EEVblog #933 - Keysight U1272A EMC Issue

[TheAmmoniacal]

Do we know if all board revisions of the U1272A have this problem?

[PartialDischarge]

Owners of these multimeters have basically 3 options

-live with the problem (ie dont measure current)
-sell the multimeter
-wait for someone (Dave?) to come with a hardware hack and fix it by yourself.

don't expect anything from Agilent 

[TheAmmoniacal]

Offering firmware fixes is pretty shitty when you have to purchase the interface cable separately. In this country the U1272A is $638 USD and the USB cable is $42 (+ $10 shipping).

Definitely not worth it.

I think last time they screwed up on their range selection firmware they offered a free cable to everyone.

They offered a free interface cable to everyone with that firmware (or serial number range?), I remember trying to get one but I couldn't (I was on the newer firmware 2.04). Can't remember why I failed to get one..

[TheAmmoniacal]

Had my U1272A lock up today while playing with the signal generator on it, the meter would no longer "boot", on all ranges it would just display the make and model screen indefinitely - this persisted until I re-inserted the batteries. Anyone heard of this issue before? Strange.

Wasn't able to replicate the problem, so maybe just a fluke.

[bitseeker]

so maybe just a fluke.

Hmmm. LOL!

[EEVblog]

Had my U1272A lock up today while playing with the signal generator on it, the meter would no longer "boot", on all ranges it would just display the make and model screen indefinitely - this persisted until I re-inserted the batteries. Anyone heard of this issue before? Strange.

That's new!

[EEVblog]

Owners of these multimeters have basically 3 options
-live with the problem (ie dont measure current)
-sell the multimeter
-wait for someone (Dave?) to come with a hardware hack and fix it by yourself.
don't expect anything from Agilent 

I suspect they are working on it and will secretly release in the next hardware build. Given their recent attitude I suspect  they don't offer fixes for previous customers.

[EEVblog]

Do we know if all board revisions of the U1272A have this problem?

Mine is a really old one, one of the first run.
I'm pretty sure it's all builds.

[Cerebus]

Owners of these multimeters have basically 3 options
-live with the problem (ie dont measure current)
-sell the multimeter
-wait for someone (Dave?) to come with a hardware hack and fix it by yourself.
don't expect anything from Agilent 

I suspect they are working on it and will secretly release in the next hardware build. Given their recent attitude I suspect  they don't offer fixes for previous customers.

You mean former customers, because anybody who knows they've been caught by this, and doesn't see a proper fix for it, won't be buying from Keysight again in a hurry.

[bitseeker]

Does adding more shielding (e.g., metalized tape) to the inside of the case minimize the problem with nearby RF (i.e., when a cable with a high frequency signal is in proximity of the meter)? Although that wouldn't address noise on the wire when connected to the meter, at least it would help with general environmental interference if it worked.

[madires]

I suspect they are working on it and will secretly release in the next hardware build. Given their recent attitude I suspect  they don't offer fixes for previous customers.

You mean former customers, because anybody who knows they've been caught by this, and doesn't see a proper fix for it, won't be buying from Keysight again in a hurry.

By that attitude they would clearly say: "Don't trust us! We'll screw you. Please go somewhere else.". But they also know, that some of their products are really good, and it's hard to find alternatives. This leaves a bad taste in my mouth. I wonder how they would handle a similar situation with an US$ 10k or 20k scope for example.

[TheAmmoniacal]

Not sure I can trust this meter anymore, tried to measure the resistance of the new banana leads I ordered, I get -0.043    I even heated it up to 23 C just to make sure! This can't be normal is it? Up to spec? The datasheet says 0.2% + 10 counts on the 30 ohm range, at 23 C +- 5 C.



My U1733C gives me a precise 0.0149  every time, from 16 C to 23 C. (120 Hz)

[Floyo]

Are you sure that what you are seeing isn't the thermo-electric effect (seebeck) at work? You mention heating the meter up. When you want to do these low value resistance measurements its a rather good idea to leave all cables and equipment equalize to one temperature, if a dissimilar metal joint (the banana lead and the jack) is experiencing a temperature gradient it generates a voltage. This in turn upsets the resistance measured.

A little experiment you can do is taking two banana leads, plugging one end of each into the meter, and joining the other ends in the middle. If you then heat the joint with a lighter/soldering iron/hot air so that one side becomes temporarily hotter than the other, you will see the resistance move around a bit, and settle again once everything is at equilibrium again. You can also observe the thermocouple effect by setting the meter to the millivolt range.

I'm not saying this is definitely what you are experiencing, but its good to keep in mind.

As for my u1272a, its most certainly affected by this issue. I'm not sure if this behaviour is even outside the specifications for EMI, but I do think manufacturers of test gear should make sure their stuff surpasses the immunity norms by a healthy margin, an active prototype can radiate and conduct all sorts of stuff outside of the norms for commercial equipment.

[saturation]

I've used and owned two of 1272a since 2011 and its been a good performer.  At a list of $350, it still is cheaper than the Fluke 87V, the 28 II and is more accurate and has more features.  Its great that its IP67 compared to the 30 for the 87V.  Its also easier to field adjust the Keysight design during calibration compared to a Fluke, luckily Fluke's rarely require adjustment.

However, it has been buggier than the Fluke 87V, bug were not publicly acknowledged, AFAIK, and fixes have taken years to repair.  The EMC is yet another issue. 

The DMM market is very crowded, and there is very little room for error. 

Issues of concern to me are bolded and should have been sent as a recall or warning notification to registered owners or as a public announcement, each time. 




The 1272a firmware changelog since inception:

<sub>2015-09-21
Version 3.03
-       Change to Keysight identity
-    Change shunt calibration limit from 10% to 20%
-    Remove AC offset calibration limit
-   Bug fixed for Spider LOG issue
-    Bug fixed for voltage alert error when setting count > 65535
-    Bug fixed for APO icon not dim in setup mode when APO = OFF
-   Bug fixed for Bar0 missing when exit view mode
-    Bug fixed for incorrect BAR polarity in dBm/dBV mode
-   Bug fixed for Event log index delay one record
-    Bug fixed for AUTO HOLD feature not clear when press dual button
-    Bug fixed for ACV + dual DCV



2013-07-05
Version 2.04 fixed an issue present in the previous release.
-   The Filter setup menu item was amended to include 3 options: DC, DCAC and OFF. The factory default option is set to DC to enable Filter during DC measurement.
                The Filter function attenuates AC signals to help you read the correct DC measurement from a mixed signal.

2013-03-20
Version 2.00 fixed a major bug, a few minor bugs and included several enhancements.

-   Fix incorrect reading on the display after the rotary switch is rapidly/repeatedly turned on/off.
-   Fix wrong values display during frequency <20Hz measurement in LPF mode
-   Fixing Auto Hold function is not disabled when single press “AutoHold” button in Auto Hold mode.
-   Fixing bug in secondary display as it does not change while pressing “Dual” in Auto Hold mode.
-   Enhanced continuity flash alert response time to be as fast as the beep alarm.
-   Enhanced firmware to show “OL” sign after changing to higher range in MaxMin mode (ACDC mA function).
-   Enhanced firmware to show “OL” when overloaded in Manual Range with Auto Hold is enabled.
-   Enhanced firmware to show the “-“ sign in ACV for ZLow function while pressing Trig Hold/Auto Hold button.
-   Enhanced the consistency in Temperature unit F-C or C-F display.  It should show “F” only or “C” only in both 1st and 2nd display.


Version 1.30
-    Initial release

NB: that was 2011</sub>




 

[Dwaine]

Had my U1272A lock up today while playing with the signal generator on it, the meter would no longer "boot", on all ranges it would just display the make and model screen indefinitely - this persisted until I re-inserted the batteries. Anyone heard of this issue before? Strange.

Wasn't able to replicate the problem, so maybe just a fluke.

What were you doing at the time you experienced the lockup?   Everyone could test and see if they can duplicate the situation.

[mrnuke]

There is a vendor, which wishes to remain anonymous, who has taken notice. They are liquidating their Keysight multimeter stock due to this EMC issue.

 I was able to negotiate a 1253B for only $250 US.   

[Zbig]

There is a vendor, which wishes to remain anonymous, who has taken notice. They are liquidating their Keysight multimeter stock due to this EMC issue.

 I was able to negotiate a 1253B for only $250 US.   

Good, with what you've saved, you can now afford a basic clamp meter to perform a quick sanity check before using Keysight to measure current, each and every time. That's what I'm doing.

[bitseeker]

There is a vendor, which wishes to remain anonymous, who has taken notice. They are liquidating their Keysight multimeter stock due to this EMC issue.

 I was able to negotiate a 1253B for only $250 US.   

That's excellent for anyone who wants to buy one since the U125xB isn't affected by this issue.

[TheAmmoniacal]

I did own both the U1253B and U1272A at some point, the OLED screen is sexy - I'll give you that. But I did decide on the U1272A eventually.

[Keysight Technologies Rep]

Hello everyone. Thank you for the continued discussion and feedback. We take pride in the quality and accuracy of Keysight products. This is a core value and is integral in our goal to provide excellent customer satisfaction.

We’re troubled by the EMC-related findings with Keysight’s U1270 series of handheld digital multimeters, and apologize for any problems this has created for our customers. Resolving it is a top priority with our development and manufacturing teams, and we have been working diligently on it for the past three weeks.

We have determined the filter design for the product does not sufficiently attenuate external noise from RF signals. Because we stand behind our products and solutions, we are offering our U1270 series handheld digital multimeter customers the following choices at no cost:

 -- A higher performance U1280 series handheld digital multimeter; or
 -- A redesigned U1270 series handheld digital multimeter (available in February, 2017), and in the meantime, a complimentary U1173B IR-USB PC connectivity cable so customers can upgrade their current U1270 series multimeter to the latest firmware version.

Please contact us at this special webpage (https://www.keysight.com/main/editorial.jspx?cc=US&lc=eng&ckey=2806392&id=2806392) if you own a Keysight U1270 series digital multimeter and want one of these options. We value your satisfaction. We believe in our products, and we want you to be happy with them.

[PartialDischarge]

That is actually excellent news for owners and a shows great commitment from Keysight to their customers. Double    

[2N3055]

 

[dr.diesel]

Although I agree this is great news, it wasn't their initial response and likely only motivated by the public shaming here on the EEVBlog.

Thanks goes to Dave and the great community he's grown here.

[HighVoltage]

What a great response from Keysight.
Thank you.

Is it confirmed that the U1280 does not have this problem or other problems?


I have requested a
" -- A higher performance U1280 series handheld digital multimeter"

[eliocor]

Quote from: HighVoltage on Today at 09:19:07

What a great response from Keysight.
Thank you.

Is it confirmed that the U1280 does not have this problem or other problems?

It will be surely a big monetary loss for them...
I'm certain they have checked throughly before doing the announcement!