[R-390] Meter Meister?

[Barry Hauser]

Joe & List:

If it isn't particles or a bad protective diode, it may be that the armature
has come off one of its bearings or is loose.  Depends on the design, but
many meters have needle bearings which are adjustable.  It's sometimes
difficult to spot because just the very tip of the tiny shaft may become
warn enough to slip out of center and jam.  Usually the needle won't move at
all, but I've seen cases where they'll move partway in one direction.  If
the meter has adjustable bearings, you can loosen a locknut and turn in the
bearing slightly to tighten it up.  If that's the case, be careful not to
overtighten and make sure the shaft lines up straight as you do so or you'll
damage what's left of the pointy end of the shaft or bend it altogether.
(Center the shaft somehow and just tighten a small amount, then blow on the
needle to see if it swings freely.  If/when it does -- stop.  A bit too much
and the needle won't move, then back off a smidgen.)  Often these adjusters
are secured with a droplet of glyptol or cement. Usually a partial situation
is obvious because when the shaft is crooked, the needle hits the scale, but
sometimes it's the "tail" of the needle or some other part that binds
because it rubs up against something, or even the spring itself gets out of
sorts due to the misalignment. Those situations are not so obvious.

Barry


----- Original Message -----
From: "Joe Foley" <redmenaced@yahoo.com>
To: <r-390@mailman.qth.net>
Sent: Saturday, June 14, 2003 10:29 PM
Subject: [R-390] Meter Meister?


>
> >
> > I need someone to tell me what I just did to ruin
> > this
> > DC voltmeter.
> >
> > I was checking the voltage on a UPS when my Steel
> > Six
> > meter decided to crap out!  Not good, I liked that
> > meter!
> >
> > It seems to have either demagnetized the magnet or
> > magnetized the vane, not sure  which.  The coils are
> > Ok because when I reverse the probes the needle is
> > drawn below zero, it just won't go above about 2
> > volts
> > on a 50 volt scale.
> >
> > If there was an AC component on the DC I was
> > measuring
> > would it have done this?  The charger was on, I was
> > trying to determine if the batteries were charging.
> >
> > Thanks,
> >
> > Joe
>
>
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