Author Topic: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)  (Read 133850 times)

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Offline EEVblog

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EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« on: February 07, 2015, 12:50:53 pm »
Dave shows why Uni-T multimeters generally suck in this teardown (and a little bit of a review) of the $180 UT71E 0.025% accuracy multimeter with power measurement capability.
He also opens the UT71A, UT61E, and compares the input protection and rating with a Brymen BM257.

http://uni-trend.com/UT71E.html
MAX6190 Voltage Reference: http://datasheets.maximintegrated.com/en/ds/MAX6190-MAX6198.pdf
OP1177 Opamp: http://www.analog.com/static/imported-files/data_sheets/OP1177_2177_4177.pdf
Cyrustek ES51922 DMM chipset: http://www.cyrustek.com.tw/spec/ES51922.pdf
Holtek HT1621 LCD driver: http://www.ywslcm.com/Upload/tbDownload/2013-4-13_9_37_49.pdf
AD636 True RMS Converter chip: http://www.analog.com/static/imported-files/data_sheets/AD636.pdf

 

Online mariush

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #1 on: February 07, 2015, 01:11:15 pm »
The weird ass adapter looks like it has the classic European mains sockets (well, most of Europe)

Only viewed the first 6 minutes so far but it seems you're unfair comparing and saying it sucks because it doesn't match the metrahit which is 4 digit in cost.

agree with the fuse choice...

4:50 : you can't wiggle those round metal things once the case is closed, the case would press on the metal keeping it in place.



« Last Edit: February 07, 2015, 01:29:17 pm by mariush »
 

Offline EEVblog

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #2 on: February 07, 2015, 01:28:18 pm »
Only viewed the first 6 minutes so far but it seems you're unfair comparing and saying it sucks because it doesn't match the metrahit which is 4 digit in cost.

If a multimeter can measure power, then damn straight I'm disappointed if it can't measure that over all its ranges.
 

Offline iloveelectronics

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« Last Edit: February 07, 2015, 01:40:15 pm by iloveelectronics »
My email address: franky @ 99centHobbies . com
My eBay store: http://stores.ebay.com/99centhobbies
 

Offline Lightages

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #4 on: February 07, 2015, 01:43:13 pm »
This was the first multimeter I posted about here in 2010. It arrived at 0.4% accuracy. After getting some "help"from Uni-T I got it working OK. If you want to know to see the schematic I have uploaded one. It appears that the UT71E is the worst deal amongst the UT7X series. There are some here who think the UT71D is a good deal. The UT71E is the same as the Voltcraft VC940, and the UT71D the Voltcraft VC960.

Uni-T has stepped up their game with their latest meters. The UT171X series, UT181, and the UT139C are much better for input protection.

It was because of my disappointment with the UT71E that I started down the rabbit hole of multimeter quality and safety.
 

Offline Smokey

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #5 on: February 07, 2015, 01:43:57 pm »
Did you really actually buy that meter yourself like you implied in the video?  Are you saying you bought a piece of test gear from a company you know makes crap without even looking at the specs first?  Why would you even consider spending money on this if you know you already had far superior tools like the Gossen?  You couldn't get someone to give/loan you one for videos? 
 

Offline Chrisdlb

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #6 on: February 07, 2015, 02:15:09 pm »
Irrefutable evidence that Uni-T metres are shit, provided by dave, but yet still for some reason, people try to defend them!  :palm:
 

Offline Lightages

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #7 on: February 07, 2015, 02:20:06 pm »
Irrefutable evidence that Uni-T metres are shit, provided by dave, but yet still for some reason, people try to defend them!  :palm:

Irrefutable that the old models of Uni-T are almost all shit. They really have improved things on some new models.
 

Offline wilfred

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #8 on: February 07, 2015, 02:25:52 pm »
"We've got ourselves a voltage reference, Maxim, If it's genuine." "I'm sure it is"

Why bother speculating it might not be genuine with one breath and then with the very next breath claim to be sure it is? What's going on?
I don't personally care for the full-on shitcanning style you like using from time to time but I know it is popular.

It looks to me you started out with the intention of hammering the crap out of UNI-T and then as time went on you started to do a review and you got a bit more objective.

I'm no fanboy and if UNI-T claim some standard and then fail to meet it they deserve all the criticism you can heap on them. But for viewers like me who aren't intimately familiar with CAT ratings and PCB design to meet them it would be better if you toned down the noise and increased the explanation. The information IS there but you make it harder to distil it out.  The most useful part was when you started comparing with other examples of how things can be done better. A complete novice, who is more likely to consider a cheaper meter, would have an even harder time than I did filtering out the noise.

I kept wondering WHY you bought it in the first place. It sounded like you made a mistake and then wanted to throw a brick through UNI-T's front window.
 

Offline george graves

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #9 on: February 07, 2015, 02:32:36 pm »
I'd expect a review of more then one Uni-T meter before claiming that all "Uni-T Meters Suck".  Sucks compared to what?  A meter costing 10x as much?  |O

I think the inner multimeter snob conosur in Dave came out a bit too much in this video. 

These are tools.  Tools cost money(that not everyone has).  Tools have limits.....knowing the limits of your tools is the more important thing.




« Last Edit: February 07, 2015, 02:40:00 pm by george graves »
 

Offline alter Ratz

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #10 on: February 07, 2015, 02:52:20 pm »
Hi all,

What I personally really hate about the UNI-T meters is that they are REALLY slow (not only continuity but also range switching). Has this gotten better with the new models?

Best regards,
Bernhard
 

Offline sakujo7

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #11 on: February 07, 2015, 03:50:48 pm »
Putting "CAT IV 600V" on a meter that clearly cannot meet that spec is just... :wtf:. Being overly optimistic about accuracy is one thing, but you do NOT mess with safety ratings.

It's a shame, because some of their meters (eg. the 61E) work reasonably well for the price point for low-voltage only. (I own one and occasionally use it for this purpose).

A suggestion for anyone still buying one: scrape off the Cat III/IV labels.
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #12 on: February 07, 2015, 03:56:40 pm »
 few things to note:
-UT71C/D/E is only 0.025% on the 400mV range. It's 0.05% up to 400V. The 400mV range probably bypasses some of those trimmers because the input impedance is different also (2.5Gohm vs 10Mohm).
I've had a UT71D for 3+years and a Fluke 87V for 2+years and both of them have always (and still do) agree within 5 counts on DC.
-To be fair the screw hole via going through the current trace doesn't reduce the trace width too drastically because of the plating inside the via and the meter is only rated for 5A continuous anyway. 10A rating is <10seconds with 15minute cooldown.
-The datasheet linked on youtube is for the ES51922 instead of the ES51966 which is a 44000/440000 count meter chip http://www.cyrustek.com.tw/spec/ES51966.pdf
-See if you can get a true 40,000 counts of resolution on resistance or current out of the UT71 ;) (spoiler: there is some kind of lower res + averaging funny business going on).

It's not that bad for the price really. Terrible as an everyday meter, good cheap companion to something like a Fluke 87 for electronics work.



« Last Edit: February 07, 2015, 04:01:56 pm by TMM »
 

Offline Nerull

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #13 on: February 07, 2015, 04:02:52 pm »
"We've got ourselves a voltage reference, Maxim, If it's genuine." "I'm sure it is"

Why bother speculating it might not be genuine with one breath and then with the very next breath claim to be sure it is? What's going on?

Are you familiar with the term 'sarcasm'?

Quote
I don't personally care for the full-on shitcanning style you like using from time to time but I know it is popular.

It looks to me you started out with the intention of hammering the crap out of UNI-T and then as time went on you started to do a review and you got a bit more objective.

I'm no fanboy and if UNI-T claim some standard and then fail to meet it they deserve all the criticism you can heap on them. But for viewers like me who aren't intimately familiar with CAT ratings and PCB design to meet them it would be better if you toned down the noise and increased the explanation. The information IS there but you make it harder to distil it out.  The most useful part was when you started comparing with other examples of how things can be done better. A complete novice, who is more likely to consider a cheaper meter, would have an even harder time than I did filtering out the noise.

I kept wondering WHY you bought it in the first place. It sounded like you made a mistake and then wanted to throw a brick through UNI-T's front window.

The Uni-T pretends its rated for measurements directly on the outputs of a power transformer to a building, where there are no breakers to protect you and available current is north of 10000 amps (the limit for Class 3). If this meter were used on such a circuit improperly or experienced a spike it would quite literally explode in your hand and stands at least a half-decent chance of taking you with it. The rating is a complete lie, and if they're willing to lie about basic safety what else is wrong?
« Last Edit: February 07, 2015, 04:05:26 pm by Nerull »
 

Offline feetwet

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #14 on: February 07, 2015, 04:12:05 pm »
I just wanted to say the EE man is back. It's nice to see Dave back in his rare form. I thought the review of the Uni-T UT71E was spot on. Nice work Dave.  :-+

 

Offline gonzoid

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #15 on: February 07, 2015, 04:15:28 pm »

Quote
"Well, it's not a fluke. It's... you know what I mean."
Perfect timing to post this video. Advertisement at its finest!!  :-DD :wtf:

What I personally really hate about the UNI-T meters is that they are REALLY slow (not only continuity but also range switching). Has this gotten better with the new models?
If you happen to have one of the UT71 series, you can press and hold the blue button while powering on the meter to enable its 4000 counts mode, which is way faster.
« Last Edit: February 07, 2015, 04:36:51 pm by gonzoid »
 

Offline DanielS

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #16 on: February 07, 2015, 04:39:38 pm »
Putting "CAT IV 600V" on a meter that clearly cannot meet that spec is just... :wtf:. Being overly optimistic about accuracy is one thing, but you do NOT mess with safety ratings.
And that would likely be why Uni-T has no official distributors and meters are only available through third-party sellers on places like Amazon, Craigslist, eBay, etc.

If Uni-T had official ties outside China, that would expose them to lawsuits for wrongful death or injuries attributable to failure to meet their safety rating claims if there has been any.
« Last Edit: February 07, 2015, 05:13:33 pm by DanielS »
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #17 on: February 07, 2015, 04:46:56 pm »
If Uni-T had official ties outside China, that would expose them to lawsuits for wrongful death or injuries attributable to failure to meet their safety rating claims if there has been any.
Well they sort of do. Uni-T meters are sold under the "Tenma" brand through Farnell/Element14 for example. If anyone knows if the Tenma variants are built safer I'd be interested to know.
 

Offline gonzoid

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #18 on: February 07, 2015, 05:15:43 pm »
Well they sort of do. Uni-T meters are sold under the "Tenma" brand through Farnell/Element14 for example. If anyone knows if the Tenma variants are built safer I'd be interested to know.
Appart for the case color, they don't seem to be any different according to the photos on http://sigrok.org/wiki/UNI-T_UT71x_series
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #19 on: February 07, 2015, 05:20:00 pm »
I just don't get the pricing on these product's, either the middle men are
making a truck load [...]
And the same can't be said for particular Fluke and Agilent products? It's worth whatever people are prepared to pay for it, and people do buy them so what's the issue?

The UT71D which is basically what Dave reviewed minus the power measurement capability can be found for ~US$130 including international shipping. That doesn't seem like a half bad deal to me for a ~0.05% meter with USB datalogging and 10,000 points memory.
« Last Edit: February 07, 2015, 05:26:13 pm by TMM »
 

Offline DanielS

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #20 on: February 07, 2015, 05:30:24 pm »
Well they sort of do. Uni-T meters are sold under the "Tenma" brand through Farnell/Element14 for example. If anyone knows if the Tenma variants are built safer I'd be interested to know.
I know there are variants of the UT61E which actually have MOVs. My UT61E is one of the no-MOV variant.

I just don't get the pricing on these product's, either the middle men are making a truck load [...]
And the same can't be said for particular Fluke and Agilent products?
At least, Fluke and Agilent are not carrying fake safety ratings.

Pop the back on most Uni-T multimeters and you quickly realize that safety ratings on them are blatantly criminally fake, which is a shame when minor PCB layout changes are often all that would be required to make them considerably safer - along with proper fuses which many models lack.

The lack of precision parts in something that claims to be a precision instrument is not exactly reassuring either, even if it has been trimmed into the next time zone to bring it somewhere within specs.
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #21 on: February 07, 2015, 05:58:01 pm »
Pop the back on most Uni-T multimeters and you quickly realize that safety ratings on them are blatantly criminally fake, which is a shame when minor PCB layout changes are often all that would be required to make them considerably safer - along with proper fuses which many models lack.
While I hope no one buys one of these meters hoping to use it on high energy circuits, you'd be kidding yourself to think that Uni-T are the only ones who put dubious ratings on their meters. Also depending where you live it may not be illegal to sell a meter that displays a CAT rating but has not been compliance tested.

Input protection is a non-issue for people who only plan to dick around on the bench with low power electronics anyway so many of us are willing to overlook the safety claims because Uni-T meters present a unique combination of features/value that very few others provide.
 

Offline bitshape

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #22 on: February 07, 2015, 06:02:28 pm »
Thanks for the nice Ranteview Dave!  :clap:


And really; buying a decent multimeter is not impossible, even for a Fluke in fluking-expensive Europe:

I bought a Fluke 287 for €270,- (incl.vat), and it was almost never used before and even with the original (half-empty) batteries in it. After buying I filled it with a set of rechargeable Eneloop-AA and it is still my best portable meter on the bench.
And some time later an new and unused 'open box' Fluke 28II for €200,- (incl.vat), and seriously, nothing wrong with it. This meter has now got a fresh set of Energizer Lithium-AA's for the long run. :-+

Thus it is possible for everyone to buy something safe & decent (read: not a €190,-* Uni-Trash) for a 'decent' price, only if you are patient and regularly look on some closing-business-auction-sales and your local/online marketplace.

* Uni-T UT71E  incl.vat & delivery
« Last Edit: February 07, 2015, 06:41:49 pm by bitshape »
 

Offline EEVblog

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #23 on: February 07, 2015, 07:16:00 pm »
"We've got ourselves a voltage reference, Maxim, If it's genuine." "I'm sure it is"
Why bother speculating it might not be genuine with one breath and then with the very next breath claim to be sure it is? What's going on?

Welcome to non-scripted off-the-cuff video blog. I press record and something comes out.

Quote
I don't personally care for the full-on shitcanning style you like using from time to time but I know it is popular.

IIRC you don't seem to care for much of what I do at all, you seem to be always criticising  ::)

Quote
It looks to me you started out with the intention of hammering the crap out of UNI-T

You are wrong.
I was hoping this meter with it's rare power measurement function would actually be OK.

Quote
I'm no fanboy and if UNI-T claim some standard and then fail to meet it they deserve all the criticism you can heap on them. But for viewers like me who aren't intimately familiar with CAT ratings and PCB design to meet them it would be better if you toned down the noise and increased the explanation.

I've done videos on this stuff before, go watch them, I can't repeat everything in every single video every single time.

Quote
I kept wondering WHY you bought it in the first place. It sounded like you made a mistake and then wanted to throw a brick through UNI-T's front window.

Stated above.
 

Offline EEVblog

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #24 on: February 07, 2015, 07:20:10 pm »
I'd expect a review of more then one Uni-T meter before claiming that all "Uni-T Meters Suck".

I have yet to find a single Uni-T meter that is well engineered and manufactured.
Prove me wrong, please.
 


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