My guitar is hurting me!

  • Thread starter Thread starter heatmiser
  • Start date Start date
heatmiser said:
I am not dead. I know you're all really concerned that I was lying in a smoldering heap on the floor next to my amp, but I was just at work.

I come back and 7 pages of stuff that I will try to sort through later. I will note that the amp is 2 prong. I am also totally with Lt Bob on the safety thing. This is really just an annoyance at this point. Kind of like licking the end of a 9 volt battery, only 4-5 times stronger. I've actually done it intentionally a few times just to confirm the experience, but it isn't so fun when it is unexpected. The house is old and the wiring is probably sketchy with a mixture of 2 and 3-prong outlets (3-prong used here). It does have circuit breakers, and they uh...appear to be in order? The guitar is really old and noisey too. Only the Roland is newer and in reasonably good shape.

Someone mentioned static electricity, and while I have noticed an abundance of that this winter, I don't think it could account for a jolt of this magnitude?

Someone mentioned a picture...there are photos of the room in the "let me see your studio" thread around page 340 something...but it would be hard to capture the actual event on film, so I drew a quick sketch to further illustrate my situation. I hope this helps:

View attachment 70980

Oh, good news - I'm still crack-free!
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lol @ curly leads. :D It's like how kids draw houses with tie-back curtains and smoke curling out of the chimley. :D
 
Jon Stoppable said:
You can't really call an ignition system AC as it charges with DC then lets the field collapse once per spark. You get a bit of ringing because it's a tuned circuit, but it's more akin to the way a DC converter circuit works. It doesn't really matter when you are talking about potential across a load anyway, 20kV is gonna hurt whether AC or DC.

More than anybody probably wants to know:

Pulse Transformer Theory, Pulse Transformer Operating Principles, Pulse Transformer Theories
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Cars are almost all DC. The alternator is the only AC part of the electrical system, and it converts the voltage to DC.
 
Heat, you got an old amp with a non polerized plug, just unplug it, turn it over and plug it back in and see if the shock goes away.
 
Track Rat said:
Heat, you got an old amp with a non polerized plug, just unplug it, turn it over and plug it back in and see if the shock goes away.
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Yes, I will try that. I was still reading everything first.

I didn't realize that might make any difference at all. If that doesn't work, I'll try to plug both devices into the same outlet. Those are by far the two simplest potential solutions.
 
Jon Stoppable said:
You can't really call an ignition system AC as it charges with DC then lets the field collapse once per spark. You get a bit of ringing because it's a tuned circuit, but it's more akin to the way a DC converter circuit works. It doesn't really matter when you are talking about potential across a load anyway, 20kV is gonna hurt whether AC or DC.

More than anybody probably wants to know:

Pulse Transformer Theory, Pulse Transformer Operating Principles, Pulse Transformer Theories
Click to expand...

It sure ain't straight DC. It may keep polarity but it constantly changes amplitude, otherwise it would never be stepped up in the coil which after all is an Inductor. Remember 2xPixFxL?

VP
 
Once you saturate an inductor you won't get an increase in the charge stored in the magnetic field, so the principle at operation doesn't have to be varying in amplitude, you could charge the inductor to saturation with DC and hold it there for an arbitrary period of time. That is not done in practice because you would be wasting power.

The principle at work is not inductive reactance as you have stated, but rather the equation for stored energy:

E = 1/2LI^2

Anyway, when you have a circuit where the direction of current doesn't change, you have pulsed DC, not AC.

The current does not have to change direction to be induced in a coil. Once the magnetic field is formed by one coil in a transformer, when that field collapses there will be current induced in both coils (at which point in an ideal realization the primary is open circuit with no current flow).
 
Jon Stoppable said:
Once you saturate an inductor you won't get an increase in the charge stored in the magnetic field, so the principle at operation doesn't have to be varying in amplitude, you could charge the inductor to saturation with DC and hold it there for an arbitrary period of time. That is not done in practice because you would be wasting power.

The principle at work is not inductive reactance as you have stated, but rather the equation for stored energy:

E = 1/2LI^2

Anyway, when you have a circuit where the direction of current doesn't change, you have pulsed DC, not AC.

The current does not have to change direction to be induced in a coil. Once the magnetic field is formed by one coil in a transformer, when that field collapses there will be current induced in both coils (at which point in an ideal realization the primary is open circuit with no current flow).
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I understand how transformers and inductors operate. Varying DC is also what happens in a Vacuum Tube Amplifier, notably a Class A one, the Output Transformer changes it to AC.

VP
 
You should really check the other panel



















arcadeko-shocks-heat.webp

:laughings::laughings::laughings:
 
Lt. Bob said:
let me jump in and say that people, and there's gonna be a lot of them, that will chime in and say how deadly this can be are seriously exxagerating the situation.
Google the number of people who have actually died from this and it's like 2 or 3 people out of literally billions of instances of people playing thru amps and surely million and millions of times where they played while getting shocked.
The potential for harm exists but it's very, very small.

Sure ..... you want to fix it but mostly because it's really distracting to get shocked while you're playing/recording.
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Exactly...I've been shocked at hundreds of shows I've played over the years.

But, yeah fix it...you don't wanna be that 3 in a billion.
 
Dont try this at home................

VP
 

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mjbphotos said:
The 'power' is coming from the amp. The recorder is providing the ground path. The problem has to be with the amp. If it's a 60s amp, most likely it has a 2-prong plug with no polarity - you can try plugging it in the other way, but you might get more amp hum. I'd advise getting the amp head to a decent repair shop and have them install a grounded power cable (they can ground the chassis itself).
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This is the correct answer.

The ground pin broke off my 5150 (as it seems they do, thanks peavey). I replaced it pretty quick.
 
Yes, flipping the amp's 2-prong plug around has made it go away at least for now.

I have had this same amp for over 20 years and have plugged it into 2-prong outlets, 3-prong outlets, power strips...everything, and I've never had this problem before. It seems strange that switching the plug around in the outlet would make such a difference. You'd think it would've been plugged in both ways in the past many times just by chance. There are probably other contributing factors in this specific scenario, but I'm just happy the shocking has ceased for now.

I took this amp to the only local repair place I know of a few years ago and they charged me more than I paid for the amp and kept it for like 6 months (with modest results), so I don't think I'm taking it anywhere again.
 
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