no tube. They played the amp and it worked.
I'm wondering if this could be a transition amp.
If it indeed does have the slot could I go back to a tube rectifier?
I was wondering about meter calibration on the old beckman, I have one but the dc isn’t accurate, is this something for a specialist to undertake or can I do it myself?
great and usefull videos
nice work
how old is this amp
Awesome, I have the exact same issue, just got the SS 22.. I noticed the squeal when tilting the combo back slightly, also noticed it bleeding through to the other pots/EQ.. then found this video boom! Awesome I'll be opening it up later & take ur advice & replace those poor quality caps..
What manufacturer/Brand would you suggest?
Great video
Hey Terry,
Great job! Quick question, to change the caps would you use your Jhook method or would you pull the pc board out to solder the caps in. I can really see why many engineers prefer point to point wiring vs pc board.
Thanks Terry.
this would depend on what the situation is. if you have to spend more time that should be charged but the customer is on a budget, then it may be ok to j hook. But, it is always better to solder the caps to the board. Pc board components are a pain. Especially with a bunch of wires connected to the board. other times you have to do it.
@@sandiesjoys9777
Thanks Terry!
What no wine?
Beware of those crocodile clip cables people! Remember you are taking several hundred volts of DC outside of the chassis. Even after the amp is powered down until you discharge the HV caps.
👍🤘
Some guys swear by IC caps, and some guys swear at them...what's up with that?
I've seen another video that says that IC has different lines for different price points. The better ones are good. But their cheap ones turn to garbage pretty quickly.
Excellent Terry.
Dear Fender, please stop putting IC caps into your amps. Are you trying to ruin your good name?
It wasn't only IC that had this issue. It was electrolytic industry around the early aughts.
en.wikipedia.org/wiki/Capacitor_plague
Sounds like the great capacitor plague of the 2000s.
Or is this a new plague?
Man can I send you my amp
I suppose Fender doesn't care? or ever see these repetitive failures/repairs from their side? as the amps make through the warranty period. So much for caring about your customers, and Fender's new amps aren't cheap at this point, with new prices on par with the low end boutique amp offerings. :(