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Post subject: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 9:09 am
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What's your story? Who here has been zapped by an amp and lived to tell about it? Please, no criticism about how stupid we were and dangerous amps can be. We all know that, or at least should. But sometimes "stuff" happens. So open up. What's your "favorite" amp bite experience? Here is mine that I have posted several times.

Back in college (circa 1975) I worked on my dorm mates amps. I took the full brunt of the B+ from an original Blackface Twin Reverb. I was trying to measure the B+ supply. I had the VTVM (You know what those were, right?) probe in one hand and couldn't get a reading, so I gave the power transformer a whack with my other hand. Knocked me backwards about six feet into the wall behind me where I sat for about 15 minutes in a stupor before closing the amp up and giving it back to my friend. :shock: :lol:

This was at the dawn of cheap, commercially available Integrated Circuit chips. I swore off working on anything over 18 volts. Now I design and build tube amps. :D

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 9:18 am
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Somehow I have (miraculously) avoided being zapped when working on an amp, but a friend of mine bought an old tube powered oscilloscope from eBay which was 'spares or repair'.

I went over to offer some advice, to find him sat with the cover off of the scope holding a screwdriver. He laughed and said, "Don't worry mate, It's unplugged, I'm not stupid!" I managed to get out "Watch out for those big capacitors, they might still hold a..." before the room was full of incredibly loud swearing and a slight smell of cooking bacon. :lol:

I've had a couple of jolts from dodgy gig electrics, not very keen on that happening again!


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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 9:37 am
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Oh yes. 267 Volts DC. Feels utterly horrible. Pretty sure I felt my heart suddenly contract.

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 9:41 am
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The hardest strike I ever had, was on March 1, 1969, at the Dinner Key Auditorium on stage in Coconut Grove, Miami. An Acoustic 261 lead amp, 125 Watts RMS. 275 Watts Peak, knocked a few feet back, and seeing stars.

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 10:36 am
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Keep 'em coming. These are great stories. :D

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 10:49 am
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Guitarist I knew years back smashed the glass envelope on a 6L6 in the back of his red knob Twin amp ... being a cheapskate and knowing less than nothing about electrical safety, he attempted to "repair" the broken tube ...

with Blu-tack.

And with the amp plugged in and powered up.

He slipped, touched the high-voltage plate inside the tube and got thrown right across the room by the jolt.

DISCLAIMER: DO NOT ATTEMPT TO REPAIR VACUUM TUBES WITH BLUTACK

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 10:53 am
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GilgaFrank wrote:
Guitarist I knew years back smashed the glass envelope on a 6L6 in the back of his red knob Twin amp ... being a cheapskate and knowing less than nothing about electrical safety, he attempted to "repair" the broken tube ...

with Blu-tack.

And with the amp plugged in and powered up.

He slipped, touched the high-voltage plate inside the tube and got thrown right across the room by the jolt.

DISCLAIMER: DO NOT ATTEMPT TO REPAIR VACUUM TUBES WITH BLUTACK


This anecdote qualifies for submission as a "Darwin Award".

:lol: :lol: :lol:

Arjay

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 10:54 am
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Lets see, that last time I gave myself shock therapy was when I was building my 18watt lite IIb. Just doing the normal voltage checks and inadvertently zapped myself.

I'll be honest with you, I've never experienced the types of shocks that I've read about. I don't know if being 6'2", 230lbs has something to do with it or I've just been lucky.

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 10:57 am
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He would qualify but he was fortunate not to kill himself in the process.

If we're going to discuss bad electrical practice then I do feel obliged to link this excellent thread on the safe way to deal with tube (valve) amplifiers.

Safety Practices, General and Ultra-High Voltage

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 12:10 pm
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Almost 20 years ago working on a high power amp (not a guitar amp though). Got lost in my own head thinking about what I was going to do, instead of what I was doing. Never hold a direct earth ground in one hand while tweaking things with the other! Got launched about 6 ft. burns up both arms, and the feeling of total stupidity.

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 12:21 pm
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GilgaFrank wrote:
He would qualify but he was fortunate not to kill himself in the process.

If we're going to discuss bad electrical practice then I do feel obliged to link this excellent thread on the safe way to deal with tube (valve) amplifiers.

Safety Practices, General and Ultra-High Voltage


Another good source:

http://www.aikenamps.com/SafetyTips.html

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 12:22 pm
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Location: Natural Bridge, Virginia
GilgaFrank wrote:
Guitarist I knew years back smashed the glass envelope on a 6L6 in the back of his red knob Twin amp ... being a cheapskate and knowing less than nothing about electrical safety, he attempted to "repair" the broken tube ...

with Blu-tack.

And with the amp plugged in and powered up.

He slipped, touched the high-voltage plate inside the tube and got thrown right across the room by the jolt.

DISCLAIMER: DO NOT ATTEMPT TO REPAIR VACUUM TUBES WITH BLUTACK


What a fool. Everyone knows you should use duck tape. :lol: :lol: :lol:

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 12:32 pm
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My last near miss didn't zap me but it did scare the crap out of me.

Before I bought a bias probe, I was attempting to bias my BDRI. I was using my DMM on measure plate voltage on pin 3 of one of the 6L6GCs. The probe slipped and shorted the plate to the screen grid at pin 4. LOTS of sparks and even a small fire between pins which scorched the PCB. :shock:

I quickly shut the amp off and put out the fire (It was real small so a quick puff of air blew it out, no need for a fire extinguisher. :lol: ). After gathering my wits, I unplugged the amp, drained the caps, and used an electric tooth brush with some alcohol to clean up the board. Amazingly the amp worked just fine afterwards. Still have a small mark between pins where the PCB melted slightly.

I immediately ordered a bias probe. :lol:

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 12:36 pm
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bluesky636 wrote:
... The probe slipped and shorted the plate to the screen grid


Crocodile clips. Always. Don't be poking probes into an amp, clip test leads on then power the amp up.

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Post subject: Re: Have you been "Electrocuted" By An Amp?
Posted: Sun Apr 07, 2013 2:05 pm
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Ohms other law - If the Amp don't get you the Volts will

His other being - Resistance IS NOT futile


Last edited by ripitup555 on Sun Apr 07, 2013 2:21 pm, edited 1 time in total.

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