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Kenwood C2 basic rebuild/refresh

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by patfont, Sep 21, 2014.

  1. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    Hi,
    I am usually in the Marantz/Pioneer forums, but have AKer Warrens C2 here. There is not much out there on this model so just wanted to put this up for informational purposes in case it can help some one out.

    Warren wanted to refresh the power supply caps and maybe do something with the op amps. The phono was intermittent if he wiggled the cable it would go on and off.

    In this pic you can see where the phono input to the board has cracked in a circle from normal daily insert and removal of cables:


    [​IMG]



    What we did was reflow and refresh all of the input legs to the board to make sure they are sturdy. I also found 2 other cold/bad/ joints one on the pre board and one on the filter board: here are all the inputs across the back:


    [​IMG]


    Warren will be using this mostly for vinyl so here is the original op amp:

    [​IMG]



    Here is a view of the main board lay out, very nice clean and orderly!



    [​IMG]
     

     

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  2. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    I have my usual suspects cap wise for most locations on each board, but in the C2 there are some areas where certain values/size limitations come into play. One location was the 2200uf feedback caps and the other on the phono supply board the rear caps could only be maybe 16mm max height as the phono selector cable runs right over them. So some different choices had to be made.

    Will cont with more pics etc later.
     
  3. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    continuing on and the main board is mostly empty.
    -the phono BP caps are replaced with Elna Silmic bipolors, and the flat amp BP caps are still to come out.

    [​IMG]
     
  4. SPL db

    SPL db It's all about the music! Subscriber

    Messages:
    17,746
    Location:
    Omaha, NE
    Good luck with the restoration, I have one of these that has sound at the headphone jack but the preamp out won't turn on at all.
     
  5. DeltaWye

    DeltaWye New Member

    Messages:
    49
    Location:
    Toronto
    How's the balance control? It's a known defect with this preamp, it causes the signal to go off on one side or cut in and out. I managed to repair mine by taking it apart and reattaching metal wipers (actually, doing a google search on C2 balance control is how I found Audiokarma).

    I did a write-up but the pictures I took were pretty bad:

    http://www.audiokarma.org/forums/showthread.php?t=473466
     
  6. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    balance control is good, on this one.:D





     

     

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  7. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    ok here are some pics:

    -Upgraded the phono op amp to a 4580DD, this is a "low noise" op amp. It is installed in a socket so rolling here is now available.


    [​IMG]


    Here is one of the power supplies on the main board: caps were changed to Silmic II, and Nichicon FG's. The diodes on the power supplies were changed so there would not be over voltage at the op amps. A thank you to Leestereo for his input in this area, as per his C1 rebuild.

    [​IMG]



    Here is the flat amp, it already had a "DD" op amp, the BP caps were changed out to Nichicon ES.

    I prefer "audio grade" caps when ever possible.


    [​IMG]


    will get the rest up tomorrow!
     
    Last edited: Sep 22, 2014
  8. Leestereo

    Leestereo Super Member

    Messages:
    2,144
    Location:
    Ottawa, ON
    As always, very nice work, Pat!
     
  9. W.ALLEN

    W.ALLEN AK Subscriber Subscriber

    Messages:
    733
    Location:
    Montgomery Tx.
    Looking forward to getting this back , should be here Thursday or Friday .
     
  10. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    here are some more pics:

    The main board looks real nice!

    I have added arrows to the 3 places I had to make minor changes due to size constraints.

    [​IMG]

    [​IMG]
     
  11. W.ALLEN

    W.ALLEN AK Subscriber Subscriber

    Messages:
    733
    Location:
    Montgomery Tx.
    I am going to say it was definately worth having the C2 restored and repaired . I have got about two hours of listening time on it as of now and was told it will even get better with more time , very impressed with it now , have listened to several different LP's so far and it sounds excellent . I am very happy I had this done .
     

     

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  12. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
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    Warren I am glad you are happy with the C2! I was listening to it myself when done, and I can see why it is well liked. It just has a nice smooth musical non fatiguing sound. Just makes you want to pull out all your favorite recordings to hear them again. And yes, as the caps burn in it will get better!
     
  13. W.ALLEN

    W.ALLEN AK Subscriber Subscriber

    Messages:
    733
    Location:
    Montgomery Tx.
    I have to make another comment , this system has never sounded this good , even with a untouched M2. The phono section on this pre is crystal clear , my LP's have never sounded better .
     
  14. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    awesome, and it may get even better!

    :music:





     
  15. Zolton

    Zolton Well-Known Member

    Messages:
    819
    Location:
    Southern Ontario Canada
    I've posted a thread requesting a copy of the C2 owner's manual.

    Any of you guys happen to be in possession of an electronic copy?

    They seem to be very hard to come by.

    :music:

    BTW...the guy I purchased my C2 from mentioned that he had performed the balance switch bypass.

    I notice the left channel cutting in and out and am wondering if he did it correctly or if it's a different issue
     
    Last edited: Sep 29, 2014
  16. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
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    Sorry I missed this, thanks Ben! Are you working on anything at this time?:scratch2:







     

     

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  17. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
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    I do not have one, as you mention the SM is easily available.








     
  18. DCS

    DCS New Member

    Messages:
    13
    Hello,
    I have just received my first Kenwood C2 and am doing a quick inspection before I put power to it. I pulled the cover off and it is very clean inside. Not a spec of dust, I really wasn't expecting it to be this clean. Is it possible to tell if this thing has already been recapped? All of the electrolytic caps I can see are Elnas, are those typically what these shipped with?
     
  19. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,836
    Location:
    South Jersey
    Probably stock, but post up a pic
     
  20. DCS

    DCS New Member

    Messages:
    13
    Not sure how to do that.
     

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