Actually, even better, in my hurry, that meter has a "beep" continuity test above the Ohm reading. So that setting you can hear the result without looking at the screen.
If it beeps, it's shorted.
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Also, ideally, swap the meter leads on the device under test both polarities since this is AC. In other words the meter supplies and checks with DC one polarity, but since the device (TVS) is bi-directional AC and could fail in one direction only, we check both polarities for short.
RETESTED with the 'other' setting
Both ends connected
The 'red' lead is disconnected
I wasted a lot of people's time here because of one comment made WAY at the beginning about the meaning of a '0' read. My apologies.
THANKS -- watl
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@Vernon Barry posted:It's a diode, you should be using diode check on that meter. That's why you might get readings you cannot make sense of.
Not really, this is a special kind of diode, and we're just looking for a shorted or open indication. Unless the meter tests diodes with around 40 volts, you won't get any reading on the TVS he's using.
That "OL" reading on a digital meter throws a lot of people. Most agree it stands for "open loop" which means you do not have continuity, otherwise.... an open circuit. This is one reason why I tend to use my ancient radio shack analog meter whenever I can....
@hokie71 posted:That "OL" reading on a digital meter throws a lot of people. Most agree it stands for "open loop" which means you do not have continuity, otherwise.... an open circuit. This is one reason why I tend to use my ancient radio shack analog meter whenever I can....
I actually never really even "see" that, I just read it as open. When we started this discussion, I was somewhat at a loss as to the exact indication, as I just "see" infinity. 
Are you sure it didn't say OL? That's often used to denote "overload" and is what you see when there is a very high resistance or open circuit.
Edit: sorry looks like others beat me to it as I left the page open to go do some chores.
@walt rapp posted:Thanks John. I was going by a comment that Bruce Brown made:
If the resistance reads "0", then the TVS is shorted.
Well, I'm getting into trouble again. I should have stated that OL = infinity and .0 = zero (shorted) on digital meter resistance scale. Highlights an advantage of the "old" analog VOM markings where ∞ (sideways 8) = infinity and 0 = zero!
@gunrunnerjohn posted:It says what it says.
One clue is the M Ω on the right, and the analog bar at the bottom at max.
Yeah sorry John I was actually replying to Walt's first reply but got busy and forgot to reload the page before replying. A lot of meters display OL when a voltage or current measurement is over the selected range.
It's sort of a vestige on newer auto range meters and MAX would probably make more sense, but that would require an 11 segment display.
@hokie71 posted:That "OL" reading on a digital meter throws a lot of people. Most agree it stands for "open loop" which means you do not have continuity, otherwise.... an open circuit. This is one reason why I tend to use my ancient radio shack analog meter whenever I can....
Another day not wasted....learned something again!
So Walt, now that we are on the same (testing) page, are there any of your TVS's that are reading shorted; 0.0 ohms, or beep on the test setting? If not, then your short that you saw (the one that started this topic) must be caused by something else.
By the way, your method for installing the TVS's on the lockons is quite effective, and unobtrusive. Nice idea!
My most recent shorted TVS was at our Xmas trainshow layout this last December. I typically use a TVS on each TIU input, or transformer output. In this case they are on the TIU inputs and one day we had a mysterious short on one of 6 loops, that persisted after all trains were removed. Disconnecting the output wires to the track from the TIU made no change, so next was disconnecting the TVS. Sure enough problem cured, and the TVS was quite warm to the touch. So it shorted for whatever reason. I'd like to think that it died whilst doing its job.
Rod
This was why I suggested using other "modes" of the typical meter- to assist in potentially avoiding confusion of overload, true 0 Ohms and other edge cases. In addition, deep under the layout- audible beep continuity test can be quicker, easier, and less guessing.
Again, depending on the meter, some "bundle" beep continuity test and diode check, where this meter had separate settings.
YMMV
@gunrunnerjohn posted:It says what it says.
I am throwing the "foul" flag, no fair using a multimeter that costs more than a boxcar....
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@hokie71 posted:I am throwing the "foul" flag, no fair using a multimeter that costs more than a boxcar....
Yes, but it's a very nice boxcar ...
... and it's scale sized...
... and it has a lot of detail ...
... and it's protypically correct ...
... and it's made by the long-time recognized leader in the business.
Mike
Vernon made a comment that intrigues me: " In addition, deep under the layout- audible beep continuity test can be quicker, easier, and less guessing."
Is he saying that if I test a TVS for continuity it will 'beep' (meaning there's continuity) if the TVS is GOOD?
That's an easier test TO ME.
thanks walt
@walt rapp posted:Vernon made a comment that intrigues me: " In addition, deep under the layout- audible beep continuity test can be quicker, easier, and less guessing."
Is he saying that if I test a TVS for continuity it will 'beep' (meaning there's continuity) if the TVS is GOOD?
That's an easier test TO ME.
thanks walt
While I realize everyone is at different stages of learning and terminology, we have to reach a baseline to have a conversation
Open circuit- no continuity- AKA not a complete path
Closed circuit- possibly shorted on a circuit not intended to be closed by this device- thus "continuity".
@Vernon Barry posted:If it beeps, it's shorted.
Again, if you put the meter leads across the TVS and the meter is set to continuity "Beep"-- and you get a beep, then that TVS likely has failed and shorted. Again, picture below, meter red and black leads on the TVS diode by itself not connected to track, meter set to "Continuity" and has the "beep" or sound symbol.
if you get NO beep, that indicates hopefully that TVS is NOT shorted and thus not "bad". Again, at best, no beep = TVS is not shorted and shorted = failed.
Just to be clear, we really cannot tell 100% good with just a simple meter test, but we can identify a definite hard shorted failure.
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@walt rapp posted:Vernon made a comment that intrigues me: " In addition, deep under the layout- audible beep continuity test can be quicker, easier, and less guessing."
Is he saying that if I test a TVS for continuity it will 'beep' (meaning there's continuity) if the TVS is GOOD?
That's an easier test TO ME.
thanks walt
Walt, I think Vernon made this comment as a generalization for working under the layout.
If a TVS beeps on the cont test setting, IT IS SHORTED OUT AND FAILED, period. If it does not beep, it is open circuit and likely just fine. Understandable?
Rod
Put another way, when testing the TVS and you get a continuity BEEP- that TVS is "beeped".
You guys are awesome. Thank you
I guess it’s obvious I am not very smart about electrical things
I learned so much in this one thread I really appreciate everyone’s contributions
As always, Thanks Walt
Also, some auto ranging digital meters take a while to beep while they adjust.
You can often fix this behavior by touching the leads together and waiting for the beep, then hit the Range Hold button. After that when it sees a short it will beep instantly.
