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Almost Got My Eye Poked Out

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coppercone2:
I wear safety glasses when dealing with any power PCB. capacitors can go off too.

coppercone2:

--- Quote from: PwrElectronics on June 06, 2021, 06:21:51 pm ---Had a near miss long ago.  Shortly before I needed to wear glasses I was working on something and a TO-92 package device blew and a chunk when whizzing past my head just past my eye.  Found the piece 1/2 way across the room behind me.

At a prior work place, I was a engineer at the factory responsible for some production testers.  We made power supplies.  There was this bare board assembly that was 90-240VAC to 48VDC that got tested separately before being installed in the chassis and final assembly.  The test fixture was a box with a clear plastic lid that the test operator put the board into and connected the cables and closed the lid (on a interlock switch).  This board had a bunch of electrolytic capacitors on it that were installed by hand on the line and wave soldered.  It was not uncommon for that to be done wrong with 1 or more of them in backwards.  Those caps were off of the line rectifier for a off-line switcher topology.  They would not blow right away but seemed to let go when the test sequence changed from the nominal 120VAC tests to the 240VAC tests.  Then they would vent violently and loudly.  That plastic lid had to get replaced with a sturdier material after it cracked from impacts and it was also melted.  There was a very "jumpy" young woman that usually ran that station and she soon learned to check those boards carefully for backwards caps before hitting the start button on the tester!

--- End quote ---

might be wise for production to put sharpie marks on top of the capacitor (arrow) so you can see from the top if they are installed in the correct polarity, it might be worthwhile if you have enough power capacitors

You would think they would put a top side marker on capacitors that plainly visible because their expensive, fail bad, inserted manually, difficult to rework (goo). They treat it like a stupid 2 cent passive component but they are like $6 each for a good one. Like a red dot. Granted good capacitors are asymmetrical.

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