Most embarrassing junior tech moment? Go! - Page 1
Forum section: electronics / general

author: mkiijam
author_rank: Regular Contributor
timestamp: May 11, 2023, 01:43:27 am
content: I once installed a transistor (H.O.T.) backwards. When the senior tech looked at the TV to see why it wouldn't work, he immediately noticed the error. "Did you install this...backwards?" "Uh... oh!" I said, playing it off like a simple mistake, But the truth was, and here's the embarrassing part, I had no idea what he was talking about. "They have front ways and backways???" is all I remember thinking!

author: EEVblog
author_rank: Unknown
timestamp: May 11, 2023, 02:02:45 am
content: My first job at Pacific Communications. Late at night pizza session trying to finish firmware (Z80) for a client demo the next day, I was the testing guy.Firmware guy burns the EPROM and gives it to me to test. I of course proceeded to install it backwards and the magic smoke escapes. That was our only EPROM of that size

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: May 11, 2023, 05:12:27 am
content: Student job at a Telecom Australia lab, back when Telecom (now Telstra) had labs.One of the Tech officers asked me to complete the build of a 12VDC to 240 VAC converter, and test it. It used TO-3 power BJTs.Build complete and powered up. With my left hand I touched one of the TO-3 cases. Hmm, hot but not too hot. Then, with myleft hand still in contact, I touched the other case with my right hand.One of the techs had to shoulder me aside, to break the circuit. Apparently I was just standing there, not breathing, my eyes all weird.He told me he felt a shock when he shoved me clear.The lab techs believed that fresh Engineering Uni students know nothing, and pose a danger to themselves. Hypothesis confirmed.

author: JPortici
author_rank: Super Contributor
timestamp: May 11, 2023, 05:37:09 am
content: crocodile clips from the power supply slips from my hand.of course they fall over the MCU causing a bang and some smoke

author: Halcyon
author_rank: Unknown
timestamp: May 11, 2023, 06:18:20 am
content: Quote from: thermistor-guy on May 11, 2023, 05:12:27 amGees! Lucky you're still here!

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: May 11, 2023, 06:40:31 am
content: Quote from: Halcyon on May 11, 2023, 06:18:20 amAbsolutely.The Lab had an iron rule - no-one works in the lab alone. I wouldn't be here if I had broken that rule.

author: David Hess
author_rank: Super Contributor
timestamp: May 11, 2023, 02:43:41 pm
content: Most embarrassing?I once installed several banks of socketed DRAM backwards. Luckily the hundreds of dollars worth of DRAM chips survived.I picked up a heavy 25,000 volt neon sign transformer by the insulators ... while it was powered. Luckily I managed to set it down rather than throwing or dropping it.Caught my hair on fire in the chemistry lab.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 11, 2023, 05:09:32 pm
content: A couple of my early stories.

author: Black Phoenix
author_rank: Super Contributor
timestamp: May 11, 2023, 06:01:57 pm
content: 555 timer was not making his function. Me, a newbie who also at the time was in the PC Overclocking community thought that extra voltage would be the solution for it.Ended with an audible pop and a crack on the substrate. Replaced the timer, forgot to change the voltage, another one to the trash...

author: madires
author_rank: Super Contributor
timestamp: May 11, 2023, 06:03:07 pm
content: Junior tech in a data center was told to install an additional card in a Catalyst 6500 (big and expensive switch). He somehow managed to insert the card upside down by applying unreasonable force and let the magic smoke out. That was a US$ 50k+ oopsi.

author: tom66
author_rank: Super Contributor
timestamp: May 11, 2023, 06:11:14 pm
content: On my internship, I broke an £800 low impedance high bandwidth scope probe by pressing too hard and snapping the (apparently non-serviceable) tip.

author: David Hess
author_rank: Super Contributor
timestamp: May 11, 2023, 08:05:16 pm
content: Oh, yea, I once did a board layout where I reversed power and ground on just half of it.

author: Njk
author_rank: Frequent Contributor
timestamp: May 11, 2023, 09:35:56 pm
content: Designed a new board version, that uses a cable for power and signals. For better PCB layout, changed power and ground pins in the cable connector. Sent the engineering note to the factory in China, requesting to manually swap the PWR and GND pins in the existing cable stock. But the factory guys are very smart and well trained. They quickly realized that the pins in the cable connector needs to be swapped. On reception of my note, they swapped the pins one more time, resulting in the original configuration...

author: aeberbach
author_rank: Regular Contributor
timestamp: May 11, 2023, 10:22:26 pm
content: Dataplex, around 1995 - I installed a (very expensive) 540MB 2.5" hard drive in a prototype controller for a SNMP-managed bank of modems. A chip on the bottom of the drive exploded, a piece flying across the room. Of course it was NOT the engineer's fault for using a non-keyed drive connector, it was mine for not knowing that he had and which way was it was supposed to go!

author: themadhippy
author_rank: Super Contributor
timestamp: May 11, 2023, 11:35:31 pm
content: mistaking the fire alarm circuit for a socket circuit,meter out to confirm its dead and bells started ringing,one office evacuation and 2 fire engines later i found the correct cable.

author: PwrElectronics
author_rank: Regular Contributor
timestamp: May 12, 2023, 02:59:33 am
content: Hand made single sided through hole PCB. I made maybe 3-4 of them. I had a 1-1 photo negative of the plotter output from AutoCAD v12 for DOS that I was using. Brute force hand layout not suited for PCB work at all. I used the negative with photo-sensitized boards. Place the negative over the board and expose it (outside in the sun, no black lamp available) then rinse and etch and hand drill it. This could take most of the work day to make one board.So, I made one of these boards and didn't notice I had the negative upside down when I exposed it until I went to insert partsIt was the cleanest etch of all of them I made and it was junk. I have it someplace...

author: Berni
author_rank: Super Contributor
timestamp: May 12, 2023, 05:59:33 am
content: Quote from: PwrElectronics on May 12, 2023, 02:59:33 amYep did that one a few times back when etching PCBs. My solution for it was to start always putting some text somewhere on the board or at least outside the board area, so that if i can't read the text it is wrong.I did soon start printing the transparency mirrored on purpose because that meant when flipped correctly the ink was on the bottom side, so it is closer to the PCB and gives a sharper result.

author: jonpaul
author_rank: Super Contributor
timestamp: May 12, 2023, 11:03:53 am
content: 1970 my second job as an EE.Vibration/Real Time FFT analyzer system in 6' rack.Drove to demo at Wash DC wtih my manager.In the hotel room, Assembled units into the rack, and plugged in 100 pin cable connectors.Turn ON! HUGE bang , smoke from EVERY rack unit!It had an oven for a VCO or Xtal, heater had 120V mains.Turned out the plugs were not ploarized!One plug with 120V was reversed and the mains hit a common clock bus, blowing up may TTL ICs on many units and boards.Worked all night and by moring it was sort of doing something, at least not blowing up.Off to the Gov Demo, it WORKED enough...they did not notice the remaing bugs...Walked away from another one....Jon

author: TERRA Operative
author_rank: Super Contributor
timestamp: May 12, 2023, 12:13:37 pm
content: Quote from: madires on May 11, 2023, 06:03:07 pmI was on the receiving end of a damaged line card a few years back.It was for a Juniper router and worth US$52,000. I opened the box and almost slid it into place when I luckily noticed the smashed backplane connectorsbeforeI tried to seat it home in the mainframe...No damage on the outside of the box, so the tech who packed it must have dropped it and stuck it in the box anyway, hoping we could claim insurance from Fedex.Unfortunately, logistics, in an attempt to save money, only declared its value as a few hundred dollars, so the cost of a new card had to be eaten by my employer ....Some frantic emails to Juniper begging for repair, but they (understandably) said NOPE! As they were not willing to take the liability and warranty obligations for any hidden damage in a piece of critical internet infrastructure. A single cracked trace or intermittent connection and nightmares ensue..Could you even pull a 200+ pin press-fit backplane connector from a 15+ layer PCB without damage? The PCB was like 5mm thick!I have noticed things are declared at much closer to their real value since then.I bet there were a few spanked bottoms over that one..

author: TERRA Operative
author_rank: Super Contributor
timestamp: May 12, 2023, 12:25:45 pm
content: Oh, another one.Back when I was in the water treatment game, we were servicing the UV sterilising system that would disinfect the water as a last step before leaving the sewerage treatment plant back into the ocean.The UV tubes were long quartz fluorescent tubes without the phosphor (like a massive UV EPROM eraser tube) all racked up in quartz 'test tubes' with double o-ring plugs in the end and submerged into the canal.IIRC there were 2 banks in sucession, each consisting of 4 racks wide each holding 12 tubes arranged 6 tall, 2 wide.We were cleaning the insides of the tubes as the UV light along with the small amount of moisture leakage and other science reasons forms a brown coating on the quartz 'test tubes' which requires the use of phosphoric acid to clean off.The guy I was working with wasn't wearing gloves, which I warned him about but because the acid didn't immediately burn, he dismissed my warnings and said he's fine.Well..... the next day... his hands looked like they had been underwater for a week and the top layer of skin was sloughing off.Dude basically gave himself an epic chemical exfoliation.He wore gloves religiously after that. I bet his hands were sensitive foraaageess

author: Black Phoenix
author_rank: Super Contributor
timestamp: May 12, 2023, 12:44:39 pm
content: Quote from: TERRA Operative on May 12, 2023, 12:25:45 pmHad a similar situation when I was working on the CNC machines. The company also were selling UV treatment equipment, from Hanovia.I didn't do instalation of the equipment but the preventive maintenance, replacement of seals, lamps, quartz tubes etc was done by the maintenance team. I had a little of phosphoric acid fall on my arm skin and heck did I look like a snake sheading skin...

author: srb1954
author_rank: Super Contributor
timestamp: May 12, 2023, 01:12:17 pm
content: Back in the olden days when I first started using CMOS devices I found that debugging such circuits was a little different from the TTL circuits I had previously been used to.I had a new logic board for testing but was having some trouble to get it working correctly. It seemed to work most of the time but for some combinations of inputs the logic gave incorrect results. After wasting a few hours checking and rechecking the logic design I realised I had forgotten to turn the PSU on when starting testing that morning!The whole board was being powered by the pulse generator providing the clock input. There was enough current being coupled through the protection diodes on the clock input chip to power the logic most, but not all, of the time.

author: ShaunT
author_rank: Newbie
timestamp: May 12, 2023, 01:18:24 pm
content: Well this was at college but it was a job our tech should have done.I was ahead in A level electronics so while everyone was on TTL and playing with transistors I had moved onto CMOS gates. We shared a power supply with a box termination in banna sockets. So my circuit kept false triggering and placing a local electrolytic cap did not work. So I fitted electrolyic caps to ALL boxes. Then someone for a joke swapped the leads to the power supply which normally only kills a couple of projects but this time the ALL the boxes exploded with plastic shower of shrapnel. I was in another lesson and watched as this very stunned kid was taken to headmaster for causing so much damage.That's how I learned about decoupling and one electrolyic is not enough and may need to add sat a ceramic rather than keep having bigger capacitance!Back in the eighties when we could not afford individual power supplies as cheap as now and just have one big one for all which I think came from a telephone exchange!

author: armandine2
author_rank: Frequent Contributor
timestamp: May 12, 2023, 01:22:26 pm
content: mildly embarrassing momentcompany made bespoke SPC (statistical process control) test measurement rigs with LVDT transducers. I removed one of a rig's component blocks from a unit without first removing the two LVDTs which were in that block. In doing so I sheared the tip ends of the LVDTsI still blame the poor design. Though it was a good unit - used on Ford Galaxy ignition block die castings.

author: madires
author_rank: Super Contributor
timestamp: May 12, 2023, 02:46:19 pm
content: The small and harmless things can be quite entertaining too. At the university we had a few computer rooms including one with SPARstation IPCs (small Unix workstation, seehttps://en.wikipedia.org/wiki/SPARCstation_IPC) and large Sun CRT monitors. The IPC comes with a 3.5" floppy drive. For one course we had to write some unix shell scripts and save them on a floppy disk. So you insert the floppy disk, copy the scripts, and then you suddenly realize there's no button to get the disk out of the drive...There's a shell command to eject the floppy disk.The large Sun monitors came with remote controls, similar to the small ones for car stereos or LED controllers. Of cource they were locked up in some drawer, but a student working as tutor had one. And he had a lot of fun with his RC and some students he didn't like.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 12, 2023, 03:49:18 pm
content: My first design that I also did the layout for had all the electrolytic caps backwards. I like to think there was a bug in the OrCAD library but still...

author: hans
author_rank: Super Contributor
timestamp: May 12, 2023, 03:52:09 pm
content: Was called in to look at a particular customers field terminal, which had a SBC that emitted a ton of EMI. It was a chronic issue, but since its a small company with little cashflow, it was fixed on a case-by-case basis (only customers that listened to particular FM radio stations on their tractor). A wide recall was out the question.We were also unsure about "the fix" the employ, because all field terminals were hand built and had slightly different interface boards etc.Usually "the fix" would include grinding down powdercoats internally, using copper tape around all plastics to create a faraday cage. And adding the highest impedance 10A+ ferrite beads we could find on ANY power line and extra beads on data signals. I was called on to look at it early in the morning. I mean, before coffee timeSo what do you do with a drowsy mind after adding a power ferrite? Swap +12V and GND on a 20A bench supply, ofcourse.Poof.Luckily no customer data lost. The SBC had to be replaced with a newer faster model, which didnt had these EMI issues. However it included an overhaul of all interface boards, labour, etc. so was a few hours works for one of the production guys.I went to my boss with good and bad news: the bad news is I blew up this EMI-troubled SBC, so that terminal needs a complete refurb, which costs us money... but the good news is we now have one less of these awful SBCs out in the field. Honestly, that SBC was a ticking time bomb, as it was haunted by many other issues in the years following.

author: globoy
author_rank: Frequent Contributor
timestamp: May 12, 2023, 04:36:29 pm
content: One of my first circuit board designs as a fairly new EE. A video graphics board for an engineering workstation using VRAMs (dual-ported dynamic RAMs used back in the day in graphics systems). Whole bank of them. Got a prototype board back, could not get it to work. The VRAMs seemed completely dead even thought it looked like power and signals to them were fine. After some time of searching for every possible explanation, I realized I had used the pinout for the DIP package variant even though they were SIP devices (I guess I made the wrong association for the CAD program). I was so depressed because in those days getting prototype boards was a many week affair and expensive. But my boss said that the two packages used the same die so very possibly the signals were in the same order. He was right! Solution was to move each part up six positions and wire 6 wires back to the now empty mounting holes. Thankfully I had a tech to do the dirty work. Board worked like a charm. His comment was, "well you learned something didn't you". I never forgot that bit of leadership.

author: TopQuark
author_rank: Frequent Contributor
timestamp: May 13, 2023, 02:29:05 am
content: First year in uni, was in the robotics team competing in Shenzhen for a competition called RoboMaster. (Fleet of ground robots and drones firing plastic pellets and golf balls at each other)Competition rules dictate robots cannot draw more than 80W from the battery or it will be automatically shutdown for safety reasons (over speeding). I spent the whole year designing a system that stores surplus energy into a supercapacitor bank when the robot draws below 80W, and gives the robot an extra boost (>800W) from the super cap bank on command.Anyways, after nights of sleep deprivation and sleeping on the floor (we stood up the bed in the hotel room to fit the robots), the night before round of 16 at 5am, I hooked the 5 assembled systems one by one up to a power supply so that I can flash the newest firmware to the controller board. First controller board didn't respond to the debug probe, nor did the second one, nor the third and fourth one. I finally realised something was up and started to probe around with a multimeter.Well turns out despite using a polarised connector, I hooked the power supply lead up in reverse to the supply, and silently killed 4 out of 5 systems. I did design in reverse polarity protection, but never had the heart to actually test it before hand for fear of killing my precious creations. Well at the end I tested it the hard way, and turns out it didn't work properly.Anyways, the remaining system worked fine, and broke the all time speed record in the competition. Future versions of the game rules severely limited the amount of capacitive energy storage allowed in a robot, so I believe my speed record still holds today.

author: KE5FX
author_rank: Super Contributor
timestamp: May 13, 2023, 03:13:39 am
content: Quote from: jonpaul on May 12, 2023, 11:03:53 amAmazing that you were able to recover from that in one night.Was that the HP 5451A?

author: Halcyon
author_rank: Unknown
timestamp: May 13, 2023, 04:38:19 am
content: Quote from: TERRA Operative on May 12, 2023, 12:25:45 pmI did something similar with flux cleaner. Thought "she'll be right" until about a day later my hands started to go puffy and pretty bad blisters formed. I also must have touched my face at some point (after washing my hands) as around my eyes were puffy as well.Always wore nitrile gloves after that when cleaning electronics. Not sure how bad flux cleaner is normally for skin, but I have particularly sensitive skin.

author: bookaboo
author_rank: Frequent Contributor
timestamp: May 13, 2023, 04:56:09 am
content: Spending well over an hour soldering a 40-pin Lemo connector then realising I'd forgotten the sealing gland.

author: TERRA Operative
author_rank: Super Contributor
timestamp: May 13, 2023, 05:54:28 am
content: I feel that one..A lot of welders use the circular Amphenol Military style connectors for control signals.You soon learn to double check you have everything in its place before soldering.

author: mfro
author_rank: Regular Contributor
timestamp: May 13, 2023, 07:21:43 am
content: Not an embarassing, but definitely a distinctive junior tech experience:in the outgoing 80ies, when I finished my engineering degree (as an automotive engineer), I started my career as CAD consultant at Control Data. In my very first week (literally my second day), they sat me into a plane to Turkey to hold a CAD training at a Turkish university. Had done the same at home as an intern previously, but this was my very first business trip abroad and my very first training to be held in English language (which obviously isn't my mother tongue). Besides that, the number of words I knew in Turkish was about five or six with no Google translate or Siri at hand as both still had to be invented. You probably can imagine that I started the trip with some mixed feelings...Anyway, I started to gain some self-confidence as the first day went relatively smooth, training went better than expected (with a lot of nice help from the students that were really eager to learn), only interrupted by several intermittent power cuts while we needed to wait for the mini (I think it was a Cyber 930) to come up again. However, during the following night, there apparently was another power cut and that obviously was one too much for the poor 930 : it refused to come up again.I didn't have any experience in hardware, neither had seen a 930 in flesh before nor knew any but the most basic NOS/VE commands to bring the CAD system up, but my students looked at me full of expectations since, after all, I was the CDC expert. With no mobiles, not even a fixed line at their "data center" besides the ultra-modern single phone link that was used for the 930 to call home (which it couldn't since that only worked after it came up), it obviously was my task now to do that (CDC didn't have any mini-capable local services as it was allowed to import such high-tech as the 930 into Turkey only just recently).Remember: no mobiles, no Internet, no Google, not even a camera to take a picture of the cryptic console messages the sick 930 spit out.Anyway, with the really nice help of the students, an improvised phone line to the console (a cable running cross-buildings through about half of the campus), my CDC colleagues at the phone remote-controlling my hands, a soldering iron (to repair a broken connector of the replacement disk unit they had which was my very first soldering job) we eventually managed to fix the 930 and bring it up again and lost only like six hours.My first week as a CAD consultant.

author: nctnico
author_rank: Super Contributor
timestamp: May 13, 2023, 10:33:00 am
content: I quickly learned that I'm always rightSenior engineer had put two electrolytics in series to achieve higher voltage rating. When I made a remark about that not being a good idea, he claimed it would work. When I took the system (high 6 figure number worth of equipment) to the customer (a bank), the electrolytics blew with a large puff of smoke in their equipment room during testing. And ofcourse this happened right when the manager from the bank overseeing the project had taken his supervisors to the equipment room to show progress. Needless to say I turned a bit pale... No, I vividly remember wanting to crawl under the raised floor. It wasn't my mistake but I felt 1000% responsible.

author: temperance
author_rank: Super Contributor
timestamp: May 13, 2023, 11:27:11 am
content: Not really a technical failure but one I will never forget.It's my first day at a new job. I share a desk with a colleague and my colleague has a radio. At 10h30 they announce the new candidates for the daily music quiz on the radio and one of the candidates has this unusual name which, translated into English, would be something like Mr. The Fucker. So I comment on that and said: if I had a name like that I would think about changing my last name. My new colleague raises his head above the console between my desk and his desks and asks me: can you guess my last name?... The only thing I could say after a few seconds was: yes, I think I can.@nctnicoAn other colleague of mine still thinks I was thinking about trying to kill him after I installed a rather large capacitor backwards. But that's typically me. Focusing on the getting the circuit and values right and installing things backwards.

author: madires
author_rank: Super Contributor
timestamp: May 13, 2023, 02:19:49 pm
content: PVD without vacuum:A contractor was working on a DC power distribution rack which feeds one aisle in a data center. That rack was powered via two pairs of thick wires going directly to large battery and PSU banks, classic -48V system. While fastening a terminal screw with a wrench he managed to create a nice short. Boom! He was pushed back a few meters, but luckily sustained no injuries. The inside of the rack was covered by a metal film, and the door's glass window too - the wrench has been literally vaporised.

author: jonpaul
author_rank: Super Contributor
timestamp: May 13, 2023, 04:18:52 pm
content: KE5FX: >>>>Amazing that you were able to recover from that in one night. Was that the HP 5451A?>>>>Yes, I know that HP spec an system, anso waired at Federal Scientific and knew Nicloet, and Spectral Dynamics.Ours was the first FFT real time with a custom Nova 800 and huge PC boards.1024 pts in 1 mS.Rackmount by a division of a French firm for ESRO, European Space Agency for vibration analysis.I have the original phoos and info in my archives...Enjoy,Jon

author: chukin
author_rank: Contributor
timestamp: May 16, 2023, 03:30:30 pm
content: My personal moment of ultimate negative glory occurred when I was a physics doctoral student in the eighties in London. My supervisor and I were trying to simulate far-IR absorption in the atmosphere under conditions of UV-stimulation using a decidedly low-tech setup – a copper sphere irradiated with a high-pressure Hg lamp on one side (to provide UV and FIR radiation) and a Golay detector on the other to detect the FIR absorption. To fire up the mercury lamp we used a Tesla coil that gave a spark about an inch long. Never had a problem….Well, we collaborated with a group in the UK’s premier radio and signals research institute (no names, no pack drill…) who one day generously lent us the use of a brand new IMPATT* diode which produced lots of millimeter wave energy, ideal for the absorption measurement. No one told me, the callow student dogsbody, that a) IMPATT diodes were the latest thing in mm-wave sources and therefore horrendously expensive, and b) ESD sensitive.So when I fired up the mercury lamp with the Tesla coil the spark instantly killed about 8000 quid’s worth of diode…..They were very good about it – I didn’t get fired, or even beaten around the head with a Tesla coil.*IMPATT = Impact Avalanche Transition TimePeter

author: Stromlo
author_rank: Newbie
timestamp: June 26, 2023, 07:26:25 am
content: Did a prototype design that had 6 boards daisy-chained with comms/power, on separate connectors. Not different connectors, just separate. Power was 12VDC. A friend came over and I wanted to show him that it works. I put the comms in the power socket, and vice versa. I will never forget what that looked like! 6 identical PCBs, with 6 MCUs all glowing and smoking at the same time.The client demo was less than a week away, and those were the only prototypes.I've never made that design mistake again!

author: tszaboo
author_rank: Super Contributor
timestamp: June 26, 2023, 07:46:36 am
content: I was making modifications to a large PCB design. I was following a TI appnote, opamp was connected as a voltage follower, it had positive pin as feedback. I just copied it blindly.It's still not fixed on the application note (figure 6):www.ti.com/lit/an/slyt355/slyt355.pdf

author: Miyuki
author_rank: Frequent Contributor
timestamp: June 26, 2023, 08:52:19 am
content: Some classic moments with charged mains capacitors and one CRT holding a charge, that was intenseBut the most embarrassing as a starting freelance was sending out untested design, thinking it was so easy. Gues what, it blew at the customer.