Common-Mode Choke Failure

[@Apismeliffera]

I had one fail open on me, just one winding. That was after it was in use for nearly 30 years. After discovering that, I unwound it, measured the wire diameter and rewound both coils with some new wire and normal operation was restored. Mine was in an antique computer power supply. Replacements were no longer available. But the repair was simple enough. If you look at the ends of the wire carefully with a good magnifier, you might be able to see wire deformation at that ends caused by small diagonal wire cutters. Nice video, thank you for posting it.

[@W1VLF]

Following your logic, I thought perhaps one of the wires was broken at the terminal... But when you measured both sides opened it got quite suspicious. I really enjoyed watching your video.. Thank you for making it !

[@Duracellmumus]

May pull out the pins when something put some force on this side or the white gule get smaller when it gets set. This is why practical to bond the components to PCB and not to eachother. Because only the pcb has any mechanical support from case itself.

[@jacobsteel]

Great video. I agree with previous guesses that heat-expansion might have caused it... strange though...

[@nitin2668]

Awesome video..what is function of it

[@paolodelavictoria]

Hello, when u buy a new replacement choke and unlike the original broken one with "white glue" still on it as an indication or reminder which side it was original facing on the pcb as lengthwise it's symmetrical and can also be inserted the other way around, how do u know it's proper orientation or it doesn't matter? Im only concerned about the markings on the pcb which specifically indicates a tiny square on the edge so meaning it's kinda "polarized". appreciate the response.

[@felixcat4346]

OMG, OMG, Now I need to check all my chokes!

[@xyloeye]

I was troubleshooting an old Tek scope today and one of the common mode chokes in the line input filter started making noise and then emitted a bunch of smoke - part of the SMPS voltage to smoke converter phenomenon, I guess. I wasn't even taking measurements when it happened. It also blew a hole in the side of a bypass cap adjacent to it. I'm guessing the cap spontaneously shorted and took out the choke. Anyway, thanks for a great video.

[@williamhazelwood8288]

Cool video, the gap does not seem to far, possible to bridge it with a jumper or huge messy blob or solder?

[@EdEditz]

I'd take one from an other power supply and use that. I've got a drawer full of those things all desoldered from broken power supplies.

[@eIektrinis]

you have dropped it on a side, and the inertia slightly pulled out two pins out of plastic body. Must have been a good drop.

[@educationaltechnology8363]

enjoyed watching and is what I was looking for thanks for sharing

[@randydicotti3975]

"You! Yes, you! Stand still laddy!"

[@gordslater]

^^^ Poems everybody! The laddy reckons himself a poet !!! If you don't eat yer meat how can you have any pudding??? How can you have any pudding if you don't eat yer meat???

[@frankgeeraerts6243]

looks like there's an unhappy worker at the factory ..........( soldered and cut after )

[@johncunningham5435]

That is bizarre; In all the years of servicing I have never come across a double failure in a choke. After careful consideration and looking very closely I believe it was sabotage, you can clearly see it was cut on both sides of the leg. If one side had been affected that could change my opinion, however when you consider that it slipped through quality control undetected one must wonder.

[@Edu_RJR]

that may be a common failure since they used so much gunk, maybe something wrong with the manufacturing and later stress during assembly of the case

[@JimmyJoXS]

looks like the pins pulled out from mechanical shock.

[@hpevans9041]

Very well explained, thanks

[@dendanedjalil2436]

you can still fix it ... a wire soldring and an good lacquer fo isolation

[@davecc0000]

Unwrap 1 turn of wire & resolder.

[@FlyingShotsman]

He'd have to unwind all of it. The cut ends were at the start of the windings. See close-up at 4:40.

[@tayro7265]

@@FlyingShotsman That sux. I would have said the same thing about unwinding a turn butttt...

[@sayoosayoo-px9es]

Oh yes , I solve similar problem in 2 min last week 😀😀😀..

[@TheMichaelJohnD]

Clever; well done

[@wolfgangbeginners-mind2853]

Its happed to me, cheap quality wire in the chokes.

[@gamemaster1324]

huh... interesting failure point... I've seen transformer failed, but not this...

[@seanzeng2185]

My company produces this product with fully automated equipment

[@riloariichoariicho884]

In my case my transformer is gone and cant replace it

[@vant4888]

The wire was winded with tension so after a couple of months of heating/cooling cycles it just snap. Viva China! I had an ancient precision resistor bank where wires in coils break in multiple locations...

[@jugnu361]

great

[@samueldaniel7]

its due to heat