I don't know if I blogged the incident a few weeks ago when I connected my Dell Auto-Air adaptor in reverse polarity. After that, it no longer functioned on 12V but still worked with AC power through my inverter. I did some checks, and found that there was power coming out the tail end of the cigarette-lighter plug but not out of the D-shaped connector that plugs into the adaptor. I suspected there was a fuse hidden in the EMI suppressor; today I decided to test this hypothesis.
I cut the plastic from around the ferrite cylinder, and cut the wires on either side of it. Prying the plastic end-plugs out with pliers, I finally got something that looked like a fuse, covered with shrink tubing, on my worktable. Cutting open the shrink tubing, there was a blown T8A250V fuse. Aha!
Now to splice everything back together, sans fuse, and see if the damned thing works with 12V again.
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last updated 2013-01-10 20:54:18. served from tektonic.jcomeau.com