On the FLUKE vs. the "inexpensive" meters....
BUY THE FLUKE! I bought one of those "METRIX" Brand knock offs,
that cost about 1/2 the price. Quite happy at first, but couldn't
figure out why my voltage at a radio connection was only 8V. Odd,
starting tracing it back to the battery, what 8.2v at the battery...
but the headlights were BRIGHT when I turned them on. After spending
too much time on the problem, I pulled out my trusty handheld O'scope
which confirmed the 12.8v was really there. That @#$%! meter still
read incorrectly.
Finally, after switching to another voltage range... another reading.
Took a while, but finally discovered the "wiper" switch was tarnished.
If you rotate the dial back and forth for a while, it will give a
reasonable reading... for a day! Arrg!
So that "Metrix" meter is still in the tool box, which I let my six
year old son use to "help me". I bought the FLUKE to use (model 73...
about $100, and worth it!
Oh, when my son gets old enough to use a meter... I'll get him a FLUKE,
too. ;-)
TECH NOTE: Around here I have a couple of O'scopes, and a handfull of
various electronic gear... for "simple" trouble shooting I still like
a TAIL LIGHT BULB with two alligator leads. Since a meter takes "zero"
current to read a voltage, a corrosive terminal can fool you. With the
light you'll notice it is dim, and visually is great when I have my
head under the dash.
TECH TIP II: For those of you who run out an buy a O'scope, do remember
that the back emf on the primary side of the coil will be around 400V.
That is enough to blow the front end circuitry out of a nice scope.
When I worked at Bosch my coworker did just that, hey good thing that
$10,000 instrument wasn't mine! ;-) [Hand held scopes are just the
thing for the spouse's fuel injected vehicle... that is another story.]
Cheers,
Tom "life is too short, enjoy the drive" Walter
Austin, TX.
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