Is my new Fluke 289 multimeter faulty? - Question #2 - Page 1
Forum section: electronics / beginners

author: evava
author_rank: Regular Contributor
timestamp: May 10, 2017, 07:20:00 am
content: (I bought second-hand Fluke 289. It is in like new condition, outside and inside), but:LoOhm range(50.000 Ohms with 1miliOhm resolution)behaves strangely:Immediately after shorting input posts (Volts and COM), Ohms readings slowly decreases from about 50.000 ohms to the 0.000 Ohms during about 15s (seconds !) and through 0.000 Ohms continues to "countdown" even to the minus Ohms readings slowly and still very slowly continues to "countdown" (countdown slowly slows down), just like in that videos and seems never stops completely - until after 1 minute(!) it practically settles to almost stable -0.015 Ohms.My problem is not minus readings (because I can REL that), problem is that countdown takes sooo loooong... - why?And the same becomes again and again, when I connect some resistor, the same sloooow settling takes place !So, when I want to REL thoroughly, I have to wait at least 1minute, and then after I connect DUT I have to wait again 1minute to settle.It is normal behaviour? Can someone confirm if his meter behaves in the same manner?Or is my meter broken?(these are not mine movies, I found them after some googling).

author: AndyC_772
author_rank: Super Contributor
timestamp: May 10, 2017, 07:34:19 am
content: Mine's exactly the same. I'm guessing there's a low pass filter in there with a long time constant.Think about the voltage that's being developed across the terminals. The Lo Ohm range uses a test current of 8.3mA.I wouldn't like to have to design a circuit to measure that voltage at all, never mind both accurately and quickly.

author: evava
author_rank: Regular Contributor
timestamp: May 10, 2017, 08:26:57 am
content: Thank you. That's what I was afraid of when I found and saw that videos..So my meter is not faulty.I'd rather have that time constant to be much shorter.When I multiply 0.001Ohm x 0.0083A it gives 8.3uV - that should not be much problem for such meter, but it is evidently.Maybe because someone at the same time could connect it to 230V AC, there are various auxiliary and tracking circuits, and outcome is just such.I will try to live with that.

author: Electro Detective
author_rank: Super Contributor
timestamp: May 10, 2017, 09:36:57 am
content: Have you opened the meter and checked that battery leaked fluid hasn't trailed/crept along and landed on the circuit board?Check that the internal supercapacitor (cRapashitter) has not leaked or grown a beardClean the input terminals, if you see black gunk on your cotton buds, that's resistance you don't need!Check your leads, clean them too, ensure they 'push' firmly against the input terminal metal,there is no free ride whether it's a cheap or overpriced multimeter.FWiW: The Fluke leads supplied with this model meter are a very tight fit (too tight!), with no assurance of good metal to metal contact. Other manufacturers nicer flexible leads with the same Cat specs (and better HV crosstalk immunity btw) and slightly thinner plastic sheathing work a lot better.You can tell when their plastic and metal contact connection is 100% when plugging in to the 289.I suspect a last minute Fluke oversight or corporat nogas on this, that perhaps wasn't considered important enoughto include better fitting leads, rather than their bog standard ones which are ok (but not the best) for all their other meters.Are they kidding at the price of the meter to not spend 50 cents more on leads, and not subject their loyal customers with athritis and tennis elbow to pushing and pulling hard to remove leads, playing a feverish painful VOA tug o war?Compare and stress test Benning or APPA meter silicone leads to Fluke ones, and it's obvious the Fluke leads are a 30 yo design anyway.I still like the Fluke leads, but there are new players on the scene kicking some goals too, and should take note.Lastly, don't expect a good meter like this that does a LOT to be 100% perfect in everything, it's just not going to happen.As an all rounder with many bells and whistles(with the latest up to date firmware)the 289 is hard to beat

author: joeqsmith
author_rank: Super Contributor
timestamp: May 10, 2017, 11:14:14 am
content: About 2 seconds on my modified UT181A to go from an open to a short fully settled with autorange. I have been looking at some Gossen meters and one of them is spec'ed at 8 seconds.

author: evava
author_rank: Regular Contributor
timestamp: May 10, 2017, 11:44:32 am
content: You like your 181a, I know.But this time it is not winner, AFAIK it has just 0.01Ohm resolution, not 0.001Ohm.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 10, 2017, 09:57:50 pm
content: Quote from: evava on May 10, 2017, 11:44:32 amCorrect, both my Brymen and that UNI-T are 0.01 resolution. The TPI can go down to 0.001. That pretty far into the muck and worthless on all three. I have trouble with my 34401A with 4W when we start going down that low. The 3458A would be my choice. That meter is so good, it's just fun to play with.I tried my friends 289 from an open to a short, maybe three seconds on the high side.