Have You Ever Been Shocked Working On An Amp

[sebastian]

I take 435 volt about one time each month ......
About one year ago I'm working on a H & K Triamp,and the loop circuits had some shielding problems.....(the sound traveled to power amp also with volume at 0,because the cables that go from preamp to effect loop board were not shielded) and I tried to shield the stage with my hand (when I put my hand near a cable non shielded,if there is some inductive couplings,the sound that after pass through the effect loop inductively is killed by my hand that work as "shield" ,the other hand strummed the guitar.... ) and I put my hand on the B+ at 470 volt.The big current shock me a bit,cause me a little burned hole at the tip of one of my finger,and I pull the hand with extreme power to me..... the head went down from th desk and all the power tubes crashes to the floor,and also some preamp tubes.The power cord brake the plug ecc ecc,a disaster!!!

Is very dangerous have all the hands into the chassis....now I am more serious working with tubes..

[Andy Le Blanc]

worked on an amp once that was about 150 to 200 watts that used 6550's
it had a voltage double in it.....with a cardboard sleeve over one of the filter caps in the power supply....
it got swtiched some how before I got to it...
I got one hell of thrill checking the trannies for heat.... the wood floor probably saved me .....

[gtrcollectr]

Caps had a bit of residual voltage and I completed the circuit on accident....with my hand, that was not fun.

[ampgeek]

My first Ampeg V4 rehab included a replacement filter cap can with a conductive shell and fiber insulated mount. The first filtering stage has the funky series/parallel with equalizing resistors gig.

Silly me...wired it up just like the schematic directs without realizing that the individual internal caps grounded out on the cap can shell.

Fired it up...worked great. But...the first time that I reached around the back to fiddle with something while it was powered up, I brushed up against the cap can which was sitting at ~280V.

Not the only time that I have been zinged but certainly the most surprising one!

Dave O.

[Alexo]

More times than I can count.

I am reminded of a psychology lesson I had in college. A shrink had a patient with 24 hour amnesia - that is, she could remember nothing from the previous day. So one day, at the end of their session, he shook her hand, but he had planted a tack in it and it gave her a good little prick.

The next day, he went to shake her hand again, but she hesitated. Even though she could not consciously remember their previous encounter, a different part of her memory recorded the pain and warned her unconsciously.

I have experienced this myself, walking down the street, getting a strange feeling to cross to the other side, then realizing I had nearly poked my eye out walking into a stick on that side the other day.

And when I do get shocked by an amp, I notice there is always a a strange resentment or mistrust I will harbor towards it and a resistance to use it. There was one project I worked on that shocked me so badly that I had to call it quits. I still feel uneasy and overly cautious when I harvest parts from its chassis. The human mind is a funny thing.

Now to go and order a rubber mat for the concrete floor in my new shop...

BTW, does anyone else's cat stalk and attack them after they get shocked?

[briane]

worst time was putting up xmas lights in the rain...I was connected to the circuit until I could force myself to fall over, to get away from the outlet. It actually felt kind of refreshing afterwards though, like sipping on a supreme energy drink.

Early on, before I had a cap discharger, I thought I would discharge a 400 uf cap with my pliers (plastic handles, of course). Big mistake, even bigger spark flying across the room, but no real damage.

[Structo]

I'm a plasterer by trade and years ago I was working with the old boy that taught me the trade.
We were in an electrical room where all the breaker panels were.
But a lot of them didn't have covers on them.
I told my boss that I thought the busses were hot but he disregarded my advice to come back when everything was buttoned up.
He starts throwing stuff around and one of the panel doors he tossed landed against the hot power buss. Three phase 240v I believe.
All of the sudden sparks and slag start blowing up all around us.
I was almost blinded by the flash and smoke and got some slag in my eyes.

We left that room alone until it was ready for us............

[theundeadelvis]

Did it today. Working on the bias vary trem in my DR build and I hit something with my pinky. Burnt the tip of my pinky bad and the ring finger next to it. Also burned the index finger of my other hand where it must have been grounded. Amp chassis went crashing to the floor, and I went rolling backwards in my desk chair 2 or 3 feet.

[Structo]

Ouch, so it went across your chest?
Hope you're ok!

[Luthierwnc]

I get myself every so often. Usually it is a charged cap. Recapping an old Ampeg requires extra care.

For safety I have a little Xmas tree light coming off the variac. I can tell at a glance whether it is hot. I also have an old car timing clip and wire that has a 5 watt 10k resistor on the end and probably three layers of shrink tubing around it. I clip that dude to the chassis and touch all the caps before I dig back into work. Don't forget the relay caps Dumble guys!

Skip

[oldmacman]

I've never been bit by an amp, but I've come close a couple of times.

One of the first amps I worked on was a Traynor Bassmate that I recapped. There was no bleeder resistor in the power supply, and for some reason I had run the amp without tubes in it. I decided to discharge the filter caps with a screwdriver before putting the tubes back in (bad idea) and there was a huge spark. I actually ended up welding the tip of the screwdriver to the steel chassis.

Since then I've been careful...

[Darkbluemurder]

I used to measure the voltage when working on open and unplugged amps(and I still do it). Once I just did this with the preamp plate - no voltage left. It was a Marshall 50 W with a blown fuse. Due to the blown fuse the main filter cap could not drain - that's where I got bitten.

Since then I always measure the main filter caps AND the preamp caps and I routinely install bleeder resistors for the main filter caps.

[Tybone]

Too many times to mention. I should know better by know but I am always surprised by the sounds I make when I am part of the circuit....it is usually vowel sounds.

Larry

[jaysg]

Probably around 5 times. 117V AC only....thank God for small favors.

[keithrick]

There are two types of amp builders

1. Those who have been shocked!

2. Those who are going to be shocked!

I have been hit a few times. Luckily I am here to type about it!