[sdiy] FW: [AH] DMM Calibration?

[Ron Malleis]

-----Original Message-----
From: Ron Malleis [mailto:tb303head at earthlink.net]
Sent: Wednesday, July 31, 2002 1:02 PM
To: Paul Schreiber
Subject: RE: [AH] DMM Calibration?
Importance: High



I was measuring "low voltage" at my house, and the utility asked if my meter
was calibrated properly when they came out for a service call (don't worry,
the AC feeds were so low, that even with any possible DMM error on my
behalf, it was STILL low, so they replaced the connection from the pole at
the house:^).  I then measured it again, and my DMM was still getting low
readings, although higher than before the service call (yes, I had checked
the batteries inside my meter, and they're fine)Later in the day, I compared
it to a couple of Flukes' readings in an AC receptacle, and my meter was ~3
volts too low in comparison (all the other functions were spot on with the
Flukes, including the DCV.  Rat Shack doesn't seem keen on providing any
info towards calibration, they want me to bring/send it in.

So, do the trimpots (well,they LOOK like trimpots, anyway) affect only the
ACV calibration, or is it dependent on where the rotary switch is as to
which function is calibrated (encoder?).  Hope this is more specific, and
any help is appreciated (can't be without my meter by sending it in!!!)

Thanks,

-R
-----Original Message-----
From: Paul Schreiber [mailto:synth1 at airmail.net]
Sent: Wednesday, July 31, 2002 12:14 PM
To: tb303head at earthlink.net
Subject: Re: [AH] DMM Calibration?


Well, I *designed* it, but that was about 15 years ago!

The trim pots are a "Coarse" and a "Fine" for calibration, that much I do
remember. How do you
know it's off?

Paul S.


----- Original Message -----
From: "Ron Malleis" <tb303head at earthlink.net>
To: "Ahot at Retrosynth. Com" <ahot at retrosynth.com>; "Synth-Diy at Dropmix.
Xs4all. Nl"
<synth-diy at dropmix.xs4all.nl>; "Analogue at Hyperreal. Org"
<analogue at hyperreal.org>
Sent: Wednesday, July 31, 2002 1:56 PM
Subject: [AH] DMM Calibration?


> Hi,
>
> My DMM is out of calibration when measuring AC volts.  There are 2
trimpots
> inside, but I don't want to start indiscriminately turning them
(especially
> since every other function seems to be accurate).  Any info on how to get
it
> into shape?  I'm having trouble finding info on this (FYI, it's Radio
Shack
> DMM #22-174B).
>
> TIA,
>
> -R
>
>