Epic repair Trevor, nice work! I never understood the "videos too long" folks. I watched at my own pace, always able to return where I left off, lot's of interesting challenges to learn from. Thanks for the great content! - JRH
Great video. Everyone who works on a Carver seems to come away with something very new learned from it. xraytonyb also worked on a couple of them and came away with about the same thing. They are quirky amps (just as Bob Carver is) but they have their place in the audio "spectrum". Thanks for taking us along for the ride, Trevor!
Thank you again for an excellent video. Great to share the journey of proper diagnosis with limited resources. It is always a pleasure to watch someone so skilled and experienced doing what they do best! Please keep making these videos, you are the best on youtube!
The video is not too long if it contains a lot of valuable info, some people like to spend half the time talking nonsense but your videos have very little extraneous content ! I like the long video format, it's perfect for people who have the time to follow along but I suppose some people just want 2 minute videos because that's their attention span !
This was a great video. I used to have this amplifier back in the 1990s, along with a Ramsa WP9440 and two Crown Power Base-2 units when I had a band and when I provided sound reinforcement for other bands. We used the Carver for monitors, the Ramsa for subs, and the two Crown units for mids and highs. We didn't have any issues with any of the amps over about 10 years of weekend gigging. The Carver was much lighter than the others...and now I know why. That transformer is small. Interesting to see how it works and what the internals look like. Thanks for spending the time sharing your experience!
Good vid Trevor. Yes, those "commercial" amplifiers get a beating. I had pleasure of repairing an 80's fender BXR Dual 400 SS bass head and the heat damaging the traces was horrendous- the traces were thin anyway. However got it done with patches like yours and solder mask. On another note- below the description of that chinese OP amp tester- also explains the flickering red led. Application: Single op amp and dual op amp screening circuit board, the circuit board can judge whether the IC can be used for amplification, and can roughly judge the conversion rate of the chip at the same time. Can find out those low-speed chips that pretend to be high-speed chips. Working Voltage: DC 12V Working Current: Above 100mA Principle Introduction: IC1a in the circuit is connected to a multivibrator with a frequency of about 1Hz, and the OP Amp. to be tested is connected to a unity gain inverting amplifier working state. IC2 is an EX-OR gate, and its truth table is that the output is 1 when the two inputs are inverted. Therefore: If OP Amp. is normal, points A and B of IC2 must be reversed, so C is 1, and it is still 1 after IC1b and 1d, so the yellow LED D3 lights up; If the OP Amp. output is open, the point C of IC2 must always be 0, and it becomes 1 after IC1c, so that the red LED D4 lights up. If the internal short circuit of OP Amp. makes the output voltage fixed to positive or negative, the output of IC1c is also a 1Hz low frequency square wave, and the red and yellow LEDs will flash alternately. For chips with a low conversion rate, the status indicated by the LED is always yellow, and red will flicker faintly. This can also be used to roughly judge the conversion rate of the chip. Because most of the second-hand chips on the market use low conversion rate instead of high rate, it can also judge whether the chip is counterfeit or not. The actual test of low conversion rate chips such as: OP07, LM741, the yellow light is always on, the red light is slightly bright. The actual test of high conversion rate chips such as: TL071, NE5534, MC34071 and other chips, the yellow light is always on, the red light is off. Single op amp model: LM741, LF356, NE5534, TL071, TL081, OP07 and other standard package single op amp. Dual op amp model: LM358, NE5532, TL072, TL082, MC1458, RC4558, OP275, AD827 and other standard package dual op amps.
I did this exact model several months back, bad output transistors, some damaged signal transistors in the driver circuit and several charred resistors. Luckily luckily the board was nowhere near as bad as yours. I too found the emitter resistors difficult to get to when setting bias, I bought some long gripper probes specifically for it. I did end up installing standard RCAs since it was going to be used in a home with standard equipment, not pro equipment. I do not remember getting any noise like that when driving it into clipping.
I made 2 sets of short testleads with dual banana jacks at one end, and open wires at the other. So i just solder them on to the emitter resistors when i shall adjust the bias. Or one to the emitter resistor, and the other to the midpoint if that shall be adjustet at the same time. That way i get a good solid connection and accurat readout. At that low voltages a good connection is important.
I enjoyed this video Trevor, so "happy happy happy" does not only apply to your experience here, some of us can relate. For sure my first advice to you (since my never commented advice to buy a thermal camera was already fulfilled) is to Ali for some 400 Watt dummies for your power tests ! Just wondering where the power will stop....
Those inputs are for in and out to EQs, electric drums, etc... Red into drums, and black to out. For solo instruments to the mixing board. Some are black in red out from drums, why I don't know.
Man, that triac sounds angry, even when it's working properly...I guess you won't hear it with 300w going into a speaker instead of a resistor, but geez.
What's with that electrical noise when you've been increasing the signal....is that normal? You never commented on that. Great repair and restoration of course!
He mentioned it was a noisy transformer @2:26:34, this happens as a result of A/C in some coils, most of the noise comes from loose case parts vibrating from the resonance, it usually isn't a problem when the amp is powering speakers because they will drown out most amp noise.
If you look at the manual for this you'll see that it is a "Carver Professional" amp , thus the 1/4" TRS jacks and rack ears. Are you sure those are unbalanced (not that it would matter; I have an effects unit with balanced TRS jacks that work fine with unbalanced)? If so, and if using it as a home audio amp, I would definitely change them to RCA. I'm guessing someone made the same mistake you did with the bias pots but cooked this thing before they figured it out.
As far as the rack ears go, many (if not most) of Carver components had them regardless. I have the Carver C-1 Preamp, AV-64 power amp as well a a lower-end TFM-6C amp and they all have rack ears (some can be removed if desired).
Maybe you can block this “john senchak” from viewing you vidoes. He must be the most negative person alive, no one else has any objection about the length of your videos.
When I saw you had a video that was 2.5 hours long, I was genuinely excited to watch it. I don't mind long videos.
yes me too
Epic repair Trevor, nice work! I never understood the "videos too long" folks. I watched at my own pace, always able to return where I left off, lot's of interesting challenges to learn from. Thanks for the great content! - JRH
Great video. Everyone who works on a Carver seems to come away with something very new learned from it. xraytonyb also worked on a couple of them and came away with about the same thing. They are quirky amps (just as Bob Carver is) but they have their place in the audio "spectrum". Thanks for taking us along for the ride, Trevor!
Thank you again for an excellent video. Great to share the journey of proper diagnosis with limited resources. It is always a pleasure to watch someone so skilled and experienced doing what they do best! Please keep making these videos, you are the best on youtube!
The video is not too long if it contains a lot of valuable info, some people like to spend half the time talking nonsense but your videos have very little extraneous content !
I like the long video format, it's perfect for people who have the time to follow along but I suppose some people just want 2 minute videos because that's their attention span !
Great video Trevor! Carver amps are a different beast. I'm still not comfortable working on them. Good for you for digging in.
This was a great video. I used to have this amplifier back in the 1990s, along with a Ramsa WP9440 and two Crown Power Base-2 units when I had a band and when I provided sound reinforcement for other bands. We used the Carver for monitors, the Ramsa for subs, and the two Crown units for mids and highs. We didn't have any issues with any of the amps over about 10 years of weekend gigging. The Carver was much lighter than the others...and now I know why. That transformer is small. Interesting to see how it works and what the internals look like. Thanks for spending the time sharing your experience!
Lots of great info. Thanks!
I fumble through repairs all the time that's how you learn 💯 🤷
The most cooked board I have ever seen, surprised it did not catch on Fire. Trevor if you can make this produce sound, you are a genius.
Good vid Trevor. Yes, those "commercial" amplifiers get a beating. I had pleasure of repairing an 80's fender BXR Dual 400 SS bass head and the heat damaging the traces was horrendous- the traces were thin anyway. However got it done with patches like yours and solder mask. On another note- below the description of that chinese OP amp tester- also explains the flickering red led.
Application:
Single op amp and dual op amp screening circuit board, the circuit board can judge whether the IC can be used for amplification, and can roughly judge the conversion rate of the chip at the same time. Can find out those low-speed chips that pretend to be high-speed chips.
Working Voltage: DC 12V
Working Current: Above 100mA
Principle Introduction:
IC1a in the circuit is connected to a multivibrator with a frequency of about 1Hz, and the OP Amp. to be tested is connected to a unity gain inverting amplifier working state.
IC2 is an EX-OR gate, and its truth table is that the output is 1 when the two inputs are inverted.
Therefore:
If OP Amp. is normal, points A and B of IC2 must be reversed, so C is 1, and it is still 1 after IC1b and 1d, so the yellow LED D3 lights up;
If the OP Amp. output is open, the point C of IC2 must always be 0, and it becomes 1 after IC1c, so that the red LED D4 lights up.
If the internal short circuit of OP Amp. makes the output voltage fixed to positive or negative, the output of IC1c is also a 1Hz low frequency square wave, and the red and yellow LEDs will flash alternately.
For chips with a low conversion rate, the status indicated by the LED is always yellow, and red will flicker faintly. This can also be used to roughly judge the conversion rate of the chip. Because most of the second-hand chips on the market use low conversion rate instead of high rate, it can also judge whether the chip is counterfeit or not.
The actual test of low conversion rate chips such as: OP07, LM741, the yellow light is always on, the red light is slightly bright.
The actual test of high conversion rate chips such as: TL071, NE5534, MC34071 and other chips, the yellow light is always on, the red light is off.
Single op amp model: LM741, LF356, NE5534, TL071, TL081, OP07 and other standard package single op amp.
Dual op amp model: LM358, NE5532, TL072, TL082, MC1458, RC4558, OP275, AD827 and other standard package dual op amps.
Great Video. Lesson . Thanks . New Subscriber from QLD Australia.
Thank you for another excellent video. So informative, I really like the detail
Impressive work restoring this unit. I'm not sure how I feel about these Carver designs, however.
This is great. Some folks have to attempt repair on what they have, burnt up pc and all.
Man, what a mess. Poor thing
I did this exact model several months back, bad output transistors, some damaged signal transistors in the driver circuit and several charred resistors. Luckily luckily the board was nowhere near as bad as yours. I too found the emitter resistors difficult to get to when setting bias, I bought some long gripper probes specifically for it. I did end up installing standard RCAs since it was going to be used in a home with standard equipment, not pro equipment. I do not remember getting any noise like that when driving it into clipping.
I made 2 sets of short testleads with dual banana jacks at one end, and open wires at the other.
So i just solder them on to the emitter resistors when i shall adjust the bias.
Or one to the emitter resistor, and the other to the midpoint if that shall be adjustet at the same time.
That way i get a good solid connection and accurat readout. At that low voltages a good connection is important.
This video is NOT Too Long ! This is a teaching tool !
Do not remove the 1/4" jacks. Just add 1/4" to RCA adapters. So the amp will be mostly stock.
I enjoyed this video Trevor, so "happy happy happy" does not only apply to your experience here, some of us can relate. For sure my first advice to you (since my never commented advice to buy a thermal camera was already fulfilled) is to Ali for some 400 Watt dummies for your power tests ! Just wondering where the power will stop....
This oughta be good! I like my Carver well done. I’ve stayed away from them but supposedly they sounded great when not going critical mass.
Yes, regular rca jacks for the inputs. Add an input air shroud to the fan to outer case vent holes. imho
Those inputs are for in and out to EQs, electric drums, etc... Red into drums, and black to out. For solo instruments to the mixing board. Some are black in red out from drums, why I don't know.
Why not buy a new pcb? There are a lot of manufactores . Instead of fighting with that think
I hope you didn't pay much for this.
there is a really big line cord on this amp, assuming big current !
Man, that triac sounds angry, even when it's working properly...I guess you won't hear it with 300w going into a speaker instead of a resistor, but geez.
another good detailed video but that is a very noisy amp !!!
What's with that electrical noise when you've been increasing the signal....is that normal? You never commented on that. Great repair and restoration of course!
He mentioned it was a noisy transformer @2:26:34, this happens as a result of A/C in some coils, most of the noise comes from loose case parts vibrating from the resonance, it usually isn't a problem when the amp is powering speakers because they will drown out most amp noise.
Transformer buzz
Lol we use the same flux
Let's see if we can learn something from you. I know I did ;-)
Nope put a modern fan in it
If you look at the manual for this you'll see that it is a "Carver Professional" amp , thus the 1/4" TRS jacks and rack ears. Are you sure those are unbalanced (not that it would matter; I have an effects unit with balanced TRS jacks that work fine with unbalanced)? If so, and if using it as a home audio amp, I would definitely change them to RCA.
I'm guessing someone made the same mistake you did with the bias pots but cooked this thing before they figured it out.
As far as the rack ears go, many (if not most) of Carver components had them regardless. I have the Carver C-1 Preamp, AV-64 power amp as well a a lower-end TFM-6C amp and they all have rack ears (some can be removed if desired).
@@SergZak2023 Now that you mention it, I remember that being the case (it's been since the 90's since I've seen one).
Maybe you can block this “john senchak” from viewing you vidoes. He must be the most negative person alive, no one else has any objection about the length of your videos.
STOP SENDING LONG VIDEOS
😂😂😂😂😂
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