Your daftest mistakes??

[Sideband]

We had a tabletop radiogram which was also used as an extension speaker. I had connected a twin lead across the speaker and brought it out to a two-pin 5 amp plug (it fitted a two-pin 5 amp socket fitted to an FM radio connected across the output TX secondary). We also had 5 amp two pin mains sockets in the old house at the time but as the mains lead from the radiogram was brown and the twin lead from the speaker was clear, you couldn't get them mixed up could you.....?!! It's quite amazing how loud the bang is when a 3 ohm speaker is connected across the mains.....!


Rich

[hamid_1]

When I was about 7 years old, my Dad brought home some items from his office when it closed down, including a battery-operated wall clock and a Grundig Stenorette reel to reel dictation machine. I got hold of these items to play with, as my Dad had no use for them himself.

The clock worked quite well for a few weeks, then eventually slowed down and stopped. I guessed the battery had run out. I also noticed an identical looking wall clock made by Gent of Leicester in use at my school, the only difference was that the school's clock was mains-powered. So, rather than buy a new battery, I decided to run my clock off the mains, just like the one at school. I cut the mains wire off an old table lamp, stripped the ends and twisted them on to the clock's battery terminals. Unaware of the consequences of connecting 240v AC directly to the clock's 1.5v DC battery holder, I then plugged in my new "electric" clock ... and it went B A N G !!!

It was lucky I didn't blow myself up. I unplugged the smouldering clock and smothered it with a damp flannel to stop the smoke, then buried it in the dustbin. But my Dad worked out what had happened, and instead of telling me off for fooling around with electricity, he bought me a book about how to repair electrical appliances safely. I read it from cover to cover. That started me off on the path that led to a career in electronics repair. Along the way, the aforementioned Grundig reel to reel tape recorder was taken to bits and destroyed after it broke ...

[theoldtrout]

A few years ago I wasted a lot of time trying trace a noise fault in a piece of equipment - it disappeared when I turned off my newly acquired magnifying lamp! I did feel a bit of a berk.

[Nickthedentist]

...and that mysterious end-sensor fault with the video you were trying to fix probably went away too!

[AndiiT]

Hi,
Wanting to check out the Monitoring facility of our Fidelity Playmaster tape recorder, I dismantled my grandmothers Dansette junior to gain access to the innards, connected the patch cord, supplied with the Fidelity, across the speaker terminals (one of which was "supposed" to be returned to mains Neutral, as the Dansette was of AC/DC design, but read on....)

So Dansette amplifier and Fidelity Playmaster both plugged in to the one mains socket in the front room, the room usually reserved for the Vicar and Insurance man , via a multiplug adapter.

I then went to plug the Phono plug end of the lead in to the 'MON' socket of the Playmaster and BANG!!! at least one blown plug fuse and a rather trembling nine year old boy.
I wasn't to know the effects of connecting the Mains live to the Mains earth at that age, now was I?

Andrew

[slidertogrid]

Hi
It seems a few of us have blown battery valve heaters early in our careers!
As a kid I built a set from scrap parts and saved up to buy the valves, it was all crudely made on a piece of wood but picked up a few stations between the whistles and howls.
I took it next door to proudly show my grandfather, to my horror one of the HT wires came off and touched the filament connection.
I heard a ping.. that was the valve heaters and several weeks pocket money up in smoke!

Rich.

[MrElectronicman]

Hi,
I had an EHT generator that came out of an old projection TV set which I was playing around with. I knew the dangers of EHT and while it was not a mains transformer type, I was still being careful?.
For some reason or other I also had an amp sitting on a plastic sheet and was drawing sparks from the case, when my Mom called me for tea, so I switched of the EHT generator, and picked up the amp. wham! I went flying across the room and nearly threw the amp though the window. The case of the amp had been charged up by the EHT due to the plastic sheet insulating it from table.

I was then doubly careful around any high voltages.

[emeritus]

I had been given a 1940's Cossor 'scope that had one of the sharpest traces I have ever seen, but was suffering from an intermittent fault. When I took the covers off to investigate, the fault cleared, so I thumped the side, forgetting that the insides were exposed. I don't know what voltage I touched, but the jolt fortunately threw my arm away from the innards. (It was a mains EHT model and it turned out that the mains transformer insulation had failed: I put an ad in "Television" and someone took it away for spares.)

[Phil G4SPZ]

I'm glad I'm not the only one to have blown battery valve filaments, but I did that to a set of four newly-purchased NOS octal valves for a 1939 Ever Ready portable. A moment's distraction, misreading the paper labels I'd attached to the leads resulted in 1.5 volts on the HT, which did no damage, but 90 volts on the LT, which did. Twenty quid up in smoke and a very red face.

And this was only last year...

[G6Tanuki]

When I was about 11 I was given an old late-1940s portable record-player: I rapidly dismantled it and recovered the amplifier.

EF37, CL33, CY31, AC/DC design, series-connected heaters with a dropper.

I fed it with the output of my crystal-set and it worked rather well.

One day my outdoor aerial fell down (the far end being attached to a tree in a rather exposed location). Going outside into the garden to reattach aerial to tree, I grabbed the end of the aerial wire and got one hell of a "belt" from it.

That was the day I learned about "Live to rectifier, neutral to chassis" wiring on AC/DC kit.

--G6Tanuki.

[Skywave]

Reading this thread, two incidents spring to mind.

First, when I was an ignorant, but enthusiastic youngster, I replaced the old, worn and dangerous-looking mains lead on a very small & compact wireless. When I switched it on, all the valve filaments went 'pop', one by one! It was only several years later that I learnt about voltage-dropping mains leads.

Second, when I was lot older and a good deal more knowledgeable, I was given a chunky-looking 5 GB PC hard drive, when such things were expensive. To test it, I connected it to the PC's PSU, but got confused over the colour-coding of the d.c. rails. TTL does not like being powered from +12 volts!

I can excuse my first mistake - but not the second one. The only consolation I can draw from such mishaps is that experience is an effective - but unforgiving - teacher.

Edit: However, having read some of the above posts, I don't feel quite such an idiot now!

Al.

[Andy - G8MNM]

As a nine or ten year old I had picked up a battery valve radio from the jumble sale which of course without batteries didn't work.
I came home from school one day to find my older brother had connected his Hornby OO train controller/transformer to a couple of the power leads in my radio - it was making a loud humming sound - as it was AC!
I imagine all the valve filaments must have lit up like Christmas tree lights for a microsecond before they blew on 12V AC!

Many years later I fitted a plug in memory card into a PC the wrong way around - horrible smell and blistered TTL chips on board and a rather embarassed me Although it should have been better designed so it couldn't fit either way round.

Andy

[Jonster]

Originally Posted by Skywave

Reading this thread, two incidents spring to mind.

First, when I was an ignorant, but enthusiastic youngster, I replaced the old, worn and dangerous-looking mains lead on a very small & compact wireless. When I switched it on, all the valve filaments went 'pop', one by one! It was only several years later that I learnt about voltage-dropping mains leads.


Al.

How does that work when you have a series heater chain?

By poetic licence!

[Audio1950]

Putting 6 x U2 batteries from my Philips record player into my mother's brand new gas cooker to "recharge" them. The resulting explosion was spectacular, and retribution was both swift and painful!

Barry

[Breton56]

I remember easing a 15A plug out of it's socket with a large screwdriver when I was about 11 years old and being thrown across Dad's workshop by the shock.Years later I repaired a voltage/current calibrator which had a valve rectifier and headroom of around 700V.A colleague borrowed it and thinking that he understood how the unit worked,disconncted the feedback link (external bare wire link) to connect one of our current generators in it's place-why I have no idea and thus connected himself to the uncontrolled 700V supply-result one very stunned colleague prone at my feet

[julie_m]

Not my daft mistake, but it has something to do with me ..... bear with me .....

Once upon a time in a village on the outskirts of Stoke on Trent, a shy young lady who worked in an electronics factory received a tape recorder as a birthday present; and, seeking a pretext to ask out a young gentleman she fancied who worked in a different department of the factory, and knowing that he knew a bit about electronics, she decided to ask him if he knew how to wire the tape recorder to her record player in order to record records onto tape without using the microphone and so picking up ambient noises.

Now, he did exactly what I would have done under the circumstances: He drew her a diagram and lent her his soldering iron.

The young lady, slightly disappointed but resolved not to allow herself to be deterred (after all, she would have to see him again to return the soldering iron), waited until her parents and brother were out of the house; then she began work. Unfortunately, in his haste, the young man had omitted an important step in the instructions: Be sure the record player is unplugged from the wall before commencing work. (In fairness, this most probably would have been so obvious to him, that he would have assumed anyone would do it anyway.)

As the earthed tip of the soldering iron came into contact with a live terminal inside the record player, there was an almighty bang and everything electrical in the house suddenly stopped working.

Fortunately, the telephone still worked. She rang the one person she hoped would be able to help her. As she sobbed into the phone, he reassured her that everything could be sorted before her parents found out; then he jumped on his moped and rode around to her house. With the aid of a flashlight borrowed from beside her brother's bed, he soon ascertained that it was the company head fuse that had failed (or succeeded, if you prefer to think of it that way).

Now, ordinarily, only the electricity board officials would be authorised to touch this fuse. But time was off the essence now, and the M.E.B. would be unlikely to be able to come around until Monday. This was a desperate situation and it called for a desperate remedy.

They rode around to a newly-built housing estate, and liberated a company head fuse from the showhome. He then used this to replace the blown one, poking the wire back into the lead seal with a heated darning needle.

Once he had put the lights on for her, there was still some time before anyone was due to return; so she put the lights off for him. And then he put his trousers back on, helped her complete the record player wiring job and rode off into the sunset on his moped.

Nine months later, I was born

[Skywave]

Originally Posted by Jonster

How does that work when you have a series heater chain?

Y'know, after all these years, (more than 50), I cannot recall, in any degree, the details of that set - apart from (what I later discovered) was the mains dropper lead. As for the 'accident' itself, all I do recall - and this is permanently etched in my memory - is the way each filament glowed very brightly and then went out . . . one by one. And, just for what it's worth, I've never come across a wireless with a mains lead dropper since! ('Orrible idea, anyway! )

Al.

[fetteler]

Originally Posted by ajs_derby

Not my daft mistake, but it has something to do with me ..... bear with me .....

Once upon a time in a village on the outskirts of Stoke on Trent, a shy young lady who worked in an electronics factory received a tape recorder as a birthday present; and, seeking a pretext to ask out a young gentleman she fancied who worked in a different department of the factory, and knowing that he knew a bit about electronics, she decided to ask him if he knew how to wire the tape recorder to her record player in order to record records onto tape without using the microphone and so picking up ambient noises.

Now, he did exactly what I would have done under the circumstances: He drew her a diagram and lent her his soldering iron.

The young lady, slightly disappointed but resolved not to allow herself to be deterred (after all, she would have to see him again to return the soldering iron), waited until her parents and brother were out of the house; then she began work. Unfortunately, in his haste, the young man had omitted an important step in the instructions: Be sure the record player is unplugged from the wall before commencing work. (In fairness, this most probably would have been so obvious to him, that he would have assumed anyone would do it anyway.)

As the earthed tip of the soldering iron came into contact with a live terminal inside the record player, there was an almighty bang and everything electrical in the house suddenly stopped working.

Fortunately, the telephone still worked. She rang the one person she hoped would be able to help her. As she sobbed into the phone, he reassured her that everything could be sorted before her parents found out; then he jumped on his moped and rode around to her house. With the aid of a flashlight borrowed from beside her brother's bed, he soon ascertained that it was the company head fuse that had failed (or succeeded, if you prefer to think of it that way).

Now, ordinarily, only the electricity board officials would be authorised to touch this fuse. But time was off the essence now, and the M.E.B. would be unlikely to be able to come around until Monday. This was a desperate situation and it called for a desperate remedy.

They rode around to a newly-built housing estate, and liberated a company head fuse from the showhome. He then used this to replace the blown one, poking the wire back into the lead seal with a heated darning needle.

Once he had put the lights on for her, there was still some time before anyone was due to return; so she put the lights off for him. And then he put his trousers back on, helped her complete the record player wiring job and rode off into the sunset on his moped.

Nine months later, I was born

Superb

Cheers,
Steve.

[Radio Wrangler]

How many of us know......?

David