I got shocked by my amp yesterday

Pierre

Stratologist
Now LUCKILY, by design, my amp empties its filter caps and internal voltages very quickly, in a matter of seconds.

I accidentally touched the fuse terminal inside the chassis while also holding on to the chassis itself. Now if this had been any other amp I'd have gotten close to 450V through me. I got lucky and received 10V. Still...


Strangely enough it took me a good second to release my finger. It was only an accidental, light touch, but the shock didn't actually push me away from the source. I eventually pushed away.

Then just to make sure, I looked inside the chassis and realized I'd dropped the wrench I was holding... and it was shorting the main filter cap. If I'd turned the amp on after this I'd have fried everything, started a fire, or dunno what other catastrophe. Always check if you've dropped something inside!!

So I took some insulated pliers, checked the voltage (was at 0V by this point anyway) and pulled the wrench carefully.

Some lessons to be learnt there. I'm ALWAYS very careful. I don't poke around with high voltages. I don't slip. I don't do anything careless. I've been doing this inside my amp for years. Accidents DO happen. If the amp had been on, I'd likely have been dead or in pretty bad shape by now. Now I do know my old Laney does empty its caps pretty quick, which increases my confidence and how soon I can take care of repairs as soon as the amp is off.

If this had been a Deluxe Reverb for instance, I think I'd invest in a proper resistor to empty all internal voltages. And everyone should do the same. Heck I'm considering it for my own amp despite its cap emptying abilities.

People tell you 'watch out for internal voltages, these things can kill you' in every other post on here or most other amp forums. There's a reason for it. Those 10Vs didn't feel nice at all. I don't want to imagin what 500 would feel like.
 
Re: I got shocked by my amp yesterday

It's stuff like this that scares me away from doing any real work on my own amps. Glad nothing more happened to you, Pierre!
 
Re: I got shocked by my amp yesterday

Well SHOCK ME! Careful dude - that stuff is dangerous. I don't and won't do it at all.
 
Re: I got shocked by my amp yesterday

Be very careful! I got spanked real good by my Marshall. It was like getting hit with a small lightning bolt!
 
Re: I got shocked by my amp yesterday

10V is usually not enough to break skin resistance, try touching a 9V battery - no effect, unless you lick it. How did you measure 10V?
 
Re: I got shocked by my amp yesterday

Yeah it was way more. I measured 10V AFTER the shock. So it was probably quite a lot more than that.
 
Re: I got shocked by my amp yesterday

Go to a 'real' tech page and learn how to drain those caps or prepare yourself for the after-life.
 
Re: I got shocked by my amp yesterday

voltage is fine, its the amperage that gets ya. if you've ever been hit by a sparkplug wire, an old crappy points car is like 10,000v, but at really low amps.

and yeah you usually wont pull back
 
Re: I got shocked by my amp yesterday

Caps were drained. There was just some residue, not much. This amp drains its own caps very quick, and I ALWAYS check that there isn't too much left before I even go inside with any tools. This time I must have not checked everywhere :( It wasn't much though.
 
Re: I got shocked by my amp yesterday

voltage is fine, its the amperage that gets ya. If you've ever been hit by a sparkplug wire, an old crappy points car is like 10,000v, but at really low amps.

And yeah you usually wont pull back
+1
 
Re: I got shocked by my amp yesterday

voltage is fine, its the amperage that gets ya. if you've ever been hit by a sparkplug wire, an old crappy points car is like 10,000v, but at really low amps.

and yeah you usually wont pull back

That's actually a misunderstanding the general public has about electricity. The reality is, either one can kill you. It's the ratio between volts and amps that is important -- too much of one, with enough of the other will is most certainly lethal. For example, most high tension lines are carrying 10k+ volts but low amperage. A transformer at the pole steps down the voltage to the standard 240v, thereby increasing the current to the 100A or 200A service entries most homes have. High voltage will kill you just as fast and just as dead as high current. The NEC defines high voltage as being any voltage over 600v (which is why Romex cable is rated for 600v max). A 450v discharge from a filter cap, while not technically "high voltage" is nonetheless enough to write your obituary. FWIW, depending on your body's electrolyte levels, it only takes 3mA to stop your heart from beating.
 
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Re: I got shocked by my amp yesterday

it happened to me yesterday evening as well. :)
(to be honest, it was already this morning 0400)

i was lucky, because i only touched the chassis and the ac input fuse
with my left hand. i was messing around with my grounding scheme
and finally forgot to unplug the power chord, as i got tired.

i believe in electrical superpowers inside me now. normally after only 3h
of sleep, i should have awaken with a terrible headache. but i'm fine.

cheers, martin
 
Re: I got shocked by my amp yesterday

I got shocked twice while building stuff, once 220V AC from the wall and the other time it was 180V AC from the amp.
 
Re: I got shocked by my amp yesterday

That's actually a misunderstanding the general public has about electricity. The reality is, either one can kill you. It's the ratio between volts and amps that is important -- too much of one, with enough of the other will is most certainly lethal. For example, most high tension lines are carrying 10k+ volts but low amperage. A transformer at the pole steps down the voltage to the standard 240v, thereby increasing the current to the 100A or 200A service entries most homes have. High voltage will kill you just as fast and just as dead as high current. The NEC defines high voltage as being any voltage over 600v (which is why Romex cable is rated for 600v max). A 450v discharge from a filter cap, while not technically "high voltage" is nonetheless enough to write your obituary. FWIW, depending on your body's electrolyte levels, it only takes 3mA to stop your heart from beating.


Nailed it. . . thats some good info there bro.
 
Re: I got shocked by my amp yesterday

well, glad you're still with us. But did you finish what you were doing at least?
 
Re: I got shocked by my amp yesterday

i used to get shocked by my tube amp cuz it was a two prong plug and my lips would touch the mic sometimes lol... but nothing serious... but either way i still changed the plug...good thing are ok man
 
Re: I got shocked by my amp yesterday

I was an electronics tech in the navy for a few years, dealing with high power pretty often. The worst shock I copped was 110V from a faulty plug that had shorted hot to the casing. That shock taught me not to rest my head on earthed equipment (which was tempting because the ship was rolling around). One of my colleagues very nearly took 15,000V after some idiot contractor removed a danger tag without permission, though. Yikes :S
 
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