Bob
+7
Cubdriver
audiobill
sailor
sKiZo
deepee99
wildiowa
Bob Latino
11 posters
Bad multimeters
Bob Latino- Admin
- Posts : 3263
Join date : 2008-11-26
Location : Massachusetts
- Post n°1
Bad multimeters
I seem to have more and more Emails from customers about voltages that are "way off"... A USA line voltage at 137.5 volts? I don't think so .. In all cases we find out later that the meter is defective or the battery in the meter is bad - but some DIY'ers will religiously believe that meter even when the reading that they get makes no sense at all ? At the very least, check the (usually a 9 volt) battery inside and see if it has the proper voltage. Get your self a good and reliable multimeter or better yet > Always have TWO meters on hand so that you can check one against the other. I have here three multimeters - A B&K that I use on a daily basis which is accurate, a Fluke 115 that is even more accurate and an inexpensive Chinese meter that I got off Ebay that seems to work well. The Fluke sits in a drawer and is only brought out to cross check with the other two meters. Another thing ... When you buy a meter, it makes good sense to get one that also measures capacitance. (With the amp OFF) taking a few capacitance readings especially of the high voltage system can sometimes tell you a lot about why your amp/preamp is not functioning as it should. OK - enough said ... Sorry if this sounded like a rant but (IMHO) all people doing DIY work should have a reliable meter and a back up meter to cross check readings if the readings seem wrong ...
Bob
Bob
wildiowa- Posts : 237
Join date : 2012-03-19
- Post n°2
Re: Bad multimeters
"Interesting/Unique Uses for Multimeters" - My 90 year old mother recently had a raccoon problem that could not be solved. I got a pretty beefy electric livestock fencer for her back deck and we had no more raccoon problems after they got lit up a couple of times. I did make the mistake of checking the fence wire with my multimeter to see if it was functioning after setting it up and needless to say that meter is no longer with us. I don't know how many volts are in those things I thought 600v would be OK but it fried it good. Expensive mistake. A word of caution....
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
- Post n°3
Re: Bad multimeters
Get a Fluke and be done with it.
sKiZo- Posts : 1530
Join date : 2013-04-01
Location : Michigan USA
- Post n°4
Re: Bad multimeters
Another option, and yet another great tool for the crib, is a Kill-A-Watt meter ...
Good for cross checking the AC side of a VOM anyway ...
All bets are off if you're still using an analog meter. Those are only accurate within a small range of needle movement due to parallax error. The farther you go from the set level listed in the specs, the less accurate. Pegging the needle when using the wrong range doesn't help either. This holds true even for the TOTL meters to a certain degree. A digital meter is also way more forgiving when it comes to polarity or range ooPsies.
And yes, a couple quality meters are handy to have for cross checking other ranges. For good middle of the pack meters, try Tenma ...
Some other quickie checks to use ... If you set the DMM to ohms and touch the probes that came with the meter together you should see something less than 0.5 ohms. On the DC volts input a fresh AA or C battery should measure 1.3 to 1.6 volts. As mentioned, plugging into home AC isn't all that accurate as that can be all over the place depending on time of day and system load.
PS ... if you really want to ensure accuracy, set one multimeter aside as a multimeter tester. You can test that with a multimeter tester tester, and test that with a multimeter tester tester tester. Just to make sure you've not had a tester go bad during the testing, you should then backtrack, testing the multimeter tester tester tester with the multimeter tester tester and then test that with the multimeter tester, and finally one last crosscheck using the multimeter to test the multimeter tester.
Repeat as needed ...
Good for cross checking the AC side of a VOM anyway ...
All bets are off if you're still using an analog meter. Those are only accurate within a small range of needle movement due to parallax error. The farther you go from the set level listed in the specs, the less accurate. Pegging the needle when using the wrong range doesn't help either. This holds true even for the TOTL meters to a certain degree. A digital meter is also way more forgiving when it comes to polarity or range ooPsies.
And yes, a couple quality meters are handy to have for cross checking other ranges. For good middle of the pack meters, try Tenma ...
Some other quickie checks to use ... If you set the DMM to ohms and touch the probes that came with the meter together you should see something less than 0.5 ohms. On the DC volts input a fresh AA or C battery should measure 1.3 to 1.6 volts. As mentioned, plugging into home AC isn't all that accurate as that can be all over the place depending on time of day and system load.
PS ... if you really want to ensure accuracy, set one multimeter aside as a multimeter tester. You can test that with a multimeter tester tester, and test that with a multimeter tester tester tester. Just to make sure you've not had a tester go bad during the testing, you should then backtrack, testing the multimeter tester tester tester with the multimeter tester tester and then test that with the multimeter tester, and finally one last crosscheck using the multimeter to test the multimeter tester.
Repeat as needed ...
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
- Post n°5
Re: Bad multimeters
Or just do the tongue-test across the mains. That will verify current.
sailor- Posts : 269
Join date : 2011-04-04
- Post n°6
Re: Bad multimeters
Suckered my wife into licking a 9 volt battery, but only once. Twenty years later and she hasn't forgot. Any time I ask her to do something she isn't sure about she says: Not another 9 volt test is it?
I use my kilawatt on a regular bases. Not only is it very accurate on the voltage but most important it makes it simple to see how many watts are being consumed. I just used it yesterday to find out what the different TV's in the house were using.
One last thing, if you use your multimeter to test capacitors check the cap first with the volt setting to make sure it is completely discharged or you may fry the capacitor section of your meter.
I use my kilawatt on a regular bases. Not only is it very accurate on the voltage but most important it makes it simple to see how many watts are being consumed. I just used it yesterday to find out what the different TV's in the house were using.
One last thing, if you use your multimeter to test capacitors check the cap first with the volt setting to make sure it is completely discharged or you may fry the capacitor section of your meter.
audiobill- Posts : 425
Join date : 2014-03-13
Location : Albany, NY
- Post n°7
Re: Bad multimeters
For those interested, take a look at the Tenma 10410, now 60% off at MCM.
sKiZo- Posts : 1530
Join date : 2013-04-01
Location : Michigan USA
- Post n°8
Re: Bad multimeters
sailor wrote:One last thing, if you use your multimeter to test capacitors check the cap first with the volt setting to make sure it is completely discharged or you may fry the capacitor section of your meter.
... and ALWAYS use any special test leads provided with the meter to minimize any error. My Tenma came with some high grade shorties just for that.
audiobill wrote:For those interested, take a look at the Tenma 10410, now 60% off at MCM.
Great price! And a reminder to familiarize yourself with your equipment. I've had my Tenma for years and just noticed a "new" feature when I went to check the price. It's does temperature! Had to dig some to find the box, and found the special probe. Which of course doesn't look anything like what's pictured in the manual, so I've got an excuse for not knowing what it was. And not really needing it, not really caring what it was ...
Cubdriver- Posts : 83
Join date : 2014-01-21
Age : 59
Location : Southeastern Litchfield Co, CT
- Post n°9
Re: Bad multimeters
sKiZo wrote:PS ... if you really want to ensure accuracy, set one multimeter aside as a multimeter tester. You can test that with a multimeter tester tester, and test that with a multimeter tester tester tester. Just to make sure you've not had a tester go bad during the testing, you should then backtrack, testing the multimeter tester tester tester with the multimeter tester tester and then test that with the multimeter tester, and finally one last crosscheck using the multimeter to test the multimeter tester.
Repeat as needed ...
So you expect me to buy a bunch more meters, Skiz? What, do you have stock in Fluke?
-Pat
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
- Post n°10
Re: Bad multimeters
Nah, he has stock in Radium Shack.
If he had a Fluke he'd only need one.
Actually knew John Fluke when he was chmn of a company I worked for in Olympia, WA decades ago. Meanest SOB I ever met; that's the kinda guy you want building/flying things such as we play with.
If he had a Fluke he'd only need one.
Actually knew John Fluke when he was chmn of a company I worked for in Olympia, WA decades ago. Meanest SOB I ever met; that's the kinda guy you want building/flying things such as we play with.
Cubdriver- Posts : 83
Join date : 2014-01-21
Age : 59
Location : Southeastern Litchfield Co, CT
- Post n°11
Re: Bad multimeters
He has Rat Shack stock? We should keep an eye on him, make sure he doesn't jump out of a high window or the like... I still wonder how they're hanging on; they're barely even a shadow of their former selves.
I lucked out and managed to snag a pair of the Fluke 27s that the Army surplussed a while back on Evil Bay. Nice additions to my old 87-II
-Pat
I lucked out and managed to snag a pair of the Fluke 27s that the Army surplussed a while back on Evil Bay. Nice additions to my old 87-II
-Pat
Tom- Posts : 217
Join date : 2011-04-04
- Post n°12
Re: Bad multimeters
So what you're telling me is that the meter
I got at Advance Auto Parts for $14.95 might be wrong?
Who knew...
I got at Advance Auto Parts for $14.95 might be wrong?
Who knew...
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
- Post n°13
Re: Bad multimeters
You could check your tire pressure with it, though.Tom wrote:So what you're telling me is that the meter
I got at Advance Auto Parts for $14.95 might be wrong?
Who knew...
Dale Stevens- Posts : 201
Join date : 2014-07-06
Age : 75
Location : Loris, SC
- Post n°14
Re: Bad multimeters
Recently retire from BellSouth (ATT). My boss offered a retirement party, I said wanted to save the company money just wanted something I had in my desk drawer; agreed! Fluke 189, score. Dale
Roy Mottram- Admin
- Posts : 1837
Join date : 2008-11-30
- Post n°15
Re: Bad multimeters
I haven't had any troubles with inexpensive meters, but ALOT of meters both cheap and not so cheap, are NOT accurate at reading AC voltages.
Also, I refuse to use an auto-ranging multimeter. I get so many emails from customers with auto-ranging meters that are having troubles reading voltage correctly.
If you know what the voltage SHOULD be that you want to check, then you also KNOW whether it is AC or DC and what range you want to use.
Also, I refuse to use an auto-ranging multimeter. I get so many emails from customers with auto-ranging meters that are having troubles reading voltage correctly.
If you know what the voltage SHOULD be that you want to check, then you also KNOW whether it is AC or DC and what range you want to use.
GP49- Posts : 792
Join date : 2009-04-30
Location : East of the sun and west of the moon
- Post n°16
Re: Bad multimeters
The biggest pains in the butt for those doing servicing work were the old Radio Shack meters (and others) where you had to change the hot (RED) test lead between sockets to do resistance vs. voltage measurements. You'd be swapping them all the live-long day! Or you'd forget and the reading wouldn't make sense, or the meter would overload.
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