Vintage Two Prong Amps & "Death Caps"

peobryant

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Hello gentlemen, I'll start out by saying I am very ignorant to the workings of tube amps. That being said, I have done some research but can't figure out whether or not my amp has a "death cap." Here is my amp;





It is a 1959 Gibson GA-5 Skylark and it still has the original two prong power cord. I intend to have the power cord replaced with a three prong, grounded cord but I'm not sure if that is all I need to do. I've read that even with a grounded power cord, the "death cap" can still fail and shock the user and that is something I'd rather avoid. So, to those a lot more knowledgeable than I, does my amp have a "death cap" that needs to be removed, or will a modern grounded power cord be enough?

Thank you in advance for helpful answers, I appreciate it.
 

monty john

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Oh thought maybe you were eating mushrooms and showing off playing the amp??? dunno LOL....yes take to a tech
 

el84ster

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If you can solder you could do it. Google the proper way to convert to a 3 prong. Yes it does involve removing the cap. But easy job.
 

cooljuk

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If it's all original from 1959, you'll probably want a bit more service than just the cord/death cap.

There are modern caps made specifically to run across the mains lines. They are designed to fail in an open and not fail in a short (that's the potential problem with "death caps" - failing in a short). Not a suggestion, just a related observation.
 

spoony

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According to a schematic that I found with a quick Google search, yes it does have a death capacitor. I'm not aware of any old amp that does NOT have one, if they have a two pronged power cord.
This is true and yes take it to a tech.


It can be lethal, cause death, poking around inside an electrical device such as an amp. I don't like the word advice but, I would strongly advise against doing the work yourself!

Almost forgot, nice amp. They really are great little amps and that is a very clean example. Nice LP as well, congrats!

s
 
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Mike I

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Just remember that a tube amp can carry lethal voltages, even after being unplugged.

It's a fairly easy job to do for any amp tech.

Nice amp! I had one years ago, and it's fun.
 

yamariv

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Take it to a tech, it a very easy job to remove it and install a 3 prong cord. If you have no experience in live amps, please don't try to do this yourself.

I've built several amps and restored others and love the hobby and am very comfortable working on live amps. A couple weeks ago though, I had a brain fart and zapped my pinky while the amp was off and unplugged but the caps still had a charge. I was lucky it was only 160vdc as the caps drop fast and stay at that voltage on that design for quite a while but it still stung like a MF'r and left a burn. Be careful with tube amps at all times
 

Caretaker

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Take it to a QUALIFIED tech.
Don`t do it yourself. You do not want to ride that lightning.
They don`t call it a death cap for nothing.
 

el84ster

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Well, I think it’s good to learn to do it yourself rather than to pay others. Read up on being safe and go for it! That’s how I got started.
the hardest part of the whole procedure is fitting the new cord and strain relief in.
 
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Mike I

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Besides changing the cord and removing the cap, the tech can look the amp over for the usual trouble spots, like the condition of, and most likely replace, the filter caps, and other little gotchas that come along with old amps.

It's not much money spent for peace of mind that the amp is safe and will give you the joy and good tones you expect.
 

yamariv

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Besides changing the cord and removing the cap, the tech can look the amp over for the usual trouble spots, like the condition of, and most likely replace, the filter caps, and other little gotchas that come along with old amps.

It's not much money spent for peace of mind that the amp is safe and will give you the joy and good tones you expect.
Agreed^^ If your bringing it to a tech, might as well do the caps, clean the pot and give it an overall health check and you're now good to go for another 60 years!
 

ARandall

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Its best to just ask the tech what they recommend you do on such an amp, rather than trying to dictate or overthink it.

There are endless mechanical/repair type people with stories of rampant timewasting on jobs where the client tried to self diagnose and wild goose chases were embarked upon.
 

RickRandom

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Unexpectedly detailed answer:

On the specific model and year of Gibson Skylark amp in OP's photo, the "death cap" is usually a black cylindrical Sprague brand capacitor with red lettering on the side. Other brands were sometimes used. The electrical specs of the capacitor are .022 uF at 600 volts. One end of the cap is connected to the fuse holder, and the other end of the cap is connected to a ground lug on one of the tube sockets.

A three-wire cord conversion on this amp is very straightforward:
* Disconnect the old power cord from inside the chassis.
* Connect the white and black wires from the new power cord to where the two wires from the old power cord used to be connected.
* Make note of where one end of the death cap is connected to a ground lug on one of the tube sockets.
* Disconnect the death cap and discard it.
* Connect the green wire from the new power cord to the ground lug where the death cap used to be connected.

Tip: Hooking up the new cord inside the Skylark chassis will be easier if you make the green wire a few inches longer than the other two wires before hooking anything up.

Disclaimer: When working with high voltage wiring, there is of course some risk of zapping yourself into oblivion if you don't know what you're doing. If you have any doubts, stay safe and get a pro to do it.

Source: former repair tech
 

peobryant

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Judging by the OP's opening statement, I don't think he's comfortable doing this type of work.
Absolutely not. I've been in contact with a few people in my area already, so hopefully I'll have the work done in the next few weeks.

Thank you everyone for all the responses and information, I really appreciate it.
 


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