Author Topic: EEVblog #933 - Keysight U1272A EMC Issue  (Read 146081 times)

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Offline agmbass

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #575 on: May 16, 2017, 10:44:29 pm »
I also received the U1282A  . Thanks Keysight !
 

Offline Electro Detective

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #576 on: May 26, 2017, 04:48:11 am »
I complained and bitched so hard about all these bugs,  |O   
demanding a meter for all seasons that actually worked, sick and tired of being someone's Beta Test Whipping Boy!!!    :rant:

Finally they got back to me, sending yet another new 'fixed' meter with a waiver form to sign upon delivery,
that the 'matter is now officially closed upon acceptance',
arriving in the mail soon.   

Apparently this time it's a Fluke..  ;D

« Last Edit: May 26, 2017, 09:56:23 am by Electro Detective »
 

Offline Zbig

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #577 on: May 26, 2017, 12:16:29 pm »
I complained and bitched so hard about all these bugs,  |O   
demanding a meter for all seasons that actually worked, sick and tired of being someone's Beta Test Whipping Boy!!!    :rant:

Finally they got back to me, sending yet another new 'fixed' meter with a waiver form to sign upon delivery,
that the 'matter is now officially closed upon acceptance',
arriving in the mail soon.   

Apparently this time it's a Fluke..  ;D

There sure is quite a bit of emotion ;) Could you please calmly elaborate what the actual issues you keep having are? ;)
« Last Edit: May 26, 2017, 03:53:56 pm by Zbig »
 
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Offline Electro Detective

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #578 on: May 27, 2017, 12:42:44 am »
I complained and bitched so hard about all these bugs,  |O   
demanding a meter for all seasons that actually worked, sick and tired of being someone's Beta Test Whipping Boy!!!    :rant:

Finally they got back to me, sending yet another new 'fixed' meter with a waiver form to sign upon delivery,
that the 'matter is now officially closed upon acceptance',
arriving in the mail soon.   

Apparently this time it's a Fluke..  ;D

There sure is quite a bit of emotion ;) Could you please calmly elaborate what the actual issues you keep having are? ;)

No more orange meter issues, the Fluke is working fine  ;D
 

Offline lowimpedance

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #579 on: May 27, 2017, 01:36:24 pm »
 :-//



So a change of color did the trick ?.



 :-//
« Last Edit: May 27, 2017, 01:38:15 pm by lowimpedance »
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline Electro Detective

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #580 on: May 28, 2017, 12:10:13 am »
yes, it was a LEMON masquerading as an orange  ;D
 

Offline HighVoltage

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #581 on: May 30, 2017, 10:00:39 pm »
I had one more U1273A that I had forgotten about and just today I received the replacement unit.
Thanks so much Keysight!
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline lowimpedance

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #582 on: May 30, 2017, 11:58:34 pm »
yes, it was a LEMON masquerading as an orange  ;D
If you would care to elaborate more on the 'bugs' you have found (apart from those already covered here) I'm sure many "lemon" owners would be most interested and indeed could perhaps be considered a safety issue and doing us a favor in sharing.
 I am actually curious what further issues remain, as so far in my lab situation at least I have not had any measurement issues yet but of course I have not used all the functional capabilities thus far either.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline Electro Detective

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #583 on: May 31, 2017, 03:58:21 am »
I can't elaborate anything more than the same bugs as "those already covered here"

which was more than enough to test my patience, and run back to my eye candy challenged Fluke meters,

begging for forgiveness   :-[ 

;D
« Last Edit: May 31, 2017, 04:02:16 am by Electro Detective »
 

Offline bambadoo

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #584 on: June 05, 2017, 10:54:01 am »
Anyone got a "tax and customs" bill from DHL when getting a new item from Keysight?
I got one at about 60USD.
Keysight tells me not to pay and they will fix it but payment due is tomorrow and I really dont like being late ;)

Best Regards
 

Offline Sbampato12

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #585 on: June 05, 2017, 12:15:57 pm »
Anyone got a "tax and customs" bill from DHL when getting a new item from Keysight?
I got one at about 60USD.
Keysight tells me not to pay and they will fix it but payment due is tomorrow and I really dont like being late ;)

Best Regards


I've paid for the USB cable. After paying I send an email, and they told me that if that happens again, to not pay until emailing them. But it doesn't happened again to me.
 

Offline HighVoltage

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #586 on: June 05, 2017, 06:25:43 pm »
I have received two instruments through DHL Express and never was bothered by the customs service, although this would be very typically in Germany.
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline Mr. Scram

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #587 on: November 22, 2017, 09:02:06 pm »
Original Agilent mods complete , for now!.
Indeed it would have been interesting to know the design choice for the original specified parts, but I think that will be only speculated on. What we do have is what changes have been considered necessary to harden the spec for  EMI resistance.

 Out of curiosity I changed only BD4 and 5 first to a resistor value of 0.2 \$\Omega\$ as per what values bernoth used and tested the EMI immunity with the result being now only a few milliamps indication on the display was shown when a 10Mhz 100mV signal was applied to the Amp terminal and this reading did not seem to change with activation of the LPF. So a considerable improvement in de sensitizing the current mode to external EMI but not quite there.
 So next was to change BD7 and R55 to both 2K4 \$\Omega\$. And now testing this complete mod shows no obvious EMI effect at the applied RF signal (or any stray effects when a hand is placed around and on the meter). Now its quite possible that more signal amplitude or different frequency may have a different outcome but for my uses I'm more than happy to leave it there with now two 1272's.
 I did test the ohms ranges and noted the CAL was still good with an input short. Both meters showed identical behavior when presented with a short in the ohms mode. I did note that the LSD on the old Agilent '72' in Current mode was sitting between 2 and 3 counts so perhaps a RE CAL of that function may be needed. Looking at the CAL. procedure it looks as if it maybe possible to do an individual function as opposed to the whole meter. Perhaps I'll give it a go sometime if I get motivated enough and will post here whether successful or not!.
Just to get this right: replacing two sets of resistors should fix the problem on afflicted multimeters? Has this affected the calibration in any noticeable way?
 

Offline lowimpedance

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #588 on: November 28, 2017, 05:47:31 am »
There does appear to be some change in the ohms zero, and maybe a few digits in dc mA range. After testing on a Fluke 5500a calibrator the only function to be notably affected by the mod's would be the ohms.
I have done the ohms cal on the 'modded' meter and now the zero is indeed zero with a direct input short. Not entirely sure if the rest of the ranges needed cal as well besides the input short test, but I did them anyway.
 Need to test the replacement from Keysight under the same conditions to see what ohms reading it has with an Input short etc.
Pictures of testing and zero ohms input short after adjustment. (was 0.05 \$\Omega\$ or thereabouts prior!).

edit : forgot to note the 3458a was for cross reference of the calibrators ohms output, to be sure you know  :D.
« Last Edit: November 29, 2017, 02:57:58 am by lowimpedance »
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 
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Offline Mr. Scram

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #589 on: November 29, 2017, 12:42:22 am »
There does appear to be some change in the ohms zero, and maybe a few digits in dc mA range. After testing on a Fluke 5500a calibrator the only function to be notably affected by the mod's would be the ohms.
I have done the ohms cal on the 'modded' meter and now the zero is indeed zero with a direct input short. Not entirely sure if the rest of the ranges needed cal as well besides the input short test, but I did them anyway.
 Need to test the replacement from Keysight under the same conditions to see what ohms reading it has with an Input short etc.
Pictures of testing and zero ohms input short after adjustment. (was 0.015 \$\Omega\$ or thereabouts prior!).

edit : forgot to note the 3458a was for cross reference of the calibrators ohms output, to be sure you know  :D.
Thanks! Just a few more questions, as it seems I might attempt a repair. Did you ever figure out whether you can calibrate just the ohms range? And if you replace the four resistors, might it be important to match the pairs somehow?
 

Offline lowimpedance

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Re: EEVblog #933 - Keysight U1272A EMC Issue
« Reply #590 on: November 29, 2017, 02:57:22 am »
Yes, you can just CAL the ohms without doing any other function, (indeed any of the other functions can also be done singularly to),  but be wary that trying to do the short and open tests of the 'ohms CAL' alone will not do it seems.
I just tried that with the replacement meter, ie doing the 'Short and then Open' part only and then exiting the adjustments without doing the complete ohms CAL.
 And when the meter restarted with no leads connected the display showed around 5M \$\Omega\$ on the display  :-//. I noted that behavior with the 'modded' meter but thought I did something wrong and dismissed it as I went on and did the full ohms CAL.

 So my recommendation would be do the mods and check as best you can (comparison with other Meters etc) that its still within spec. and don't try the CAL unless you have the required stable known resistors to hand. IIRC as I stated earlier only the ohms and possibly the DC current zero's shifted a bit and adjustment was not really needed.
Remember the NULL function. I have noted too that the ohms zero will drift around a few counts anyway (temp. related!).
Also I did not bother with any matching of the resistors.

Having access to the required calibrator has made it easier for me of course to do the CAL. but I would have been happy leaving it as is. Particularly if cross referencing with other meters gave similar results within their respective specs.

An interesting side note, when I checked the number of CAL cycles the new replacement 1272a that Keysight sent me it had already done 15  :o....... go figure.
« Last Edit: November 29, 2017, 02:59:52 am by lowimpedance »
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 
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