Re: P6042 -- bad line cord

Chuck Harris
 

In the days of my youth, I used to get many of
the necessities of life from the local dumpster.
Irons, ironing boards, TV's, microwaves, toaster
ovens, hair dryers, vacuum cleaners... stereos,
stuff like that. (no computers, they weren't yet
available to the masses.) I was in a college
town, so you could count on the students throwing
away enough to furnish an apartment every year...
if you weren't too fussy, and knew how to clean
and make repairs.

One thing I came to notice is that power cords
break, and when they do, they always break in the
exact same way: the bundles of fine wires looked
like they were snipped off square with a shear...
only there was still insulation, so that would be
an amazing snip job, if it were possible.

What I figure happens is a weak strand breaks,
which increases the stress on the neighboring
strands, at the weakest point, which is right at
the break in the broken strand... So, as more
flexing occurs, another strand breaks at that weak
point, which further increases the motion there,
which breaks another strand, and on, and on, and
on, until the wire bundle has been sheared off
square, one strand at a time.

Finding the break in the two wire power cords was
easy, just stretch the cord, by bending it into a
flat curve, and the break will be where the insulation
stretches, and thins... because there is no copper
under it to keep it full diameter.

For sheathed power cords, you have to guess at
which end the break will be, and remove that end.
Then pull on the wires, hard, and the broken wire
will pull out of the insulation, revealing the nicely
squared off end, and the length to the break.

The location of the breaks would always be about 1/2
inch outside of clamp, in the strain reliefs, on the
hand held side of the cord...

-Chuck Harris


sdturne@q.com wrote:

Oh, also, it looks like the problem is in or near the plug. I used some advanced probing techniques (really just a normal 10x probe held near the cord) to note that the 60 Hz AC waveform disappears nearly entirely past the plug, compared to a known good line cord that shows a waveform all the way down.

Sean

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