I need some help with my 4 digit wemos clock.

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3 months 4 weeks ago #11345 by Galesloot
update!
I took a closer look at the faulty inductor. I cut the winding at one leg and unwound it.
I would expect there to be a fusion somewhere but that was not the case. I was able to unroll it without any problem. Wire thickness 0.2mm and 75cm long. Then rolled up again and soldered the wire to the leg again.
And guess what, it's another inductor instead of a resistor. The short circuit has disappeared.
The measurement now indicates 0.06MH and is therefore far too low! I will not use it again.
Thanks for all the help and see the pictures.

Best regards, Wim
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3 months 4 weeks ago #11346 by Ty_Eeberfest
Thank you very much for the detailed report! I too was expecting you would find fused wires or at least burned insulation. So the cause remains a mystery. My best guess - and it is only a guess - is that the winding machine was making tiny scrapes in the lacquer insulation that day and two scrapes happened to touch. It seems unlikely but that's all I can think of (without examining every inch of the wire under strong magnification - no thanks!).

So I'm going to say that a mysterious factory defect in the inductor caused it to short out and kill the MOSFET.

Look into it later when the dust is clearing off the crater.
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