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Carver C-4000 recapping
- Thread starter P.L.F.
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Smokey....
Works are finished with some surprises - I misplaced two boards: delay function and sonic holography. Could find my glasses at the key moment and on those PCBs connections were shifted by one pin... Shame, I know. After pushing mains button I realized that heat sinks got warm very quickly, no output only 'buzz effects', so the gear went back on bench.
The mistake was corrected but there were two resistors heavily burnt: R39L and R39R (18 ohms). Could find ideal replacements so I've put 20 ohms in there. All functions got back to work as they should except low level delay output, where the sound is very harsh (I didn't check power amp outputs...)
My question to you Guys is what else I've possibly smoked there too? Your indications will limit the spectrum of further testing / bad components' identifying...
BTW - I connected the preamp to my main system and can tell you that sonically the recapping projects has brought more clarity and speed to the sound. Really nice.
Many thx!
Works are finished with some surprises - I misplaced two boards: delay function and sonic holography. Could find my glasses at the key moment and on those PCBs connections were shifted by one pin... Shame, I know. After pushing mains button I realized that heat sinks got warm very quickly, no output only 'buzz effects', so the gear went back on bench.
The mistake was corrected but there were two resistors heavily burnt: R39L and R39R (18 ohms). Could find ideal replacements so I've put 20 ohms in there. All functions got back to work as they should except low level delay output, where the sound is very harsh (I didn't check power amp outputs...)
My question to you Guys is what else I've possibly smoked there too? Your indications will limit the spectrum of further testing / bad components' identifying...
BTW - I connected the preamp to my main system and can tell you that sonically the recapping projects has brought more clarity and speed to the sound. Really nice.
Many thx!
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Last edited:
Przem,
I think everything is correct .
The sound of delay unit is poor .
It's designed in this way ( bandwidth , etc ) : you must not ear the rear speakers .
It's only a delay unit and not Dolby Sorround unit .
If low level outputs are O.K. means that power amp is O.K. , because the signal comes from it
via a 20 dB att.
In the owner's manual it' s written clearly that the sound of delay unit is poor ,
but it's sufficient for its purpose .
My suggestion ( my solution ) is to use internal power amp connected to low cost speakers .
Enjoy your C4000.
Ciao
Marco
P.S: Suggestion : replace the connectors of power amp with banana connectors .
I think everything is correct .
The sound of delay unit is poor .
It's designed in this way ( bandwidth , etc ) : you must not ear the rear speakers .
It's only a delay unit and not Dolby Sorround unit .
If low level outputs are O.K. means that power amp is O.K. , because the signal comes from it
via a 20 dB att.
In the owner's manual it' s written clearly that the sound of delay unit is poor ,
but it's sufficient for its purpose .
My suggestion ( my solution ) is to use internal power amp connected to low cost speakers .
Enjoy your C4000.
Ciao
Marco
P.S: Suggestion : replace the connectors of power amp with banana connectors .
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Thank you Marco,
Actually I'm not going to use the delay unit (amp or low signal) at all. Simply it was rather my bad feeling that with not enough attention one of the preamp's function was not working correctly. Therefore intention to retrofit to the proper state of all features... But your explanation is clear.
Best regards, Przem
Actually I'm not going to use the delay unit (amp or low signal) at all. Simply it was rather my bad feeling that with not enough attention one of the preamp's function was not working correctly. Therefore intention to retrofit to the proper state of all features... But your explanation is clear.
Best regards, Przem
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Lost entire day to try repairing, partial success but no TONE control - help!
Hi,
There were some modernization works of external PS 240VAC line to my house going on when I was listening to the music and apparently something got burned in my C4000. Here is what had happened:
First I heard two/three thumps on the left channel and at the same time a number of clicks of Don's DC protection module, then the channel was dead. I checked fuses on my PL700s2 (the one upgraded by Lee) and one out of four rail fuse went down (5A 240V AGX). After its replacement I put all pots at the minimum and turned on the amp - ufff, it started OK. However the first attempt to increase volume of the amp (I tried about 50% clockwise) started that strange clicking of relays on the DC protection board - so back to zero. While setting the amp volume at about 20% one could hear the music, however only one channels sounded crispy, the other (surprisingly - right) sounded boomy dark... And any movement of C4000 pots or any its button pressed was causing unpleasant harsh sounds on my speakers.
I have another C4000 (candidate for recapping), which was plugged in and everything looked OK. I was trying to roughly verify possible amp's output failure (without opening the gear and measuring for shorted outputs), so I played the music really hard and loud for a longer while. Both channels seem to work in robust way as before (by the way: should I re-check the outputs if there are any shorted transistors anyway?).
Then I took the preamp on my 'bench' and started some basic measurements. One channel output voltage was like 40% of the other with the same level trigged inputs and on the scope it was visible a DC line too. That DC problem with C4000 reminded me something I had read before but could not remember what was it. Finally after reading all the pages of C4000 SM, on its lat page (of course…) there was this kind of issue treated. Bingo! I replaced two FETs (2N5458’s) with BF245C (https://www.fairchildsemi.com/datasheets/BF/BF245C.pdf) and switched on the preamp with no buttons pressed, vol at minimum. I connected signal generator and the scope, increased the volume and the previously unbalanced output voltages L and R were back to order. Then connected music source and headphones. It sounded nice with no any button switched on.
Unfortunately it was only a partial success. When I pushed the TONE button - dead silence… Also the PEAK UNLIMITER seems not working at all…
Well I am lost a bit and need some time to rethink and also - above all - some advice
. I suspect PCB connectors, so they will be all re-soldered, but it would be too simple...
Maybe I should also mention that on the tone PCB I have replaced earlier on two IC’s: TL072 with BB OPA2134 and RC4136 with Brown Dog 2xOPA2134 from Cimaron (http://cimarrontechnology.com/rc4136upgradeadapter.aspx). I found this setup sounding just great, incomparably better than the original one. After the failure I tried the original IC’s just in case but it didn’t cure the problem.
The link to C4000 SM is here: https://www.usahifi.com/sites/default/files/product/610/manuals/Carver C-4000 Service Manual.pdf
Any advice what went wrong?
Hi,
There were some modernization works of external PS 240VAC line to my house going on when I was listening to the music and apparently something got burned in my C4000. Here is what had happened:
First I heard two/three thumps on the left channel and at the same time a number of clicks of Don's DC protection module, then the channel was dead. I checked fuses on my PL700s2 (the one upgraded by Lee) and one out of four rail fuse went down (5A 240V AGX). After its replacement I put all pots at the minimum and turned on the amp - ufff, it started OK. However the first attempt to increase volume of the amp (I tried about 50% clockwise) started that strange clicking of relays on the DC protection board - so back to zero. While setting the amp volume at about 20% one could hear the music, however only one channels sounded crispy, the other (surprisingly - right) sounded boomy dark... And any movement of C4000 pots or any its button pressed was causing unpleasant harsh sounds on my speakers.
I have another C4000 (candidate for recapping), which was plugged in and everything looked OK. I was trying to roughly verify possible amp's output failure (without opening the gear and measuring for shorted outputs), so I played the music really hard and loud for a longer while. Both channels seem to work in robust way as before (by the way: should I re-check the outputs if there are any shorted transistors anyway?).
Then I took the preamp on my 'bench' and started some basic measurements. One channel output voltage was like 40% of the other with the same level trigged inputs and on the scope it was visible a DC line too. That DC problem with C4000 reminded me something I had read before but could not remember what was it. Finally after reading all the pages of C4000 SM, on its lat page (of course…) there was this kind of issue treated. Bingo! I replaced two FETs (2N5458’s) with BF245C (https://www.fairchildsemi.com/datasheets/BF/BF245C.pdf) and switched on the preamp with no buttons pressed, vol at minimum. I connected signal generator and the scope, increased the volume and the previously unbalanced output voltages L and R were back to order. Then connected music source and headphones. It sounded nice with no any button switched on.
Unfortunately it was only a partial success. When I pushed the TONE button - dead silence… Also the PEAK UNLIMITER seems not working at all…
Well I am lost a bit and need some time to rethink and also - above all - some advice
. I suspect PCB connectors, so they will be all re-soldered, but it would be too simple...Maybe I should also mention that on the tone PCB I have replaced earlier on two IC’s: TL072 with BB OPA2134 and RC4136 with Brown Dog 2xOPA2134 from Cimaron (http://cimarrontechnology.com/rc4136upgradeadapter.aspx). I found this setup sounding just great, incomparably better than the original one. After the failure I tried the original IC’s just in case but it didn’t cure the problem.
The link to C4000 SM is here: https://www.usahifi.com/sites/default/files/product/610/manuals/Carver C-4000 Service Manual.pdf
Any advice what went wrong?
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Przem ,
two suggestions :
-replace the tone board with the one of the other C4000 and verify if O.K or K.O .
-verify the correct placement of de thump fets .
( probably you have to rotate them of 180 degrees ) .
It's very easy to make a mistake because you to solder them on the opposite site of the PCB
in case of replacement . I presume that this is the issue , because IC2 is connected to the de thump circuit .
Ciao
Marco
two suggestions :
-replace the tone board with the one of the other C4000 and verify if O.K or K.O .
-verify the correct placement of de thump fets .
( probably you have to rotate them of 180 degrees ) .
It's very easy to make a mistake because you to solder them on the opposite site of the PCB
in case of replacement . I presume that this is the issue , because IC2 is connected to the de thump circuit .
Ciao
Marco
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- Joined
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- Messages
- 419
- Location
- Poland, Warsaw (Central Europe)
- Tagline
- I love BIG amplifiers!
- Joined
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- Messages
- 419
- Location
- Poland, Warsaw (Central Europe)
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- I love BIG amplifiers!
Well, it was not easy to find the problem. Nothing to do with de-thump FETs. This part I repaired OK. It was my bad soldering the cause of the preamp malfunctioning... 
My eyes are apparently far from what they were only a couple years ago. And I wore my glasses, not enough though... I must buy a magnifying glass on top, otherwise such problems will appear more often.
So what happened? Two bad solder places and one cold solder joint - all while installing the IC's sockets for RC4136 and TL072 Burr Brown replacements. It was quite easy to heat ICs' PINs while de-soldering a bit too long and some ('hair' thickness) hot tin solder went under PCB enamel and created short circuits with traces going in-between the PINs in these two sockets, one leg/pin each (see the example on attached photo)... Everything bloody small... Still it's a shame...
I cleaned the mess I've done and reinstalled the ICs again. With Burr Brown 2134 upgrade the sound is extended towards bottom end and definitely without sibilance. Lots of new details while listening known music - that's nice. And less noise. Overall much better that before to me.
One of lessons learned is NOT to repair AND upgrade at the same time. If something goes wrong one can get lost so quickly...
Now with everything back to normal and I can shake my house a bit... Latest AC/DC?
My eyes are apparently far from what they were only a couple years ago. And I wore my glasses, not enough though... I must buy a magnifying glass on top, otherwise such problems will appear more often.
So what happened? Two bad solder places and one cold solder joint - all while installing the IC's sockets for RC4136 and TL072 Burr Brown replacements. It was quite easy to heat ICs' PINs while de-soldering a bit too long and some ('hair' thickness) hot tin solder went under PCB enamel and created short circuits with traces going in-between the PINs in these two sockets, one leg/pin each (see the example on attached photo)... Everything bloody small... Still it's a shame...
I cleaned the mess I've done and reinstalled the ICs again. With Burr Brown 2134 upgrade the sound is extended towards bottom end and definitely without sibilance. Lots of new details while listening known music - that's nice. And less noise. Overall much better that before to me.
One of lessons learned is NOT to repair AND upgrade at the same time. If something goes wrong one can get lost so quickly...
Now with everything back to normal and I can shake my house a bit... Latest AC/DC?
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Today I finished recapping of the other C-4000 preamp I have and this time I did't create any mess . For the first time I was using PanaVise PCB holder - what a great tool!!!
The C-4000 sounds so crisp & clear now and with expected bass extension. Surprisingly after recapping the loudness contour function started to work again...?
This unit together with fully comp PL700 II (for cooling there are two 120 VAC fans connected in series); Yamaha CD-S300-RK Rackmount CD Player, where one can plugin an iPod with Apple Lossless files to avoid frequent disk changing, and Yamaha PA S4115H speakers will serve garden parties this summer ...
Pity I live so far from you guys but will try play loud then
...
. For the first time I was using PanaVise PCB holder - what a great tool!!!The C-4000 sounds so crisp & clear now and with expected bass extension. Surprisingly after recapping the loudness contour function started to work again...?
This unit together with fully comp PL700 II (for cooling there are two 120 VAC fans connected in series); Yamaha CD-S300-RK Rackmount CD Player, where one can plugin an iPod with Apple Lossless files to avoid frequent disk changing, and Yamaha PA S4115H speakers will serve garden parties this summer ...
Pity I live so far from you guys but will try play loud then
...Attachments
Last edited:
Today I finished recapping of the other C-4000 preamp I have and this time I did't create any mess . For the first time I was using PanaVise PCB holder - what a great tool!!!
The C-4000 sounds so crisp & clear now and with expected bass extension. Surprisingly after recapping the loudness contour function started to work again...?
This unit together with fully comp PL700 II (for cooling there are two 120 VAC fans connected in series); Yamaha CD-S300-RK Rackmount CD Player, where one can plugin an iPod with Apple Lossless files to avoid frequent disk changing, and Yamaha PA S4115H speakers will serve garden parties this summer ...
Pity I leave so far from you guys but will try play loud then...
. For the first time I was using PanaVise PCB holder - what a great tool!!!The C-4000 sounds so crisp & clear now and with expected bass extension. Surprisingly after recapping the loudness contour function started to work again...?
This unit together with fully comp PL700 II (for cooling there are two 120 VAC fans connected in series); Yamaha CD-S300-RK Rackmount CD Player, where one can plugin an iPod with Apple Lossless files to avoid frequent disk changing, and Yamaha PA S4115H speakers will serve garden parties this summer ...
Pity I leave so far from you guys but will try play loud then
...
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