Dumbest 'electronic' mistake you ever made

[rhomanski]

Re: Dumbest 'electronic' mistake you ever made

The P-3c has a dual power supply for the central computer. It's mounted in an aluminum box on the bottom of the rack. You had to lay down and take the cover off to check it. They sent two of us to work on it. You always went in pairs when possible, just in case. I got out the digital multimeter, he took the cover off. We got hooked up and it was low. As soon as he got close with the small screw driver, it sent out an arc over his head and to the rack behind him. He let out a yell, I let out a cuss word and jumped up and killed power to it. Then ran over and pulled the breakers. By that time he had backed out of there and was standing up. I asked if he was okay, he said he was and we both started laughing. We sent that one to the shop with a warning to the bench tech it shot a three foot arc. After putting in a new one and adjusting it the computer worked fine. It was loud though, like a lightning strike. Scared the bejeebers out of both of us.

[Agent24]

Re: Dumbest 'electronic' mistake you ever made

When I was a kid, I was fixing a fan heater with parts from 3 different units I found dumped, in the process I got my hand too close to an element assembly to see if it was heating up: there was no heat, but it was certainly hot!

First and so far the only time I've touched 240v, no desire to do that again, I'm much more careful now...

[reaper57]

Re: Dumbest 'electronic' mistake you ever made

Well, I've rested my hand on a monitor power supply, it left a few small dots on my hand where I had touched the points. I think I shocked by the voltage coming out of the primary cap, and not the AC input, but it still did shake my hand and made it do weird things. The weird thing is that I sort of liked it. I mean it wasn't something I would do on purpose, but it did make me feel "alive".

Another stupid thing I've done was when I was repairing a cheap laptop power supply. I had gotten two of those for like 2-3$ each off of ebay, and one was working fine, but the other would randomly stop working from time to time. So I popped it open and I found out that the one of the pins of primary cap was lifted, along with a part of the trace. So anyway I fixed that, but the stock LED wasn't very bright and was barely visible with the top cover on, so I decided to replace it. Everything was working well, I was happy. So I had disconnected it and I had began putting it back together, but I was like "Damn, that blue LED I put on there sure looked awesome! I should take a picture.". I pull it out of the plastic case and put it on my workbench, plugged it in and instead of the cool blue LED to turn on, there was a loud boom, the fuse in the fuse box was fried and the power to most of the shop was cut. Turns out I hadn't rolled my solder wire back and it was going across my workbench and I had put the power supply on it... -.- And all of that for a stupid picture...

[rhomanski]

Re: Dumbest 'electronic' mistake you ever made

I was adding a new system to a plane once. When terminating a wire, I popped a pin out of the plug to see what type it used and reinserted it in the wrong spot. Inducing a problem into a different system. Luckily it was found in the checkouts. You always test every system that could be disturbed after a modification like that. When they told me about it a few days later, I didn't even remember popping the pin out. Took me about 10 minutes to remember doing it.

People thought I screwed up one time on another one. I was assigned a job I couldn't do. Others were working where I needed to be. I waited all shift and they never finished. So before giving it to the next shift I sat down in the cockpit reading the paperwork one more time. While sitting there I heard a noise in the cabin. I glanced back there but didn't see anyone. Someone else came running up telling me all the oxygen masks dropped in the cabin. Well that explained the noise. They looked at me like I had moved the switch. It was still safety wired. I didn't touch it. They all thought I did, I could see it in their faces. Nobody made the accusation though. I felt bad about giving it to the next shift and they didn't look pleased about having to repack all of them masks. Takes a couple hours to do it. I didn't feel bad too long though, wasn't my fault. I watched the history of the plane to see if it happened again for about a month but it didn't. Just one of those things.

[Hondaman]

Re: Dumbest 'electronic' mistake you ever made

Dumbest electronic mistake? What about the time I replaced the spark plug wires on my parents' 1977 Chevrolet? It was a V-8 engine with a distributor and electronic ignition (HEI, no points).

The new wires were "off" by one position on the distributor (I have no idea how this happened). You had to keep your foot on the gas at all times or the engine would stall. I think we rotated the distributor 1/8 of a turn to fix it.

Why didn't I replace one spark plug wire at a time? I don't know.

(Thankfully anyone else who knew about it has forgotten the incident or died.) (Yes, I am very, very hard on myself. I never forget my screwups and I try to guard against them EVER happening again.)

[goontron]

Re: Dumbest 'electronic' mistake you ever made

i was trying to get the screen out of a nokia 3310 when i striped a cople of screws so i proceeded to throw it on the ground to try and separate the case, well, it bounced back into my face and chipped a tooth. dont mess with the 3310!

[joshnz]

Re: Dumbest 'electronic' mistake you ever made

Got too close to a mot output, That hurt lots.

voltage regulator on breadboard common lead disconnected allowing 19v into micro controller and lcd micro controller still works but lcd got cooked.

[ben7]

Re: Dumbest 'electronic' mistake you ever made

The stupidest thing I can remember is frying my MP3 Player when trying to charge it with an old PC PSU.
I accidentally connected USB connector power pins to 12V instead of 5V.

That sucks

While trying to repair this monitor, I rested my hand on the power supply and realized that I forgot to unplug it. My hand touched the metal chassis and the solder joints for the power input plug at the same time.

LOL, I bet you had to change your underwear after that!

[ddscentral]

Re: Dumbest 'electronic' mistake you ever made

The stupidest thing I can remember is frying my MP3 Player when trying to charge it with an old PC PSU.
I accidentally connected USB connector power pins to 12V instead of 5V.

[lti]

Re: Dumbest 'electronic' mistake you ever made

While trying to repair this monitor, I rested my hand on the power supply and realized that I forgot to unplug it. My hand touched the metal chassis and the solder joints for the power input plug at the same time.

[kc8adu]

Re: Dumbest 'electronic' mistake you ever made

my 2 worst were adjusting the focus on a magnavox t991 and laying my arm across the tripler.that took months to heal.
my 70 elcamino has a fist print in the center of the hood from me getting bit just right with the hei ignition i was installing.i missed all the braces and left a nice print in the hood.
i still want to find a junk hood and intentionally punch it to see if i can replicate the damage.
the involuntary reaction is said to do much more damage than the shock.

[Sirgu]

Re: Dumbest 'electronic' mistake you ever made

Probably not my dumbest one, but the first that comes to mind of recent mishaps:

I had just refurbished one laptop heatsink fan. Dismanteled, cleaned and relubricated `n all this stuff... and then hastily burnt the coil by giving it 12 volts with regulated power supply. Well, I had just priorly tested the sound of some usual case fans of desktop PC which were waiting for their turn. Forgot to adjust it back onto 5V by the time laptop fan got ready.

Conclusion: Always doublecheck your adjustments before pressing any important button. Or simply don´t do cross-tasking near regulated power supply if your equipments are in need of different power.

[goodpsusearch]

Re: Dumbest 'electronic' mistake you ever made

Did it's leakage current increase at all?

I'm afraid I don't have the equipment to measure that. I'd like to believe that the dielectric layer rebuilt itself.

[ben7]

Re: Dumbest 'electronic' mistake you ever made

I was playing with a cheap psu once and I removed its HEC primary caps that had real capacity 423uF to replace them with Teapo LXK 200V 470uF with a real capacity of 490uF.

I plugged the psu to AC, turned it on and everything was ok at first but then started a boiling sound! 1 of the primary caps I had connected backwards!! I was lucky to stop it before the cap exploded. When I touched it after AC disconnection it was hot enough to burn my finger.

Oddly, the cap survived! It didn't vent and its ratings (esr, uF) didn't change. The cap got lucky!

It's the cap on the left.

Did it's leakage current increase at all?

Not exactly a mistake, but I had an issue with a bad connection in a breadboard before. Had a zener regulator to give a chip about 12V off of a 50V-60V or so bus (low current, hence the inefficient zener regulator). Yep, it worked fine for a bit, then I bumped the thing and the freakin breadboard had a bad contact on the zener diode. Basically, the chip popped it's lid. Shards of epoxy/plastic were implanted in the wall ... now I always wear safety goggles ... LOL.

-Ben

[goodpsusearch]

Re: Dumbest 'electronic' mistake you ever made

I was playing with a cheap psu once and I removed its HEC primary caps that had real capacity 423uF to replace them with Teapo LXK 200V 470uF with a real capacity of 490uF.

I plugged the psu to AC, turned it on and everything was ok at first but then started a boiling sound! 1 of the primary caps I had connected backwards!! I was lucky to stop it before the cap exploded. When I touched it after AC disconnection it was hot enough to burn my finger.

Oddly, the cap survived! It didn't vent and its ratings (esr, uF) didn't change. The cap got lucky!

It's the cap on the left.

[ben7]

Re: Dumbest 'electronic' mistake you ever made

Shh... you can't put the smoke back in once you've released it. I tried- needed a 9V regulated power supply to test something, so whipped one up with a "zener boosted" 7805. Only I put a 6.3V nichicon HM on the 14V input.

Hmm... idle current seems a bit high- Hsssssss! Wow! That smells like ammonia!

I had a similar experience. I was at my computer looking something up for some sort for circuit, and I had the breadboard with me. After I was done, I moved to my workbench ...
Well, it turns out, that the bulky capacitor on there popped out (darn crappy breadboards). I had just pushed it back down onto the breadboard. Well it ended up being connected backwards. Powering on the circuit, all of a sudden I noticed a faint bubbling sound, and the power LED dimmed ... I caught it just in time, that cap almost popped. It was a vented cap though, so it would have just made a puff of steam, but still! ... it SCARED the hell outta me ... now I double check capacitor polarities, lol.

Separated a neutral splice in a house. It turns out it was a shared neutral and put 240 volts through 10 cfl's, they ran real bright for about 30 seconds and started releasing all the magical smoke.

Hahaha

I've got a very long list. The dumbest would have to be involving high voltages.

Hahah, same. Like the first time I took apart a camera flash unit. Yep, got quite a surprise out of that one.

or you could fit a fuse - just saying.

LOL ... or pull the plug, or turn off the power switch (if there is one) xD

[kaboom]

Re: Dumbest 'electronic' mistake you ever made

Separated a neutral splice in a house. It turns out it was a shared neutral and put 240 volts through 10 cfl's, they ran real bright for about 30 seconds and started releasing all the magical smoke.

That could've gone worse, as you know. At least it was just cheep (compared to electronics) CFLs. ASSuming you didn't fry any electronics...

Tripped a 480-volt ground fault protection breaker that took out 1/3 of a school. I did that one by adjusting a 277-volt switch in a box to put a plate on it. Turns out a wire was damaged going to the switch and got pinched. That fault tripped 3 breakers in 2 different panels.

More things similar to that have happened......

Shh... you can't put the smoke back in once you've released it. I tried- needed a 9V regulated power supply to test something, so whipped one up with a "zener boosted" 7805. Only I put a 6.3V nichicon HM on the 14V input.

Hmm... idle current seems a bit high- Hsssssss! Wow! That smells like ammonia!

[delaware74b]

Re: Dumbest 'electronic' mistake you ever made

Not so many 'electronic' mistakes unless you count some of my more famous electrical mistakes such as:

Cutting through a conduit that had no AC in it - it was only for the fire alarm in a state police barracks. 10,000 angry crickets in my ears after shutting off my reciprocating saw. Didn't get in trouble, they were pretty cool with it.

Troubleshooting a 15 year old message board. Pulled out 2 8x7 pixel elements and it went stupid. I had 2 470uF 35V Panny caps grenade in my face. They retired the sign and it stayed that way for about 6 years until the pylon sign was replaced with a regular sign.

Separated a neutral splice in a house. It turns out it was a shared neutral and put 240 volts through 10 cfl's, they ran real bright for about 30 seconds and started releasing all the magical smoke.

Tripped a 480-volt ground fault protection breaker that took out 1/3 of a school. I did that one by adjusting a 277-volt switch in a box to put a plate on it. Turns out a wire was damaged going to the switch and got pinched. That fault tripped 3 breakers in 2 different panels.

More things similar to that have happened......

[Calchaqui]

Re: Dumbest 'electronic' mistake you ever made

high-voltage is fun,
high-current is the danger.

there are video's - probably on utube of people dropping spanners and buss-bars across a 12v car battery.
800+ Amps makes for one hell of a makeshift bomb!!!

Yes, Joule effect kills you in a bad way , high voltage-low current gives you a heart attack . Those are my ideas, dunno for sure.

[stj]

Re: Dumbest 'electronic' mistake you ever made

I bet you tell us at last one!. I'm pretty sure High Voltage is a plus+ for mistakes, and the most hazardous ones .
A colleague of mine got ruined his whole triceps muscle when fixing a microwave oven, a tiny tip of the wire pierce the high voltage transformer insulation and stick in his elbow till a siemens breaker saved his life but got permanently numb the triceps. I've read in local newspapers of amateur repair people who was found dead in bed from a heart attack after receive a discharge trying to fix their microwave oven, meaning it has a killing delayed effect.

high-voltage is fun,
high-current is the danger.

there are video's - probably on utube of people dropping spanners and buss-bars across a 12v car battery.
800+ Amps makes for one hell of a makeshift bomb!!!