Tony.... You really need to open your own repair shop and employ people to do the work and you just need to supervise and pass on your beautiful gift of knowledge and skill to the world.... Hell I would ship my equipment from Australia just to have it serviced by the world master... I always prefer to deal with people who have a reputation with what they do as opposed to someone I don't know... Even if I knew that you are expensive. I know that when my equipment comes back it will be as it should be. I watch all of your videos regardless of what it may be about, I bet that you could do a video on a dog turd and I would still watch it to the end and still walk away with something new that I have learned LoL... You have a gift and you need to pass it on so that your legacy will continue on long after you are gone.... I'm sure that I'm not the only one who finds themselves watching videos done by others doing something similar and finding their way of work frustrating and yelling at the screen "What are you doing? OMG Tony would have fixed it by now, Why aren't you replacing the rest??? Can't you see that capacitor??? Hell I can see the problem all the way from Australia!!!! Grrrrrr so frustrating!!!!. Anyway LoL As always keep those videos coming and look after your good health.
Nothing like having a working example of what you're trying to bring back to life in order to hunt down the fault and good job pinpointing the fault, but, personally, I would have just replaced all semiconductors in that circuit (after checking all passive components were alright), not only to save diagnostic time (which is far more expensive than routinely replacing components), but also I've found replacing just the one component which had failed accellerated the demise of other, equally old, components in such circuits, going forward in these old amps. Now, given how this is set up, I don't think this will come back to bite you, but, you know, just to share experience as to how to acchieve an effective repair.
I enjoy your vids more than the three or four other UA-cam amp techs. You are an excellent teacher. While a little late on commenting, I am curious how Carver's triac circuit with the three stages in amplification differs from NAD's two-stage?
The large filter caps strapped down with zip ties and hot glue looks so diy. What are they even sitting on? Is it so hard to put them vertically or make a metal bracket and ground bus bar? The sunfire amps he did at least had a metal bracket to clamp them down. But a similar negative terminal connection of a soldered 16-18awg solid wire across solder lugs, only also with additional ground wires wrapped around them. And another 1 inch 18awg solid running to a thin soldered lug at the chassis star ground point. Now allowance for thermal expansion or strain from the screw terminals or screw at the ground. Over time movement, age and heat tends to compromise that solder joint and then things hum in the wrong way and go boom as ground reference is lost. For the price of these things would a proper buss bar be so hard?
Maybe I am wrong, but I think you still have some oscillation riding on top of that sine wave at full throttle. There is some ringing going on. Maybe that would be more clearly visible on an analogue scope if you could enlarge that area.
That's mostly because of all the test equipment connected all over the place as well as all of the covers being off. That will go away when everything get put back together.
By George, I think he's got it! Veddy Ieenteresting! (Laugh in) Who knew, just one little j-fet! You will or have recapped the second amp, correct? I look forward to the final video that ends with them going back home. What's the THD of the fixed amps and can you measure IM at all?
Thanks for watching! Both amps will be re-capped and fully aligned. I will try to test the performance, but this thing has enough output to fry a lot of my test equipment if I'm not careful!
Yes, its ironic when protection circuitry fails and causes problems, but its lot cheaper to fix one JFET that the output stage or the transformer or the speakers :) Is that JFET the first semiconductor seen by the input signal BTW? If so it might have caught a static discharge or something at some point.
I notice at 30:00 when you ran up the amp to full power there was still a bit of “fuz” on the positive half cycle of the sine wave. Do you know what this was.
How were you staring the test at 11:00? The reason I ask is there's a lot of clipping on startup. It's fine when it settles in, but that's not very "musical". I'm guessing it's a artifact of your test setup, but I can't tell.
Carver amplifiers are very greedy power wise. I have a TFM-25 and my circuit can hardly handle it at high volumes and my amp is 225 Watts per channel at 8 ohms. It is capable of peaks up to 450 for short durations. So I would gather that these are more greedy yet and I am not sure that 20 amps is enough. Hard to say, unless you try a different plug.
I know, right. Who needs a stove. My amp is smaller, but still if I want to listen to it loud I have to make sure it is the only thing on that circuit. They are greedy, but sound good. Luckily for me I have not yet needed to repair my amplifier. It has been going strong since I purchased it new back in 1989. I have always liked Carver gear and I was able to meet him briefly.
Great job troubleshooting that circuit and isolating the defective J-FET, looks like your friend will have two good amps ready to go.
Wow, I eat my words ! Hahaha!... great diagnostics, fascinating and very educational...cheers.
Awesome troubleshooting. You found it a hell of a lot quicker than I could of. Good video!!
These are incredible amps.
Tony.... You really need to open your own repair shop and employ people to do the work and you just need to supervise and pass on your beautiful gift of knowledge and skill to the world.... Hell I would ship my equipment from Australia just to have it serviced by the world master... I always prefer to deal with people who have a reputation with what they do as opposed to someone I don't know... Even if I knew that you are expensive. I know that when my equipment comes back it will be as it should be. I watch all of your videos regardless of what it may be about, I bet that you could do a video on a dog turd and I would still watch it to the end and still walk away with something new that I have learned LoL... You have a gift and you need to pass it on so that your legacy will continue on long after you are gone.... I'm sure that I'm not the only one who finds themselves watching videos done by others doing something similar and finding their way of work frustrating and yelling at the screen "What are you doing? OMG Tony would have fixed it by now, Why aren't you replacing the rest??? Can't you see that capacitor??? Hell I can see the problem all the way from Australia!!!! Grrrrrr so frustrating!!!!. Anyway LoL As always keep those videos coming and look after your good health.
I just had a nice meal, and now this. There must be a god. :)
Nothing like having a working example of what you're trying to bring back to life in order to hunt down the fault and good job pinpointing the fault, but, personally, I would have just replaced all semiconductors in that circuit (after checking all passive components were alright), not only to save diagnostic time (which is far more expensive than routinely replacing components), but also I've found replacing just the one component which had failed accellerated the demise of other, equally old, components in such circuits, going forward in these old amps.
Now, given how this is set up, I don't think this will come back to bite you, but, you know, just to share experience as to how to acchieve an effective repair.
I enjoy your vids more than the three or four other UA-cam amp techs. You are an excellent teacher.
While a little late on commenting, I am curious how Carver's triac circuit with the three stages in amplification differs from NAD's two-stage?
Hi Tony. Most houses with 100 amp service have 220 volt service. Then you can run under 20 amps.
For this rig, that would be a really good idea!
The large filter caps strapped down with zip ties and hot glue looks so diy. What are they even sitting on? Is it so hard to put them vertically or make a metal bracket and ground bus bar? The sunfire amps he did at least had a metal bracket to clamp them down. But a similar negative terminal connection of a soldered 16-18awg solid wire across solder lugs, only also with additional ground wires wrapped around them. And another 1 inch 18awg solid running to a thin soldered lug at the chassis star ground point. Now allowance for thermal expansion or strain from the screw terminals or screw at the ground. Over time movement, age and heat tends to compromise that solder joint and then things hum in the wrong way and go boom as ground reference is lost.
For the price of these things would a proper buss bar be so hard?
Maybe I am wrong, but I think you still have some oscillation riding on top of that sine wave at full throttle. There is some ringing going on. Maybe that would be more clearly visible on an analogue scope if you could enlarge that area.
Yeah, I noticed the same thing.
That's mostly because of all the test equipment connected all over the place as well as all of the covers being off. That will go away when everything get put back together.
@@xraytonyb I have a pair of these 9t's and both meter lights are out. What do I need to do and would you be willing to service them if I ship to you?
By George, I think he's got it! Veddy Ieenteresting! (Laugh in)
Who knew, just one little j-fet! You will or have recapped the second amp, correct? I look forward to the final video that ends with them going back home. What's the THD of the fixed amps and can you measure IM at all?
Thanks for watching! Both amps will be re-capped and fully aligned. I will try to test the performance, but this thing has enough output to fry a lot of my test equipment if I'm not careful!
Yes, its ironic when protection circuitry fails and causes problems, but its lot cheaper to fix one JFET that the output stage or the transformer or the speakers :) Is that JFET the first semiconductor seen by the input signal BTW? If so it might have caught a static discharge or something at some point.
I notice at 30:00 when you ran up the amp to full power there was still a bit of “fuz” on the positive half cycle of the sine wave. Do you know what this was.
Really good job!
I have a couple of TFM Carver amps
Do you still work on them?
How were you staring the test at 11:00? The reason I ask is there's a lot of clipping on startup. It's fine when it settles in, but that's not very "musical". I'm guessing it's a artifact of your test setup, but I can't tell.
The tie-down manufacturers need to upgrade their nylon formula. They degrade in less than a year exposed to UV.
No UV in the black box, probably heat, or as you say naff Nylon.
What is the preset pot for labeled RP1.
Carver amplifiers are very greedy power wise. I have a TFM-25 and my circuit can hardly handle it at high volumes and my amp is 225 Watts per channel at 8 ohms. It is capable of peaks up to 450 for short durations. So I would gather that these are more greedy yet and I am not sure that 20 amps is enough. Hard to say, unless you try a different plug.
These would work better if used with 240VAC. Now if I could just get my wife to let me unplug that stove! ;)
I know, right. Who needs a stove. My amp is smaller, but still if I want to listen to it loud I have to make sure it is the only thing on that circuit. They are greedy, but sound good. Luckily for me I have not yet needed to repair my amplifier. It has been going strong since I purchased it new back in 1989. I have always liked Carver gear and I was able to meet him briefly.
I'll say it like Bill Gates.
nobody will EVER need more than 4 sh1tloads of amplifier
Wouldn't you agree that those units should be on a 240 volt 30 amp circuit , on each one?
each one is 120v. you need one 240v split phase circuit to run both
@@josephbeasley5193 He's saying they would work better if they where set up for 240 on each one.
Nice!!