Re: Earth resistance

On Fri, 25 Jan 2008 13:10:29 -0000, Doki <mrdoki@xxxxxxxxx> wrote:


"Doki" <mrdoki@xxxxxxxxx> wrote in message news:5vu50cF1njaj9U1@xxxxxxxxxxxxxxxxxxxxx

"Dave Plowman (News)" <dave@xxxxxxxxxxxxxxx> wrote in message news:4f664e3564dave@xxxxxxxxxxxxxxxxxx
In article <5vrtndF1nuj0jU1@xxxxxxxxxxxxxxxxxx>,
Doki <mrdoki@xxxxxxxxx> wrote:
I'm trying to track down a fault with my car's clocks. One earth is
showing very low resistance (negative for some reason on my cheapy
multimeter), and the other is showing around 50 ohms. Does this sound
anything like right?

If the meter zeros ok on the ohms scale sounds like there's some volts
there.

50 ohms is far too high - I doubt it ever was a true earth connection.
What colours on the wire?

Grey.

By the way, the clocks started playing up after a battery charger was connected up in reverse. Several sets of clocks have exhibited the same faults, so I reckon it's the wiring. Am I right in thinking that the diode between pins 3 and 13 would have allowed basically an open circuit so it's likely the wiring's knackered somewhere? Or should it have munched a fuse?

If you're sinking a reasonable amount of current all the time you might have blown a diode short circuit, which would bugger up your resistance readings.
.

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    ... showing very low resistance (negative for some reason on my cheapy ... and the other is showing around 50 ohms. ... 50 ohms is far too high - I doubt it ever was a true earth connection. ...
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