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Most embarrassing junior tech moment? Go!
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PwrElectronics:
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 parts  :palm: :-[

It was the cleanest etch of all of them I made and it was junk.  I have it someplace...
Berni:

--- Quote from: PwrElectronics on May 12, 2023, 02:59:33 am ---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 parts  :palm: :-[

It was the cleanest etch of all of them I made and it was junk.  I have it someplace...

--- End quote ---

Yep 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.
jonpaul:
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



TERRA Operative:

--- Quote from: madires on May 11, 2023, 06:03:07 pm ---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.

--- End quote ---

I 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 connectors before I 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! :-/O

I have noticed things are declared at much closer to their real value since then. :D I bet there were a few spanked bottoms over that one..  :-DD
TERRA Operative:
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.  :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
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