Author Topic: EEVblog #832 - Keysight U1282A Multimeter Teardown  (Read 26407 times)

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Online Fungus

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #25 on: December 22, 2015, 11:30:55 am »
Why is it on almost every multimeter I see there is either no AC current range or AC current mode is selected using a 'shift' function, yet capacitance measurement has it's own position on the knob? It's an industrial meter and in industry there is often a requirement to measure the current drawn in an AC circuit.

Because in an 'industrial' setting you usually measure current with a clamp.

 

Offline Muttley Snickers

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #26 on: December 22, 2015, 12:02:14 pm »
I haven't read the manuals on these meters as yet and only had a brief look over the specs, through my eyes though they look like a very nice meter and until it was placed alongside I didn't think that the U1272A could be out done aesthetically.

I don't ever recall Agilent - Keysight having an intrinsically safe meter before and if they are chasing the Fluke 28 II market then this may be an indication of something ahead.

Many thanks for the teardown and I will load up on popcorn and soft drink tomorrow ready for the review, put a ticket aside for me.
 

Offline mux

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #27 on: December 22, 2015, 12:12:16 pm »
I wonder about the long term stability, too. Will that rubber last for many years? I hope they sell spares.

Mind you: If you need a waterproof multimeter then you can probably afford to replace them every ten years or so.

It's not actually waterproof though, it's only temporarily submersion resistant (hence no grease, etc.). There are better meters in this category, you'll likely go for those if you actually need guaranteed waterproofing. This is more of a 'oh shit I'm on an oil rig and just spilled half a ton of oil over my worksite'-jobby. Nothing against this meter, it's just a different application.

If it's proper rubber-rubber (and not butyl or something) it will survive for *decades*. Rubber only really deteriorates under the influence of fluorine, ozone and high-energy light (blue sunlight, UV), which is no issue in this meter. I have a Fluke 73 (1982) with rubber seal on the inside, it's still perfectly intact.
 

Online EEVblog

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #28 on: December 22, 2015, 12:31:37 pm »
The inductor with silastic gunk is to prevent acoustic noise. They chose the wrong DC/DC converter that operate in burst mode or skipping mode, instead of PWM mode (or deliberately for low power consumption), so there will be hiccup noise falling into acoustic range at light load. A simple bulge will be simply gunk it up and damp any mechanical vibration in acoustic range.

Could very well be!  :-DD
 

Online EEVblog

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #29 on: December 22, 2015, 12:32:33 pm »
Just saw in the manual that this meter does indeed have a setup menu and Auto-Hold.
Setup is accessed by holding Shift while turning it on. There, one can activate the Auto-Hold function instead of Trig-Hold.

Geeze, why can't it just operate like the U1272A?
 

Offline alho

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #30 on: December 22, 2015, 02:20:11 pm »
That rubber is quick and easy to assemble, slap a rubber mat on or dick around with two o-rings. Hands are big part of assembly cost and Taiwan Malaysia isn't cheapest place.

Let's say you are replacing batteries and drop the meter on dirty and dusty factory floor when its open. O-rings have hard to clean thin grooves where dirt can lodge while this meter looks like you can just shake it clean.
« Last Edit: December 22, 2015, 06:47:56 pm by alho »
 

Offline Muttley Snickers

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #31 on: December 22, 2015, 02:44:28 pm »
Sorry I'm back again, that remote switch had me intrigued and I couldn't sleep without finding out more...... :palm:

Most distributors are currently throwing the U5404A remote switch in with the meter as a deal, it retails for about $60 US alone, Element 14 are doing it but not sure about Trio Test, I expect that they probably are but cannot confirm at this time.

As Dave said in the video the U1282A multimeter is listed for $500 US, unfortunately down here they are going for $751 plus 10% GST so about $826 AUD, not that this meter is rated for it but It's not intrinsically safe for me to bring home anymore test equipment for a while after some recent purchases, sparks would fly if I came home with another meter and that 342 Keysight deal might be a problem, anyway I have until the end of February.

Trio Test and Measurement Australia
http://www.triotest.com.au/shop/keysight-technologies/3848-keysight-u1281a-handheld-digital-multimeter-5-digit-.html

Element 14 Australia
http://au.element14.com/keysight-technologies/u1282a-u5404a/digital-multimeter-handheld-4/dp/2499696

U5404A Remote Switch
 

Offline Christe4nM

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #32 on: December 22, 2015, 04:01:37 pm »
I might be picky, but I actually dislike the new button design on these meters. I much rather have the old solid/single color rubber ones without a LED behind them like on the U1272A and U1461A.

All in all it seems to me this meter is really aimed at field use and therefore its ruggedness. If you need a general electronics meter for bench use you don't get this one, but say the U1272A. So size wise, it depends on your toolbox if this one is too big. Once you put it next to the U1461A you can clearly see the reused the case from that one. Clever design reuse in my opinion.

I am glad they went with the traditional LCD as oposed to OLED. Especially when you want to use the meter outside, in daylight, readability on a normal LCD is much better than OLED in my experience. Hence I wondered why they put the OLED in the U1461A in the first place as that seems to be aimed at field work as well.

Anyway, I loved the teardown. I found myself actually leaning towards my computer screen to not miss any details ;)

 

Offline boffin

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #33 on: December 22, 2015, 04:03:20 pm »
That rubber is quick and easy to assemble, slap a rubber mat on or dick around with two o-rings. Hands are big part of assembly cost and Taiwan isn't cheapest place.


Good thing it's made in Malaysia then, to keep the cost down.
 

Offline Mark Hennessy

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #34 on: December 22, 2015, 04:14:41 pm »
Apologies if I missed it, but I don't think it was mentioned: surely those spring-clip connections to the current terminals are to do with the Input Warning feature, rather than sensing for current measurements?

They look to be insulated from the current path to me, which would make sense - they are presumably shorted to the current inputs when a probe is plugged in. Likewise, this is not a PSU, so you don't need sensing at the terminals; rather, you need to sense the voltage directly across the shunt. Also, the large series resistors from the "sense" terminals need to withstand a high voltage when the fuses open...
 

Offline joeqsmith

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #35 on: December 22, 2015, 04:23:57 pm »
Anyone knows what is the reason for heatshrinking those resistors and PTCs?

joeqsmith managed to turn a few PTCs into green dust over in the "here kitty" thread.  I'm guessing the heatshrink is to stop them messing up the inside of the meter when you zap them too hard.

Although if you're regularly exploding your PTCs you might want to consider a whole new meter just in case, and wrapping them in heatshrink might hide any damage  :-//

On a side note: How fast do PTCs react? Surely they have to physically heat up and that takes a few milliseconds at least. Joe's PTC-destroying pulses are only a few microseconds long.

And MOVs, how fast are they? Presumably a lot faster than PTCs.

MOVs will switch much faster than a GDT.  GDTs are in the microsecond range.   They are good for high energy, long long duration but because they are so slow, I would have something to help them out.  You could get away using a smaller MOV as it would only need to handle the energy until the GDT fires.  If they use some sort of diode clamp, there must be another layer of R after that last GTD.   Would be interesting to sketch it out and see if at least on paper that it could survive something with a fast edge.   

I have seen a few HV resistors fail in the meters and a few PTCs.  You are right, the PTCs when coated will come apart even with very low energy levels.  I have had a few where there is nothing left but the leads when I put a little more in them.   It makes sense that they heat shrink them to prevent the fragments from getting into the meter but I am not sure if that really is the reason for it.  :-//   

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline gildasd

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #36 on: December 22, 2015, 06:14:25 pm »
I wonder about the long term stability, too. Will that rubber last for many years? I hope they sell spares.

Mind you: If you need a waterproof multimeter then you can probably afford to replace them every ten years or so.

It's not actually waterproof though, it's only temporarily submersion resistant (hence no grease, etc.). There are better meters in this category, you'll likely go for those if you actually need guaranteed waterproofing. This is more of a 'oh shit I'm on an oil rig and just spilled half a ton of oil over my worksite'-jobby. Nothing against this meter, it's just a different application.

If it's proper rubber-rubber (and not butyl or something) it will survive for *decades*. Rubber only really deteriorates under the influence of fluorine, ozone and high-energy light (blue sunlight, UV), which is no issue in this meter. I have a Fluke 73 (1982) with rubber seal on the inside, it's still perfectly intact.
I think OILPOL and MARPOL would be my major concerns, not the multimeter...
I'm electronically illiterate
 

Online Ice-Tea

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #37 on: December 22, 2015, 06:34:31 pm »
(...and why would anybody want 60000 readings per second on a multimeter?)

I figured counts relates to how accurate rms measurments would be? And up to what frequency they would be accurate?

Offline brutester

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #38 on: December 22, 2015, 07:19:45 pm »
(...and why would anybody want 60000 readings per second on a multimeter?)

I figured counts relates to how accurate rms measurments would be? And up to what frequency they would be accurate?
This parameter is given as bandwidth in data sheets/specs. It also shows maximum frequency of signal at which you will get a valid reading
 

Offline ECEdesign

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #39 on: December 22, 2015, 08:02:37 pm »
mikeselectricstuff mentioned on the YT comments about the absence of a full LCD test on startup.  This is available, if you hold down the "hold" key on startup the LCD display will show all the options so you can check to make sure everything is working.
 

Online PA0PBZ

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #40 on: December 22, 2015, 08:22:39 pm »
Anyone care to comment about what they did here?

Keyboard error: Press F1 to continue.
 

Online Fungus

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #41 on: December 22, 2015, 09:04:14 pm »
Anyone care to comment about what they did here?

That's so the electrons can't go too fast down that wire.
 

Online PA0PBZ

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #42 on: December 22, 2015, 09:20:51 pm »
Anyone care to comment about what they did here?

That's so the electrons can't go too fast down that wire.

With those sharp corners the electrons will be all over the place don't you think?
Keyboard error: Press F1 to continue.
 

Online Ice-Tea

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #43 on: December 22, 2015, 10:06:22 pm »
mikeselectricstuff mentioned on the YT comments about the absence of a full LCD test on startup.  This is available, if you hold down the "hold" key on startup the LCD display will show all the options so you can check to make sure everything is working.

I don't think one excludes the other? I'd say for accurate rms readings you need hefty oversampling, hence the high count numbers?


Online EEVblog

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #44 on: December 22, 2015, 10:48:52 pm »
Apologies if I missed it, but I don't think it was mentioned: surely those spring-clip connections to the current terminals are to do with the Input Warning feature, rather than sensing for current measurements?

Yeah, that's what I meant.
 

Online EEVblog

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #45 on: December 22, 2015, 10:50:56 pm »
Anyone care to comment about what they did here?

Clearance rule with that other node in the red circle?
 

Offline Muttley Snickers

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #46 on: December 23, 2015, 05:47:42 am »
Wow !, I just read the manual and found a huge amount of setup options, possibly unsurpassed for configuration options in a handheld, some will like this stuff.. :) and others may not.. ???

Both the U1240 and the U1280 series meters come with the IR-USB interface as standard, this I think is a good move on Keysights part, charge a little extra and chuck it in the box. We saw what happened with the U1272A where they had to post out this cable for free so people could do the firmware upgrade on the early versions, only they know how many went out and what it cost them.

On a side note both series meters appear to have an option for the continuity alert, beeper only, LED only or both, the U1230 series I believe is similar with beeper only, backlight only or both.

The U1272A has only the variable tone option and is both audible and visual via the backlight unless they have changed this in recent firmware which I have not installed as yet.



 

Online EEVblog

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #47 on: December 23, 2015, 08:18:24 am »
Wow !, I just read the manual and found a huge amount of setup options, possibly unsurpassed for configuration options in a handheld, some will like this stuff.. :) and others may not.. ???

To have all that setup functionality and not make it obvious how to get into the setup like on the U1272A is just stupid.
Or perhaps it was the outcome of some focus group that said that field users shouldn't be dicking around with setups.
 

Offline Muttley Snickers

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #48 on: December 23, 2015, 08:34:48 am »
I've mentioned this before in regards to the U1272A that they should provide a small laminated options menu cheat sheet tucked in behind the bail. anyway people can make their own I suppose if they feel the need.

There is already one brief Youtube video review on this meter, more of an introduction really and it's locally made.
 

Offline NANDBlog

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Re: EEVblog #832 - Keysight U1282A Multimeter Teardown
« Reply #49 on: December 23, 2015, 08:50:51 am »
Wow !, I just read the manual and found a huge amount of setup options, possibly unsurpassed for configuration options in a handheld, some will like this stuff.. :) and others may not.. ???

To have all that setup functionality and not make it obvious how to get into the setup like on the U1272A is just stupid.
Or perhaps it was the outcome of some focus group that said that field users shouldn't be dicking around with setups.
So it is working as the U1252B. I dont think it is a big deal, just RTFM.
One other thing I saw, that there is a programming guide for the multimeter. So they give you the list of commands for the meter, so third party software can be made now. I dont think it is a too much of a big deal, I mean, it is not like we will see this built into a test rig or anything, cause the battery and the range switch, but still, could be interesting.
 


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