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'65 Vibro Champ What Is That Cap??

Discussion in 'Shock Brother's DIY Amps' started by bugbiteaudio, Jan 30, 2013.

  1. bugbiteaudio

    bugbiteaudio Tele-Meister

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    Hello There,
    Just re-capped most of my Vibro Champ. But I am trying to figure out what these 2 capacitors are there for. They are the two caps coming from the rectifier tube socket to chassis ground (see pic).
    [​IMG]
    I don't see these on any schematics or any pictures of anyone else's amps.
    Any help would be appreciated.
    Thanks,
    Tony
     
  2. stingray_65

    stingray_65 Tele-Meister

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    .047uf?

    My guess would be someones attempt to get rid of hum....... sort of reminiscent of "death caps"

    I can't see them clearly, but do those big drops have a black bar printed on them? to the ground no less? if so they are from a very old mod or someone is using vintage caps.

    Ray

    ***EDIT***

    I'd loose em quick if it were my amp.
     
  3. bugbiteaudio

    bugbiteaudio Tele-Meister

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    Yes, they are .047uf caps. No black bar. You think it would be good to get rid of them? What are the potential problems of having them?
    ****EDIT****
    I take it back they are .1uf caps.
     
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  5. Wally

    Wally Telefied

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    That amp might need a pro look at it.
    Those large .047mfds attached to the red AC votlage feed to the rectifier do no belong there....as stingray notes.
    fwiw....that amp has not been fully recapped. The original multisection can is still there....and that is where the main filter caps are. Ime, these are the caps that are most likely to need replacement at this point in that amp's life....along with the bias cap and those board electrolytics.

    And cut that 'death cap' out....it is sitting at the fuse going to ground.
     
  6. stingray_65

    stingray_65 Tele-Meister

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    Holy Smokes I missed that!
     
  7. Wally

    Wally Telefied

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    Stingray, we might need to observe that if one or both of those .047mfd Orange Drops went directly short, that would be what.....according to the schematic 365VAC to ground...even worse than that 'death cap' taking wall voltage to ground, right?
     
  8. stingray_65

    stingray_65 Tele-Meister

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    I really do agree with you Wally.

    Gives me the shivers!.... but only when I touch the mic LOL

    Seriously though caps CAN and DO fail in a direct short. in all likelihood it would be a nice smelly bang and the cap would auto-remove itself, but amp grounds, tavern electrical outlets and all that COULD lead to a very tragic condition.

    Ray
     
  9. bugbiteaudio

    bugbiteaudio Tele-Meister

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    OK. So take out the blue .047 cap that is going from the fuse to ground? I believe that is what you guys are referring to as the "death cap". That cap is on the schematic.
     
  10. stingray_65

    stingray_65 Tele-Meister

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    Yes Tony, that is the one.
     
  11. Wally

    Wally Telefied

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    YEs, bugbite....and take out those big Orange drops. Imho, repalce the multisection cap can so that the amp has fresh filter caps. Without donig this, the 'recap' is not a recap, ime.
     
  12. bugbiteaudio

    bugbiteaudio Tele-Meister

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    Ok. THe big orange caps from the rectifier to ground are gone. I will remove the death cap from the fuse. I have the replacement filter cap can from mojotone, but I am trying to figure out the installation. It is 40/20/20/20 so I am not sure which lugs to use and the physical width of the bottom of the can is bigger than that of the original. I am wondering if I would have to widen the hole to accomodate.
     
  13. Wally

    Wally Telefied

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    bugbite, is that an AES can? My advice is DO NOT enlarge that hole in that chassis. IT appears to be a nice 1966 BF VC....and if you hack that chassis, the value will be affected. There is no reason to enlarge that hole, because there is a can that fits there exactly...built with the machine that built the can that is sitting in that amp right now, in fact.
    As to values.....IF the can fit, then I would suggest using the 3 20mfd sections and leaving the 40mfd idle. The 5Y3 rectiifier is rated for a max of 30mfd, so that 40mfd section is a bit much for the rectifier. Some would say go ahead and use the 40mfd section for the first stage of filtering. ...it will stiffend up the low end. I tend to abide by specs.
     
  14. hackworth1

    hackworth1 Friend of Leo's Vendor Member

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    Don't cut on your valuable original chassis to replace the cap can. If you shop around, you can find a cap can that is a direct replacement with the correct physical size and values. Try looking here for electrolytic capacitors:

    www.tubesandmore.com

    Without checking, I think you need a 20/20/20

    You don't want a 40uF first filter cap in that amp.

    Cap cans often have a code or a legend which is easily seen. A triangle marking near one lug might be 20uF, a square might be another 20uF or a 15uF, etc

    IOW, the lugs are labelled. The code is on the side of the can.

    One lug is often the common ground for all caps in the can.

    If not, then the shell of the can is grounded to the chassis by the tabs on the can's shell. Again a common ground for all caps in the can.
     
  15. bugbiteaudio

    bugbiteaudio Tele-Meister

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    I will measure more carefully to see if the can I have will fit. But just from eyeballing it, it looks as though the lugs might short out on the chassis.
     
  16. Wally

    Wally Telefied

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  17. bugbiteaudio

    bugbiteaudio Tele-Meister

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    Great. I will see if I can get the one I have to work without any chassis modding. If not, then I will pick up one of those CE cans. Thank you for the info everyone!
    -Tony
    It's almost there...
    [​IMG]
     
  18. muchxs

    muchxs Doctor of Teleocity

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    Here's the cheezmo way to do it.

    Disclaimer: I didn't do it!

    But... you can fly 3x 20uf axial caps from the board the power supply ground lug. 'Cuz admittedly it's a ***** to do a tidy job of removing and replacing the original Mallory Type FP cap can if you haven't done it before.

    You can see the death cap is still in place.

    Ideally it should look stock. If not from Fender's factory at least from someone's factory.


    The stock caps on the board are axial style, leads from each end. Radial style has leads on one end.



    .
     

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  19. bugbiteaudio

    bugbiteaudio Tele-Meister

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    Ok. I used the clamp they sent with the cap can. (I did have to drill 2 small holes for the clamp, but in the grand scheme of things, it is a very small mod and barely noticeable). I think it looks pretty good. But more importantly, it sounds AWESOME!
    [​IMG]

    [​IMG]
     
    Last edited: Jan 31, 2013
  20. andyfromdenver

    andyfromdenver Friend of Leo's

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    That looks a bit dangerous.

    Careful! :)
     
  21. bugbiteaudio

    bugbiteaudio Tele-Meister

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    If you mean it looks dangerous because the lugs of the cap can are close to the chassis, I see what you mean. However, if you saw it in person, you would see that there is a ton of clearance and the can is extremely secure in the clamp. I might go ahead and tape around the edges of the hole just in case, but I think it would be unnecessary.
    -Tony
     
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