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

Sat Mar 15 12:02:35 EDT 2014

 Bill, you hit it! I looked at the SM resistors and was trying to read the code on the resistors in the X1 circuit. What I thought was flux or some other crud on the resistor, was indeed a fracture. Using an old resistor sub box and a precision resistor (in the X1 circuit), I simply placed the new resistor in the unused thru-hole already there.
This has been one of those things that has been bugging me, but just now had time to look at it.

Thanks again!!

ron
N4UE

-----Original Message-----
From: Fuqua, Bill L <wlfuqu00 at uky.edu>
To: bonddaleena <bonddaleena at aol.com>
Sent: Sun, Mar 9, 2014 7:58 pm
Subject: RE: [Test-Equipment] "possessed'" VOM(s)

I have never heard of a shorted resistor either. That is why I was thinking 
there may be a voltage divider in the X1 ckt and the a resistor has opened up 
providing full battery voltage to the circuit. 

73
Bill wa4lav

________________________________________
From: bonddaleena at aol.com [bonddaleena at aol.com]
Sent: Sunday, March 09, 2014 6:25 PM
To: Fuqua, Bill L; test-equipment at mailman.qth.net
Subject: Re: [Test-Equipment] "possessed'" VOM(s)

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.
I can almost (!!) guarantee that the ohmmeter was connected across a voltage 
while troubleshooting a problem in one of my old Swan radios.
Just never heard of a resistor 'shorting' before. Then, as mentioned, I'm not a 
sm expert! ha ha

ron
N4UE

-----Original Message-----
From: Fuqua, Bill L <wlfuqu00 at uky.edu>
To: bonddaleena <bonddaleena at aol.com>
Sent: Sun, Mar 9, 2014 5:39 pm
Subject: RE: [Test-Equipment] "possessed'" VOM(s)

  What is really strange is that it reads all (zero) or nothing (infinity).
Is there no value that gives you a reading in between?
Very strange behavior for an Analog meter unless it has some active
devices in it. But I doubt it does.  Does it have two batteries like the 260 or
just one?
If only one it may use a voltage divider to drop the voltage to a lower value
for the X1 range
and then passes it thru the meter and zero set resistor.  If so then perhaps the
lower
side of the voltage divider is open providing full voltage to the rest of the
circuit.
  Gee, they used to have schematics with meters in the old days.
73
Bill wa4lav

________________________________________
From: bonddaleena at aol.com<mailto:bonddaleena at aol.com> [bonddaleena at aol.com<mailto:bonddaleena at aol.com>]
Sent: Sunday, March 09, 2014 4:57 PM
To: Fuqua, Bill L; test-equipment at mailman.qth.net<mailto:test-equipment at mailman.qth.net>
Subject: Re: [Test-Equipment] "possessed'" VOM(s)

Hi Bill. No, it's strictly analog. I have a LOT of VTVMs, etc, as mentioned. All
were bought off of eBay and I have refurbished them all. I collect Test
Equipment (some kind of disorder). Just to put a stake in the ground, I have
over 24 'scopes I have fixed / refurbished. This particular VOM is a 'Sunwei
Model YX-360TR'. These are only $15 on eBay, with free shipping, so I consider
them a 'throw away'.
I have several other 'nicer' VOMs that are just digital and some that are analog
/ digital.
I guess I'm 'not right', because I like the strictly analog meters, just for the
reasons listed above. Yes, I have several 260 meters also......
The only thing I can figger is that one of the sm resistors (for the X1 range)
is shorted. All the other resistance ranges are fine.
What is SO frustrating is there is almost NOTHING in there!

So, I ordered another Sunwei and will determine what's up.
These are a pretty nice VOM for the $. MUCH better than the VOMs sold in Lowes
and Home Depot.... ha ha

ron

-----Original Message-----
From: Fuqua, Bill L <wlfuqu00 at uky.edu<mailto:wlfuqu00 at uky.edu>>
To: bonddaleena <bonddaleena at aol.com<mailto:bonddaleena at aol.com>>
Sent: Sun, Mar 9, 2014 3:57 pm
Subject: RE: [Test-Equipment] "possessed'" VOM(s)

  Can you tell us more about the cheap Chinese VOM. Is it digital as all of the
current ones are and cost a few bucks.
73
Bill wa4lav

________________________________________
From: test-equipment-bounces at mailman.qth.net<mailto:test-equipment-bounces at mailman.qth.net><mailto:test-equipment-bounces at mailman.qth.net<mailto:test-equipment-bounces at mailman.qth.net?>>
[test-equipment-bounces at mailman.qth.net<mailto:test-equipment-bounces at mailman.qth.net><mailto:test-equipment-bounces at mailman.qth.net<mailto:test-equipment-bounces at mailman.qth.net?>>]
on behalf of bonddaleena at aol.com<mailto:bonddaleena at aol.com><mailto:bonddaleena at aol.com<mailto:bonddaleena at aol.com?>>
[bonddaleena at aol.com<mailto:bonddaleena at aol.com><mailto:bonddaleena at aol.com<mailto:bonddaleena at aol.com?>>]
Sent: Saturday, March 08, 2014 6:00 PM
To: test-equipment at mailman.qth.net<mailto:test-equipment at mailman.qth.net><mailto:test-equipment at mailman.qth.net<mailto:test-equipment at mailman.qth.net?>>
Subject: [Test-Equipment] "possessed'" VOM(s)

OK, I'm almost embarrassed to post this, but it's driving me crazy....
I have a LOT of VTVMs, FET VOMs, VOMs, etc. At one of my test benches, I use an
el-cheapo Chinese VOM that gets a lot of use. Although for serious work, I have
a dedicated VTVM there, the VOM gets a lot of use.
Recently, I noticed that the X1 ohms function didn't work correctly. (all other
functions/ranges are OK). When selecting X1, no matter what resistor is being
measured, it indicates ZERO Ohms. Of course, when not connected, the meter reads
infinity.
ie: putting a 1K resistor across the leads, it reads 0 Ohms, but when switching
to X10, X100, X1K, the readings are OK.
So, I pull it apart and other than some sm resistors and a couple of diodes for
AC/Audio, there's nothing in there. I have looked at the contacts, the board,
etc, and can see nothing wrong.

The thing that bothers me, is that this problem is exactly the opposite of what
would seem logical.......If a resistor in the circuit were open, there wouldn't
be ANY movement on X1. If a resistor were shorted, wouldn't there be an
indication as soon as X1 was selected?

Tomorrow, I'll try to check the sm resistors but they have some strange
markings.

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.

ron
N4UE
______________________________________________________________
Test-Equipment mailing list
Home: http://mailman.qth.net/mailman/listinfo/test-equipment
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Test-Equipment at mailman.qth.net<mailto:Test-Equipment at mailman.qth.net<mailto:Test-Equipment at mailman.qth.net<mailto:Test-Equipment at mailman.qth.net?>?>

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html