EEVblog Electronics Community Forum
EEVblog => EEVblog Specific => Topic started by: pmrlondon on May 18, 2011, 09:09:05 pm
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Well, that is some proper weirdness there with that meter. I hope it turns out to be something simple, at least in explanation, as odd faults like this can be a pain to track down.
The stuck readings remind me of my Precision Gold WG021 - that could be odd like that sometimes - but it was manual range and more obviously wrong when only the decimal point moved.
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It looks like a microcontroller in that thing is running wild. Of course this assumes there is a microcontroller in it. My first suspicion would be something wrong with the brownout detection or reset circuit.
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Just watched the video, and actually three times..
Well I am a bit confused .
I have see the pictures of PetrosA teardown , and still I do not have understand , if the LCD is on a separate PCB ?
or how it connects with the PCB.
From my own experiences , if there is an connection problem , between the main PCB with the secondary for the display,
or even if the rubber zebra is not in place 100% , or even if an common hair of our head, drops in the path of the rubber zebra , it could lead to issues.
I have not get my own sample yet ( still in mail ), and I can not offer any test results.
Dave , just recheck the unit ... inspect the connection ( display & PCB ) and use an magnifier glass too.
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I am evaluating the same meter myself and have run into problems. Nothing permanent and major, but certainly problematic for such a high priced meter, at a price were there are other competitors with no known issues that would make one skeptical about its long term reliability for making accurate measurements.
In the middle of testing, once or twice in 10s of hours of testing, while I switched from range to range, it did go berzerk briefly as the switch hung between ranges, then became right again once it was in seated in the range. I also had it once read hundreds of Vac in the low Z range as I quickly switched from range to range and it was again, not seated fully in the range setting, and the leads were not connected. I would not have thought much of these 'glitches' as I haven't been able to repeat it and its only happened, maybe no more than 3x, but reading Dave's comments and video, I'll now concentrate on seeing if I can repeat them consistently.
But this is with several days and multiple hours of testing, and it working right now. Not sure what the cause is, and I continue to stress it.
I have not taken it apart.
The importance to me is, is before I take this DMM on a mission critical trip, it better live up to basic accuracy that is rock stable.
I'm glad to see that in Dave's test unit, there is no problem with Vdc calibration.
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where is eevblog #170. is it missing? or is it just me?
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I have seen the same thing on my 1272 meter but didn't think much of it at that time. I will for sure test it more tonight! I haven't taken my apart.
(you can find the eevblog #170 on youtube, appears there before here)
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I haven't experienced this issue on my 1272. It did freak out when I first got it, but that was the warning beeper for leads, not jumpy readings (I wrote about it in my teardown thread IIRC). Since mine had come direct from Malaysia and the problem only occurred within the first 10-15 minutes of use, I wondered if it might be some corruption from security scanners EMF or something else during transport. I don't think it had anything to do with tearing down the meter...
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where is eevblog #170. is it missing? or is it just me?
Hey Mecha,
The video is here:
EEVblog #170 - Agilent U1272A Multimeter FAIL (https://www.youtube.com/watch?v=1fC382Tog0k#ws)
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where is eevblog #170. is it missing? or is it just me?
I upload onto Youtube first, often the night before it makes it to eevblog.com (upload and go to bed).
A little tip, all the Youtube videos get automatically added here:
http://www.eevblog.com/episodes/ (http://www.eevblog.com/episodes/)
So you'll see it there straight away before it makes the main page.
Dave.
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o ok thanx. i used to go to main page, download and play it locally. mosty i will keep in my HDD. youtube sometime lost in the cache files or i have to dig it or broken download/play is hurting as the net here is slow and BW limited.
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I watched the video just now and my unit has exactly the same problem, tough switching it on and off "fixes" the issue most of the time. The first time this happened I was measuring ohms and I was like "wtf is happening here, shitty resistor or something". Then it turned out to be this glitch, readings all over the place for no apparent reason, exactly as Dave described.
I tried to replicate the problem just now, but no luck.
I think it might me a software glitch, at least I hope so that owners of the meter can simply update it. If it where to be a hardware problem Agilent should do a recall (A).
Now let's hope that Agilent looks in to this problem quickly and is open about what the problem actually is, I really appreciate companies being open about their mistakes (and things they get right for that matter).
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Thanks for the confirmation Floyo.
Agilent are looking into it.
Dave.
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beta testing in progress! :D the plague already infected hardware! :D
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Let's see if Agilent will fix it like Fluke fixed the GSM issue with the 87V...
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Thanks for the confirmation Floyo.
Agilent are looking into it.
Dave.
So it seems it wasn't you taking it apart. No esd or so...
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...like Fluke fixed the GSM issue with the 87V...
they do? afaik its only fixed in 28II if i'm not mistaken the name is.
edit: just by coincident browsing the new replied thead here.
Hey Kiriakos, wasn't it your FLUKE that got "killed" by your cellphone? Did FLUKE fix it?
Yep , actually it got replaced with one of my choice, because there was not an quick fix about the 87.
And also got 8 Fluke fuses for free .
I got truly impressed , and I will always favor them, for their immediate response.
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Let's see if Agilent will fix it like Fluke fixed the GSM issue with the 87V...
Yeah, never heard back about that one!
Agilent have a good opportunity to show up Fluke here!
Agilent fixed the hardware problem in the scope LAN module ASAP which was very encouraging.
So I think they'll take this one pretty seriously.
Extech, BK Precision, and Agilent have come to the party before, so lets see what Agilent have to offer again this time around.
Dave.
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First of all I like to say something to Dave, about my suggestion above , about the recheck ,
I do trust the man , and it was not an sign or behavior due disrespect, or of having doughs for his opinion.
I did not received my unit, even today.
So far I had no plan to tear down the unit ..
But now I will do .
Even so I will keep my word to Agilent , about reporting to them directly ,
anything as remarks. ( for the first 30 days ) .
The story with the Fluke 87V , ended as Circus show , from young ones who started to play with it and their GSM phones.
I do not wish to see, the same thing to happen again.
No matter if this specific device , hides or not , an imperfection under the hood.
So far, we had see many people owning HH of Agilent ,
and there was no even one similar issue , with all those models.
And so dear friend Shafri , I do not see any " plague " near by ..
And if you do again an such of joke about this DMM ,
I will tell to all the world , that your UNI-T does not know how to measure " Peak to Peak " LOL
Kiriakos ..
Edit:
The Fluke 28II , never had an GSM issue .
Inside haves other fresher microprocessor than the 87V .
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And so dear friend Shafri , I do not see any " plague " near by ..
i mean, beta testing usually involved in software. but i dont know if its happening in hardware as well, but it seems starting like that. except they dont call dave a beta tester. but the worst thing is... i dont want to say that. :P and i dont mind if you say uni-t cannot do peak to peak my friend ;) thats by design and i admit its in cheapo range of price. it served my purpose. i will not use it to measure oscillation except pure mains sine. ;) i hope Agilent take this seriously and hopefully not Malaysia made/assembled. if it is, then they must take it seriously otherwise i will be ashamed!
ps: i have future plan to build a product/hardware, but before selling it out, i think i will ask few people as "beta testers" to prove the product non-flawed :P
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It didn't look like the GSM issue is a quick fix. Given that the phone has to be fairly close to the DMM for the interference to occur, its unlikely to be an major issue in real world use; I can see if a technician were to receive a phone call with his phone placed ontop of the DMM used in speakerphone mode while actually working with the DMM, but if he moved it 6 inches or so away, it would stop.
Fluke 87v versus Agilent 1252a Ohms range (https://www.youtube.com/watch?v=9C7mQMUE8VE#)
By contrast, the unstable megaohm measurement issue I raised with the 1252a is still with the 1272a, since its the same design, is a practical problem. Measuring megaohms without a filter on the Agilent can be difficult.
Fluke 87v versus Agilent 1252a Ohms range (https://www.youtube.com/watch?v=9C7mQMUE8VE#)
Let's see if Agilent will fix it like Fluke fixed the GSM issue with the 87V...
Yeah, never heard back about that one!
Agilent have a good opportunity to show up Fluke here!
Agilent fixed the hardware problem in the scope LAN module ASAP which was very encouraging.
So I think they'll take this one pretty seriously.
Extech, BK Precision, and Agilent have come to the party before, so lets see what Agilent have to offer again this time around.
Dave.
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And so dear friend Shafri , I do not see any " plague " near by ..
and i dont mind if you say uni-t cannot do peak to peak my friend ;) thats by design and i admit its in cheapo range of price. it served my purpose. i will not use it to measure oscillation except pure mains sine. ;) i hope Agilent take this seriously and hopefully not Malaysia made/assembled. if it is, then they must take it seriously otherwise i will be ashamed!
ps: i have future plan to build a product/hardware, but before selling it out, i think i will ask few people as "beta testers" to prove the product non-flawed :P
Aaaa you are aware that I like you as friend , and you are taking advantage of it ..
Keep shooting I am bullet proof .. ;)
Unfortunately more delay added about getting my sample, as it will arrive from Germany to Greece,
and it is not even send yet , due a mix-up.
Lets hope that those good for nothing Germans, they will send and all the additional accessories too. :P
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its unlikely to be an major issue in real world use; I can see if a technician were to receive a phone call with his phone placed ontop of the DMM used in speakerphone mode while actually working with the DMM, but if he moved it 6 inches or so away, it would stop.
And so what if it stops ?
I do not wish to have such a unit, in the field with me , and that's final.
By contrast, the unstable megaohm measurement issue I raised with the 1252a is still with the 1272a, since its the same design, is a practical problem. Measuring megaohms without a filter on the Agilent can be difficult.
I hold my horses on that , until to see the complete video review of Dave .
And I would become an believer if I see your own video about it.
But even if you do one , it will show , that the new layout of the buttons ,
will had another degree of response at about how the display flickers.
Bottom line , if the operation of the buttons does not effect the measurement,
no one cares about flickering , the Fluke flickers a bit too.
And its not capable to measure above 50MOhm ..
I would be interested to see the Fluke one to measure 150M Ohm ,
and to have the same stability as it does at below 50M Ohm.
But I bet that I will not see that , in this Fluke series ,
probably because they can not jump that high !!
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After what you experienced, I expected many Fluke 87V to be bricked. But more than just yourself have tried it, the video I posted is an example, Dave tested it, and I did so on mine, none have been bricked.
However, given the it actually did happen, I concur with you, that its of higher risk. I use the Series 85III when travelling outside the USA because its more reliable.
its unlikely to be an major issue in real world use; I can see if a technician were to receive a phone call with his phone placed ontop of the DMM used in speakerphone mode while actually working with the DMM, but if he moved it 6 inches or so away, it would stop.
And so what if it stops ?
I do not wish to have such a unit, in the field with me , and that's final.
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After what you experienced, I expected many Fluke 87V to be bricked. But more than just yourself have tried it, the video I posted is an example, Dave tested it, and I did so on mine, none have been bricked.
Just one word about that ... I had the LCD back light on , when I did my tests ... because I had in my other hand the digital camera,
so to take a picture of it ..
Does this detail matters ? so to be totally killed ? ( I do not know , and I do not care to find out )
However, given the it actually did happen, I concur with you, that its of higher risk. I use the Series 85III when travelling outside the USA because its more reliable.
Good for you ..
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I am willing to bet that dave did not make a mistake on the rebulid. I would hope he would have checked the zebra strip on the L.C.D. I am gravitating towards an E.S.D problem. Good job Dave on the video love it!
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I am willing to bet that dave did not make a mistake on the rebulid. I would hope he would have checked the zebra strip on the L.C.D. I am gravitating towards an E.S.D problem. Good job Dave on the video love it!
It's not ESD.
Same problem has been reported above by Floyo, and John at Tronixstuff has also reported weird readings and lockups.
So all points toward I didn't damage it in any way (nor would I have expected to).
BTW, zebra strips are self aligning, that's the point of them (several conductive strands per pad), and ESD damage does not fit the symptoms.
I wouldn't rule out a switch alignment/contact problem of sorts, but the likelihood of that is low I think.
Firmware seems to be the odds on favorite at this stage.
Dave.
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Yea dave you are right... I was "blowing shit up" as you say and i found a brand new cheap multi-meter in my mail box put a 9-volt in and.... similar problem. It was all over the place the L.C.D. was lit up like a shit house in a snow storm. I never found the problem it didnt matter i blew it up anyway. I know it was a cheap-o but just some info that it dose happen on garbage too!!! Thanx Dave
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Hmm, some other strange bug. I was trying to replicate the problem by switching the meter from off to Vac, I have the beep switched off against te noise :P. At one point It started doing the start-up beeping again, software settings reported beep on at default freq. I was able to replicate this three times (switch beep off, switch back and forth from off to Vac quickly multiple times --> meter beeps)
Further testing confirms the meter does a factory reset.
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Hi Floyo,
I tried this, so far cannot replicate the issue. What is your firmware version?
To get it press NULL/Scale, turn DMM on, screen shows p-code. Mine is 1.3.
Hmm, some other strange bug. I was trying to replicate the problem by switching the meter from off to Vac, I have the beep switched off against te noise :P. At one point It started doing the start-up beeping again, software settings reported beep on at default freq. I was able to replicate this three times (switch beep off, switch back and forth from off to Vac quickly multiple times --> meter beeps)
Further testing confirms the meter does a factory reset.
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Mine is also 1.30. It only happens when you switch the unit on and off in quick succession for a few times, so it´s not much of an real life issue but it happens, to me at least.
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Well, Agilent from Germany , called me today on my mobile phone.
About the final arraignments about shipping, I had to find for them an business registered address ( but this is another story by it self).
Even so, my point is , that the device that it will actually come to me , will be from the European stock ( batch ).
It will be interesting to see , if it is the same firmware revision with what we have see so far.
And so, now I have to ask Floyo , of where did he lives ? ( Country )
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I live in the Netherlands and I bought the unit from Conrad, a German company with a Dutch subdivision.
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I live in the Netherlands and I bought the unit from Conrad, a German company with a Dutch subdivision.
Thanks friend , my contact is at Boeblingen, Germany.
Agilent Technologies, Basic Instruments Division
One more week of waiting.
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Yea dave you are right... I was "blowing shit up" as you say and i found a brand new cheap multi-meter in my mail box put a 9-volt in and.... similar problem. It was all over the place the L.C.D. was lit up like a shit house in a snow storm. I never found the problem it didnt matter i blew it up anyway. I know it was a cheap-o but just some info that it dose happen on garbage too!!! Thanx Dave
If you're ever in the mood to blow something up again, could you please record a video of it? :)
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Mine is also 1.30. It only happens when you switch the unit on and off in quick succession for a few times, so it´s not much of an real life issue but it happens, to me at least.
Mine is 1.30 as well.
Dave.
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Hmm, some other strange bug. I was trying to replicate the problem by switching the meter from off to Vac, I have the beep switched off against te noise :P. At one point It started doing the start-up beeping again, software settings reported beep on at default freq. I was able to replicate this three times (switch beep off, switch back and forth from off to Vac quickly multiple times --> meter beeps)
Oooo, you can turn off that bloody annoying turn-on beep?
Dave.
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Hello,
what a coincidence. Got my new U1272A yesterday. Got it from Datatec here in Germany. They have a trade in sale, 25% discount on any 'Orange Agilent' if you send in any old Fluke. So I guess Agilent is really trying to get a better market share against Fluke.
So, I unpacked my new meter, played around a little, next thing, checked Dave's blog - it is an everday routine - and bang, there was his devastating verdict on my new U1272A !!!
First I thought, maybe Dave left one of his big screwdrivers he always uses to poke around on delicate circuit boards, in the meter. But now my U1272 acted the same way - and I haven't even opened it up. Today it did not stop beeping in the Ohms mode with no probes atached. I had to remove the batteries, now it's working again! - So Dave, you did nothing wrong, no screwdriver left in there ;D
Did some measurements today, the resistor in the low-Z mode must be a PTC, I measured 250Vac, it went from 1,4Kohm to 15Kohm after half a minute.
I really like the orange display illumination, but current goes up from 4mA in Vdc or Ohms, 9mA in Vac, to 70mA with illumination.
I do a lot of repair on old audio amplifiers/tuners, so one reason I bought the Agilent, was that 'auto diode' mode, checking transistors in circuit, without having to reverse the leads - this works as expected.
I'm looking forward for Dave's full teardown, but I guess I still like my new agilent!
Regards, Thomas
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Hello,
what a coincidence. Got my new U1272A yesterday. Got it from Datatec here in Germany. They have a trade in sale, 25% discount on any 'Orange Agilent' if you send in any old Fluke. So I guess Agilent is really trying to get a better market share against Fluke.
So, I unpacked my new meter, played around a little, next thing, checked Dave's blog - it is an everday routine - and bang, there was his devastating verdict on my new U1272A !!!
First I thought, maybe Dave left one of his big screwdrivers he always uses to poke around on delicate circuit boards, in the meter. But now my U1272 acted the same way - and I haven't even opened it up. Today it did not stop beeping in the Ohms mode with no probes atached. I had to remove the batteries, now it's working again! - So Dave, you did nothing wrong, no screwdriver left in there ;D
Did some measurements today, the resistor in the low-Z mode must be a PTC, I measured 250Vac, it went from 1,4Kohm to 15Kohm after half a minute.
I really like the orange display illumination, but current goes up from 4mA in Vdc or Ohms, 9mA in Vac, to 70mA with illumination.
I do a lot of repair on old audio amplifiers/tuners, so one reason I bought the Agilent, was that 'auto diode' mode, checking transistors in circuit, without having to reverse the leads - this works as expected.
I'm looking forward for Dave's full teardown, but I guess I still like my new agilent!
Regards, Thomas
Thanks, I'll forward on to Agilent yet another person with a problem.
Wow, this is getting serious, and does not appear to be a rare event!
Yes the LowZ ressitor can't just be a standard tempco resistor, otherwise at 240V it would heat up just a tad at 1.5Kohms! :o
The teardown is fine, the design and build quality is first class, I really couldn't fault it. Will upload that now.
Dave.
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I think it's obvious that they simply accidentally loaded Windows Vista on to the meters instead of the proper software.
Just select the menu option "Install Windows Genuine Advantage" and you should have no further problems!
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Oooo, you can turn off that bloody annoying turn-on beep?
Dave.
Yes you can, but then the machine doesn't beep at all. One thing I would like to see added to the firmware is a function where the meter only beeps when its necessary, Auto Hold, probe in current jack, Continuity and so forth, and that it remains silent for the rest of the time. I find the beeping every time a button is pressed rather annoying.
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I like a gentle beep when the buttons are pressed, but I hate the LOUD beep when the thing switches on.
Shame you can't select any option you want.
Dave.
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" Gentle Beep "
Well, if the people who works with electronics, dislike the power of it ,
I bet that this DMM will end up like the "Helen of Troy" for the electricians .. :D
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I could reproduce the problem on my 1272 tonight, but I don't know how really.. I was playing around with the ohms and turn it off and on an it hang up after some jumping around of the scales and high voltage indication. Problem was fixed by off-on. Then I could not reproduce it again. My fw is version 1.3 as well.
I saw a reviewer of this meter over at element14 also reported problem with the meter hanging up and scales jumping all over.
Can be found here: http://www.element14.com/community/roadTestReviews/1002 (http://www.element14.com/community/roadTestReviews/1002)
So I guess that makes it 6 cases, so far..
I could also reproduce the problem with factory reset:
Hmm, some other strange bug. I was trying to replicate the problem by switching the meter from off to Vac, I have the beep switched off against te noise :P. At one point It started doing the start-up beeping again, software settings reported beep on at default freq. I was able to replicate this three times (switch beep off, switch back and forth from off to Vac quickly multiple times --> meter beeps)
Further testing confirms the meter does a factory reset.
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And so dear friend Shafri , I do not see any " plague " near by ..
i mean, beta testing usually involved in software. but i dont know if its happening in hardware as well, but it seems starting like that. except they dont call dave a beta tester.
The company I work for sends out a couple of Alpha units as demonstrators to real world installations, and then sends out Betas to various companies with instructions to use them as often as possible and to try to break them.
A couple of times the answer has come back that the Beta units were fine, only to find that when they reached full production some small issue came out of the wood work, either as a bug that was introduced when something else was fixed or something that was just plain missed.
If the Agilent fault is only repeatable when turned off and on again quickly, I would (software hat on) expect it to be a power issue with the micro-controller not being properly reset - clearly a hardware issue.
Neil
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I haven't been able to replicate the random screen issues on my 1272a, nor do I have the long wait auto-ranging issue. I will keep trying as I did see something like it but I can't replicate it.
When I switch to ohms, it does seem to go berzerk, but its the auto-ranging algorithm, as it eventually settles on OL if I do nothing, but it will quickly read when I short or put a resistor on the probes.
I am still going through a lot of tests.
I've had 1 major issue, it was shipped with the Vdc range out of cal. Its running at 0.11% at all ranges while its rated at 0.05%. Its easy to fix properly but its a fairly odd finding in a new DMM with a valid certificate.
I do like the meter's potential, it has features far better than a Fluke 87V if it continues to work reliably and could be a game changer in the industrial DMM arena. Its Vac range is more accurate than the 87V particularly past 1kHz.
So why these issues are happening to the 1272a is puzzling. I have a 1252a that is flawless compared to the 1272a, and the 1252a can easily excel against the Fluke 87v in accuracy and data logging.
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If the Agilent fault is only repeatable when turned off and on again quickly, I would (software hat on) expect it to be a power issue with the micro-controller not being properly reset - clearly a hardware issue.
Neil
I had never played with range switch of my Fluke 28II or 87V , so to see if it has issues, after repeatable reboots.
When working on the field , you just turn on the meter normally and you just work with it.
If the meter goes crazy , when it boots it's and every time , it is damaged.
If this happens ones every 100 boot up , it's a small issue .
Most people had said so far, that when or if, it happens , an simple power off , restores it for operation.
The most unacceptable would be to act crazy , when it boots normally and after.
One of my own personal tests , would be to test both ( Fluke 28II and the U1272A ) by having them connected to mains for four complete days.
That's an true electrical test .
In my eyes even the Fluke 28II is untested by me, about electrical robustness,
and so at my own score board,
the game Fluke VS Agilent is 0-0 .
I am not specialist about the software,
all that I can tell about that, is that I have do five firmware updates, in my mobile phone,
and some times , it does collapses too.
And it was had 400$ retail price.
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Well I have two questions for the people who they own the U1272A ,
and if they can test and report it would be nice.
1)
Set the DMM to DC volts, and use your PSU at 32V volts .
Start drooping the voltage, until the 30.000 counts resolution to become active again.
Report this voltage.
2)
Set the DMM at Ohms range , measure one resistor of 1.8K or 2.2K Max, and one resistor of 3.3K or 4.7K Max.
Check the display response , do you find it , to react faster in any of the two measurements ?
Thanks. :)
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1) Around 26.5 Volts
2) The 4.7K seems to be faster then the 2.2K, tough this is a bit subjective since I haven't used a stopwatch, but it would make sense because the meter has to switch to a lower range for the 2.2K.
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Thank you Floyo, for the fast respond. :)
About the resistance check .
It would be more practical , to do it like this .
1 ) Power on --> Ohms mode.
2 ) cross your leads = Auto range drops to ohms.
3 ) measure the low in value (1.8K or 2.2K )
4 ) cross your leads = Auto range drops to ohms.
5 ) measure the high in value ( 3.3K or 4.7K)
6 ) compare the display response. ( give an estimate of the display refresh rate. )
So far from the Fluke documents its known that the 80 series , and the 28II model.
At the 20.000 counts they refresh the display , only ones per second.
When they work at lower counts , they come close to 4 refreshes per second.
The U1272A in theory is capable for five refreshes per second,
and I am a believer , but I have to ask in which resolution ?
I am seeking for the truth , and only the truth, so help me God.. :D
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When I do the measurement like this the correct value appears almost in an instant. I don't exactly know what you mean by refresh rate, the time it takes to display the proper value in the proper range, or the updating of the bar graph.
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When I do the measurement like this the correct value appears almost in an instant. I don't exactly know what you mean by refresh rate, the time it takes to display the proper value in the proper range, or the updating of the bar graph.
Well, lets forget the bar graph for now.
Yes, my interest are for the time that it takes so to display the proper value , 30.000 & Low resolution.
The higher resolution are always the slower one.
The difference that I had ask for you to find, could be smaller than a blink of the eye.
And so just forget about it .
About the 26.5 Volts ( high resolution activation ) , its not as good as I was hope for.
Also in Fluke ones the voltage must drop about 4V lower than the 20 , so the high resolution to be active again.
And so there is no winner even from this aspect, that at list it matters to me.
Well even if plain numbers, are not that important for the most of the people,
they are important when you actually compare things.
But we will have the opportunity to speak about that,
at the proper thread , when Dave manages to finish the review .
And I will only confirm too, that the people of Agilent, are up to this issue that happened to Dave, as we speak.
Personally I would love to had a tour on their facilities in Malaysia,
who knows , maybe the lucky one would ended to be our Dave.
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Hi Dave,
Had time to examine the 1272a in more detail and examine the issue you raised. The closest I came to a problem that looks very close to yours has to do with the off/on switch. Its better to see it that describe it.
One other thing that a bit scary at first is that the Low Z mode can sometimes show 100s Vac briefly, or for seconds, sometimes some kV levels too. It was first shocking to see it, given it wasn't connected to anything. I was able to duplicate that bug too and again trace it to the switch.
Although the DMM are connected to ~ 4Vdc here, but the issue occurs too with probes off.
They are both very reproducible. Wiggling the switch too can cause it to happen when in the Low Z range.
Random digits from the Agilent u1272a, a switch issue? (https://www.youtube.com/watch?v=kHOMc_J69Gg#)
Switch issue on low impedance mode Agilent u1272a (https://www.youtube.com/watch?v=xkoVpozrQ7c#)
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Thanks Saturation
Mine does similar stuff but not on the LowZ thing.
Almost certainly mechanical manufacturing tolerances between units causing this.
I've forwarded your videos onto Agilent, I think they have a very serious problem on their hands...
Will be interesting to see what they do here, because they have a lot invested in this new design with a big marketing push, and it's been out for some time now.
Dave.
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My Mastech MS8226T has similar problems if the range switch is dirty. Some dielectric grease on the contacts seems to work well at preventing the problem.
At work, I solved a problem with some Agilent data acquisition multimeters they were using in an automated test setup. The problem was that the meters would often lose the connection to the control PC, especially if they were used with USB hubs. A firmware update fixed that. (I initially thought it was a bad hub or USB controller, so I switched out the hub several times and even swapped out the entire PC. Then it dawned on me to try using the latest drivers instead of the ones provided with the test distribution and that's when I found the firmware update.)
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Almost certainly mechanical manufacturing tolerances between units causing this.
Dave.
I can only agree , this is why some companies has specific notes about how to Reassembling the Meter,
in their own calibration lab ...
Example: 27 II/28 II Digital Multimeters Calibration Information ( Page 23 )
You need an special screwdriver with torque control !!
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You're welcome. It makes the u1272a a better meter, since I know were the bug is coming from. However, given the marketing around this meter, its a bit ironic.
One last major issue, why my u1272a was out of cal with a valid Agilent cal certificate. I received this DMM factory fresh. I maintain my own 10.000 00 VDC standards and keep my instruments at tight tolerances, as pictured. The first image is 10VDC, the second is 1004.7 VDC.
I'm 90% done with performance testing and can't find significant faults. This one remained annoying so finally I calibrated the 1272a yesterday. Its hard to prove to Agilent if they asked for the DMM back for examination because once its calibrated the problem is gone, so the pictures have to tell the story. But I've let it linger for almost 3 weeks and I can't field test this further with it reading off.
Calibrating this meter is the easiest I've ever done.
You can calibrate just a single range without having to adjust all the meter's other functions, which the Fluke 87V has you do. You can jump into calibration mode at any time, in the middle of a measurement, just turn the DMM on, and hold the blue and orange buttons down for over 1 second, then enter the password. It requires many keystrokes thereafter to go through the menus so that its very unlikely you'll accidentally calibrate this DMM, just turn it off without completing a single range sequence will abort the adjustment.
If you have to calibrate every range to adjust just one range like a Fluke 87V, its very time consuming if you don't have an automated calibrator. To the Fluke's credit, I've never had to adjust it ever though.
Thanks Saturation
Mine does similar stuff but not on the LowZ thing.
Almost certainly mechanical manufacturing tolerances between units causing this.
I've forwarded your videos onto Agilent, I think they have a very serious problem on their hands...
Will be interesting to see what they do here, because they have a lot invested in this new design with a big marketing push, and it's been out for some time now.
Dave.
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This one remained annoying so finally I calibrated the 1272a yesterday. Its hard to prove to Agilent if they asked for the DMM back for examination because once its calibrated the problem is gone, so the pictures have to tell the story.
About the ethical and legal part of the story, you had no authorization to act like that.
Even so, my own personal opinion is that the few words in text and some photos , had zero creditability.
Especially when it is an direct public accusation, coming from an anonymous source.
I would trust Dave or Alm about subjects related to quality control and multimeters .
But I would not trust any one, who acts like you did .
Keep up the good work.
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I noticed that if the switch is a little off (close to or between two settings) the warning for wrong connection of the probes does not work. When this happens the meter looks to be working, nothing strange on the display but there is no response from the buttons (for instance the backlight cannot be turned on). If you move the probes for correct connection, without touching the switch, it sure does measure as it should.
So to be safe it's good practice to always try to turn on the backlight after each operation of the switch. ::)
I don't know how likely this is to happen in really life but I guess Mr Murphy will make sure it does happen!
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Hello elCap ..
You are correct, in the real life you worry more for your own Boss ,
and less about Mr. Murphy, or your Multimeter.. :D
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I've had 1 major issue, it was shipped with the Vdc range out of cal. Its running at 0.11% at all ranges while its rated at 0.05%. Its easy to fix properly but its a fairly odd finding in a new DMM with a valid certificate.
That's not easy to fix for everyone, and if you think from a another perspective, the calibration is about half of the darned thing's price: it definitely should be in cal with a traceable cal cert it's shipped with. >:(
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Blaming the DMM about be out of calibration it is easy to do..
Lets see if there is any smart one among us , so to blame the Fluke calibrator, who actually did the calibration to this DMM.
1) Agilent does not make calibrators .
2) Before the DMM gets calibrated , it passed from QC inspection.
3) Got calibrated , the calibrator print the calibration certificate.
4) The boys of Agilent with confidence , sent this DMM for distribution.
Pick up a target , any one you like , and shoot it.
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Yes, that's one reason I did nothing for so long, but no one else here reported it, so I presume its fairly rare. Agilent did not request it back so I have to move on with testing.
But since the DMM was given to me to keep, and I am supposed to use it as a working meter, I can't do more with it reading as is. The DMM logs all calibration changes, and on receipt it began as zero adjustment count. There are still more issues that will be feedback to the company directly first before I post, but the one's on this thread are major ones; other people who bought/own this meter and maybe using it for real work should be aware of the major issues because it will impact usability immediately. Other issues are not major but still reflects on quality control.
Now that the meter is reading well, I can put it through what its intended to do in the field.
I've had 1 major issue, it was shipped with the Vdc range out of cal. Its running at 0.11% at all ranges while its rated at 0.05%. Its easy to fix properly but its a fairly odd finding in a new DMM with a valid certificate.
That's not easy to fix for everyone, and if you think from a another perspective, the calibration is about half of the darned thing's price: it definitely should be in cal with a traceable cal cert it's shipped with. >:(
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Not everyone has access to calibration equipment to resolve this issue. A calibration cert cames with the Agilent DMM and you would expect the meter to be in proper order not just in the level of calibration but also function accurately to spec.
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Not everyone has access to calibration equipment to resolve this issue. A calibration cert cames with the Agilent DMM and you would expect the meter to be in proper order not just in the level of calibration but also function accurately to spec.
No one said that this calibration " Issue " will be something that every one will face , when he gets this model.
If any one say something like that, he must be nuts ..
I did an comparison of the serial number of the DMM that Tronixstuff had , with the one that Dave got ,
it looks that there is out there , hundreds of thousands of such units.
And also the Google spying monster , its totally clean from complains too. :)
Not to say, that this expensive DMM , has as target mostly professionals,
and those people, are capable enough to contact the company and resolve any issues.
And they do have, more than one DMM to work with !!
So to send back the possibly problematic one, even just for inspection.
All those contracts about check and calibration between the maker of the DMM ,
and the large factories or private companies (that are the customers) ,
serves exactly this purpose .
No matter what , you are covered .
The single consumer just uses the warranty plan , it simple and effective.
And I am here and writing all those words as an reaction,
because I have sense in the atmosphere unjustified exaggerations.
That's all.
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A new product should simply not has this fault period.
On the contrary, I think your reaction is exaggerated.
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A new product should simply not has this fault period.
There is no chance to have an dialog , with someone who uses the word "period"
And so I will save my words too. :)
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Yes, that's one reason I did nothing for so long, but no one else here reported it, so I presume its fairly rare.
I have a grainger-discounted U1252A which came with a cal cert, but only way I could think of to verify validity of that is to have it re-calibrated and that would set me back more than what I paid for the meter itself. :(
Makes one to think twice about the measurement confidence Dave touts about.
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One day your meter may get drift off calibration, but you never know when. If you have only one DMM, you won't be able to confirm a critical reading or do a spot check, because you have no comparison.
I have that 1252a too from grainger.com and its faultness, except for some peculiarities in its megaohm resistance reading; its too sensitive and picks up quite a bit of EMI or static, could use an optional filter section. To confirm its accuracy I just did to it what I did to the 1272a against my other meters.
Yes, that's one reason I did nothing for so long, but no one else here reported it, so I presume its fairly rare.
I have a grainger-discounted U1252A which came with a cal cert, but only way I could think of to verify validity of that is to have it re-calibrated and that would set me back more than what I paid for the meter itself. :(
Makes one to think twice about the measurement confidence Dave touts about.
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One day your meter may get drift off calibration, but you never know when. If you have only one DMM, you won't be able to confirm a critical reading or do a spot check, because you have no comparison.
I have that 1252a too from grainger.com and its faultness, except for some peculiarities in its megaohm resistance reading; its too sensitive and picks up quite a bit of EMI or static, could use an optional filter section. To confirm its accuracy I just did to it what I did to the 1272a against my other meters.
I can compare it to other meters to know whether it's all out of whack, but it's not really a feasible way to determine if it's spot on as when comparing it to 0.5% accuracy meters I can't really know for sure even when I can get my hands on dozen meters to compare it with.
I suppose getting more meters of similar accuracy could be warranted, but no-one I know has need for such and I certainly don't have plans to buy several myself. :D
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Agilent give calibration cert for a purpose, wonder if the cert does not actually certify anything then what's the point? Is that just a marketing gimmick?
A product that does not perform to spec new is a faulty product. There is no discussion necessary on this issue. With or without your own calibration capability i think this is not acceptable.
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I have that 1252a too from grainger.com and its faultness, except for some peculiarities in its megaohm resistance reading; its too sensitive and picks up quite a bit of EMI or static, could use an optional filter section. To confirm its accuracy I just did to it what I did to the 1272a against my other meters.
I've seen this in other meters. I've assumed this is due to the very low current at high resistances (because of the limited compliance of the internal current source in the DMM). Induced current will influence these measurements, not sure how filtering is going to help, apart from the standard CMRR/NMRR stuff. Guarding the connections should help, but is somewhat impractical in a hand held meter. Maybe the other meters that are less sensitive use a higher test current/compliance or have better CMRR/NMRR?
If a meter calibrated by Agilent is found out of spec within the calibration interval, something is either wrong with the stability of the meter, or there's a serious issue with their calibration equipment/procedure.
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Hi shadowless , in your post above you just repeating your self for an second time in the row .
Do you expect some sort of reaction from some one ?
If Saturation wishes to sell to you the specific unit that he owns , do not buy it.
Our topic is about the trouble that Dave had with his own sample .
I do not act as moderator !! I am just ask questions so to find out what is really hidden at the back of your head.
The 98% of every one who reads this topic , had buy an DMM with out calibration certificate.
And its not a crime to return a multimeter back to the maker , because there is something wrong with it.
As long there is not printed on the carton box of it, any questionable ancient quality standard's like " Zero defects " or "Six Sigma" ,
its just a product for consumers , and that's all about it.
If you have never return a product in your life , you are just lucky so far , do no expect this luck to last for ever :)
Nothing does .
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The way you are defending Agilent would make you think they had given you a free meter or somthing ??? :)
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The way you are defending Agilent would make you think they had given you a free meter or somthing ??? :)
I was prepared even for an such of reply too .. ;D ;D ;D ;D
This specific U1272A it will be the first one , that will enter in the Greek borders,
not even the main distributor of Agilent in Greece does not have actually touch one yet.
Their " Mix up " had cause almost damage to me, I am in danger to loose my face.
I have write to all of my friends about this subject. In the Greek forum ( about electronics) that I am member too.
There is 2500 views in the "Reads counter" and five pages with messages with congrats about me,
and still , I have to write excuses for almost 30 days , about what happened with it.
You are correct when you implying that I am in love with Agilent ,
but only if you are saying it as joke, and laugh about it , as you did .. ;)
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You don't even have one in your possession to defend for. Saturation from posting his real experience. I post twice and it still doesn't seems to register need i say more.
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The way you are defending Agilent would make you think they had given you a free meter or somthing ??? :)
I was prepared even for an such of reply too .. ;D ;D ;D ;D
This specific U1272A it will be the first one , that will enter in the Greek borders,
not even the main distributor of Agilent in Greece does not have actually touch one yet.
Their " Mix up " had cause almost damage to me, I am in danger to loose my face.
I have write to all of my friends about this subject. In the Greek forum ( about electronics) that I am member too.
There is 2500 views in the "Reads counter" and five pages with messages with congrats about me,
and still , I have to write excuses for almost 30 days , about what happened with it.
You are correct when you implying that I am in love with Agilent ,
but only if you are saying it as joke, and laugh about it , as you did .. ;)
;D ;D ;D
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You don't even have one in your possession to defend for. Saturation from posting his real experience. I post twice and it still doesn't seems to register need i say more.
Thanks for replying , it looks that there is some sort of language barrier problem,
because I do not understand you point's , and I got no answers too.
Have a nice day. :)
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Hello, alm long time no chat. There is a video of it somewhere I posted, just search for it.
I concur with your diagnosis, but I think there are other factors too. EMI and RF may be culprits too as shielded cables or makeshift grounded guards do help.
For a portable meter, a simple solution uses the minmaxave mode, as the average is consistent over time [being the DC component], and the longer its allowed to read the average, the more it smoothens spurious input.
As for the calibration issue, no one else reported it among posts on the net, but other than Dave's spot check I haven't seen other reviews doing range checks against the spec sheet. The other ranges are in spec, so its more likely the meter was cal'd in error rather than drifted off spec. Since the meter is warranted, its simple to return the meter.
Lessons are:
A cal certificate is no guarantee calibrations persist to the next scheduled cal date or that its actually done properly. Flukes 80s don't ship with such certificates, but their reputation for lifelong accuracy is known.
Its good practice to performance test new gear to insure it lives up to specs; if users just require 0.1 - 1% accuracy or had no other DMM to compare it too, that cal error would go unnoticed.
From the 1272a service manual, see png.
I have that 1252a too from grainger.com and its faultness, except for some peculiarities in its megaohm resistance reading; its too sensitive and picks up quite a bit of EMI or static, could use an optional filter section. To confirm its accuracy I just did to it what I did to the 1272a against my other meters.
I've seen this in other meters. I've assumed this is due to the very low current at high resistances (because of the limited compliance of the internal current source in the DMM). Induced current will influence these measurements, not sure how filtering is going to help, apart from the standard CMRR/NMRR stuff. Guarding the connections should help, but is somewhat impractical in a hand held meter. Maybe the other meters that are less sensitive use a higher test current/compliance or have better CMRR/NMRR?
If a meter calibrated by Agilent is found out of spec within the calibration interval, something is either wrong with the stability of the meter, or there's a serious issue with their calibration equipment/procedure.
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So far the posts on this thread have been about the negative aspects of this DMM, so just to balance things out here are the positive compared against the Fluke 87V, showing it has promise once the mentioned bugs are worked out:
All AC ranges, V or A, are at least 2x more accurate
In DC & ohms ranges, its at least equal
It has higher frequency counter limits
The datalogging and serial connection are flawless in lab conditions
It reads faster
Its physically slightly lighter, and the material makes it easy to grip
Orange is easily more visible to see in most any conditions, more than yellow
dual display is far more informative than switching between readings, as in Flukes way
Its read AC+DC
the basic IP rating is higher but only real world field use can tell how it survives expsoure
From 0F, to 100F ambient temps without drifting out of spec
Work in 100% RH, its above spec, rated only to 80% RH
It can be field calibrated, if you know how, the Fluke 87V cannot
AAA powered, not 9V battery
I have more than 1 unit under test, so the performances, both good and bad, are not one-offs or "flukes" ;)
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It can be field calibrated, if you know how
Lets hope that you did the calibration at the specific lab with adjusted room temperature,
locked at 23 °C ± 1 °C .. as stated in the document that you have in your hands ,
at the Calibration Procedures section.
If not , you had calibrated thin air .
Every one is capable to push buttons.
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It can be field calibrated, if you know how
Lets hope that you did the calibration at the specific lab with adjusted room temperature,
locked at 23 °C ± 1 °C .. as stated in the document that you have in your hands ,
at the Calibration Procedures section.
If not , you had calibrated thin air .
Every one is capable to push buttons.
My mother language it's not English, but your comments tends to be a little bit aggressive. Chill out! I like what saturation have done.
[RANT]
Shame that a "Big Company" like Agilent is being caught with it's pants down!
I still trust more on Fluke than Agilent. More even, on DMM market there is no brand like Fluke, and on the Osc. market LeCroy and Tektronix, both have strong brands, even stronger than Agilent.
One tends to question why Agilent it's so expensive when their brand has fallen on disgrace... it no longer HP.
Agilent needs to wake up and rebuild it's brand, it's easy, good products, superb precision, no standalone equipment with Windows Embedded, good design and above all... long time reliability. I love their documentation, they just needs better products to accompanied them.
[/RANT]
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My mother language it's not English, but your comments tends to be a little bit aggressive. Chill out! I like what saturation have done.
I will not called my self as aggressive , but I am feeling a bit jumpy , because your hero pretends the tiger who had grab Agilent from the balls.
And it does not matter what you trust more like A vs B brand , its a matter or ethics.
I do not try to control the others people opinion , but I will not stop expressing my own.
Every one is responsible for him self , when he press the Post button.
[RANT]
Shame that a "Big Company" like Agilent is being caught with it's pants down!
There you are, acting as predicted .
But where is your own proofs ?
Your rant looks more like flaming to me.
I still trust more on Fluke than Agilent. More even, on DMM market there is no brand like Fluke, and on the Osc. market LeCroy and Tektronix, both have strong brands, even stronger than Agilent.
Nothing to say here ..
One tends to question why Agilent it's so expensive when their brand has fallen on disgrace... it no longer HP.
Take a big breath and look who is the partner - supplier of parts that Agilent use in their DMM .
http://www.hmrohm.co.kr/html/aboutus.asp (http://www.hmrohm.co.kr/html/aboutus.asp)
Does the word Vishay DALE rings a bell to you ?
Agilent needs to wake up and rebuild it's brand, it's easy, good products, superb precision, no standalone equipment with Windows Embedded, good design and above all... long time reliability. I love their documentation, they just needs better products to accompanied them.
[/RANT]
Do you see any member among us to called as Agilent ?
Send them one email with your RANT .
That's a more wiser way to pass your message than writing in forums,
or else your RANT looks like an anonymous prank .
I am here to learn and educate my self , or aid the one who needs help .
Or aid the brand who needs help .
I need better and reliable tools , and I want to help , any one who bust his ass to build them.
Because at the end, he works for me ...
This is my RANT to any one who thinks like you.
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So what's the take-away from all this for someone looking for a new meter?
Should the U1272A (or the U1271A) even be considered at this point? Or "go for it" but know that it may need to be returned to the distributor/manufacturer if said issues are encountered?
Any reports of people *not* having the range-switch "bezerk-ness" issue?
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I didn't notice the range switch berzerkness until I started fidgeting with it. In normal use I'm switching directly from OFF to whatever range I need, probably fast enough that signals aren't getting mixed up. The only time I noticed the crazy alarms (see my other thread with video) at work was yesterday when I was checking current on a group of LEDs and must have overswitched to uA and back to A before starting.
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So what's the take-away from all this
I can speak only for my self.
My own take -away is that there is some software related bugs.
The findings is so fresh , that every one here scratches his head head about them.
And if I was aware , that the firmware update process on this thing ,
is possible to happen by just using the USB-IRDA modem, and some sort of updating software that works in windows
( like flashing the Bios in your motherboard), I would feel safe and relaxed.
PetrosA nicely described the root of the problem , by saying : signals aren't getting mixed ( by properly using the range switch).
My own technical instinct as troubleshooter , was telling me same thing from the start ,
And if you check this thread and my messages ,
I had point out repeatedly that the proper use of the range switch, can minimize software related glitches , if there is any.
Lets hope that the boys in Agilent, could deal with the software problems equally fast ,
as the people from ASUS does , about Bios releases for their motherboards.
I feel bad by watching one so perfect engineering ( parts related ) ,
to loosing face due software bugs.
Time will tell , if our predictions haves any real base , but it is very soon for any reliable answers in your questions.
Stay close to this forum, and you will be from the first ones , who will know how it goes. :)
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Do you see any member among us to called as Agilent ?
Send them one email with your RANT .
That's a more wiser way to pass your message than writing in forums,
or else your RANT looks like an anonymous prank .
I am here to learn and educate my self , or aid the one who needs help .
Or aid the brand who needs help .
I need better and reliable tools , and I want to help , any one who bust his ass to build them.
Because at the end, he works for me ...
This is my RANT to any one who thinks like you.
A rant is a rant... purely personal opinion, take it or leave it. As you said it has no value. But I want to express my self, and find other people opinions.
I miss the old days when documentation, service manuals and schematics were the norm... I don't defend enterprises that thinks it's customers are potential competitors.
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For everything it worth's, I will just say that I do respect your opinion.
And currently I have a ton of my own problems to deal with.
Possibly I got over excited by this Agilent story , and acted mostly from impulse.
Take care.. I need you as friend and tomorrow.
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It's ok, I know you like Agilent. ;)
They will fix this, since it's their name that we are talking about.
My personal rant it's because I miss the old HP, the HP that died when Lew Platt toked it under it's tenure (and for the sake of it, Carly Fiorina too).