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Trying to find capacitors for tube amp

Discussion in 'General Electronics Discussion' started by drumminor2nd, Nov 22, 2010.

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  1. drumminor2nd

    drumminor2nd

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    Nov 21, 2010
    I have a generic 60's era phonograph with a built-in amp and detachable speakers. I'm trying to find some capacitors to stop the hum coming out of the unit.

    [​IMG]

    The biggest capacitor, which is a paper one and seems to be leaking a waxy paste of some kind, is a .15 400v. I'm having trouble finding one online. Anyone know where to get one?
     
  2. shrtrnd

    shrtrnd

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    Jan 15, 2010
    You won't find them made out of wax and paper anymore.
    I don't know what stores are near where you are. But check with an electronics supply
    store in your area. Tell them what you want, and they'll be able to tell you an equivalent.
     
  3. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    If you're handy and want to keep it looking original even inside you can remove the guts of the caps and install modern (physically smaller) capacitors inside the old.
    For the wax/paper type look for axial plastic film capacitors (0.15uF 400V). Which supplier(s) would you prefer to use?
    Did you check out if the big chassis mounted aluminum electrolytic caps might be responsible for the hum?
     
  4. drumminor2nd

    drumminor2nd

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    Nov 21, 2010
    I am just starting out with working in electronics, and I really don't know where to buy caps and such online. Any suggestions on a good dealer would be appreciated.

    As for locally-bought units, I live in the middle of nowhere (look on Google Maps, and you'll see a blank spot in Western New York and northern Pennsylvania... That's where I am:) ), and the best I have locally is a Radio Shack with only low-voltage (like, 10-volt)caps for transistor radios and such.

    http://www.flickr.com/photos/[email protected]/5199247308/
    This is one of the ones I'm looking for.

    http://www.flickr.com/photos/[email protected]/5198660335/
    This is the only other paper-type cap in the unit, which I don't even know how to start looking for. Is this what you're talking about?
     
  5. Resqueline

    Resqueline

    2,848
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    Jul 31, 2009
    I have some doubts about the 0.15uF 400V capacitor being bad. It seems to be in the power supply though. Does it look bad? Do you have a capacitor tester?
    The brown paper-clad capacitor is a multi-section (triple) aluminium electrolytic smoothing capacitor. I'm quite certain that's the one that has gone dry.
    It contains one 50uF and one 30uF 150V cap, and one 20uF 25? (or 250) V cap.
    Replacement values will have to be 47uF, 33uF & 22uF. DigiKey, Farnell, Mouser, Newark, & RS comes to mind as possible online (& "nearby") suppliers.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
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    Jan 21, 2010
    The latter one is three capacitors in one package. You need to get three individual capacitors and connect them, As mentioned in the case the negative lead of all of these capacitors are connected together.

    There are a variety of companies that can supply parts, google for Digikey, mouser, or maybe Newark.

    For that latter capacitor, you would be looking for electrolytic capacitors, and note that the capacitance measure "mfd" is obsolete. The abbreviation used these days is "uF".
     
  7. drumminor2nd

    drumminor2nd

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    Nov 21, 2010
    Negative on the capacitor tester (I guess my digital multimeter won't do that).

    OK... so what you're saying is I need these capacitors:
    a 47uF, 150V
    a 33uF, 150V
    a 22uF, 25V

    What kind? Aluminum? A different kind?

    And what I do is hook them all together by the negative lead, and then connect the positive leads to their respective terminals on the other components? Does that sound right?
     
    Last edited: Nov 23, 2010
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
    2,779
    Jan 21, 2010
    Yeah, Aluminium is fine.

    Did you check that the component says 25V for the last capacitor? From your photo it is not possible to determine if there's another digit there.

    Remember to connect the common negative to wherever that is connected in your circuit. It is the black lead.
     
  9. drumminor2nd

    drumminor2nd

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    Nov 21, 2010
    Yeah, it's 25v
     
  10. drumminor2nd

    drumminor2nd

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    0
    Nov 21, 2010
    Thanks all. I placed an order with Newark for the caps. We'll see how this works out.
    Thanks again,
    --Bob
     
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