Your daftest mistakes??

[Peter.N.]

My first job was in London in 1954, I worked in the radio/TV/HiFi dept of a well known photographic firm. There were many changes happening in London at that time one of theses being the standardisation of the electricity supplies. Our shop in Cheapside had a strange split phase system which gave 110 volts either side of earth, it was in the process of being standardised to the normal live and neutral arrangement.

The electricians had installed one of these new fangled consumer units before the actual changeover had taken place so the 'neutral' side was no longer fused - you can probably guess what's coming, as in a previous account I managed to short the 'neutral' and earth pins together, there was a loud bang and tremendous flash and everything went dark - the TV dept was in the basement as was the occupied projector demonstration room, the insurance company next door also lost their power.

I was given a job to do the other side of town which would 'last me the rest of the day', next morning I was summoned to the managers office and it was suggested I might like to find employment elsewhere, I did, in the TV shop just round the corner to where I lived where I stayed until I got married in '63.

Peter

[McMurdo]

Daftest for me was in my first job and I was asked to fit new bearings to an AC motor. I took it apart, pulled off the old ball races, got two brand new SKF ones out of the stores. Heated the first one up, put it on one end of the stator shaft and tapped it home. Heated up the second bearing, got it in the pliers and put it on the same end of the shaft as the first bearing. Unfortunately the boss walked over before I could find the pullers.

[Boom]

When working in a shop in East London many moons ago a woman came in and asked in very broken Engrish for me to make a lead up. In those days it was common practise for telly shops to make up leads to suit the masses of different connectors.

The lady was quite adamant that the plug she chose was the correct one and that all she wanted was a 13A plug and a lead connected to her chosen plug.

She came back a couple of hours later with a very charred Speak and Spell and asked if we could sort it out. She'd plugged the mains straight into the external DC socket.

I asked her if the S&S called her anything before it died.

[der man]

Many moons ago (early 60's age 11 or 12). I was fed up getting batteries for my Tri-ang (there's a name from the past) railway, I know I thought to myself, I'll wire up an old volume control and plug into mains. Well a volume control turned sound up and down, so I thought it'll turn the mains up and down as well!

So volume control was built in an old Holborn baccy tin. Brilliant I thought, plugged said unit into mains, and kaboooom, blacked out ours and next doors house. My dad gave me a right ear bending,(being polite here).

[PWH]

Well last week, I tested a capacitor 500V rating with a megger. It seemed OK, so I tested again with my multimeter on Capacitance setting. Small flash, end of meter. The capacitor was fine.
I never make the same mistake twice, I can always manage new ones.

[Billy T]

A monumental mistake, not mine, but I was there at the time and enjoyed the performance:

I was working in the TV service department of a large service company, and a client had complained to the Manager about the delay in returning his TV, which was in for a CRT change. He had a rental contract and expected that we should cast all other work aside to get his set back to him.

Unfortunately it was a bonded-screen CRT (so no safety glass fitted) and we couldn't get the size needed quite as fast as he expected as they were out of stock in all our local branches.

The Manager came down to the workshop (an ex-tech and good guy to boot) to ask all the obvious questions. Yes we had tried all suppliers and also all of our branches within reasonable driving distance, so he suggested we find a substitute. Somehow or other a rimband CRT was produced that looked like a close match for the screen surround and he suggested that we try to install that.

After a short while the apprentice reported back that he couldn't get it in because the mounts were in the wrong place and the rimband was also obstructing the fit. So, the manager said "cut it off then!"

Okay, we thought, this is going to be interesting, and we reminded him of the reason for the rimband and the potential outcome if it was removed.

In an extraordinary display of unity, we refused to allow our apprentices to undertake such a hazardous task, and since we techs anticipated having a family at some time the future, we were wary of being anywhere near the procedure in case it went off and sterilised the spectators.

Well, I said he was a good bloke, and his reponse was that he would not ask anybody to carry out a task that he would not do himself, so he donned a dustcoat, put on the safety glasses, cut off the rimband (which released the mounts) fitted the bonded screen mounting and tightened it up, put the CRT back into the cabinet, powered it up and set up the geometry etc, then the afternoon tea bell rang.

We left the set running and all trooped into the canteen for a cuppa. We'd not been in there five minutes when the was a gigantic explosion from the direction of the workshop. We rushed out, and sure enough, there was glass from eyebrows to breakfast. To his credit, the Manager grinned and said "Whose silly b....y idea was that then?"

In similar vein, but less explosive, a similar (bonded crt) rental set was enroute back to the customer via the motorway when it fell out the back of the delivery truck at 100kph, landed smack on its face and skidded down the lane for a 100 metres or so before parking itself on the hard shoulder. Nothing broke, it still worked when they brought it back, and cabinet damage was minimal (but a replacement CRT was needed).

They were interesting times!

Cheers

Billy

[majoconz]

Many years ago, trying to tune up a 400watt NDB transmitter into it's antenna but not getting any sensible results - then noticed that the earthing wand was still hooked over the bare copper tubing feeder - lifted the earthing wand off and produced a wonderful long spark for a few seconds! Fortunately the protection circuits did their job and shut it down before any real damage was done. I had to have a quiet sit down for a while though.

[Boom]

This one was a cracker.

I don't watch broadcast tv much so I run Twonky which is a server from the main pc and I pump all my music and video around the house on Panasonic Viera sets. These are all singing, dancing sets which you can put Internet and media into which is all stored on the main pc. Saves transferring with DVDs and USB sticks.

Last night around 7pm the configuration screen vanished but the server stayed up. Obviously I had no control at all over Twonky. The config page kept saying it was trying to use port 9100 and there was no way of changing that to the port 9000 that it should be even by reinstalling the server software.

After three hours of messing around with the setup I started to think of viri and so reinstalled Avast but still no joy.

Today at 5pm and with foam coming from the mouth, for want of something to do and in desperation I switched the modem/router (BT Infinity) off and back on and up comes the server!

For some reason the router firewall was locking out certain ports and 9000 (the wanted one) was one of them. I didn't think of the modem/router as everything seemed fine as usual. Why the server stayed up at all I haven't a clue.

Live and learn.

[Tractorfan]

Hi,
Not the daftest thing I've done by any means, but it may amuse you. I was trying to fix the telly (a 17" Emerson) and took out the EY86. I used a fingertip to try and locate the holder in the dark & dust to refit it. I knew I'd found it when the tube discharged itself up my left arm!
Another demonstration of my stupidity was asking for a PCL84 because I thought it was the next one up from a PCL83!
Doh!
Cheers, Pete

[unitelex]

When I was a kid we got our first colour TV, it was rented from Granada Rentals, possibly a Thorn/Ferguson. Being an experimenter I had collected various parts from dismantled radios etc including a quite powerful ring magnet from a speaker... To my delight I found that I could influence the colours of the TV by bringing the magnet near the front of the TV. I assumed it was a temporary effect... but I learnt the error of my ways later that evening my parents were puzzled why the TV presenters had a strange purple faces. Of course I knew nothing... The TV repairman was summoned and I think the set was replaced, being almost new. Not sure why the degauss coil did not recover the problem....

[Fidelity Fan]

This is a very silly one: When I was around ten, I used to collect record players. I had a Fidelity HF35 with a TAA611B IC amplifier. It needed a replacement BSR motor with a 12v overwind. I could not drop on one. The obvious solution would have been to fit an ordinary standard BSR mains motor (which I had plenty) and power the amplifier from a separate 12v mains transformer. But no, I did something incredibly stupid, I got a BSR motor from a real to real tape player, connected it's brown wire to the live side of the mains switch, the black wire to one of the AC inputs on the amp's bridge rectifier, with the other AC rectifier input connection going to the neutral side of the mains switch!

I thought somehow that with the motor being rated at 230v, there would be about 10v left over from the mains (then 240V), to power the amp. On switch on there was a big blue flash and the amp never worked again!!!

[davegsm82]

When quite young I fixed up my first TV, a 21" philips somethingorother, with a blown BUT11AF in the output stage. The operation had been taking place on the floor of my bedroom at my mum's house, I was sitting behind the TV with it facing the door.

I had replaced the transistor, with due care and heatsink paste. Clipped the spring clamp over it, powered up and bingo, it was working! I was thrilled, so I jumped up and leaped over the TV to seek my mother, to prove that my tinkering wasn't in vain. My trouser leg caught a pin of something on the tube base and that's all that was needed to rip the pip off the tube and crack the whole base!

Hisssssss.....

I can also remember lifting the tube out of a set which was face down on the floor. Bringing the tube up to my chest to carry it away and... ZAP.. The anode bit me in the stomach. The tube went rapidly back towards the floor, good job it was knackered as it ended up in quite a state.

Dave.

[Nickthedentist]

Originally Posted by davegsm82

I was thrilled, so I jumped up and leaped over the TV to seek my mother, to prove that my tinkering wasn't in vain. My trouser leg caught a pin of something on the tube base and that's all that was needed to rip the pip off the tube and crack the whole base!

What a sad story, Dave, I'm surprised you didn't give up on TV repair altogether!

[Tractorfan]

Hi,
Another two mistakes spring to mind, one possibly more fatal than t'other. Both involved Ekco TV sets. The first was when I and a couple of mates were tinkering with a console set in the physics lab at secondary school (no H&S in 1966!) Set switched on, back removed, me between said set and a nearby radiator. With one hand on the radiator I bent down and touched the chassis. Result; 240volts across my chest, the worse possible path! . My guardian angel was on full alert that day!
Second mistake? Round tube (uncoated) set with an EHT smoothing cap mounted on the support quite close to the focus knob. I reached round to adjust it while watching the screen. And . . . ZZZAAAPPP! the full EHT up my right arm. Luckily no completed circuit this time!
It's a wonder I'm still here really.
Cheers, Pete

[bobbyball]

Probably the most stupid thing I ever did was when I was about 7 or 8.

My parents used to have a collection of foreign coins which always fascinated me.

One day I found one that wedged exactly bewteen the 3 pins of a 13A plug.

Of course I then plugged it in....

I think the surge actually blew the main electricity board's fuse and needless to say I was banned from being "anywhere near" anything with a plug for "some time"....

Eventually my father, an electronics engineer himself, had the patience (amazing for him as he never had any) to explain to me "why" things like that "should not be done". The "bang" was fun at the time though!!!


Robert

[G6Tanuki]

Trying to clean a 3-gang 500pF variable-capacitor by dunking it in caustic soda solution.

And then getting distracted.

A day later, it was not a variable-capacitor any more: the NaOH had completely dissolved the aluminium vanes!

[Bob_Moss]

I had just finished repairing a '50s AC/DC receiver, taking utmost care because of the live chassis. I had it out of its case on soak test then noticed a dial lamp was flickering. MES 100mA bulb, where's the harm in that?
Went to tighten it and BANG - yes, I got a belt - it was right at the top of the heater chain!
Complacency strikes again!

[Junk Box Nick]

Daftest mistakes?

All those old wireless sets I pulled apart when I was a kid.

99% of the parts never did 'come in useful'.

(However, some of the stuff is still around so given my current interest you never know...)

[matthewhouse]

About 9 years ago now I was replacing a storage heater, I had checked at the isolator switch that the power was off disconnected the flex, and removed the old heater. After the new one was fitted I needed to renew the isolator switch. For some reason I thought it was on, even though I had tested previously and the neon indicator wasn't lit. So instead of using a meter I put a screwdriver into the live terminal and shorted it to the earth terminal above.

The loud bang and massive flash indicated the power was on, fortunately I has some 15 amp fuse wire with me to replace the fuse. The night store timer had switched on for the 1 PM 1 hour boost! Why I had forgotten to remove the fuse and what made me think the power was back on I'll never know. How careless, the screwdriver now is more suited to pig nose screws.

[high_vacuum_house]

Good evening,
I have had a really daft mistake today whilst at work. I was fault finding on a diesel electric railway loco which has a high power V16 engine driven 3 phase alternator which is then rectified with a huge bridge rectifier to DC between 920v and 2500v depending on the exitation current. Thyristor invertors then create a 3 phase supply from this to power the traction motors.

There was a fault with the main 3 phase bridge rectifier which I decided to test for shorts. It was disconnected and meggered with an electronic type megger at 1Kv It did not occur to me at the time for some reason that the slowly rising insulation resistance was a capacitor across one of the diodes charging up to 1Kv !! After satisfying myself there was a fault with this rectifier I then started to unbolt the clamps which hold the module in. I touched the still charged up terminals of the rectifier which made me jump backwards violently with my back hitting the safety handrail along the walkway of the locomotive. The force of hitting the handrail has given me a very bad back and I am currently in a lot of pain and can hardly bend down. Now having learnt the hard way that there are capacitors in the brige rectifier module!!

Christopher Capener

picture of the Siemens DI8 locomotive that are currently working at Redcar steelworks