# Death Cap Removal



## Johnny (Nov 30, 2010)

Earlier this year I posted a three prong cord conversion on an old CORD tube amp that I have. The amp plays fine but I never took out the "death cap" so I thought I'd do that. Well, I removed the cap but now it seems the amp has more noise than before. Should I put it back? Is there any harm in leaving it in? Any info or comments would be appreciated.


1st picture is of original cord Greenish rectangular cap (death cap?) at top right (from fuse to chassis) was what I removed.








Here is the replacement cord with green grounding wire and death cap(?) still on.








The amp showing removed old cord and new replacement.


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## GuitarsCanada (Dec 30, 2005)

I did that conversion on my old fender super reverb. Removed death cap. All went well on that one. Maybe one of our amp techs here can chime in as well.

http://www.guitarscanada.com/amp-tech-section/32309-vintage-amps-two-prong-plugs-conversions.html


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## Johnny (Nov 30, 2010)

Thanks for the link to previous thread on this. How important is it to attach ground to transformer bolt? As seen in my pictures I have the ground attached to one of the chassis to cab bolts. Again, this amp was much quieter before I removed the death cap. Going to check the connections and maybe try bolting to transformer.


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## greco (Jul 15, 2007)

Johnny said:


> ...... Again, this amp was much quieter before I removed the death cap.


I'm looking forward to what the amp techs advise Re: eliminating/decreasing the "noise".

I'm wondering if it will involve wire dressing issues or the addition of a cap on the AC line (for some sort of noise filtering)

Cheers

Dave


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## Johnny (Nov 30, 2010)

greco said:


> I'm looking forward to what the amp techs advise Re: eliminating/decreasing the "noise".
> 
> I'm wondering if it will involve wire dressing issues or the addition of a cap on the AC line (for some sort of noise filtering)
> 
> ...


I did move the green ground wire to the transformer bolt closest to the cord. The amp does sound better now. It is a PINE Pepco amp with CORD nameplate and overdrives real early so I think it must just be part of the amp's character. I have a few other PINE amps and this one is super fun if you want to get down and dirty. In regards to this thread and my post, I think I've achieved what I wanted to with this amp. The Death Cap is removed and the amp is not as noisy as it was earlier. Thanks.


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## Furtz (Nov 27, 2010)

Johnny. It doesn't look like it's wired properly in your second picture.
The hot wire (black) should go to the fuse. The other side of the fuse should go to the power switch. The other side of the power switch should go to the power transformer primary. The neutral wire (should be white) should go to directly to the power transformer primary.

From the picture, it looks your new power cord has both the hot and neutral wires black.

Check this out.
http://www.rru.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html


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## greco (Jul 15, 2007)

Furtz said:


> Johnny. It doesn't look like it's wired properly in your second picture.
> The hot wire (black) should go to the fuse. The other side of the fuse should go to the power switch. The other side of the power switch should go to the power transformer primary. The neutral wire (should be white) should go to directly to the power transformer primary.
> 
> From the picture, it looks your new power cord has both the hot and neutral wires black.
> ...


Thanks for the link Furtz. 

If one uses a cord with 2 black leads (as the OP , johnny, has done) how do you know which lead is "hot" and which is "neutral" ?

Cheers

Dave


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## Furtz (Nov 27, 2010)

The narrow blade on the plug is the hot one. Hook an ohm meter onto the narrow blade (prong) and to each of the wires at the other end. 
Which ever shows 0 ohms is the hot one.
It's unusual to find a three-prong power cord that doesn't have black and white and green wires.


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## greco (Jul 15, 2007)

Furtz said:


> The narrow blade on the plug is the hot one. Hook an ohm meter onto the narrow blade (prong) and to each of the wires at the other end.
> Which ever shows 0 ohms is the hot one.


Thanks

Cheers

Dave


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## jb welder (Sep 14, 2010)

Just thought I'd add a few comments about various things mentioned in this thread, in no particular order.
As Furtz mentioned, fuse & power switch should both be in the hot line, neutral should go straight to the transformer. From the plug, the first thing the hot lead should touch is the end terminal of the fuse, then out from the fuse side terminal to the power switch. This is in case a blown fuse is removed while the unit is still plugged in. If the hot was connected to the side terminal of the fuse and someone tried to change it while plugged in, they could get zapped.
Also, safety codes (for new manufacture) require that there be a dedicated screw to connect the third prong ground to chassis. Strictly speaking, it is not acceptable to use a screw that is in use for something else (like the transformer). 
The third prong ground wire should have the most slack, so if the cord is ripped out, the ground is the last thing connected.
Death cap should really be defined as a particular type of cap (anything NOT class Y), used in a particular circuit (line to ground). Many modern amps use a class Y capacitor from line to ground in the exact same circuit as we normally call "death cap". By using a class Y cap (for 120V operation class Y2 is sufficient) you can safely have a line to ground cap or the typical polarity switch circuit.
I'm not sure why Johnny solved his hum by moving the chassis ground connection to a different screw. It shouldn't really have made a difference unless it wasn't getting a good connection at the other screw. Or maybe the wires were routed closer to something in the signal path and it was the lead dress that made the difference. If the problem had persisted I would have recommended replacing the grounding cap with a class Y.
Regarding the 3 conductor cord with 2 black wires, I suspect this is something like a fridge cord. Normally with 3 conductor AC cord we have white, black, and green, all inside an outer jacket (which may be black, grey, orange, or some other colour). Some appliance cords have the green in the middle, the hot and neutral are both black, and there is no outer jacket, as seen in the 2nd and 3rd pictures.


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## greco (Jul 15, 2007)

Furtz said:


> The narrow blade on the plug is the hot one. Hook an ohm meter onto the narrow blade (prong) and to each of the wires at the other end.


I looked at some of the 3 prong cords I have (like the one johnny is using in the pics) and they don't have a wide and narrow "blade"....so, now how do you tell which is "hot" and which is neutral ? 

I assume you can just use the configuration of the wall outlets as your guide...correct?

Sorry for the perseverance with this point.

Cheers

Dave


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## jb welder (Sep 14, 2010)

Yes, wire it up so the blade that goes into the narrower slot of the wall outlet is the hot. Then I usually triple check .


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## greco (Jul 15, 2007)

jb welder said:


> Yes, wire it up so the blade that goes into the narrower slot of the wall outlet is the hot. Then I usually triple check .


Thanks for the clarification.

Cheers

Dave


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## Johnny (Nov 30, 2010)

Furtz said:


> Johnny. It doesn't look like it's wired properly in your second picture.
> The hot wire (black) should go to the fuse. The other side of the fuse should go to the power switch. The other side of the power switch should go to the power transformer primary. The neutral wire (should be white) should go to directly to the power transformer primary.
> 
> From the picture, it looks your new power cord has both the hot and neutral wires black.
> ...


Thanks a lot. I will look into it further when I have the chance. I will not play it until I investigate further. Thank you all for the correspondence. I am still new at this and want to be safe.


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