[Test-Equipment] "possessed'" VOM(s)

[Fuqua, Bill L]

  I sure wish schematics came with products these days.
Remember the Heathkit catalogs that had schematics with each 
description? Being as those schematics were small it is obvious that
things were simpler those days but they did the job.
  Now, new cars have more computing power than the space shuttle. Some
with 9 or 10 air bags, variable timing cams, GPS, Cell Phone, Satellite Radio.
No wonder that they cost half as much as a home.
  I love my 70 Beetle. And my older radios, and test equipment. 
New test equipment is impossible to repair, and some service manuals
don't have schematics and just tell you which boards to replace. 
73
Bill wa4lav

________________________________________
From: test-equipment-bounces at mailman.qth.net [test-equipment-bounces at mailman.qth.net] on behalf of k4pf at juno.com [k4pf at juno.com]
Sent: Sunday, March 09, 2014 10:24 PM
To: test-equipment at mailman.qth.net
Subject: Re: [Test-Equipment] "possessed'" VOM(s)

> Ron N4UE bonddaleena at aol.com wrote
> Hi Bill. No, there are NO active devices in it. The thing is basically a small pcb with a wiper and some sm resistors. TOO simple. The X10, X100 and X1K ranges are fine. I have a 1K resistor I use to check it.
>I found this problem 'by accident' when checking a 75 Ohm pot for my antenna rotor. I understand using the 1X range will show the slightest resistance in the Banana connectors / cables, etc. However, before connecting ANY resistor, the meter shows Inf. When ANY resistor is connected on the X1 range, it shows ZERO resistance.
<snip>

Hi, Ron

I would look vary carefully at the VOM rotary switch contacts
associated with the RX1 scale.  If the switch is as small as you imply,
probably some of the metal has been vaporized.  The meter movement
is not damaged, because over-current protection diodes
are probably present. With that RX1 resistor shorted out,
the next time you attempted to zero your Ohmmeter set to RX1,
you put all the current the AA cell can put out
through the switch contacts.

73,
Ed Knobloch

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