How to test my multimeter's accuracy - Page 1
Forum section: electronics / testgear

author: The Guy
author_rank: Regular Contributor
timestamp: March 30, 2017, 03:38:53 pm
content: Hi all, i just bought me a used Fluke 187 multimeter for cheap but in very good condition and I would like to check if it's working OK, if it's still accurate and all... Maybe it will need to get calibrated ($$$😲)?I want to use it mainly for building a couple of guitar amps and maybe some pedals...Anyway, i was wondering if there is any common household electronic device with very very very precise voltages, currents, etc where i could check my multimeter with. I don't know if i make any sense, kind of an amateur sucker talking hereMaybe I should just ask "How do I check my multimeter's accuracy without using all that fancy equipment they use when calibrating them?"Thanks tho,Guy

author: Jon.C
author_rank: Unknown
timestamp: March 30, 2017, 03:57:57 pm
content: in ebay or aliexpress search :AD584KH Voltage Reference Module

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: March 30, 2017, 04:07:57 pm
content: One basic thing to do would be checking against another meter you trust. From my experience, Fluke meters do not drift very much and in regard to building guitar effects etc. you do not really need the highest precision measurements. I used one of these chinese DT92XX multimeters for years to fiddle with stompboxes and was pretty happy with the results. Basically it came down to measuring resistance and voltage to be somewhere in the wanted order of magnitude and using the continuity feature to check switches and identify broken PCB traces...In regard to knowing what is going on with your equipment, there are some threads on building highly precise setups for calibration purpose, but I do not have the links at hand right now. Personally, I would check the 187 against some other DMMs (if you don't have more than the one, throw a party and invite people you know owning test equipment). My guess however is, that your Fluke is perfectly fine and it will very well suit your needs in regard to getting things done.

author: The Guy
author_rank: Regular Contributor
timestamp: March 30, 2017, 04:24:47 pm
content: Quote from: frozenfrogz on March 30, 2017, 04:07:57 pmDONE!! Tomorrow. Party. My place.And you guys are all invited (just make sure you bring all your freshly calibrated DMM's and/or other test/calibration equipment) 😉

author: The Guy
author_rank: Regular Contributor
timestamp: March 30, 2017, 04:28:56 pm
content: Quote from: Jon.C on March 30, 2017, 03:57:57 pmThanks! That'll do for voltage accuracy tests i guess. Will order one and see what happens.

author: BroMarduk
author_rank: Unknown
timestamp: March 30, 2017, 04:57:21 pm
content: There are a few versions out there with different chips. In theory, the AD584LH is more accurate than the AD584KH. Some of the modules state they include a AD584MH chip, but I've not found a datasheet on it, so unless its a new Asian mod of an existing chip, I'd guess that one of the other chips is in use. If anyone has one of the "AD584Mx" chip models, I'd be interested to see what the actual chip in use is (if its even marked).

author: james_s
author_rank: Super Contributor
timestamp: March 30, 2017, 05:05:53 pm
content: I believe you can send it out to Fluke and have it calibrated for a reasonable rate. Really though unless it is grossly off and malfunctioning, it's probably still well within spec. Check a few things and verify that the reading is reasonably close, fresh alkaline battery should be about 1.5V, voltage from a wall socket should be 120 or 240V depending on what part of the world you live in, frequency should be 50 or 60Hz. Measure a few resistors and capacitors, verify they measure the value printed on them within the rated tolerance. If that all checks out then it's pretty safe to say the meter is working fine.

author: retiredcaps
author_rank: Super Contributor
timestamp: March 30, 2017, 05:15:52 pm
content: Your used Fluke 187 is likely to be within specifications IF it hasn't been abused/subjected to overvoltage and you are unlikely to require a calibration check.Many have come here for help due to an oops moment or they bought an "used, but working" meter from ebay which turned out to be abused.If abused, the input protection components like the fusible resistor, MOVs and PTC are all potentially suspect.PS. I bought my 187 used as well and it is one of my favourite meters. I know mine is within spec because I have compared it to other meters and they are all within 1 or 2 mV of each other. Same for resistance values +/- 1 or 2 counts.

author: The Guy
author_rank: Regular Contributor
timestamp: March 30, 2017, 05:19:35 pm
content: Quote from: james_s on March 30, 2017, 05:05:53 pmI did all that and it checks OK, it's just that I'm sort of a OCD when it comes to accuracy ...lolI also asked and they charge me 200 bucks for the calibration. Around 150% the price I payed for the multimeter. It's crazy.

author: IanB
author_rank: Super Contributor
timestamp: March 30, 2017, 06:14:38 pm
content: Quote from: The Guy on March 30, 2017, 03:38:53 pmI think the DMMCheck would be a good option:http://www.voltagestandard.com/DMMCheck.htmlWell, oops, it seems to be discontinued. That's a shame.

author: retiredcaps
author_rank: Super Contributor
timestamp: March 30, 2017, 06:18:23 pm
content: Quote from: IanB on March 30, 2017, 06:14:38 pmDMMCheck is now discontinued. Seehttp://www.voltagestandard.com/Discontinued_Products.html

author: james_s
author_rank: Super Contributor
timestamp: March 30, 2017, 06:20:45 pm
content: Well if you're OCD enough about knowing it's accurate, then calibration is a reasonable deal. You're paying more for the paper trail and actual NIST certified accuracy than the actual process. Otherwise just use it, it's fine, Fluke meters are famous for retaining excellent accuracy.

author: Avacee
author_rank: Unknown
timestamp: March 30, 2017, 06:43:02 pm
content: Without knowing your location this suggestion might be moot but try contacting a local hackerspace / ham radio club / college / etcFor a small donation they might let you test it against a voltage standard / known voltage.Edit: Add Hackerspace linkhttp://hackerspaces.org/andhttps://wiki.hackerspaces.org/List_of_Hacker_Spaces

author: The Guy
author_rank: Regular Contributor
timestamp: March 30, 2017, 06:45:09 pm
content: Quote from: james_s on March 30, 2017, 06:20:45 pmYea... You're right. As far as I can tell it is already very accurate....i think I better take my pillslolP.d: will ask the guy that do the calibration if he can do me the favor and calibrate it without all that certification and stuff. Maybe I can spare me a few dollars that way.

author: The Guy
author_rank: Regular Contributor
timestamp: March 30, 2017, 06:47:52 pm
content: Quote from: Avacee on March 30, 2017, 06:43:02 pmThat's actually a very good idea. Thanks!

author: james_s
author_rank: Super Contributor
timestamp: March 30, 2017, 07:02:56 pm
content: Or just ask if he can do a quick check to see whether it needs calibration or not.

author: Iceberg86300
author_rank: Contributor
timestamp: March 30, 2017, 10:21:39 pm
content: Quote from: james_s on March 30, 2017, 07:02:56 pmThat's pretty much all you'll get for a "non traceable" calibration from an actual calibration shop/guy.You might be able to wrangle some pre calibration reference vs reading plots at for a lesser price.This is more likely from a large calibration operation or a guy that has A LOT of gear. They're more likely to have gear that is out of date but perfectly usable for generating a few plots.To OP: Do you have any friends that work at a medium to large manufacturing company that even remotely has something to do with EE R&D/assembly of outsourced electrical stuff? If so, there is likely a metrology department that will send the meter out.From my past experience as a design engineer (ME) working at Haas Automation it would likely take a ~month, but it'll also be free. Well, a six pack, bottle of favorite booze, dinner, whatever, would be in order.If you have such a friend and only profiling your meter is acceptable, I'm sure they could just run some quick tests against their (or a coworkers) meter that has an up to date calibration.

author: james_s
author_rank: Super Contributor
timestamp: March 30, 2017, 10:49:51 pm
content: I would expect a Fluke meter that hasn't been calibrated in 20 years to be at least an order of magnitude more accurate than the voltages reported by a PC motherboard health monitor. Same goes for most of those other sources, same goes for those other sources. One really needs access to either a precision reference, accurate to say 0.5% or better, or another known-accurate meter to get anything meaningful beyond what he already has.

author: usagi
author_rank: Frequent Contributor
timestamp: March 31, 2017, 07:42:06 pm
content: the reference moduleJon.Clinked to will be far more than sufficient to validate a fluke 187.there is also anLCR module available.