Author Topic: Most embarrassing junior tech moment? Go!  (Read 4864 times)

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Offline Alex Eisenhut

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Re: Most embarrassing junior tech moment? Go!
« Reply #25 on: May 12, 2023, 03:49:18 pm »
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... :palm:
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Offline hans

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Re: Most embarrassing junior tech moment? Go!
« Reply #26 on: May 12, 2023, 03:52:09 pm »
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 time :-// So what do you do with a drowsy mind after adding a power ferrite? Swap +12V and GND on a 20A bench supply, ofcourse. :-/O

Poof. :-BROKE

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.
« Last Edit: May 12, 2023, 03:54:49 pm by hans »
 

Online globoy

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Re: Most embarrassing junior tech moment? Go!
« Reply #27 on: May 12, 2023, 04:36:29 pm »
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.
 

Offline TopQuark

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Re: Most embarrassing junior tech moment? Go!
« Reply #28 on: May 13, 2023, 02:29:05 am »
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.
« Last Edit: May 13, 2023, 02:41:01 am by TopQuark »
 
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Online KE5FX

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Re: Most embarrassing junior tech moment? Go!
« Reply #29 on: May 13, 2023, 03:13:39 am »
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!

Amazing that you were able to recover from that in one night.   :-BROKE  Was that the HP 5451A?

 

Offline Halcyon

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Re: Most embarrassing junior tech moment? Go!
« Reply #30 on: May 13, 2023, 04:38:19 am »
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.  :popcorn:

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.  :palm:

He wore gloves religiously after that. I bet his hands were sensitive for aaageess  :-DD

I 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.

 

Offline bookaboo

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Re: Most embarrassing junior tech moment? Go!
« Reply #31 on: May 13, 2023, 04:56:09 am »
Spending well over an hour soldering a 40-pin Lemo connector then realising I'd forgotten the sealing gland.
 

Offline TERRA Operative

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Re: Most embarrassing junior tech moment? Go!
« Reply #32 on: May 13, 2023, 05:54:28 am »
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. :D
Where does all this test equipment keep coming from?!?

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Offline mfro

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Re: Most embarrassing junior tech moment? Go!
« Reply #33 on: May 13, 2023, 07:21:43 am »
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.

Beethoven wrote his first symphony in C.
 

Offline nctnico

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Re: Most embarrassing junior tech moment? Go!
« Reply #34 on: May 13, 2023, 10:33:00 am »
I quickly learned that I'm always right  >:D

Senior 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.
« Last Edit: May 13, 2023, 10:37:27 am by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline temperance

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Re: Most embarrassing junior tech moment? Go!
« Reply #35 on: May 13, 2023, 11:27:11 am »
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.

@nctnico
An 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.
« Last Edit: May 13, 2023, 11:40:34 am by temperance »
 

Offline madires

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Re: Most embarrassing junior tech moment? Go!
« Reply #36 on: May 13, 2023, 02:19:49 pm »
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.
 

Offline jonpaul

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Re: Most embarrassing junior tech moment? Go!
« Reply #37 on: May 13, 2023, 04:18:52 pm »


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
An Internet Dinosaur...
 

Offline chukin

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Re: Most embarrassing junior tech moment? Go!
« Reply #38 on: May 16, 2023, 03:30:30 pm »
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 Time

Peter
Modesty - my only failing!
 

Offline Stromlo

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Re: Most embarrassing junior tech moment? Go!
« Reply #39 on: June 26, 2023, 07:26:25 am »
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.  |O

I've never made that design mistake again!
 

Offline tszaboo

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Re: Most embarrassing junior tech moment? Go!
« Reply #40 on: June 26, 2023, 07:46:36 am »
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
 

Offline Miyuki

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Re: Most embarrassing junior tech moment? Go!
« Reply #41 on: June 26, 2023, 08:52:19 am »
Some classic moments with charged mains capacitors and one CRT holding a charge, that was intense  >:D

But the most embarrassing as a starting freelance was sending out untested design, thinking it was so easy. Gues what, it blew at the customer.
 


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