Author Topic: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)  (Read 155778 times)

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Offline iampoor

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #175 on: February 08, 2015, 02:52:03 am »
The problem with buying these meters that lie about the safety ratings is that it encourages the manufacture to keep on making them!
 

Offline zapta

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #176 on: February 08, 2015, 03:11:25 am »
There really needs to be a requirement here for people to state where they live before asking for any recommendations. This comes up over and over and over again. Where do you live? It is hard to tell you the best place to buy or what to buy if we have no idea where you are!

I just adding that they live in my town and give advise accordingly.
Drain the swamp.
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #177 on: February 08, 2015, 05:13:10 am »
If they replaced the cat text with that, would your perceived value of the product be better, worse or unchanged? I'm curious to know.

Numerous people have claimed that they consider it poor value for money solely based on the false cat rating so I'm curious if people would consider it better value if it made no claim to being safe at all

People don't seem to have an issue with sub $50 meters which make dubious claims about safety, so how is this one any different? Its more expensive but it also brings a tonne of features to the table.

If you are buying a meter with an expectation that it meets the claimed safety rating then yes it would be poorer value for money if it failed to meet them. Value is all about matching price to expectations. It isn't a measure of features per dollar.
Hmm. What i am having trouble understanding is how people are willing to accept that the chinese UT61 series for $60 is a good deal but the UT71 series for $130 isn't. Both promise cat IV and fail to deliver. The extra features justify the price hike over a UT61. I must have missed the memo that after a multimeter exceeds a certain $ point it MUST be safe, regardless of how useful it's features are otherwise, or it must be crucified on EEVBlog forums.

I'll admit the 71E seems to represent worse value compared to it's cheaper A/B/C/D brothers. A mains power dongle is obviously of limited usefulness when the input protection is of a low standard. That said, it's not reason alone to lump all of one brand of meters together and declare universally "Uni-T Meters Suck".
« Last Edit: February 08, 2015, 05:26:13 am by TMM »
 

Offline IshtarTor

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #178 on: February 08, 2015, 05:48:08 am »
For those who are not familiar with CAT rating requirements, from Wikipedia:

...The required values can vary from 0.04 mm for single insulation CAT II, 50 V, to 28 mm for double insulation CAT IV, 1000 V. The exact values are defined in the international standards.[1] Such standards should be followed rigorously during the design process of the appropriate equipment.

So yes, the fact it does not meet CAT IV standard is pretty clear.

But I wouldn't go so far as to discredit this meter altogether. Having the ability to measure power is one of its main selling point and most electricians only do mains related work and would not need an accuracy higher than 0.1 W.
Except that you DON'T want to use this on mains.
 

Offline Pentium100

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #179 on: February 08, 2015, 06:41:24 am »
Except that you DON'T want to use this on mains.
Why not? I don't think that the meter needs a lot of cats to be able to function when connected to the mains. And if you are worried about the meter blowing up somehow (wouldn't the probe melt first if you shorted the mains) just place it further away from you.
 

Offline AG6QR

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #180 on: February 08, 2015, 07:00:13 am »
For those who are not familiar with CAT rating requirements, from Wikipedia:

...The required values can vary from 0.04 mm for single insulation CAT II, 50 V, to 28 mm for double insulation CAT IV, 1000 V. The exact values are defined in the international standards.[1] Such standards should be followed rigorously during the design process of the appropriate equipment.

So yes, the fact it does not meet CAT IV standard is pretty clear.

But I wouldn't go so far as to discredit this meter altogether. Having the ability to measure power is one of its main selling point and most electricians only do mains related work and would not need an accuracy higher than 0.1 W.
Except that you DON'T want to use this on mains.

I agree that it's a piece of crap that shouldn't be used.  But let me play devil's advocate for just a moment...

We all plug in various devices into mains -- lamps, power supplies, radios, computers, kitchen appliances, etc.  The only things which I commonly use that have proper HRC fuses are multimeters.  I've seen some junk inside of consumer goods that make that awful UNI-T look fantastically safe in comparison.  Yet most consumers survive their appliances.  Most general consumer goods that most of us plug in to mains are generally safe, yet they don't have CAT ratings, and they're not as rigorously designed as a top quality industrial multimeter.  What's the difference?

One difference is that meters are often being held in your hand as you stick them in the socket, so any explosion is right next to you.  Another is that meters may sometimes be used for probing around in the main power distribution panel, where very large currents are available.  But a big difference is that it's up to us, the users, to connect the meters to mains properly every single time.   And most meters have both a high impedance mode, for voltage measurement, and a low impedance mode, for current measurement.  The mistake that is too easy to make, and potentially deadly when made with a poor quality meter, is to probe a high energy voltage source when your probes are plugged into the current terminals.  There aren't many other devices which we regularly connect to mains that have this potential for deadly user error.

That mains dongle that comes with the UNI-T meter would seem to prevent the human error of mixing up the voltage and current probing.  That's worth something, in my book.

That dongle would seem to turn the Uni-T meter into a specialized mains power consumption meter that is almost as idiot proof as the P3 Kill-a-Watt meter (common in the USA).  The Kill-a-Watt does not claim a CAT rating. 

But even with the dongle, the UNI-T doesn't stack up well against the dedicated power meter.   The UNI-T costs nine times as much, has a worse resolution of 1 watt versus 0.1 watt for the P3 Kill-a-Watt meter, and the Uni-T doesn't measure cumulative energy over time, while the Kill-a-Watt does.  The Kill-a-Watt is a $20.00 specialized device for measuring power and energy consumption of mains-powered devices, not a general purpose multimeter.  Still, if you want a power meter for mains power, you could do worse than buying a Kill-a-Watt for that particular task, while buying a general purpose multimeter that doesn't make a false CAT claim for your other tasks.
 

Offline Fungus

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #181 on: February 08, 2015, 07:06:28 am »
it's not reason alone to lump all of one brand of meters together and declare universally "Uni-T Meters Suck".

Why not? This obviously intentional - somebody in management signed off on this meter and presumably gave the order to swap the expensive HRC fuses for cheap glass ones (to increase profit!)

Why would you buy anything from a company which does that?

Its only selling feature is the "Watts" function but that only works for large Wattages so it's useless (almost).

But I wouldn't go so far as to discredit this meter altogether. Having the ability to measure power is one of its main selling point and most electricians only do mains related work and would not need an accuracy higher than 0.1 W.

Why would an 'electrician' buy that multimeter when these things cost about $30?



You shouldn't be using a multimeter for finding live mains wires, use one of these instead (much faster/safer/easier!):



You can buy both of those, get a proper multimeter for electronics work (eg. the Brymen BM257) and still have change from $180. No need to keep Unit-T in business ripping people off.

 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #182 on: February 08, 2015, 07:14:53 am »
Why would an 'electrician' buy that multimeter when these things cost about $30?

Do tell me more about it 40000 count datalogging functionality and Cat IV safety. Oh wait.
 

Offline Fungus

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #183 on: February 08, 2015, 07:18:52 am »
let me play devil's advocate for just a moment...

The mistake that is too easy to make, and potentially deadly when made with a poor quality meter, is to probe a high energy voltage source when your probes are plugged into the current terminals.  There aren't many other devices which we regularly connect to mains that have this potential for deadly user error.

This is precisely what CAT ratings are for. One of the things a CAT rating tells you is that you can connect the meter to power with any combination of leads or range-selector setting and it won't kill you. If it fails, it will fail safely (should blow a fuse at most - no internal fires allowed).

The Kill-a-Watt does not claim a CAT rating. 

The Kill-a-Watt doesn't allow you to move leads around or select a low-impedance path through it.

That mains dongle that comes with the UNI-T meter would seem to prevent the human error of mixing up the voltage and current probing.  That's worth something, in my book.

Except that Dave couldn't actually use it in the country where he bought the meter - more evidence that they simply don't care about customers and don't deserve anybody's business.
« Last Edit: February 08, 2015, 07:24:18 am by Fungus »
 

Offline WackyGerman

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #184 on: February 08, 2015, 07:19:54 am »
Well this electrician would be sucidal to use this " multimeter " for power measurements on mains . Anyway if you look at the specs the multimeter is suited for 5 A continously and more than 5 A for 10 seconds . That means you can use it from 0.1 until 1150 Watts at cos phi 1 . Measuring power for 10 sec maximum is absolutely useless . This " multimeter " is a really bad joke and for 165 Euro ist is an absolutely rip off . The input jacks are shit , the clearance inside is shit , the fuses are shit , the overvoltage protection is shit , the trace to the com jack is shit , well it is in specs , but that doens t catch the world on fire . It is a dangerous slapped together piece of shit labelled with the wrong cat rating , sold for an astronomical price . normally it has to be banned from the market and been destroyed by the authority . Even if there are several versions on the market with better input protection and fuses , the board contruction has not enough clearance to meet the cat IV regulation . You can put in 100000 movs and ptc s and anything else but this " multimeter " never never never will meet the cat IV rating , no way !!!!!!
It is a good example of crap design and planned obsolescence . One small transient and the " multimeter " is dead and if you send it back they will tell you that you used it out of the voltage rating and don t send you a new one for free and that s it . Even if you don t use it on mains , the jacks never never would give good contact after more than 1000 connections with the probes and the contacts of the range switch will be worn out quickly , so this multimeter tightly may survive the guarantee  time and after that it is fit only for a knacker s yard
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #185 on: February 08, 2015, 07:27:51 am »
The Kill-a-Watt doesn't allow you to move leads around or select a low-impedance path through it.
To be fair, neither does the UT71E when used in conjunction with the supplied mains dongle.

Except that Dave couldn't actually use it in the country where he bought the meter - more evidence that they simply don't care about customers and don't deserve anybody's business.
Pretty sure the meter Dave obtained is analogous to a grey import, regardless of what the 'distributor' would have him believe.
« Last Edit: February 08, 2015, 07:35:46 am by TMM »
 

Offline WackyGerman

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #186 on: February 08, 2015, 07:54:46 am »
Well by the way , electricians don t use the wall wart wattmeters because they are not accurate enough . In many of the VDE 701/702 insulation testers there is a built in function tester for the test item and this also measures power . But these testers are really special and cost a damn lot of money . For example the Fluke 2600-2 cost roundabout 1700 bucks .
 

Offline Fungus

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #187 on: February 08, 2015, 08:07:55 am »
Quote from: TMM
Except that Dave couldn't actually use it in the country where he bought the meter - more evidence that they simply don't care about customers and don't deserve anybody's business.
Pretty sure the meter Dave obtained is analogous to a grey import, regardless of what the 'distributor' would have him believe.

It will be interesting to see if Uni-T responds to this video, it could seriously affect their sales.

(I'm betting they won't, pretty much everything inside the meter is indefensible...)
« Last Edit: February 08, 2015, 08:10:42 am by Fungus »
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #188 on: February 08, 2015, 08:29:01 am »
Quote from: TMM
Except that Dave couldn't actually use it in the country where he bought the meter - more evidence that they simply don't care about customers and don't deserve anybody's business.
Pretty sure the meter Dave obtained is analogous to a grey import, regardless of what the 'distributor' would have him believe.

It will be interesting to see if Uni-T responds to this video, it could seriously affect their sales.

(I'm betting they won't, pretty much everything inside the meter is indefensible...)
They have actually responded to the design of the UT71 before https://www.eevblog.com/forum/reviews/uni-t-multimeter-ut71d-unboxing-and-teardown/15/

I think Dave owes it to us to tear down a UT139, UT181 or UT171 series before making blanket statements about the entire brand.
« Last Edit: February 08, 2015, 08:34:25 am by TMM »
 

Offline classical

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #189 on: February 08, 2015, 08:43:09 am »
i can't afford a Fluke at the moment and i wonder if there is any intermediate segment between no-brand cheap shit, UNI-T down and The Real Instruments up. I thought i had a good deal with my UNI-T meters but now Dave says "don't buy that crap", more or less.
For my use as hobbyist I also bought a BM857A from TME. Delivery to Germany was very quick and without issues. Nice meter with very good value (at least when I bougt it). But regarding TME you have to add the VAT!
I also have access to a BM869 which in some aspects it is a better meter and the dual display can be very helpful e.g. measuring ripple or flickering of a lamp. So you alsways have correponding U=~ and U~ values in one sample. When I bougt the BM857 it was a bit cheaper than today and the difference to the BM257 was too low to think about it.
I also have access to a BM525 which is very fine for standalone data logging.
I've been thinking of buying an oscilloscope and, well, i would have gone for a UNI-T one but now i am not so sure.
watch Daves reviews on Rigol 1054Z
If this is too expensive look for a Rigol 1052e on sale or second hand.
 

Offline Tepe

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #190 on: February 08, 2015, 08:52:27 am »
What i am having trouble understanding is how people are willing to accept that the chinese UT61 series for $60 is a good deal but the UT71 series for $130 isn't. Both promise cat IV and fail to deliver.
Mt UT-61C bought from Reichelt in Germany is silk screened "CATIII 300V" and "CATII 600V". It also displays silk screened TÜVRheinland and GS logos. The TÜV logo for some reason says ID:0000000002, though.


« Last Edit: February 08, 2015, 09:00:18 am by Tepe »
ceterum censeo systemd-inem esse delendam
 

Offline iampoor

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #191 on: February 08, 2015, 08:53:17 am »
Quote from: TMM
Except that Dave couldn't actually use it in the country where he bought the meter - more evidence that they simply don't care about customers and don't deserve anybody's business.
Pretty sure the meter Dave obtained is analogous to a grey import, regardless of what the 'distributor' would have him believe.

It will be interesting to see if Uni-T responds to this video, it could seriously affect their sales.

(I'm betting they won't, pretty much everything inside the meter is indefensible...)
They have actually responded to the design of the UT71 before https://www.eevblog.com/forum/reviews/uni-t-multimeter-ut71d-unboxing-and-teardown/15/

I think Dave owes it to us to tear down a UT139, UT181 or UT171 series before making blanket statements about the entire brand.

Why dont you do the teardown? I think its a pretty safe bet to say that Dave wont be giving Uni-T any more Simoleans after this video.  >:D
 

Offline G7PSK

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #192 on: February 08, 2015, 09:13:30 am »
What is inside the power adapter for the meter, it could have its own shunts etc and not pass the full current and voltage to the meter, not that I will be buying one. I did however buy a UT61E on the recommendation's from this forum 2 years ago. I have now just joined the yellow peril brigade and ordered a Fluke 115 for work on power circuits this is to replace my old dinosaur AVO. I was thinking of an AVO410 but why buy a re-badge Chinese meter.
 

Offline WackyGerman

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #193 on: February 08, 2015, 09:16:05 am »
Well it is a little better than the 71E but still  :scared: :scared: :scared: . Look at the clearance between the 10A fuse and the shunt resistor . Must be 2 or 3 mm clearance . They still have to do their homework at UNI-T  :-- :-- :palm:
 

Offline G7PSK

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #194 on: February 08, 2015, 09:23:13 am »
Well it is a little better than the 71E but still  :scared: :scared: :scared: . Look at the clearance between the 10A fuse and the shunt resistor . Must be 2 or 3 mm clearance . They still have to do their homework at UNI-T  :-- :-- :palm:

Could be a safety feature, acts as a spark gap shunting a HV surge to ground before it goes through the meter.
 

Offline poorchava

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #195 on: February 08, 2015, 09:28:43 am »
I am using UT71A as one of my 2 main meters (the other one being a Fluke 87). In general I'm pretty satisfied with the accuracy I must say.  Other thing is that I don't do a great deal of mains connected stuff,  so the clearances and such are of little interest to me (and if I have to measure mains,  I use fluke anyway).

Brymen might be a better deal,  but the uni-t is not bad either,  if the safety ratings are not that big of a deal.
I love the smell of FR4 in the morning!
 

Offline WackyGerman

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #196 on: February 08, 2015, 09:36:40 am »
What is inside the power adapter for the meter, it could have its own shunts etc and not pass the full current and voltage to the meter, not that I will be buying one. I did however buy a UT61E on the recommendation's from this forum 2 years ago. I have now just joined the yellow peril brigade and ordered a Fluke 115 for work on power circuits this is to replace my old dinosaur AVO. I was thinking of an AVO410 but why buy a re-badge Chinese meter.

For sure there will absolutely nothing inside the adaptor except the parallel wiring to the V and Com and in serial to the A jack . If it would the price for the UT 71e would be 350 $ at that price policy of Uni-T . There needn t to be a shunt resistor or transformer in the adaptor , it is a superduper safe multimeter with cat IV rating  :-DD
 

Offline Fungus

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #197 on: February 08, 2015, 09:45:50 am »
Anyone notice the solder joint adjacent to the ADC pin 1 @ 8:55? It looks marginal at best.

Yes, I was wondering about that.

It looks to me like all the through-hole parts that come from underneath the board are hand-soldered. Look (for example) at the flux residue around the two joints to the left of the PTC at 5:50 (the ones labelled '+' and '-'). Definitely has a hand-soldered look to it.

 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #198 on: February 08, 2015, 09:46:37 am »
What i am having trouble understanding is how people are willing to accept that the chinese UT61 series for $60 is a good deal but the UT71 series for $130 isn't. Both promise cat IV and fail to deliver.
Mt UT-61C bought from Reichelt in Germany is silk screened "CATIII 300V" and "CATII 600V". It also displays silk screened TÜVRheinland and GS logos. The TÜV logo for some reason says ID:0000000002, though.



Yes, but most people who have purchased the UT61E have the chinese version with no MOVs/SGs and purchased it with the knowledge that it shouldn't be used on high energy circuits.
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #199 on: February 08, 2015, 10:00:24 am »
What i am having trouble understanding is how people are willing to accept that the chinese UT61 series for $60 is a good deal but the UT71 series for $130 isn't. Both promise cat IV and fail to deliver.
Mt UT-61C bought from Reichelt in Germany is silk screened "CATIII 300V" and "CATII 600V". It also displays silk screened TÜVRheinland and GS logos. The TÜV logo for some reason says ID:0000000002, though.



Yes, but most people who have purchased the UT61E have the chinese version with no MOVs/SGs and purchased it with the knowledge that it shouldn't be used on high energy circuits.

Who are these "most people"?
Are you referring to the members of EEVBlog, because that is far from the numbers of these meters sold I'd GUESS.
Or do yo have number of meters sold and the education and experience of all buyers.

I already pointed out that the Brymen 857a(and you may get the improved 857S) is the same price from TME as the UniT is (I logged to get the gross price).
Why on earth would anyone even take the risk of any misleading posts about dangerous UniT here, when 857A is available.
Didn't someone here hack the Brymen data logging code too (I seem to remember a thread)?
 


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