Replace Death Cap with Safety Cap?

[jmaf]

IMHO the name "death cap" is appropriate. It creates a reference to mains ground that should not exist, even if it's just 56nF. The energy stored at 230VAC in a 56 NF cap is less than .003 Joules, it is insufficient to kill, but I think it should be called a "death" cap to remind every technician that it is REALLY not supposed to be there.

When you think of leaving it in, ask yourself the question: Would any musician agree that you install a visible capacitor from his/her guitar strings to mains? They'd be sure you want to kill them, right?

[oc disorder]

Being on the export end of USA made amps we've never had to deal with this problem.
When the mains lead and Auzzie plug were fitted usually the wires going to the switch were removed.
This meant we could find another use for the switch or the hole !
Often the cap was still there usually not rated for 240.
I've noticed usually the more expensive gear has a mains filter built into the IEC socket.
They are also available in a sealed form without the socket so can be internally fitted to save hacking the chassis of a vintage amp.

[Albert Kreuzer]

When you think of leaving it in, ask yourself the question: Would any musician agree that you install a visible capacitor from his/her guitar strings to mains? They'd be sure you want to kill them, right?

[jrfrond]

Yet again today, I was working on a BUTCHERED B18N that had a 3-wire cable with the Death Cap still intact. In this case though, the "tech" who performed a "cap job" ("CRAP job" is more like it!), clearly had little knowledge of anything except sloppy soldering!

[Dave Curtis, dB AudioTech]

"IMHO the name "death cap" is appropriate. It creates a reference to mains ground that should not exist, even if it's just 56nF. The energy stored at 230VAC in a 56 NF cap is less than .003 Joules, it is insufficient to kill, but I think it should be called a "death" cap to remind every technician that it is REALLY not supposed to be there."

Your computer has them (X/Y caps). So do (likely) all multi-outlet "plug strips". Besides, they generally weren't fitted in amps designed to run on 230V.

[jmaf]

Your computer has them (X/Y caps). So do (likely) all multi-outlet "plug strips". Besides, they generally weren't fitted in amps designed to run on 230V.

That's why an isolating transformer is essential on tube amps.

Normal home appliance usage is also a very different scenario, you rarely get in touch a conductive piece that is linked to the chassi.

[Wittgenstein]

I use the term "death cap" as well, due to this same configuration being used on old cheap amps (Lectrolabs, Silvertone, Sears amps, All American Five Amps ) that did not have a power transformer. They would run the mains from the wall (110-120VAC) straight into the amp with no isolation transformer. Now say that you have the 2-prong cable plugged in the wrong way, and and the cap goes bad...... hence "death cap". Most tube amps do provide line isolation through the PT however, meaning that even if that cap were to break, you will not die.

More reading here on widow-maker amps.

[Ted]

Here in the UK there are a lot of old imported US amps. They are often run from 240-120 auto (i.e. non-isolated) transformers. Keeping death caps is an even worse idea in this situation as with a miswired transformer you have the potential (see what I did there?) for 240V on the chassis..

A while back someone brought me an Ampeg Gemini for retube, with a two pin mains lead. The guy was impressively wasted for 3pm, which should have been a clue.
I connected via the customers step down transformer and felt a fizz of electricity as I flipped the switch. More than a fizz.It was a definite shock.
Chassis measured 110V to earth.

Fitted a three pin mains lead and removed the DC. When the guy came back for his amp I asked him if he'd ever had a shock from it. "Oh yeah. I thought that was normal".

[g1]

Plenty of examples of newer amps with ground switches and proper type safety caps in the typical "death cap" position.
As was mentioned earlier in the thread, why would someone such as Fender waste money installing them if they are useless?
With the proper type safety cap (specifically designed for such purpose) there is no hazard. Otherwise there would not be UL, CSA, etc. approvals for such amps.

[Enzo]

why would someone such as Fender waste money installing them if they are useless?

They don't on contemporary models. They put them on "reissue" models of old amps. They put them there because the old model had one.

The "death cap" was a problem in a two wire power system, because it can put 120v on your chassis. In a grounded chassis - a modern three wire system - unless the wiring is compromised, the chassis can never be hot, so the cap SOMETIMES can abate hum a little, usually it makes not difference.

[g1]

Thanks Enzo, glad to hear it can at least do something SOMETIMES, I was starting to think I had missed something theory wise .
I do recall seeing some Fender re-issues in the 90's which had the switch but it was not connected to anything. As these were Canadian models, I may have been mistaken about CSA and maybe they have a problem with the caps, even the modern safety versions. The second page of that '59 Bassman re-iss shows an export version with the switch unloaded.
On the other hand, the 5150 is not including the ground switch due to any retro consideration, it must be strictly for functional purposes.

[The Dude]

Don't forget about the guys using ground lift adaptors and/or cutting the ground pin off of their AC plug.

[R.G.]

Don't forget about the guys using ground lift adaptors and/or cutting the ground pin off of their AC plug.

Ah, yes.

A Darwin Award waiting to happen. We can only hope they don't procreate before dying.

[Enzo]

I am currently recovering from injury, so I use the little powered scooters in the stores when I shop. We have a fairly new mega store near my home where I shop a lot. Place is maybe a year old tops. In the entry foyer on the side is the row of carts, maybe six or eight of them. There is a row of standard electrical outlets where they plug in. From day one, every ground prong on the scooter plugs has been broken off. I don't doubt musicians break them off as well.

[olddawg]

Half the clubs I play in have nice née three prong receptacles with no internal ground connection. Happens all the time in old buildings.