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Help needed with Harman Kardon a220 “the lute”

Discussion in 'Tube Audio' started by Odizzieus, Aug 10, 2018.

  1. Odizzieus

    Odizzieus Member

    Messages:
    69
    I’m trying to replace the capacitors in a Harman Kardon a220 “the lute”, but the schematic calls for 4 different values for c3. Could someone post links to capacitors of equal values for c1-c4?

    Also, there is an additional capacitor in my unit that is not present in the diagram, in a picture below between the silver and brown capacitor closest to the camera. Should it be removed?
     

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  2. Odizzieus

    Odizzieus Member

    Messages:
    69
    Also, if anyone could upload a schematic of this unit it would be much appreciated
     
  3. century tek

    century tek Super Member

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    C1, C2, and C4 are individual capacitors. C3 is the silver can capacitor which houses 4 capacitors inside one can.

    You can find all of these on the web. I use tubes & more dot com for my capacitors.

    It looks like you just need 7 electrolytic capacitors altogether. There are 3 separate brown capacitors, and 4 capacitors inside the can. Can capacitors with these values can be quite spendy but you can use cheaper individual capacitors for the can. Looks like plenty of room under there.
     
    drtool likes this.
  4. Odizzieus

    Odizzieus Member

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    is it safe to assume the capacitance is in microfarads?
     
  5. century tek

    century tek Super Member

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    Yes, they are all MFD (uF) same thing.
     
  6. Odizzieus

    Odizzieus Member

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  7. Odizzieus

    Odizzieus Member

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    I’d also still like to know if anyone has a guess at the function of the additional capacitor between the c3 and c1
     
  8. s-petersen

    s-petersen Scott Subscriber

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    Radio museum has it for free
    The capacitor is part of the voltage doubler (C-2) 100 MFD
     
  9. Odizzieus

    Odizzieus Member

    Messages:
    69
    Not that capacitor, the one that is hanging above c1, c2, and c3
     
  10. s-petersen

    s-petersen Scott Subscriber

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    It's hard to see in the pic, if it is 50v likely an output tube cathode bypass cap, there is another smaller electrolytic near the bottom it's 12v? it's a cathode bypass cap for the first 12AX7 / ECC-83
     
  11. century tek

    century tek Super Member

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    I see which added capacitor you are talking about sitting above C1, C2, and C3. It looks to be connected to the diodes so its possible that it could have been a replacement for one of the capacitors inside the can capacitor C3. Look at C3 and see if any of the lugs are not connected and see if the extra capacitor has the same values as one of them in the can.

    Either way, it was needed, but if you go and buy all the replacements, it will eliminate that extra one and your circuit will be back to normal, connection wise.
     

     

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  12. buickguy62

    buickguy62 Active Member

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    I recapped an A220 some time ago. I used like values for the capacitors. The two near the center are the voltage doubler caps, note their polarity, they replaced one for one the original caps. For replacement of the multi section cap, I used four individual caps positioned in a pyramid with the negative leads commoned off. I used axial lead caps here, it's easier to connect the common leads together. My original 'firecracker' cap had the following connections and my replacement values:
    Red: 50uf, 350V, replaced with 47uf, 350V
    Yellow: 40uf, 350V, replaced with 47uf, 350V
    Blue: 20uf, 350V, replaced with 22uf, 350V
    Green: 50uf, 50V, replaced with 47uf, 50V

    In the 'pyramid: the 50uf, 50V cap is hard to see.
    I've done several of these A220's the multi-section cap in your picture is not one I've seen, possibly it's a three section replacement which would explain the additional cap, maybe not.
    I also replaced the two brown 'jelly bean' caps with 716 series orange drops and other parts, mostly resistors as necessary.
    These are nice amps when restored.
    Tom IMG_4711.JPG IMG_4714.JPG IMG_3560.JPG A220 Lute  Photofact pg. 5 rotated.jpg A220 Lute  Photofact pg. 5A.jpg A220 Lute  Photofact pg. 5B.jpg
     
    RWood likes this.
  13. buickguy62

    buickguy62 Active Member

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    A little more info: I see your multicap is fastened with screws and nuts, the ones I've seen were riveted, which supports the thought that it's a three section replacement. Also I reloaded the pics as thumbnails, may be easier to see.
    Tom
     

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  14. Odizzieus

    Odizzieus Member

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    Thanks for the info. My plan was just to cut out that extra capacitor and just replace all the other ones.
     
  15. century tek

    century tek Super Member

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    You have to see where it is connected and why it is there before you cut it out. You do that and it might quick working.
     
  16. Odizzieus

    Odizzieus Member

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    Well I realized that’s the green wire that goes to C3D so it will he replaced
     

     

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  17. century tek

    century tek Super Member

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    That's what I had initially thought that it was a part of the C3 can. :thumbsup:
     
  18. Odizzieus

    Odizzieus Member

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    My only issue is that on the schematic I can find c3a, c3b, and c3c, but I don’t see c3d.
     
  19. Odizzieus

    Odizzieus Member

    Messages:
    69
    Alright so I was able to find c3d. All the capacitors have the same ground lead correct?

    Edit: they do. Once my caps come in this repair should be easy. Thanks for all the help guys!
     
  20. century tek

    century tek Super Member

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    YUP!

    C3D = cathode bypass capacitor.
     

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