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

Sun Mar 9 18:33:55 EDT 2014

Ray, have you tried W7FG, BAMA, Google? The 'good' thing about VTVMs is that they almost always use the same circuit. I have a couple of old VTVMs (B&K Model 375s) one of which drove me nutz. These have a complicated, rotating drum / turret assembly. I couldn't get it to work the way it should. FINALLY, I found a bad ground and it's working OK again....

ron

-----Original Message-----
From: Ray, W4BYG <w4byg at att.net>
To: bonddaleena <bonddaleena at aol.com>
Sent: Sun, Mar 9, 2014 5:48 pm
Subject: RE: [Test-Equipment] "possessed'" VOM(s)

Ron,
Saw your post below.  I also collect a bunch of VTVMs.  

Currently, I'm looking for a schematic on a rather rare Superior Instruments
X-Rayometer.  It is a fairly large multi-function VTVM, with a large round
7" meter face.  The 1939-40s adds describe it as having a 9" meter, but that
would include the outside meter escutcheon.  I have been unable to locate a
manual or schematic for it.

Any chance you have such or know where I can find one?

Thank you for your attention.  Anything you can do to help will be
appreciated.
73

Ray, W4BYG

"The Republic can survive a fool for a president...  It is less likely to
survive a multitude of fools, such as those who made him their president."

-----Original Message-----
From: test-equipment-bounces at mailman.qth.net
[mailto:test-equipment-bounces at mailman.qth.net] On Behalf Of
bonddaleena at aol.com
Sent: Sunday, March 09, 2014 4:58 PM
To: wlfuqu00 at uky.edu; 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>
To: bonddaleena <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
[test-equipment-bounces at mailman.qth.net]
on behalf of bonddaleena at aol.com [bonddaleena at aol.com]
Sent: Saturday, March 08, 2014 6:00 PM
To: 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
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