Took my first power supply shock yesterday. I was lucky.

[SoulFetish]

could've been a lot worse....

First, let me say that as a rule, I'm pretty obsessive about safety practices. I work carefully, and am mindful of the equipment I work on and the tools I use to do it. Even so, simple distractions in the shop, rushing on a job, or even working under the assumption that a familiar piece of gear is working as it should, can lead you to let your guard down and make careless mistakes.
In my case yesterday, I was careless trying to remove the main board on a Rivera so I could replace the +V regulator and caps for the heater supply. Space was tight and the board was being stubborn. As I was backing the board tight up against the speaker jack pcb on the back panel to get the pots shaft to clear the chassis, I was right over the output tubes board and probably got the screen supply on the heal of my left hand and a standoff with my right hand and... that backed me right off my bench real quick. There was a little pain in my hands, but I was lucky in that I'm pretty certain that the caps weren't charged near the full supply voltage. If it were, that could be a dangerous charge with my heart in the discharge path. If I could venture a guess, I'd say maybe 80V-100V (maybe less, maybe more??).
I'll definitely take being lucky, but I would never rely on it. Luck runs out.

[glebert]

Glad you are OK. I had one recently where I'm still not sure where I made the circuit, but it scared me good. Since then I implemented a practice of jumping the caps to ground when I'm working. I'll use a resistor to drain them if I know they are charged, but direct to ground otherwise. I've taken a couple shocks over the years, but have no intention of taking another. I don't need to rush on doing repairs, I do it for fun, so taking dumb risks is especially stupid.

[SoulFetish]

Glad you are OK. I had one recently where I'm still not sure where I made the circuit, but it scared me good. Since then I implemented a practice of jumping the caps to ground when I'm working. I'll use a resistor to drain them if I know they are charged, but direct to ground otherwise. I've taken a couple shocks over the years, but have no intention of taking another. I don't need to rush on doing repairs, I do it for fun, so taking dumb risks is especially stupid.

I usually do that as well .
except when I don’t

[Mike K]

I took a good one of about 300V DC once. Felt like I was kicked by a horse. Knocked me out of my chair and burned a hole in my finger. Not recommended.

[DrGonz78]

There are times where caps will be discharged prior to a board removal. Of course I am talking PCB’s. I have heard it from numerous people and I have seen myself. You clearly discharge an amp but then it discharges with a pop and flash while removing it. I mostly see this happening on amps I was working on that had fresh caps. I observed capacitors regenerating a charge upwards to 10v. That was after discharging for a while too. I heard from others that claimed to see a spark discharge while removing the pcb even after discharging everything. So that would have to be from stored voltage much higher than 10v.

Of course 10v is nothing to make a spark and I don’t think it’s dangerous but it might confuse an ohms meter. I have seen Roland ss amps where a power amp chip goes bad blowing the associated -/+ DC power rails. The amp will normally discharge when powered down but the fuses sit between the filter caps and the power IC. So the caps will sit there fully charged unbeknownst to someone who makes a mistake. I luckily have noticed these behaviors without getting a zap. Sorry to hear about the bad experience.

[catalin gramada]

Welcome aboard !
You did a very important point mostly tend to get over: when a risk of electrocution does exist be sure you're in a safe position. I did and saw a lot of electrocution accidents. No one had injuries by electric shock but all had injuries more or less severe by falling by low hights. Falling from low hight are most dangerous from some point than falling from high heights as the body have no time to react and redresate. You cannot predict if arcing through a flexor or contractor muscle so the discharging may throw you away front and back in equal measure
I never seen a guy hospitalized by a 230V electric shock but saw a lot with broked bones after was throwed by. Of course it is a psychological remanent effect which make you scared. Still a 400-500V shock is quite painly and I keep away by anything over this potential.

[mozz]

I completed the circuit across a open standby switch once, 425v. Years back is was CRT picture tubes that would hurt, lost skin on my hands banging into the chassis pulling away.

[Mick Bailey]

I took a class on CRT maintenance to some new students and was explaining safety issues. I removed the anode cap of a recently powered-off tube and was gesturing to where you definitely don't want to touch the tube to the class and was a bit over enthusiastic. I got too close, touched the anode and got a really smart shock that I never lived down. It did show them though it was something they'd want to avoid themselves, when they saw how I reacted.

[nevetslab]

I know I've been 'tagged' a couple times over the years I've been posting on this forum. None were severe enough to throw me away from the bench or out of my chair, but certainly enough to remind me of the lethality of the energy potentials present when the gear being serviced is powered up or hasn't been fully discharged prior to taking assemblies apart. Those shocks are painful enough to suggest any thought of using electricity to commit suicide with is NOT the way to go out.

[Mike K]

I should say I didn't actually get "knocked" out of my chair. My body convulsed and I fell out. It ain't like the movies...

I had an electronics prof in college that used to say they made little capacitor bombs in their lab when he worked in industry. They'd charge up 25-50V cap and toss them at unsuspecting individuals saying "Catch"! Then when they did, they'd get a little surprise. I'm glad the rules at the school did not allow him to do this to students...

[g1]

Of course 10v is nothing to make a spark and I don’t think it’s dangerous but it might confuse an ohms meter.

An arc welder runs around 25V. You could probably arc weld with a 12V car battery and jumper cables if you wanted, I haven't tried. But I know you can melt a screwdriver if you short a car battery out.
For a cap to spark at low voltage is not all that surprising, especially big value caps. What surprises me most is how much discharged caps will self charge again, but I guess that too is similar to a car battery recovering after discharge.

[Mike K]

An arc welder runs around 25V. You could probably arc weld with a 12V car battery and jumper cables if you wanted, I haven't tried. But I know you can melt a screwdriver if you short a car battery out.

Impedance matters!

[nosaj]

McGyver did... 2 coins jumper cables and a battery
nosaj

[The Dude]

I'm pretty sure I've told this story here before, but......... When I was in tech school, my hand slipped removing a CRT anode cap and I got a quick 30kV zap. I made a reactionary jump back away from the tube and hit both elbow funny bones on a file cabinet. So I was not only buzzing from the shock, but both elbows were also revolting. It was a good lesson and never happened again.

As I wrote that, I was thinking. With modern flat screen technology, most younger folks probably have absolutely no idea what a CRT anode cap is.

[Leo_Gnardo]

You could probably arc weld with a 12V car battery and jumper cables if you wanted, I haven't tried. But I know you can melt a screwdriver if you short a car battery out.

Wouldn't recommend it, make battery 'splode, go boom, spray boiling sulfuric acid all over the place.