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

[hwhall at compuserve.com]

Based on the limited description of the innards, it sounded like the possessed meter is a digital VOM, unlike the (may I say more easily diagnosed & repaired?) Triplett 310.
 

 Wayne
WB4OGM



-----Original Message-----
From: k4pf <k4pf at juno.com>
To: test-equipment <test-equipment at mailman.qth.net>
Sent: Sat, Mar 8, 2014 7:37 pm
Subject: Re: [Test-Equipment] "possessed'" VOM(s)

 
 
 
 
 
> Ron N4UE bonddaleena at aol.com wrote 
<snip> 
What was REALLY crazy was this... I pulled out one of my Triplett 310 VOMs and  
it did the  
SAME thing. OK, the 310s are beat up and have been around the world with me, but  
at this  
point, it was time to quit. 
Is there ANYTHING in the circuit (other than the fuse) on X1? Sure doesn't look  
like it. 
All my other meters check the resistor OK. 
 
Hi, Ron 
 
On the RX1 scale of a VOM, there is a resistor in series 
with the meter and battery; its value = half-scale of the RX1 scale. 
For instance, with a Triplett 310 type 3 or type 5 VOM,  
1/2 scale on RX1 is 200 Ohms, and that's the value of R10 of the schematic. This  
resistor is used for RX1 scale only. 
 
The RX1 and the RX10 series resistors are the most likely ones to fail, 
if the VOM accidentally is put across a live circuit when set to Ohms. 
 
The resistor used for RX10 scale should also be checked, "R9", 2.2K 
for the Triplett 310 types 3 and 5 
 
73, 
Ed Knobloch  
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