The evil 2 prong plug.

[DenisS]

"A 3-prong A.C. cable gets added to every old Fender I work on."

Well you aint working on my old Fender amps!

"Though most of my stuff all has three prong plugs now you still can use a two prong if you know what your doing and you check the circuits of the places you play with a circuit tester."

A voice of reason?

Maybe I am getting sick and tired of arm chair heroes trying to save me from myself!

No you don't see the whole picture. I have been working on Fenders and all else while you were running around in three-corner pants. I am a master electrician and ran McIntosh Service clinics in the '70s. Worked on industrial, medical, scientific and consumer electronics digital, and analog all my life. Transmitters, amps, recievers, CNC machinery, spectralanalysers, whatever. If you get any packages through UPS from the Northeast, they were handled by motor controls that I designed and installed. I do all these things as a living every day.

Your "armchair" comment is presumptuous. Benefit of the doubt: won't call it ignorant, but you are forcing me to blow my own horn, and I don't like that.

Also there is a liability issue for a professional tech like myself. I can't have my people in danger of the Kieth Relf syndrom, may he rest in peace.

Do what you want. There is nothing wrong with polarizing your 2-prong by hand every time. It's not the safest way for the general public.

Fender did not do their 3-prong circuit right either at the beginning. Do you even understand why? Can you even follow this simple circuit?

When you go to an open mic with your amp, do you really upset the whole proceedings by buzzing your amp or measuring your chassis in relation to ground? Or are you one of those guys who does not notice that he is playing leads over the vocal? School yard antics.

Are you just in a grumpy mood today, or are you a raving PITA? Don't mess with me son. You got a long way to go.

DenisS.

 

[65flh5326]

"Are you just in a grumpy mood today, or are you a raving PITA? Don't mess with me son. You got a long way to go."

I know a thing or two about tube electronics, come over to the "practical machinist forum" "Monarch Lathes". tell us how to do it junior.
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[DenisS]

Nice work, son.

If you built that you can come over for dinner and we can fight in-person.

 

[SoK66]

Found on another forum, but probably worth repeating here:

Very good point Agave. I've been into a number of "converted" vintage amps, where the tech has just wired in a three prong cord in place of the old two pronger, usually at the courtesey outlet, grounded the green wire and left the ground switch and death cap as is. Bad news. In a number of cases the amps were fused on the neutral line ( white, instead of on the hot line (black). So, you've got unfused hot power going into the amp. Always eliminate the two prong courtesey outlet, death cap & ground switch entirely. Wire black to the center tap on the fuse holder, then to the switch, then to the PT. White goes right to the PT, green to the nearest PT stud. Done. You're polarized, you're safe and your amp will be buzz free. If Eric Johnson objects, send him to a doctor.

BTW, it's reported EJ will not use a vintage amp that's been recapped either.

 

[smokerjoe34]

What about the little 3 prong adapter that plugs in to the 2 prong cord to make a ground connection ?? Are these cool ??

 

[RodeoTex]

"Are you just in a grumpy mood today, or are you a raving PITA? Don't mess with me son. You got a long way to go."

I know a thing or two about tube electronics, come over to the "practical machinist forum" "Monarch Lathes". tell us how to do it junior.

Please explain to us all the difference between a grounded conductor and a grounding conductor, then get back to us. Pictures don't prove much of anything in electrical theory, no matter how pretty they are (contactors usually don't appear too much in amps)
.

Edit:
Is Rod W. still there at Key?

 

[markothefish]

You guys have frightened me into good sense . I will be re wiring a 3 pronged grounded power cable on my old Silvertone Amp this weekend . I've been meaning to get around to it but have always put it off .

 

[DenisS]

Make sure it has a power transformer first. If no then you change your strategy (like an old AA5 radio).

 

[SteveGangi]

I worked an entire career in electrical and electronics and have accrediation in each. I would absolutely never agree with anyone who refuses to install a hard wired ground to a guitar amp chassis.
If the power cable ground is properly installed, it will always be safe to touch the amp, guitar and strings. Period.
How can anyone, in this modern age, imagine a house or any other structure, wired with a "hot" ground??

Same here. Speaking also as an engineer and a repairman, anyone who says not to make your equipment safer, or who presents himself as a tech and refuses to make your gear safer, should not get your business anymore. He is a fool and you are a fool if you keep going back to him.

I'm pretty sure that you'll find one or two people in ANY field who hold an opinion that's different from the other 99% of their professional peers.

In the case of electronics, they're wrong, and their advice can kill you.

Cheers, Tim

Yes, they are idiots and can get someone killed. I myself have NO patience with that particular brand of stupidity.

Don't count on the "death cap" in a two prong system to protect you. It's a flaky system, it relies on you guessing which way to throw the switch, and if the capacitor fails, there you go. It's called the Death Cap for a reason.

Agave Blue posted the diagram on how to convert to a three prong set up. USE IT. Install the third wire, install the fuse, take out the Death Cap.

Parting shot: A few posts have various nonsensical things attributed to Eric Johnson. I can tell people with a good amount of confidence that no matter what he thinks he can hear, he is full of ****. Guitar cords are not directional. Anyone who claims he can hear which way a cord is connected is a liar. The same goes fort the “stereo experts” who claim they can hear what “direction” the speaker wire (glorified zipcord) is “going”. It’s horse ****. Even worse, removing the ground from equipment is dangerous and can get someone killed. The laws of physics are on my side.

I use strong words on purpose. Listening to fools and liars can get you killed. Go to a good three wire hard ground system and stop risking your lives.

 

[fly135]

Nice work, son.

If you built that you can come over for dinner and we can fight in-person.

But that begs the question... Why would he have anyone else working on his amp?

 

[rainedave]

I want to clarify that my posting of the paragraph from old Fender manual was done for historical purposes only.

I support safety 100%. I was not advocating the use of 2-prong cords.

I simply thought it was interesting, in the context of this discussion, to show evidence of archaic approaches on the part of a major amp manufacturer.

 

[DenisS]

Same here. Speaking also as an engineer and a repairman, anyone who says not to make your equipment safer, or who presents himself as a tech and refuses to make your gear safer, should not get your business anymore. He is a fool and you are a fool if you keep going back to him.


Yes, they are idiots and can get someone killed. I myself have NO patience with that particular brand of stupidity.

Don't count on the "death cap" in a two prong system to protect you. It's a flaky system, it relies on you guessing which way to throw the switch, and if the capacitor fails, there you go. It's called the Death Cap for a reason.

Agave Blue posted the diagram on how to convert to a three prong set up. USE IT. Install the third wire, install the fuse, take out the Death Cap.

Parting shot: A few posts have various nonsensical things attributed to Eric Johnson. I can tell people with a good amount of confidence that no matter what he thinks he can hear, he is full of ****. Guitar cords are not directional. Anyone who claims he can hear which way a cord is connected is a liar. The same goes fort the “stereo experts” who claim they can hear what “direction” the speaker wire (glorified zipcord) is “going”. It’s horse ****. Even worse, removing the ground from equipment is dangerous and can get someone killed. The laws of physics are on my side.

I use strong words on purpose. Listening to fools and liars can get you killed. Go to a good three wire hard ground system and stop risking your lives.

That diagram can lead to problems. The one on the left will give you current through your reference cap if the wall is not wired correctly, and you fail to catch it with your input-buzz polarity test. They have been known to short and rip at the seams from that. This is why an expensive safety cap should be used - its' failure mode is to go open.

The diagram on the right will float the chassis if the wall outlet has no ground or there is a 3 to 2 converter for an old outlet. May be a problem sometimes.

This is why a 3 position center-off polarity switch is used on modern equipment. And why it is good to put one on an old amp (as long as it is not a transformerless jobby). Really this is a combo of both diagrams plus center-off.

In truth no system automatically takes care of all contingencies. The hard ground with 3 position switch comes the closest, but we still need to buzz the amp for polarity switch position if we suspect the wall outlet is wanked.

I'm sure there are proponents of using an isolation transformer, like when we fix old transformerless AA5 radios on the bench. But it would be a big one for our amps. I did install one into an old series-string amp for a guy a few years ago. I don't want my customer dead, he let me do it.

You still want to make sure the mics are not hot in relation to ground, but we never do that untill someone gets their lips burnt off.

Did you ever get that blue ozone flash?

 

[SteveGangi]

That diagram can lead to problems. The one on the left will give you current through your reference cap if the wall is not wired correctly, and you fail to catch it with your input-buzz polarity test. They have been known to short and rip at the seams from that. This is why an expensive safety cap should be used - its' failure mode is to go open.

The diagram on the right will float the chassis if the wall outlet has no ground or there is a 3 to 2 converter for an old outlet. May be a problem sometimes.

This is why a 3 position center-off polarity switch is used on modern equipment. And why it is good to put one on an old amp (as long as it is not a transformerless jobby). Really this is a combo of both diagrams plus center-off.

In truth no system automatically takes care of all contingencies. The hard ground with 3 position switch comes the closest, but we still need to buzz the amp for polarity switch position if we suspect the wall outlet is wanked.

I'm sure there are proponents of using an isolation transformer, like when we fix old transformerless AA5 radios on the bench. But it would be a big one for our amps. I did install one into an old series-string amp for a guy a few years ago. I don't want my customer dead, he let me do it.

You still want to make sure the mics are not hot in relation to ground, but we never do that untill someone gets their lips burnt off.

Did you ever get that blue ozone flash?

No, my amp has the three wire power cord and a "polarity" switch. When I am not sure of someone else's gear, I check it with a Voltmeter. You are right about the safety capacitor though, I was "obsessing" over the other more obviously wrong stuff being floated.

 

[BigDaddyLH]

Story time. I lived in the UK in the late '80s, in a shared house. I got tired of burning my morning toast on the oven's eye-level grill
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so I bought a toaster. I brought it home, went to plug it in and WTF?! the electric cord had no plug on its end! My housemates laughed at me -- you have to plug separately, isn't that the way it is in Canada, too? Huh? I asked why, and they just said that's just the way it's always been, which seemed a perfectly good answer to them, but not me. Later, I also saw an advert for a stereo system that listed all its advanced features, including a remote control (which was the bee's knees at the time) as well as a "fitted plug"

 

[65flh5326]

All this dribble, "Death Caps" Danger, Danger, Danger!!!!
Complete nonsense!
Search for yourself, not one person killed by a Fender amp can be found.

I found this, very entertaining, the amp was powered up, the guy stuck his finger in it.

http://www.youtube.com/watch?v=1lozkT1zrIU

So, where are all the dead bodies?

 

[Triton Thrasher]

As we're talking about toasters again, there's a school of thought that says it's safer not to earth them, because so many people hold the case with one hand as they fish around inside with a knife, for stuck bits of toast.

 

[DenisS]

As we're talking about toasters again, there's a school of thought that says it's safer not to earth them, because so many people hold the case with one hand as they fish around inside with a knife, for stuck bits of toast.

You mean I shouldn't be doing that? How about with a fork then?

 

[BigDaddyLH]

You mean I shouldn't be doing that? How about with a fork then?

3 prong or 4 prong?

 

[postjob62]

Guys, I understand and accept that 3 prong cords are the accepted safety standard today and I don't mean to be contrary-I really don't know jack compared to some of you who do. But I do have to ask: has something happened to the nature of electricity or how wiring is done to increase this danger in the last however-many years? It just seems that players would have been dying left and right back in the day...

Also, is there anything one can do to increase his odds of living with a 2 pronger that he wants to keep stock for historical/collection reasons?

 

[tap4154]

All this dribble, "Death Caps" Danger, Danger, Danger!!!!
Complete nonsense!
Search for yourself, not one person killed by a Fender amp can be found.

I found this, very entertaining, the amp was powered up, the guy stuck his finger in it.

http://www.youtube.com/watch?v=1lozkT1zrIU

So, where are all the dead bodies?

Gotta say, you may be a master amp builder, whatever, but I see electricians with your attitude all the time, and I steer clear of them. But I do always get a kick watching those that insist on not turning off breakers, and watching them jerk away ten times, trying to be macho, I guess. I just don't get it.

And no, maybe there's not that many reported deaths, but then only the big names would make the news. Who knows how many amateurs were killed or seriously injured by old amps, not to mention; why even take the chance?

I just hope you're not a tech in my area.