(Almost) shot dead by my flash

benjiboy · Aug 23, 2011

M.A.Longmore said:
.
My father was an electrical engineer so he did warn me about tampering with
flash units. But, He didn't warn me about MagicCubes that were used with the
Instamatics, and pocket cameras. So I attempted to that one apart, and was
extremely surprised when I got my fingers burned, and severely blistered.
I Never had the need to experiment with those Cubes ever again. I can image
the YouTube videos that would be produced if those things were still being made ...

Ron
.

If I remember rightly Magicubes were triggered electronically, and Flashcubes were triggered chemically

Steve Smith · Aug 23, 2011

benjiboy said:
This is no joke, even small electronic flashes are capable of delivering 10,000 Volts and a fatal shock.

Probably no more than 400v - but a fair warning.

polyglot said:
Less hyperbole please, it's not 10,000 volts; that would cause the tubes to spontaneously conduct and you couldn't trigger them at a desired time. The main caps are at about 300-350V.

Yes, what he said!

Steve.

railwayman3 · Aug 23, 2011

Grainy said:
I once saw an old camera get toasted because of lithium AAA batteries. A loud bang was followed by smoke and the smell of toasted electronics. And then the camera was dead.

Lithium batteries can deliver a surprising amount of current (and heat) if shorted out...a colleague ended up with a hole in his jacket from a battery shorting with a bunch of keys in his pocket.

I think it's best to be cautious with any electronics which you don't fully understand...most people would never consider messing around with a TV or a cooker, but a disposable camera or small flashgun might seem innocent enough.....

Laurens · Aug 23, 2011

It's better to use a incandescent lamp to discharge capacitors than to just short them out. 2x 15w 230v wired in series makes a nice discharging tool.
An old 'Duspol' type voltage tester could also be used, if it can check voltage 'under load'. I've got an old one that draws about 50mA when measuring voltage.

If you plan to work on high voltage electronics yourself, buy a cheap multi meter and check if there's voltage on the circuit. Even after you've discharged the capacitor.

BrianShaw · Aug 23, 2011

benjiboy said:
If I remember rightly Magicubes were triggered electronically, and Flashcubes were triggered chemically

... or vice versa... as I recall the nomenclature.

Ref: http://en.wikipedia.org/wiki/Flash_(photography)

My electrical engineer father let me learn the hard way. I still see the flash from the (insert name here)-cube when I pushed the lever on the bottom with a paperclip.

BrianShaw · Aug 23, 2011

Yes... 37 years later and I'm still blinking!

tkamiya · Aug 23, 2011

Are we sure about the voltage tossed around in this thread?

I always thought the "voltage" in the range of thousands not hundreds, so I looked it up.

The "voltage" measured across terminals on both ends of the flash tube appears to be in mid hundreds.
The "voltage" applied to the trigger seems to be in mid thousands.

Like this: http://www.yongminglight.com/?product=XENON_FLASH_TUBE&c=33

The former is delivered from stored energy in a large capacitor. According to the circuit I see, this voltage is always present at the flash tube if the flash is turned on and charged up. Anywhere from low dozens to much more watts of power in very brief second is available. Enough to cause serious damage to a human body when direct contact is made.

The latter is delivered from a small step-up transformer and in order of micro amps. It is supplied to get the flash to trigger and only applied when triggered. It ionizes the gas inside the tube so that former will conduct and generate the "FLASH!" This trigger alone will give you a good "ZAP" but not capable of causing direct damage.

So there you have it folks. Depends on which one you touch, you could either fry yourself or scare yourself. I'd rather not touch either if I have anything to do with it.

johnielvis · Aug 23, 2011

FIREBALL!

oh yeah--it WAS a fireball--it left the flash housing---a real arc-flash type discharge----the aforementioned screwdriver was thrownout with the units as it was welded accross the flash tube mounts....there was some vapourized metal a flying and a burning...that was a lot of energy there in a very short time....BAM!

maybe one of the caps was fully charged or something...like maybe the pop I did only discharged one of them??? I dunno...it was acting erratic....whatever..there was a LOT of charge built up on it.

BrianL · Aug 23, 2011

Having learned about capacitors when in 3rd grade (don't ask) I have a healthy respect for them. It is actually not a good idea to short them with a screwdriver of directly but, to bleed them. Shorting them can cause them to do nasty things like overheating and burting, literally explode.

Hexavalent · Aug 23, 2011

A former employer of mine serviced the massive flashes used for aerial recon photography - capacitors the size of oil drums. Needless to say, one did not use a screwdriver to discharge them! IIRC, a bank of air-cooled resitors was used to slowly bleed the stored energy, and then "shorting bars" installed.

Jim Jones · Aug 24, 2011

johnielvis said:
YEE HAAAAAA

SAME thing happened to me...like 15 years ago---I bought these strobes from the 50's or 60's...they were like metal boxes---Hershey Hi-Pro's made in chicago, IL right by some place on Lake Street.....long defunct...ANYWAYS--can't forget that name from the equipment tags--it's literally BURNED into my memory

one acted erratic (got 2)...so I decided to see if I could fix it.....being smart, I charged it up full...then I popped it and immediately unplugged it---so that the caps would be completely dead --- SEEEE I KNOW what I"m doing...nice and safe...

anyways...so I figured It may be best to wait a day or two as well, just for good measure before I touched them...make any residual charge bleed down. See--very safe....

After a couple of days, I figured, time to take 'em apart---FIRST, to be TRIPLE safe, I figued I'd short out the terminals to the flash tube...just to make double double sure....I even got a nice insulated THICK screwdriver to do the deed with....expected...hardly nuthing....shorted itZZZZZZZZAAAAAAPPPPPPP

B O O O O M

FLASH!!!!!

all in an instant, a fireball shot out at my face.....lucky I kind of had my head WAY back just in case...WOW (and was wearing glasses)....

I threw them both right in the garbage

these had like redbull sized cans for capacators.

I talked to my friend the soundman about it--he said that it was to be expected when you leave capacitors alone for a few days, the electrolyte dielectric migragtes and it builds up a charge ON ITS OWN....he said they are VERY dangerous because of this...

live and learn.

I bought my first set of calumet travelite 750s after that and still have them to this day.

lucky

The early electronic flashes from the 1930s perhaps into the 1950s often used oil filled capacitors. For ultra high speed the capacitors might be charged to many thousand Volts. The more common home units operated at about 2000 Volts. I wouldn't recommend tinkering with this type of flash unless you have a good lectronics background. They can develop many problems, such as deteriorated insulation, over the years. Also, flash tubes and other parts for them can be expensive or difficult to find. Later, ordinary flashes began using electrolytic capacitors charged to a few hundred volts.

johnielvis · Aug 24, 2011

ha...in other words--LUCKY...

well--no worries...no Fing way I'mEVER gonna even think about screwing with theseold old flashes---not a chance--I got enough money to buy the right stuff now...I'd rather spend the money on good equpment than on a see-ing eye dog....and hey--my time is now worth WAY too much to be fixing this kind of thing myself---let the profesionals do what they do best and improve the econaomy while we're all at it. Specialization....allows me to let other do their specialty so I, myself, can specialize...HA

Worker 11811 · Aug 24, 2011

Jim Jones said:
The early electronic flashes from the 1930s perhaps into the 1950s often used oil filled capacitors.

Yeah. Those are the ones I was talking about. The ones I used to play with were about 1-1/2 inches in diameter and about 6 inches tall.

I don't know the exact number because it was many years ago but I remember that they were rated for 1,000 volts or more. We operated under the assumption that, if they were rated for 1,000 volts, they could pack 1,000 volts.

We used to do all kinds of stupid s#it with them. We'd wire them up to the leg of a metal chair. Yes, I've been lit up by them. It doesn't tickle. If it goes through your body it can stop your heart or do some other nasty things to you. We were lucky.

One kid got the bright idea to try to charge one up by hooking an A.C. line cord to the terminals and plugging it in to the wall socket. Yup! In about 2 seconds, that thing went off like a gunshot! When it exploded, it propelled the can across the room and punched a hole in the drywall, a good 10 feet away. Of course, it belched a trail of foul smelling, burned electrolyte behind it as it flew. Cleaning it up was only the start of that kid's punishment.

Did I say we were lucky?

Athiril · Aug 24, 2011

David Lyga said:
I recently bought a Vivitar SMS 30 flash for the outrageous sum of one whole dollar. It came complete with highly corroded batteries (4 AA) and I did yeoman's work opening the battery compartment only to find an utter mess.

I spent the greater of 30 minutes carefully cleaning the compartment and filing the contacts (so I could make contact!) Then came the moment of 'bargain affirmation'. I inserted four fresh batteries and heard the flash rev up!! Then I pressed the trial button and it went off! I affirmed this about 10 times and the capacitator seemed full of vigor.

Then...a loud 'shot' went off followed suddenly by a whiff of smell that seemed smoke (but not visible). The shot jolted me and I knew that the graveyard (for the flash, not me) was immanent.

What caused this? This is a warning for all to heed...NEVER take apart a flash, EVER. I am lucky that my curiosity did not get the better of me. A whole dollar shot. Imagine. - David Lyga.

I've electrocuted myself several times off a Sunpak 433 series. Charged up, but flash never fired, hurts the hand.

Worker 11811 said:
Yeah. Those are the ones I was talking about. The ones I used to play with were about 1-1/2 inches in diameter and about 6 inches tall.

I don't know the exact number because it was many years ago but I remember that they were rated for 1,000 volts or more. We operated under the assumption that, if they were rated for 1,000 volts, they could pack 1,000 volts.

We used to do all kinds of stupid s#it with them. We'd wire them up to the leg of a metal chair. Yes, I've been lit up by them. It doesn't tickle. If it goes through your body it can stop your heart or do some other nasty things to you. We were lucky.

One kid got the bright idea to try to charge one up by hooking an A.C. line cord to the terminals and plugging it in to the wall socket. Yup! In about 2 seconds, that thing went off like a gunshot! When it exploded, it propelled the can across the room and punched a hole in the drywall, a good 10 feet away. Of course, it belched a trail of foul smelling, burned electrolyte behind it as it flew. Cleaning it up was only the start of that kid's punishment.

Did I say we were lucky?

Seen a neodymium magnet crack, then explode with a shard punching a hole through a sturdy aluminium shed wall? Scary. Some of them are pulled back together in a jagged mess after exploding

Worker 11811 · Aug 24, 2011

Athiril said:
Seen a neodymium magnet crack, then explode with a shard punching a hole through a sturdy aluminium shed wall? Scary. Some of them are pulled back together in a jagged mess after exploding

Cool! I've got a 2 in. dia. neodymium magnet. Grade N-45. I'll have to give that a try!

John Koehrer · Aug 24, 2011

When you hit the contacts with a screwdriver it also demonstrates how rapid your reflexes are. If you don't have a solid grip on the screwdriver it tends to launch over your shoulder.

Peter Simpson · Aug 24, 2011

Hexavalent said:
a bank of air-cooled resitors was used to slowly bleed the stored energy, and then "shorting bars" installed.

Hexavalent makes a good point: a couple of jumper clips and a power resistor can be used to safely discharge those caps without the fireworks.

A 1K ohm 5 watt resistor should do the job...or whatever you have laying around.
You don't need many ohms to get rid of the spark, and your capacitor will thank you...they don't like the fireworks any more than you do.

Hexavalent · Aug 24, 2011

Peter Simpson said:
A 1K ohm 5 watt resistor should do the job...or whatever you have laying around.
You don't need many ohms to get rid of the spark, and your capacitor will thank you...they don't like the fireworks any more than you do.

Something to note is that some of the older caps can still retain a hefty charge even after being 'drained'. After a few minutes, or hours, the residual charge can appear at the terminals, making for nasty surprises.

Steve Smith · Aug 25, 2011

Hexavalent said:
Something to note is that some of the older caps can still retain a hefty charge even after being 'drained'. After a few minutes, or hours, the residual charge can appear at the terminals, making for nasty surprises.

Which is why everything I build with valves (tubes) in has a 100K resistor permanently across one of the HT capacitors.

Steve

steven_e007 · Aug 25, 2011

A few weeks ago someone gave me a disposable camera with a Black and White film in it and asked me to process it for them.

Easy enough... except I didn't have whatever fancy widget that was needed to open the camera. No problem, they didn't want the camera reloading or returning so I just switched the darkroom lights off, prized it open with my fingers and fumbled inside for the film.

I didn't even realise it had built in flash...

I know now.

Steve Smith · Aug 25, 2011

steven_e007 said:
except I didn't have whatever fancy widget that was needed to open the camera. No problem, they didn't want the camera reloading or returning so I just switched the darkroom lights off, prized it open with my fingers and fumbled inside for the film.

No fancy widgets or fumbling in the dark required. Tear off the cardboard and there is a catch on the bottom. The film is wound into a standard 35mm cartridge as it is used.

Steve.

steven_e007 · Aug 25, 2011

Steve Smith said:
No fancy widgets or fumbling in the dark required. Tear off the cardboard and there is a catch on the bottom. The film is wound into a standard 35mm cartridge as it is used.

Steve.

Yep... I know that too, now.

moki · Aug 25, 2011

Luckily, I learned that lesson with a simple single-use camera... of course, I took out the battery, but didn't think of shorting out the capacitor, too. The thing gave me a shock that made me drop my tools and my right thumb felt very numb for half an hour. It was pretty bad and it's the reason that I don't touch anything electronic anymore. There are people who now what they're doing, but I don't belong to them, so I just leave that stuff alone.
When even that little flash with guide number around 12 can do that, I really don't want to know, what a professional flash with several times that power can do. If you have a weak heart, these things can short you out. Seriously. Don't touch anything electronic, unless you're 100% sure of what you're doing.

benjiboy · Aug 26, 2011

There must be thousands of fatality s Worldwide annually from people trying to fix their flashguns the manufacturers aught to impress on the buyers more forcefully how dangerous this is.

Chan Tran · Aug 26, 2011

Did you use alkaline AA or NiMH? NiMH would cause the problem you described.

(Almost) shot dead by my flash

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