Fluke 177 not going Zero - Page 1
Forum section: electronics / beginners

author: amix
author_rank: Newbie
timestamp: June 02, 2016, 08:24:20 pm
content: Hi,I just got a nice deal on a Fluke 177 on eBay. But I am a bit insecure. When I switch it on, test-probes connected to DMM but open line some of the features do NULL:V (AC): It's highly fluctuating between 25 and 14 mV, whether I keep the probes still or shake them. I just don't get a zero when probes are open line.V (DC): after settled at zero, when I shake the probes, it goes up a few mV and then down again.mV (DC): goes down to zero just fine after switching to this feature, but shaking probes sends it down into the minus.When I say 'open line' I do not mean the OL in the display. I mean, that the tips of the wires are not connected to anything.Probe wires are very firm in the device, so I don't know. Is this normal?

author: Signal32
author_rank: Frequent Contributor
timestamp: June 02, 2016, 08:50:53 pm
content: It's normal/expected for high impedance meters to pick up noise on the probes when not connected to anything.Quote from: amix on June 02, 2016, 08:24:20 pmYou should look in the spec table for a parameter called "Probe jigglyness tolerance" and see if the value you're seeing is out of spec.On second thought, I might be wrong about that, what do you mean by "shake the probes" ?

author: amix
author_rank: Newbie
timestamp: June 02, 2016, 09:36:39 pm
content: Quote from: Signal32 on June 02, 2016, 08:50:53 pmJust ordianarily shaking them a little, while keeping them in hand. That "jigglyness tolerance" sounds like a value, that may cover it, but I did not find it, when fulltext-searching the PDF manual. But I guess, all will be fine, now that you told me about the noise pickup. Thanks a lot!

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 02, 2016, 09:49:15 pm
content: Quote from: amix on June 02, 2016, 09:36:39 pmHe was joking.When the probes aren't connected to anything they'll pick up ambient electric fields which will make the meter read something other than zero. Moving the probes will change the electric fields being measured, which will make the measurements change. You should only expect to read zero when the probes are shorted to each other.

author: The Soulman
author_rank: Super Contributor
timestamp: June 02, 2016, 09:50:27 pm
content: Perfectly normal, indeed picked up noise from everywhere around you.Shorting the probes together should read 0000 on all voltage and amp ranges, the resistance range could read something like 000.4 ohms that is the resistance measured from the multi meter and backso basically your test leads, the connectors and the little resistance in between the tips.

author: The Soulman
author_rank: Super Contributor
timestamp: June 02, 2016, 09:55:35 pm
content: Quote from: suicidaleggroll on June 02, 2016, 09:49:15 pm....couldn't help it...

author: amix
author_rank: Newbie
timestamp: June 02, 2016, 10:08:08 pm
content: Quote from: suicidaleggroll on June 02, 2016, 09:49:15 pmLOL, for a ns that crossed my mind, but then, I am a greenhorn.Nice to be here!Oh, and the shortening sets them to zero or very near zero.

author: ZeTeX
author_rank: Frequent Contributor
timestamp: June 03, 2016, 07:56:02 am
content: Fluke 177 as your first multi meter?

author: amix
author_rank: Newbie
timestamp: June 03, 2016, 02:06:38 pm
content: Quote from: ZeTeX on June 03, 2016, 07:56:02 amNo, it's my second. My first is an Extech EX330.