Death Cap Years?

Discussion in 'Amps [BG]' started by Grissle, Jan 22, 2014.


  1. Grissle

    Grissle Supporting Member

    Joined:
    May 17, 2009
    I have a '75 silverface, (PA 100) were they still including the Death Cap this far along? This came with the three prong cord, but it also has the three-way ground switch? I want to get in there and bypass it ASAP if its in there.
  2. LowEZ

    LowEZ Supporting Member

    Joined:
    Mar 29, 2011
    Location:
    Central NJ
    It's in there but when the ground switch is in the middle position, the death cap is out of the circuit.
  3. Grissle

    Grissle Supporting Member

    Joined:
    May 17, 2009
    Thanks, ill leave it as is then.
  4. beans-on-toast

    beans-on-toast

    Joined:
    Aug 7, 2008
    Amps are still being made today with the ground reverse switch, cap, and a three conductor power switch. The Ampeg SVT is one example. Other amps such as the Fender 59 Bassman come with a ground switch but it is not connected. They include the switch on the panel because the vintage amps had one.

    As was mentioned, on all amps with a three position switch, the middle position takes the cap, if there is one, out of the circuit.

    The line filter circuit with the "death" cap in it is safe if the cap is healthy. Today they use Type Y safety caps which are designed to be used in line connections and if they fail, do so in a safe way.
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  6. gmarcus

    gmarcus Supporting Member

    Joined:
    Apr 4, 2003
    What is a death cap? Sounds luke something we should all be aware of.
  7. beans-on-toast

    beans-on-toast

    Joined:
    Aug 7, 2008
    It's purpose is to filer higher frequency power line noise. It is connected on the input (primary) side of the power transformer between either the hot (black) or neutral (white) on the power line. The other end is connected to the chassis. There is a ground switch on the amp to select a connection to either the hot or neutral line.

    If the ages and capacitor shorts completely, you could have the line voltage on the chassis. Touch a ground, such as another amp, and you can get a shock. Hence the name but the term is exaggerated. More often these caps will leak a bit and the shock is mild.

    If you have an older amp that has this cap, have a tech check it out to ensure that it is functioning up to spec. Many people remove this capacitor when a three-conductor power cord is added to the amp. It isn't necessary though as the ground switch can still be used to minimize noise in the amp related to the power line. As I mentioned above, Type Y capacitors are available that are designed to be safer for power line filtering. They should, but not all amps have these type of caps installed. Techs have been known to throw in whatever they have available.

    More details here in the TB portaflex Wiki.
  8. Bill Hughes

    Bill Hughes

    Joined:
    Oct 17, 2013
    These are capacitors that bypass one side or the other for lowest hum. The term death cap is an acronim assigned by the un-informed.

    They met UL code when designed, and they employed "Y" caps.

    All class "D" stuff have line filters to control "conducter emissions", some (many) employing bypass caps that the words "death caps" might be applied to.

    If it has a properly installed 3 pin line cord, you can not get a shock.

    Most people fear what they don't understand.
  9. kohntarkosz

    kohntarkosz

    Joined:
    Oct 29, 2013
    Location:
    Edinburgh - Scotland
    I thought this was a thread on mushroom foraging....

    The guys on TDPRI guitar forum seem to know a lot about death caps.
  10. LowEZ

    LowEZ Supporting Member

    Joined:
    Mar 29, 2011
    Location:
    Central NJ
    TDPRI gets far deeper tech-wise than TB because it's trivial to build / repair / maintain a 14-watt tweed Deluxe compared to a 300-watt SVT. Hence guitar forums are chock full of amp builders, DIY'ers, wannabes and hacks.
  11. Garden Variety

    Garden Variety Supporting Member

    Joined:
    Oct 29, 2013
    Location:
    Columbus, Ohio
    This is a blanket statement that is misleading. You are assuming that the outlet that said properly installed 3-pin cord is plugged into is correctly wired. If it is not, and few players in many venues will be privy to this knowledge or have the ability to check it, then the player could get a shock.
  12. wcriley

    wcriley

    Joined:
    Apr 5, 2010
    Location:
    Western PA
    Disclosures:
    Uncompensated endorsing user: fEARful

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