Strange Brymen BM869 Resistance Quirk
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- Опубліковано 8 вер 2024
- A strange quirk in the Brymen BM869 Multimeter when measuring 560k resistors.
Obviously some sort of range switching hysteresis, but it doesn't seem present on other ranges or other brand Brymen meters.
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NOTE: That should have been 5.6M, but I tried that and it's fine. Definitely only 560k. The new BM786 switches ranges very cleanly at about 650k, no signs of this ranging hysteresis noise effect at all.
My Brymen 867 - same issue as your 869, also around 560k it goes bonkers. (I believe 869 has temperature measurement, 867 doesn't, otherwise identical meters)
A good reason NOT to use 560K resistor values then !
What about R600-610K (or 6-6.1M) with new BM78х?
It is a software problem, cannot decide if it wants to show kOhms or MOhms.
At 677kOm try please this value on BM786, but yes it is effect of EMFs around. AutoHold actualy helps to obtain more accurate reading of the resistance if this is rolling. Revision 78608. Shorter leads may be a good idea to use as well like 60cm or so?
That's one of the perils of autoranging meters. If you're on the transition between two ranges it can start toggling between them. Fortunately it's rare that you're measuring something bang on the edge like that.
Yes. Strange that no one can get it to do it on the higher mohm range though. You'd think the noise would be even higher and hitting the same hysteresis points.
@@EEVblog2 I wonder if they compensate for that in the higher ranges by applying a bit of filtering.
500 000 counts (5 4/5 digit)
I read this with your voice in my head. Anyone else do this?
It's because you had the red cable in the COM plug, of course :)
DOH!
Trap for young players
My thaughs exactly :)
Oh Noes! Now the elec-trickery will go the wrong way around!
that's what it is, the electrons are going backwards :-)
It happens near the boundary between two ranges, the device can't decide which range to use.
Does it start oscillating at 555 k?
You sure it’s the shirt and not the belly?
Have reproduced on a BM869 with a 565k6 (as measured) resistor. Interestingly, the mains cable I used was an extension cable with no device/load attached, so it appears to be electrostatic coupling (although that does comport with the shirt rubbing stuff). I'm not too worried though, I'm sure the whole dual slope (whatever it's called) DAC technique often has certain values/frequencies that it doesn't like. I'm guessing the dual slope cycling hits a frequency near some multiple/divisor of 50 Hz at 560k. Would be fascinating to see if folks in the US see a slightly different range at 60 Hz mains.
Replicated on three out of three meters at work. Made our company metrologist freak out. :D
Dave by day, Electrostatic man by night
Surely somebody would have already informed Brymen of this issue during the last 10 years of service
Dude I've run across so many bits of hardware and software than end up having the most obscure quirks imaginable. This is just giving me PTSD :^)
Brymen should give a 50% discount.
DAMMIT, I just bought the EEVBlog BM235, now you are coming out with the BM786. My old Fluke 87 died and I needed a new meter. So I just received my EEVBlog BM235, I wish I could have waited for the 786.
I did some testing on my BM869s and it seems that there are still some capacitive and inductive input problems. I used a resistance decades and I varied values between 510K-600K, it seems that these areas are the most affected. I used different cables, some shielded and others I shielded myself, in vain, the defect (anomaly) did not disappear. But to shorten the discussion I will tell you what I managed to get after a few hours of testing. I put a capacitor with a value of 47nF - 100nF at the input of BM869s and the device became very stable regardless of the position of the cables or the touch with my hand of its active parts or of the resistive decade. (First, I made measurements in Manual Mode and here it seems to be fine).
Was the speed of the measurement affected at all after this?
@@stanleywhiteman6450 No, absolutely not, it works normally.
BM786 is absolutely outstanding multimeter. We have attached a clamp meter to BM786 on mV range and set this clamp to 1mV/A. Then we were troubleshooting some small device with very low standby power consumption. The current this meter was able to register using the third party clamp was down to.10mA! This is absolutely great result. Then when the full power was applied the meter registered 0.36mV and it was accurate reading of 360mA. Many other meters would simply not register such low current of idling device and this one was right on the point! Also we found that during repeatative tasks the AutoHold(tm) selection makes a lot easier to trace some sources of voltage without even looking at the display. This model has great potential. Leads would be nice to get with slightly bigger and bolder handles to be honest. In battery compartment we noticed that batteries potentially if they would leak may damage (questionmark) the internals, hence we placed the fire retardant insulation material cut to the size of 3 batteries between the compartment and the main PCB board. Just a great meter. Confidence of using this meter to obtain accurate results increased in 30 min after we have start using this. It is just great. Temperature was accurate and very quickly measured. Capasitonce was somewhat slow at first on 60uF but then we saw improvement in readings it was good. Give us a second one just to put in the drawer as an investment! This is how it feels great about this meter. Switch we believe while looks a bit like a weak part seems does great the rotation etc though we did not go ballistic in this. It is some serious a value for what it cost. Leads we would not mind to get a better set because Cat 4 rating small attachement( red) not seats properly 100$ yet it so minor issue that no point to worry. Dave, please do more tests and make this "true electrical machine" even better with next releases. Would buy again this meter.Tnx
On my Brymen BM867s I was able to replicate the same fault at 560k, 556k, and 529k, but not at 508.5k, where it's back to showing 5 digits. Probably an issue with the bottom of that low MOhm range, specifically.
Tugging on your leads causes your meter to reboot? .. well, I'd get that checked out :-)
Looks like it's only switching ranges..
I just tried it on my AVO 8 no worries
Sounds like RLC resonance problem. More specifically, oscillation.
If so, it will happen in some other values other than 560k!
I wonder if one found their sweet spot in between the range change thresholds if other meters might exhibit the same behavior under similar conditions. Each meter might very well have different ranging thresholds/hysteresis algorithms.
Yes, it's got something to do with range switching hystersis, but no one can make it happen on other meters or ranges, seems very specific to the 500k range on the BM869.
It’s just the auto ranging threshold, every meter will do it at the range changeover point, needs better hysteresis.
Enhorabuena me lo paso genial 😉 contigo y con Joe Smith.
Enhorabuena 👏
this multimeter is obtained with the green lee brand the DM860A, but the DM830A is the same as the fluke 87 v with a little more functions these green lee multimeter are excellent nothing to compare to fluke
Doesn't really seem like an issue to me, it's just range hunting. Any autoranging meter that is trying to measure something bouncing between borders is going to do that, ISTM.
I assume that these meters use some variation of the good old dual-slope-integration measurement technique. If that is the case, I could imagine that they may be a lot more sensitive at certain frequencies. Doesn't excuse poor shielding design, grounding etc of course!
my brand new BM 785 - and same issue :-( but only with standard lenght test leads. Above 100k . If You have use very short test leads, its OK.
I have got a 869S and it happens with 470k, 560k, 680k and 1M. Very strange!
Mine does the exact same !!
Buddy just tried it with his and had that issue on the same ranges.
Need to check that as well. Interesting test.
Sounds like it's allergic to E12 values!
Maybe it only happens on thursdays too
As the kohm and Mohm segments are flashing, i guess it messes up the autorange part of the software. I've seen 510K and 0.53M on the display. I expect some problems between ohms and kohms too. I'm guessing they need some (more) hysteresis in the range determination before switching and clearing the display.
Knowing nothing about multimeter design specifically (gotta state the qualifications! 🤣), it seems to me like a firmware bug. The meter never technically fails, but stops providing a reading as it changes ranges in that specific resistance range. Could be as "simple" a fix as extending the autoranging hysteresis in firmware. No idea how updatable a typical multimeter is without hardware changes though -- I'm guessing the answer is "not very."
The error is just at the level where it switches from kOhm to MOhm. A bigger hysteresis would help.
So the lesson learned here is when doing an important measurement, don't rub the cables across your belly like a crazy bloke or hold them closely agaist mains leads...🙄
They should change the name to the BS869
Clearly the wires for the test leads require some shielding from induction.
Put a 0.1uF cap across the meter.
Interesting, my Brymen BM839 has an issue at the lowest voltage range where it is randomly resetting once it switches to it.
I just ran into issue today with two BM867s and BM869s when testing some 18650 cells. There was not any AC power within 30 feet from where I was testing. They will not read 67M ohms. Screen just flashes. I ended up having to revert back to using my Fluke 289’s for testing.
I cant get any of my Brymen’s to read over 51M ohms. Shouldn’t they be able to read above that with decade box?
Hello, great video, do you by any chance have the complete manual of the multimeter in question?
What next, test it in a Copper Faraday Cage? =P
Conclusion: it is not a Fluke, so once in a while you will notice strange behaviour like this...
That sounds like a fluke fanboy comment🤣.
@@xyzconceptsYT I have a bm235 at home and a fluke 175 at work. Of course I prefer and trust more the fluke than the brymen if I had both on the same workbench. And this is not because I am a fanboy, it is because I like well made & tested stuff. I would edit my initial comment as this: "it is not a high-end dmm, so the buyers will also do some testing and fault finding when using the product instead of the manufacturer doing this before selling". How does it sound now?
I had my Fluke 87 go beserk when trying to measure a mains primary resistance once, must have been just on the range threshold.
@@aicisha All good mate my OG reply was just lighthearted banter. All things have their quirks, even me, lol.
I agree exactly. Fluke multimeters have noise suppression.
better this than some wrong value
Would like to see the insides of the substitution box! ;)
There is a teardown somewhere.
ua-cam.com/video/37gYHdY0DAM/v-deo.html
No magic in there. Typically a 6/10p rotary switch and some resistors per decade. Usually 9x 1 (*10^n) Ohm or 4x "1 Ohm" and one "5 Ohm" resistor.
I shouldn't have watched this video....
That is really wierd.
My 869s do the same...
Hmm a new eevBlog multimeter. As far as I can see, this is not the one teased in EEVblog #1328. What happened to that one?
Two meters were teased in that video. This is one of them, but now in EEVblog blue. The other one, don't hold your breath.
@@EEVblog2 will there be any preordering for patreons?
@@stevenspmd You'll get first suck of the sav
@@EEVblog2 hmm I see. Well I would have preferred the other one just by looks but you have the final say...
@@EEVblog2 Dammit Dave, where the heck am i gonna get a country show dagwood dog in a pandemic????
Anyone tried this on a 60Hz mains system?
An unfortunate error in a precision multimeter that causes a loss of prestige.
Response to ac noise? Very likely, most manufacturer don't shield their test probe cable for noise, Is it possible that is the sampling frequency of this meter? Let me guess, it is made in........you know where. Made to fail in critical moments.
Made in Taiwan actually, not China.
@@EEVblog2 Taiwan is officially called the Republic of China.
@@Okurka. debatable territory actually
"shield their test probe cable for noise" - on a hand held multimeter? Shield against what RF range? You'd pay for that?
@@salat exactly, i only saw 1 lab use table size meter with this feature before, never see that in hand held.
You just discovered static electricity!!! I will also tell you that if you fill the interior with water very curious things happen or if you drop it from 70,000 meters while measuring, but I thought it was an electronics channel and what does this have to do with it? Are you out of ideas to create content? It goes back to the basics that everything we think we know is very questionable and would make us rethink the results in other orders of magnitudes, which is where we are going, it is an idea.
First yeaaaaa
hmm your belly must be noisy.