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Post subject: GETTING SHOCKED! (need help)
Posted: Thu Sep 23, 2010 3:31 pm
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I know its not a Fender but its an old vintage Ampeg and I thought ya'll would be the best to ask...

So here's the trouble: I recently got a 1968 Ampeg Rocket II (known as the Rocketreverb) and today while I was jamming with the computer I reached over to the USB terminal and shocked my self... really bad.

It didn't stop either- My amp is making me spark whenever I come into contact with anything!

I don't know if its because its a two-prong (no ground) amp. I got it hooked up to a surge protector (doesn't stop the shock). Do I need to find someone who can ground the thing?

This has only happened to me twice too- Once in praiseband and today...

Thanks so much for any help!

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Post subject: Getting shocked
Posted: Thu Sep 23, 2010 4:57 pm
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Hi jimbo612,

Was there a ground pin that was broken off of the plug? If it came with a 2 prong plug, is the plug polarized, one blade bigger than the other? If it is polarized, you could have a component problem (transformer). If not polarized, you may have to unplug, turn plug 180 degrees and plug back in. But check with a voltmeter from the amp chassis to the other objects that you were shocked on, after reversing the plug. Older amps only had 2 prong plugs (no ground), and on some that meant that the chassis could actually be hot (live 120 volts). Reversing the plug in the outlet can make the chassis neutral, instead of hot. But the best would be to put on a polarized plug or a 3 prong plug for best safety. :idea:

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Posted: Thu Sep 23, 2010 7:35 pm
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That probably explains why this has only happen twice randomly! :)

thanks so much for your help too I was afraid I was going to have to take it to a shop to get it grounded. The nearest shop was fifty miles away too...

It's my only amp, and I'm absolutely amazed by it. I've never heard an amp that sounds as beautifully clean as this one

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Posted: Fri Sep 24, 2010 2:53 am
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A 3 prongs plug is the ONLY solution, 2 prongs is dangerous and give you a false secure even is polarized.


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Post subject: Getting shocked
Posted: Fri Sep 24, 2010 8:39 am
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stratele52 wrote:
A 3 prongs plug is the ONLY solution, .....


I agree! Much better to be safe than sorry. It would be easy to forget which way to plug in the amp, it only takes one shock to kill. :shock: You've been lucky so far, maybe best to not push your luck. :) Mt 4:7

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Post subject: Re: Getting shocked
Posted: Fri Sep 24, 2010 10:13 am
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shimmilou wrote:
Hi jimbo612,

Was there a ground pin that was broken off of the plug? If it came with a 2 prong plug, is the plug polarized, one blade bigger than the other? If it is polarized, you could have a component problem (transformer). If not polarized, you may have to unplug, turn plug 180 degrees and plug back in. But check with a voltmeter from the amp chassis to the other objects that you were shocked on, after reversing the plug. Older amps only had 2 prong plugs (no ground), and on some that meant that the chassis could actually be hot (live 120 volts). Reversing the plug in the outlet can make the chassis neutral, instead of hot. But the best would be to put on a polarized plug or a 3 prong plug for best safety. :idea:


I agree. Reversing the ground on those old amps usually solves the issue. I had that problem with my '66 Deluxe Reverb, at least on them you had a ground switch to reverse the ground for you. Used to get shocked all the time off the PA System when something was reverse grounded. Replacing the plug with a modern 3 prong or at the minimum a 2 prong with a polarized plug should solve the problem.


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Post subject: Re: Getting shocked
Posted: Fri Sep 24, 2010 11:02 am
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shimmilou wrote:
stratele52 wrote:
A 3 prongs plug is the ONLY solution, .....


I agree! Much better to be safe than sorry. It would be easy to forget which way to plug in the amp, it only takes one shock to kill. :shock: You've been lucky so far, maybe best to not push your luck. :) Mt 4:7
I agree also,no need to tempt fate,electricity doesn't give you many chances to screw up...I've worked with it for 35 years,and I respect it very much.


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Posted: Fri Sep 24, 2010 11:23 am
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If you were to build your own electric power distribution system, you'd quickly discover some unexpected and strange effects. Sometimes your customers' appliances would fail for no apparent reason. And sometimes when you reached for a light switch, a foot-long spark would leap out to your hand and knock you senseless! It takes a huge DC voltage to make a foot-long spark. Why are high DC voltages appearing on your AC power lines?


The sparks occur because of a little-known fact: all the world is a gigantic electrostatic generator. There is a flow of charge going on vertically everwhere on earth. Thunderstorms pump negative charge downwards, and the charge filters upwards everywhere else on earth. Depending on the height of your circuitry above the earth's surface, depending on the area covered by your wires, and depending on whether there was a thunderstorm above you at the time, there might be a fairly huge DC charge on your electrical distribution system. This charge might be several hundred volts; enough to zap computers and delicate electronics. Or... it might be many tens of thousands of volts, enough to create enormous sparks which jump across switches and leap out of wall outlets, wall switches, across transformer windings, etc. Your electric power system is acting like a sort of capacitive "antenna" which intercepts the feeble current coming from the sky and builds up a huge potential difference with respect to the earth.

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Posted: Fri Sep 24, 2010 11:38 am
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Miami Mike wrote:
If you were to build your own electric power distribution system, you'd quickly discover some unexpected and strange effects. Sometimes your customers' appliances would fail for no apparent reason. And sometimes when you reached for a light switch, a foot-long spark would leap out to your hand and knock you senseless! It takes a huge DC voltage to make a foot-long spark. Why are high DC voltages appearing on your AC power lines?


The sparks occur because of a little-known fact: all the world is a gigantic electrostatic generator. There is a flow of charge going on vertically everwhere on earth. Thunderstorms pump negative charge downwards, and the charge filters upwards everywhere else on earth. Depending on the height of your circuitry above the earth's surface, depending on the area covered by your wires, and depending on whether there was a thunderstorm above you at the time, there might be a fairly huge DC charge on your electrical distribution system. This charge might be several hundred volts; enough to zap computers and delicate electronics. Or... it might be many tens of thousands of volts, enough to create enormous sparks which jump across switches and leap out of wall outlets, wall switches, across transformer windings, etc. Your electric power system is acting like a sort of capacitive "antenna" which intercepts the feeble current coming from the sky and builds up a huge potential difference with respect to the earth.


This sounds like a great Plot for a "B" Horror Movie.

:lol:


Best thing to do change your plug to a 3 prong and be sure it's properly done. Pretty easy to do yourself, or a cheap upgrade check your local guitar shop or TV repair shop.


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Posted: Fri Sep 24, 2010 1:47 pm
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Thanks for the great advice guys :D

Quote:
I agree. Reversing the ground on those old amps usually solves the issue. I had that problem with my '66 Deluxe Reverb, at least on them you had a ground switch to reverse the ground for you. Used to get shocked all the time off the PA System when something was reverse grounded. Replacing the plug with a modern 3 prong or at the minimum a 2 prong with a polarized plug should solve the problem.


On my ampeg there is a "polarity" switch on it, does this do the same thing as a ground switch?

I think when I have the time too I'm going to call up the shop I bought it at and see if they can replace it with a ground switch. I'm a little afraid to do it by myself, from what I've heard old amps can hold on to voltage for days unplugged and still can deliver some lethal shocks. :shock:

I don't want to die just yet. (at least I'll be having fun jamming if it were to happen)

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Posted: Fri Sep 24, 2010 2:36 pm
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Reverse a 2 prong plug is not a safe issue.

The use of the third prong (ground) wire :
In a amplifier, your guitar strings and all metal parts are connected to your amp chassis, which is the amp ground.
If a faulty capacitor or resistor or a wire inside your amp comes in contact with the chassis of the amplifier, the voltage will go directly at your guitar's strings. You'll be electrocuted.
If your amplifier is equipped with a plug with a ground , the current will pass through this ground wire and will shut off the breaker on your electric panel and the power is interrupted.
This does not happen with a 2 prong wire.You'll be shocked.


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Posted: Fri Sep 24, 2010 3:45 pm
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stratele52 wrote:
Reverse a 2 prong plug is not a safe issue.

The use of the third prong (ground) wire :
In a amplifier, your guitar strings and all metal parts are connected to your amp chassis, which is the amp ground.
If a faulty capacitor or resistor or a wire inside your amp comes in contact with the chassis of the amplifier, the voltage will go directly at your guitar's strings. You'll be electrocuted.
If your amplifier is equipped with a plug with a ground , the current will pass through this ground wire and will shut off the breaker on your electric panel and the power is interrupted.
This does not happen with a 2 prong wire.You'll be shocked.


+1000!

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Posted: Fri Sep 24, 2010 6:48 pm
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jimbo612 wrote:
Thanks for the great advice guys :D

Quote:
I agree. Reversing the ground on those old amps usually solves the issue. I had that problem with my '66 Deluxe Reverb, at least on them you had a ground switch to reverse the ground for you. Used to get shocked all the time off the PA System when something was reverse grounded. Replacing the plug with a modern 3 prong or at the minimum a 2 prong with a polarized plug should solve the problem.


On my ampeg there is a "polarity" switch on it, does this do the same thing as a ground switch?

I think when I have the time too I'm going to call up the shop I bought it at and see if they can replace it with a ground switch. I'm a little afraid to do it by myself, from what I've heard old amps can hold on to voltage for days unplugged and still can deliver some lethal shocks. :shock:

I don't want to die just yet. (at least I'll be having fun jamming if it were to happen)


I may be wrong but the polarity switch on your amp is a ground switch, just like on old Fender amps, try it and see if it does work, you may even hear a difference, less buzzing frorm your amp. You can use a VOM to measure the Voltage against a common ground such as the ground prong on a outlet, or better yet plug you're amp into a GFCI outlet and if it pops the switch when you test it for proper grounding the ground is reversed, switch the ground and try it again. As a kid I remember playing guitar in the garage barefoot standing on a piece of carpet to keep from getting shocked. Later I found all I had to do was reverse the plug on my Silvertone amp, problem solved. Another thing to consider is static electricity, can cause a shock too, this can be bad for your computer, though harmless to you, it may be as much as 10K volts or higher, remember it's not the volts that kill you it's the amps. I've been hit by 10K a few times working on old TV sets and even once as a kid pissin' on an electric fence, yea and that one knocks you on your $@!. :shock:


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Posted: Fri Sep 24, 2010 7:14 pm
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Hot damn, John ! What's that saying ? " If you piss on an electric cord once, and get shocked- it's an accident; If you piss on an electric cord a second time, you're......" Oh yeah, welcome to the Silvertone fraternity ! Art

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Posted: Fri Sep 24, 2010 8:01 pm
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Good news is that the polarity switch does act as a ground switch.

HOWEVER I'm going to make it a priority to taking it to get a new plug with a ground. I just can't find any place in town that can do it.

But I'm going to check with my good friend and teach, Joe Bennet. He's been playing since the fifties, so he probably knows how to deal with this stuff or who can take care of it.

In the meantime I got a Live-wire tester in my case that I'm going to have to use each time I plug in... :?

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