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Old 20th Jan 2004, 8:43 am   #1
ppppenguin
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Default Radio and TV hazards

This thread

https://www.vintage-radio.net/forum/...read.php?t=980

in the TV section was getting rather OT so I thought I'd start something specifically for the discussion of hazards in radio, TV etc. Post your near death experiences here!

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Old 20th Jan 2004, 10:30 pm   #2
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Default Re: Radio and TV hazards

Well, there's:

(Possibly) PCB containing oil in the line output transformer " cans " of Murphy TV's made circa 1956-1963.

PCB's were also used in many " can " type paper dielectric capcitors and EHT reservoir types in old 1950's TV's. (Trade names such as: Duconol, Visconol-X, etc.)

Lead glass used in CRT's and the phosphors, plus the risk of implosions (not happened to me yet!)

Exploding electrolytics (such as cathode decouplers, when the cathode bias resistor goes o/c (as per Philips hybrid mono TV's with a PCL85).

Defective aerial isolation capacitors in " live chassis " sets.

Open circuit neutral poles of mains switches.

Asbestos used on/near " mains droppers " .

Cadmium plated steel chassis.

I think I should ask for danger money!

Dazzlevision

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Old 21st Jan 2004, 1:57 am   #3
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Default Re: Radio and TV hazards

I have to agree with dazzlevision on open cct neutral pole on on/off switch " Nasty "
Years of breathing in solder fumes and vapours from switch cleaners etc.
Colour tubes that mysteriously recharge themselves as you carry them across the workshop
Un aided adjustment of shift controls on Decca Bradfords (for suicide jockeys this one!)
Picking up the wrong end of a soldering iron.(Not myself but seen it done)
Fully charged up smoothing blocks after mains dropper or fuse falure


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Old 21st Jan 2004, 8:20 am   #4
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Default Re: Radio and TV hazards

I've picked up the wrong end of a Soldering Iron , I was replacing broken elements and had a few of the same irons on the bench got distracted and picked up the hot iron and tried to pull the element out. This is a very sharp learning curve and something you certainly don't do twice


Mike

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Old 21st Jan 2004, 9:19 am   #5
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Default Re: Radio and TV hazards

I was working on an HMV 900 (pre-war with 5kV EHT from a mains transformer). Had the EHT switched off and the lead to the CRT dangling. After completing some work in the signal circuits I turned on the EHT. It had been on all the time and my hands must have been within an inch of the dangling lead many times. That will teach me not only to switch off but to check for high voltages and/or earth any offending connections.

As it said in one of the BBC2 trade test films:

SIDE: Switch off, Isolate, Dump, Earth
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Old 21st Jan 2004, 9:47 pm   #6
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Default Re: Radio and TV hazards

Hello there,
I had a nasty too-close experience some time ago. before I knew much about valves. I felt a tingling feeling on picking up the chassis of an AC/DC radio set. not only had I left it plugged in but the live was connected to the chassis via an incorrectly wired on/off switch . Luckily I was not poking any earthed things in the room at the time. I havent tried it again but that made me worry what could have happened.
My lecturer who taught me electronics gave himself a good belt with a charged power factor correcion capacitor in front of the class whilst attempting to demonstrate how its value is calculated but was thrown off before any damage was done (well to the capacitor at least )
Christopher Capener
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Old 22nd Jan 2004, 2:57 am   #7
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Talking about specific incidents. The first involved my HMV1124 when I first bought it, I was only 13 at the time. When I got it home I noticed the wire support on the U10 rect valve was not on properly. So I turned the set off and started to refit the springs. There was a bright flash and bang and I ended up on the other side of my bedroom. This was an early lesson that some parts (the mains fuses) can stay live even with the set switched off.
The second incident occured a few years later whilst working at home on a Bush duel standard mono set. I was testing for spark on the top caps of the line output valves. Whilst checking the top cap of the EHT rectifier the insulation of my pliers split, the resulting arc went through to my hand OUCH this left a rather nasty burn on my fingure. I also noticed some discomort from my foot. Closer examination revealed a similiar burn mark on my heel with a burn hole in my sock and a hole blown through the heel of my shoe. Needles to say I added a bit to the cost of this repair to cover the cost of new shoes and socks
By far the most scarey incident occured about 20 years ago. It involed a BRC3000 colour set, my own homebuilt tube booster, 6 prize burmess cats and a nuclear power station.But this is as far as I can go with this storey unless I can get guaranteed immunity from prosecution.
I would just like to assure all animal lovers that the cats were not injured in any way.
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Old 22nd Jan 2004, 3:47 am   #8
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The local telephone company used to dump 45V batteries that still had plenty of life left. I was probably 15 or 16, and had a dozen or more strung in series. It was fun drawing arcs between two electrodes, held in each hand with insulated pliers, until my hands slipped up past the plastic grips. Luckily the concrete wall was only inches behind me as I hit it pretty hard.

That was probably not as dangerous as the can of magnesium castings I melted in the back yard, then poured water in to see what would happen. Good thing I was crouching down, so the fireball was over my head.
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Old 22nd Jan 2004, 11:57 am   #9
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Default Re: Radio and TV hazards

Quote:
By far the most scarey incident occured about 20 years ago. It involed a BRC3000 colour set, my own homebuilt tube booster, 6 prize burmess cats and a nuclear power station.But this is as far as I can go with this storey unless I can get guaranteed immunity from prosecution.
I would just like to assure all animal lovers that the cats were not injured in any way.
Sounds like you were a " meow meow terrorist "

OK OK I Know it's an old joke I just couldn't resist it


Mike

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Old 22nd Jan 2004, 3:07 pm   #10
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Default Re: Radio and TV hazards

I've never (so far ) picked up the wrong end of a soldering iron, but I well remember using one whilst holding the correct end - until somebody tripped over the lead to it and pulled it through my grasp!

There is a moral to this, don't leave leads trailing where people can trip over them. My fault.

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Old 22nd Jan 2004, 3:29 pm   #11
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Default Re: Radio and TV hazards

I was repairing some ex-BBC video distribution amplifiers (The earlier AM4/511 series for those who are curious). These are built on a metal chassis, designed to plug into a 19" rack frame that can take 8 of them. The connector is a 15 way in line job made, I think, by Paignton. There is a locator spike at each end. Pin 1 of the connector is mains live. I'm sure you're all ahead of me by now...

I picked up the test jig in one hand and plugged a spike into live mains. Okay, it's only mains between the hands, nothing really nasty. Dropped the lot. The VDA falls spikes downwards and makes nasty gash in the lino about 2" from my foot.

It's not the shock that hurts, it's falling off the ladder

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Old 22nd Jan 2004, 4:16 pm   #12
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Default Re: Radio and TV hazards

I once grabbed the pins at the back of a DAC90A on a shelf - of course I had no plug for it, so there were wires wrapped round the pins (like you do...), and forgetting this I reached for the plug that wasn't there. Ended up 8 feet away after an involuntary dance. I was about 12.

Also (animal lovers close your eyes) a hamster climbed onto said shelf one day and as I watched it climb round the back of the DAC90A I realised too late about the still bare wires. One loud crackling sound and a burning smell later I hit the power switch (I at least had one of those!) and retrieved one extremely angry hamster with two small burn marks on its belly! It carried on to a ripe old age (actually, both the hamster and the DAC90A did!)
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Old 22nd Jan 2004, 4:20 pm   #13
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Default Re: Radio and TV hazards

And we all thought that dinner that day was going to be roast hamster.

What does an angry hamster do?
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Old 22nd Jan 2004, 5:28 pm   #14
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Default Re: Radio and TV hazards

They snort. At any rate, that's the usual response to untimely nest disturbance or the proximity of another hamster they don't like: repeated sharp exhalation through the nostrils.

If we're not careful, this thread could get itself shunted to Everything Else. Still, the title doesn't specify what radio and TV are hazardous for, so if anyone's dogs, cats, rats, fish or whatever have been put at risk the details should be legitimate enough...

Paul.



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Old 22nd Jan 2004, 5:53 pm   #15
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Default Re: Radio and TV hazards

When I was a kid I was mucking about with grandma's old radio. One day I plugged it in and the cloth covered mains lead exploded in a shower of sparks, almost in my face. No real damage except to my nerves. Being very young and impressionable at the time this almost put me off for life.

Unfortunately good sense prevailed. I replaced the mains lead and look at me now

Many years later my mother was ironing and the flex did exactly the same trick at the obvious stress point. Didn't do her nerves any good either.

This posting brings the thread nicely back on topic and promotes me to Forum God. Shows how much time I'm wasting here.
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Old 24th Jan 2004, 2:58 am   #16
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Default Re: Radio and TV hazards

Sounds like you were a " meow meow terrorist "

Cheers Mike I like that, I don't now what the cats thought of me but for ages afterwards whenever they saw me coming they would go to ground
Talking about cloth cables going back some years before I had flown the nest to run our colour tv we needed an extension mains lead so we ran a one of those cloth cables under the carpet. It was only temporary but became permanent.Our collie dog started to behave very strangly by rubbing her nose along the carpet always at the same point. This went on for a few weeks until one evening we heard a muffled explosion and the tv had gone dead. The cable under the carpet had indeed blown leaving burn and scorch marks to the floor and the underfelt of the carpet. A replacement cable was carefully routed around the door frame and the dogs behaviour returned to normal. So for all those weeks she was probably smelling the cable smouldering away under the carpet ,pity she couldn't speak or were we to stupid to understand her
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Old 24th Jan 2004, 12:40 pm   #17
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Once I had a basement shop with the workbench against an open wall that had copper water pipes. One day a hot wire brushed against a pipe, arced, and burned a small hole in the pipe. Needless to say, I went into rapid water shutoff mode and prevented any damage. Also needless to say, I covered the pipe area with wallboard.

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