Dumbest 'electronic' mistake you ever made

[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

[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).

[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!)

[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

[Agent24]

Re: Dumbest 'electronic' mistake you ever made

Melted the thing and caused the testicle to tingle

[eccerr0r]

Re: Dumbest 'electronic' mistake you ever made

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

[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.

[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.

[Dannyx]

Re: Dumbest 'electronic' mistake you ever made

Now there's something to ruin your day

[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.

[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.

[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*

[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

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 !