EEVblog #933 - Keysight U1272A EMC Issue

[bitseeker]

Yeah, I mixed up the U1250 and U1280 on the frequency ranges involved. Thanks. Fixed.

My replacement U1280 is not in the affected serial number range (MY00000000 / MY56999999).

Well Mine that was shipped on Dec 13 and arrived on Jan has SN MY564... so go figure...

Bummer. Well, if yours is affected and qualifies as a "on specified failure", then they'll fix it.

[Iwanushka]

Yeah, I mixed up the U1250 and U1280 on the frequency ranges involved. Thanks. Fixed.

My replacement U1280 is not in the affected serial number range (MY00000000 / MY56999999).

Well Mine that was shipped on Dec 13 and arrived on Jan has SN MY564... so go figure...

Bummer. Well, if yours is affected and qualifies as a "on specified failure", then they'll fix it.

Don't have arb with me to test and I somehow can't be bothered to get it from friends, but it is not affected by my led lights and/or moving my hand on it while I'm measuring like U1272A did, so I call it good unless it starts doing something strange oh and it was free, just can't register it on Keysight web somehow.

BTW did anyone receive replacements with SN MY57....?

[bitseeker]

Yes, mine is MY5700.

[bitseeker]

did any of you were able to register replacement DMM on Keysight web? I get: Unrecognized Serial Number 

I get the same error.

[TheAmmoniacal]

did any of you were able to register replacement DMM on Keysight web? I get: Unrecognized Serial Number 

I get the same error.

Register the DMM? Are we talking about a new one for affected U1282A or the old replacement form for the U1272A? Link?

[bitseeker]

Register as in add it to the myKeysight page on Keysight's web site to keep track of your equipment, associated service notes, calibration certificates, etc. When adding the replacement U1280, the serial number is flagged as unknown.

[TheAmmoniacal]

Ah, thanks. Maybe I should do that some day..

[Iwanushka]

Guys false alarm for replacement DMMs ,  looks like factory did not bother to change SN sticker,

Found at home Analog Discovery 2 (I already forgot that I have it, because project was killed for which I got it, need to dig deeper maybe I will find something else at home  ) All waveforms up to max 10MHz does not affect the readings, looked at the box of the DMM, sticker said something along the lines for internal use, so I won't bother getting 20MHz ARB from friends to test further.

Again sorry for false alarm, and thumbs up for Keysight!

Edit: PS. maybe someone found a soft case for U1280A? it does not fit in U1174A case and looks like Keysight does not have new soft cases. maybe it fits into Frankies' BM869s case?

[Dr.Trinity]

We got all our 'broken' meters replaced by Keysight.
Thank you so much !

[ddrl46]

Thank you, ddrl46.
I understand that you have recommended to do open/short tests on several ranges, probably best practice.
However, does the meter allow me to do a single resistance range calibration point (say, ohms short cal) without having to do any of the other resistance calibration points (10M, 3M, 300K, 30K, 3K...etc)?

The U1270 series service manual is here:
http://literature.cdn.keysight.com/litweb/pdf/U1271-90020.pdf?id=1996089

Sorry for the late response but it does seem to be possible to do adjust a single calibration point without adjusting all the other calibration points.

[EEVblog]

[lowimpedance]

 Dave yours corresponds to others and mine , see post 476 (few pages back) where I posted pics of the same hand soldered parts and the changes done to the old Agilent to make it the same as the updated Keysight and the improved EMC resistance.
 The LPF was enabled by default in the recent firmware update.

[sakujo7]

Track width changed under the "REV006" text, plus there's a new connector next to it.

[EEVblog]

Track width changed under the "REV006" text, plus there's a new connector next to it.

Ah, didn't notice the extra connector.
The track makes no difference.

[Scottjd]

What about C126, looks like possibly a different tantalum capacitor value?

[Tom45]

BD7 on the other side of the board was also changed. See the post by lowimpedence:

https://www.eevblog.com/forum/blog/eevblog-933-keysight-u1272a-emc-issue/476/

[aXit]

Thanks for the video Dave, I'd missed this thread.

This explains an issue I had a few months back when measuring a constant current source. As the voltage increased, the current went from a nice stable 10mA to -0.5A. Figured out it was oscillating, this issue explains it!

That hand soldering job is a bit of a mess, they at least could have cleaned up the boards. Might be worth waiting a bit for them to run out of the hand soldered stock, unless they retract the offer.

[EEVblog]

BD7 on the other side of the board was also changed. See the post by lowimpedence:
https://www.eevblog.com/forum/blog/eevblog-933-keysight-u1272a-emc-issue/476/

Ok, missed that.

[lowimpedance]

Thanks for the video Dave, I'd missed this thread.

This explains an issue I had a few months back when measuring a constant current source. As the voltage increased, the current went from a nice stable 10mA to -0.5A. Figured out it was oscillating, this issue explains it!

That hand soldering job is a bit of a mess, they at least could have cleaned up the boards. Might be worth waiting a bit for them to run out of the hand soldered stock, unless they retract the offer.

Why wait, the solder joints on mine were solid, if not the prettiest ...... and of course it enabled us all to see the differences and thus try the 'improvements' on our older afflicted units so 

Just imagine the poor dude at Keysight rockin up to work to find rows and rows of 1272's with a note to "change these parts" 

[Barny]

How does the mod affect the measurements / calibration?

[tszaboo]

I believe that is an extra film (?) capacitor there.
Yes, I also like MELF resistors.

[wraper]

I believe that is an extra film (?) capacitor there.
Yes, I also like MELF resistors.

I have REV5 agilent and it has that cap assembled.

[Monkeh]

Pretty sure that's a diode, not a cap.

[tszaboo]

Pretty sure that's a diode, not a cap.

I dont see an orientation marker. It would be easyer to tell if we would have high res, or someone would take a look at it.

[Monkeh]

Pretty sure that's a diode, not a cap.

I dont see an orientation marker. It would be easyer to tell if we would have high res, or someone would take a look at it.

I do, there's a distinct white line on the left hand side - matches perfectly the diodes off to the right.