Dumbest 'electronic' mistake you ever made

[Dannyx]

Re: Dumbest 'electronic' mistake you ever made

Yes, everything survived: installed the correct transistor and it immediately fired up just fine. Just out of curiosity I stuffed 12v in that regulator and got some nice 5v on the output I don't suppose it would've been so well in place of something like a PFC FET running at 380v Lesson learned: DOUBLE CHECK YOUR PARTS KIDS !

[momaka]

Re: Dumbest 'electronic' mistake you ever made

^ Lol, nice one.
So did the 7805 survive? What about the original working MJE13009? If both are okay, I suggest you buy a lottery ticket too - might just be your lucky day/week.

[Dannyx]

Re: Dumbest 'electronic' mistake you ever made

Good day folks. Here's something fresh to add to the pile from me: 7805 regulator installed in place of MJE13009 BJT.

I think I've repaired dozens, if not hundreds of these (pretty junky) PSUs used in some little peltier thermoelectric fridges one of our clients has installed in their hotel rooms. The MJE13009 transistors blowing is a very common fault on them. Now, I keep all my parts in perfect order and everything is neat and tidy. I like to consider my shop a temple dedicated to the pure appreciation of electronics and technology but today, as you can tell, the "altar" had a little f-up. For some reason, I mixed two 7805 regulators with the MJE13009s. This particular PSU you see only had one popped transistor, so I left the good one in place and replaced only the dead one with, you guessed it, a 7805....instant disaster and flame show you may think. Well actually no, no reaction at all: the PSU didn't start (geez, I wonder why ), but other than that nothing - not even the fuse went. Now imagine me trying to diagnose this thing for like half an hour until a ray of light shone at just the right angle on that capsule to allow me to just about make out 7805 on there *DUUUUUH*

[mutant]

Re: Dumbest 'electronic' mistake you ever made

My first sound card was lost because I was using a screwdriver while the system was on. It slipped right out of my hand while tightening a loose fan. Sparks flew when it bounced around on top of the card but the PC was ok. The sound card never worked again.

[momaka]

Re: Dumbest 'electronic' mistake you ever made

After 30 second a customer called me for a quick question. I left the device on and start to talk to customer. After 4-5 minutes I remember that BGA was still on. I run to back of the shop and what a mess.
The whole board was melted. All the components on the board was swimming.

Oh yes, I've seen that happen with BGA machines before as well. The thing to get out of this: never trust the stock profiles that come with the machine. There are way too many things that can go wrong (more than I care to list right now), especially in the first 10-100 reflows/reballs you do with a new machine. So unless the machine has been set-up and well-tested over time, never leave it unattended.

[Dannyx]

Re: Dumbest 'electronic' mistake you ever made

Now there's something to ruin your day

[uzeyironal]

Re: Dumbest 'electronic' mistake you ever made

Hi All, I was running a laptop repair shop in Turkey. After one week training with a vendor I bought my first BGA machine, which was Jovy 8500. In first attempt to fix an Acer laptop I set everything right and press the start button. After 30 second a customer called me for a quick question. I left the device on and start to talk to customer. After 4-5 minutes I remember that BGA was still on. I run to back of the shop and what a mess.
The whole board was melted. All the components on the board was swimming.

Luckily the laptop was my own. I could not imagine my self that I had to explain a customer what went wrong.

Since than no matter what If a BGA is on I always kept an eye on it.

[momaka]

Re: Dumbest 'electronic' mistake you ever made

Welp, here's another one I had fairly recently (a few months back):

I was trying to install a bathroom mirror fixture with lights and ASSumed the power lines going to the mirror lights were connected to the same light switch as the bathroom's main light (I didn't turn the breaker off because I was too lazy and didn't want to waste time figuring out which one was for the bathroom lights). But NOPE. Got a bit shocked by 230 VAC instead.

Luckily, I did sort of anticipate something like that might happen when I don't turn off the breakers (you never know if something is wired incorrectly... or in my case, a wrong assumption), so I put on my shoes (they have rather thick rubber soles). Thus, the only shock I got from that 230 VAC line was stray charge to my body.

Funny thing is, I stripped the live wire and folded the bare end with my fingers several times without getting shocked due to my skin being very dry. But the last time I tried to bend it, a sharp corner in the wire end pierced through my top skin a bit, and that's when I felt the quick jolt.

Also, luckily, I wasn't holding or leaning against any grounded objects... but I know not to do that when working with live wires (even when the breakers are disconnected).

I guess my Darwin award has been postponed for another day.

[eccerr0r]

Re: Dumbest 'electronic' mistake you ever made

Was that measure twice, cut once; or was it check twice, measure once?

[Agent24]

Re: Dumbest 'electronic' mistake you ever made

Melted the thing and caused the testicle to tingle

[mattch]

Re: Dumbest 'electronic' mistake you ever made

Touching my cheap multimeter on two live wires of 240v outdoor ac unit. Melted the thing and caused the testicle to tingle

[Curious.George]

Re: Dumbest 'electronic' mistake you ever made

Inserted a 2716 (2Kx8 UVEPROM) into programmer "upside down". All that trapped charge leaked out in a bright flash visible through the quartz window!

(At the time, the devices were selling for $50/each -- IN LARGE QUANTITIES -- so my boss was not very happy!)

[Snayperskaya]

Re: Dumbest 'electronic' mistake you ever made

"Plugged" a brand-new 1GB DDR stick (back when those costed quite a bit) off-key. The magic smoke escaped both board and the RAM stick instantly.

(the mobo actually survived, just that one slot got bad).

[Per Hansson]

Re: Dumbest 'electronic' mistake you ever made

Most recent stupidity was a year or so ago.
A co-worker gave me a servo that gave an alarm code which pointed to low input voltage.
It was a three-phase servo, without thinking I wired it up to the grid via a simple motor tester we have:
With on/off buttons and also forward and reverse (phase switching).
I switched the switch over to "on" and didn't care about the forward/reverse switch (the servo obviously wont care).
I saw that the charge warning LED on the servo lit up red, good.
Did not see any alarms on the 8-segment display.
And then about 5 seconds later: BOOOOOM!


Then it suddenly hit me: I had read the wiring plate which said 230VAC input power.
Which we do have, but obviously not when wired up for three-phase, then it's 400V!
I laughed so damn loud it was almost as loud as the bang from the servo itself!
It now rests in servo heaven, but two of it's friends have been saved from the dumpster

[eccerr0r]

Re: Dumbest 'electronic' mistake you ever made

Stupid thing I did last night: Scoping high voltage on your lap.

Last night just about ready for bed I was curious about a 325W power inverter. I had it on my lap and I didn't have pants on, assuming that the inverter should be isolated I should be fine...

well... no.

Turns out that I had one pole of the high voltage hooked up to earth ground (because the 'scope grounds one input) and the 12VDC ground was floating-and touching my skin. When I touched earth ground by mistake... I get shocked!

Fortunately it is current limited as it uses a resistor to limit current flow but not sure why the inverter references anything to chassis ground in the first place. The HFT inverter I was working with doesn't reference the high voltage to chassis ground.

Will need to investigate this further.

[RJARRRPCGP]

Re: Dumbest 'electronic' mistake you ever made

Something like $200,000 in damages.

Was that due to the building being engulfed in a fire. Or was that equipment like you would expect at a Michael Jackson facility???

[Curious.George]

Re: Dumbest 'electronic' mistake you ever made

Dumbest mistake I've seen someone ELSE make:

~17" x 70" wirewrap panels (Augat) used in a piece of custom test equipment (i.e., where the serial number is never more than one digit!) DIP technology (40 years ago). So literally thousands of DIPs covering the surface of the panels. Gobs of decoupling capacitors on the three power supplies feeding each panel. Backside a ratsnest of #30AWG Kynar.

Folks who built the panel used the wrong caps -- too low of a voltage rating. So, apply power and blow every cap on the board (400A power supplies). Of course, you can't unsolder the caps with all that wire in place...

(someone lost a shitload of money on that deal!)

[Agent24]

Re: Dumbest 'electronic' mistake you ever made

I'm amazed at how many times I've seen a faulty button cause problems in equipment. I always regarded switches as one of those components which 'never fail' - and yet, now, my experience tells me that switches (especially tactile buttons) seem to have a failure rate which matches that of any average component.

One failure I have yet to experience is a faulty transformer. (Though I've seen an inductor cooked due to a shorted transistor)

[ChaosLegionnaire]

Re: Dumbest 'electronic' mistake you ever made

more dumb electronic mistakes made by me:

first one, i didnt put the power button header on the right jumper pins on the mobo. so i thought the mobo was bricked from some kind of esd and wont power on. had to use a jumper wire to short the green wire on the atx connector to turn on the psu and board. realised the mistake a few days later. lesson learnt: dont tinker with electronics in the morning while sleep deprived.

second one, computer kept suddenly randomly rebooting after 30 mins to 1 hour from a cold boot. thought it was a psu issue. swapped psu and still the same. then another system with that psu i thought was faulty also did the same. swapped another psu again but still the same. swapped ram and still the same.

so i stuck in a post card to see what was wrong with the system and i saw on the post card, the reset button led was lit and flickered as i moved the reset button around. stuck/faulty/partly shorted reset button was the cause. pulled out reset button and system worked fine thereafter. phew!

[TechGeek]

Re: Dumbest 'electronic' mistake you ever made

You win. Close the thread.