Author Topic: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)  (Read 156040 times)

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Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #125 on: February 07, 2015, 07:27:09 pm »
Cool story, I think we have got the point that you shouldn't probe a 3 phase power plant with one of these by now.

The point I'm trying to get across is that for someone who just plays with bench power supplies, USB and battery powered devices, the Uni-t meters represent good value for money. I for one am not going to lose sleep over owning a meter with the incorrect rating printed on the front panel if I don't need a rating in the first place.


The combination of the mains power dongle and a meter that claims cat ratings which it obviously does not meet is a bit of a faff. However, that does not mean you should paint all uni-t meters with the same brush and that is exactly what Dave and others have done.
« Last Edit: February 07, 2015, 07:30:42 pm by TMM »
 

Online Quarlo Klobrigney

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #126 on: February 07, 2015, 07:35:05 pm »
Cool story, I think we have got the point that you shouldn't probe a 3 phase power plant with one of these by now.
The meter is mislabeled is my main point. One day in a pinch, or in a frenzied hurry, some unsuspecting fool will grab a meter and check the mains at home or at work, not realizing that given the right circumstances, the meter may kill them. Glass fuses with minimal spacing are not proper fuses for Arc-Flash protection. I certainly wouldn't leave the thing plugged in doing an unattended survey.
« Last Edit: February 07, 2015, 07:38:45 pm by Quarlo Klobrigney »
Voltage, does not flow, nor does it go.
 

Offline Grapsus

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #127 on: February 07, 2015, 07:40:05 pm »
I don't know why people find this so hard to understand. It's like all the car manufacturers selling V8 sports cars for $50,000. Then some chinese company comes along and sells a V8 sports car that is just as powerful for $7000 but the catch is that it has no seatbelts and the fit and finish is a bit naff. Suddenly everyone is like "Oh my God! you can't sell a car without seatbelts!". But who cares, it's $7000. Install them yourself if you are so inclined.

I think you're saying this seriously, but many of us would consider such a statement to have a high likelihood of being satirical...

I think there might be a cultural difference at play here. For example in western Europe or North America people trust regulations because those imply responsibility. Therefore in those countries you don't expect a large pothole on a highway because you know that somebody is responsible for maintaining the road in good condition. On the other hand, for example in Russia or India, I saw that people only count on themselves and assume that regulations are bullshit, so a one-meter pothole on the highway would not surprise them as much. Since Dave is from a country that is from the first kind, you can't expect him not to be shocked and say something like "wow ! a 40000 count data-logging meter for only 180 bucks, thank you Uni-T ! notice that it might blow your head off, but that's ok, we all know that CAT ratings are bullshit so just be careful when you probe a high energy circuit, after all, you're the only one responsible for your safety".
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #128 on: February 07, 2015, 07:42:50 pm »
Cool story, I think we have got the point that you shouldn't probe a 3 phase power plant with one of these by now.
The meter is mislabeled is my main point. One day in a pinch, or in a frenzied hurry, some unsuspecting fool will grab a meter and check the mains at home or at work, not realizing that given the right circumstances, the meter may kill them.
Absolutely. I would like to see uni-t remove the cat markings from the offending meters because they are wrong. That said it is moronic to discount the entire line of uni-t meters for low energy usage (which, let's face it, is 99% of electronics use) just because they have false markings on them.


To the people who are dwindling on the fact that you can pay $180 for a meter and get very little in the way of safety - is it really that hard to believe that if you can buy a $180 fluke and get a lot of safety but very few features, you could also part with the same amount of cash for a multimeter that has a tonne of features and very little safety? Regardless of claimed ratings I think its fair to point out that its unreasonable to expect a tonne of features and fluke level safety/quality for the price point. If it was, then fluke would be out of business long ago.
« Last Edit: February 07, 2015, 08:02:57 pm by TMM »
 

Offline WackyGerman

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #129 on: February 07, 2015, 07:55:41 pm »
Well for 180 $ or here in europe for the same in euro :scared: it is really far away of a good value  :-- :--. For the same money you will get a second hand gossen or fluke with lightyears away better quality in construction , accuracy and input protection .  Even it has 40000 counts resolution this is not a tool . It is a dangerous toy where the packagaging and the carrying bag is more expensive in the production price than the meter itself .
Just keep your eyes open to get a good and cheap multimeter . It s easy to find this at ebay or sometimes on the fleamarket where my old shitty crappy looking norma D 3012 came from ( made in Austria , not in Australia ) . It is a 25000 counts multimeter and the accuracy almost meet the specifications except at 1 V it has 0.04 % instead of 0.02 % accuracy . But for me it is more than enough and anyway this puppy is roundabout 30 years old and it is not a trms meter . And at that time there were no cat ratings for multimeters . But for low energy measurements it is more than good enough and it will work many times longer than this cheap UNI-T s . I m going to make a teardown soon of this multimeter and put some pics here in the forum . By the way , I paid 15 Euro for this multimeter at the fleamarket  ;D
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #130 on: February 07, 2015, 08:05:20 pm »
Cool story, I think we have got the point that you shouldn't probe a 3 phase power plant with one of these by now.


No you haven't got the point, and I am begging to think you are trolling here, and will report you for doing so soon.

It does not have "this is a dangerous piece of shit" written on the front does it?
If it did then there would be perhaps a case for this to be sold.
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #131 on: February 07, 2015, 08:06:34 pm »
What does a Brymen cost in dollar equivalent?
 

Offline Rick Law

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #132 on: February 07, 2015, 08:08:44 pm »
...

I think there might be a cultural difference at play here. For example in western Europe or North America people trust regulations because those imply responsibility

....

Speak for your self, my friend.  There is nothing in our current administration (USA) that I trust. 
In fact, I assume for the most part the opposite is true.  The Constitution of The USA is written with the premise and the for reason that government cannot be trusted.

Case and point, the administration has been singing praises to themselves about the "low unemployment" and LinkedIn Pulse (their email alerts) latest "Pulse" is "The Big Lie: 5.6% Unemployment" written by Jim Clifton, CEO at Gallup.

Private labs such as UL carries far more weight to me than anything the USA government can say.

I fault UNI-T in carrying false labels.  This in my view is fraudulent.  I think UNI-T is good enough that it has a market without falsely claiming compliance.  It has a role even as a non CATx compliant meter.

I would like it better if UNI-T simply erase the label.  Since in some cases, the PCB already made provision, UNI-T can print on the box "Upgradable to CATx ???V compliant by authorized service agent".

Rick
« Last Edit: February 07, 2015, 08:16:20 pm by Rick Law »
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #133 on: February 07, 2015, 08:12:36 pm »
It does not have "this is a dangerous piece of shit" written on the front does it?
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.
« Last Edit: February 07, 2015, 08:23:31 pm by TMM »
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #134 on: February 07, 2015, 08:20:34 pm »
A Brymen is much better value for money, and not that far off in price.

Do you have a UniT meter TMM ?
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #135 on: February 07, 2015, 08:24:58 pm »
A Brymen is much better value for money, and not that far off in price.

Do you have a UniT meter TMM ?
I own a UT71D and a Fluke 87V...
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #136 on: February 07, 2015, 08:28:46 pm »
A Brymen is much better value for money, and not that far off in price.

Do you have a UniT meter TMM ?
I own a UT71D and a Fluke 87V...

How do you feel about the quality of that Uni-t?
Have you opened it up?

A Brymen 857A is about $160 (from TME), plus some for delivery, but hey it is UL listed and built like a tank.
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #137 on: February 07, 2015, 08:40:47 pm »
I thought the datalogging cable for the Brymen was expensive and it doesn't have internal datalogging memory? It probably works out to be close to double what I paid for the uni-t.

The quality of the uni-t is 'good enough' imo. Its not fluke-level but it doesn't feel like cheap junk either. The only thing that really sucks is the poor quality voltage/com jacks.
« Last Edit: February 07, 2015, 08:42:47 pm by TMM »
 

Offline Wytnucls

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #138 on: February 07, 2015, 08:45:24 pm »
The discussion about fuses is moot. If you're worried about glass fuses, buy the 1KV version. The real CAT rating is unknown; hopefully it is at least CAT II 600V, which would be sufficient for most of us. My Gossen has that rating and it doesn't even have a fuse on the mA range, just a polyswitch.
Independent testing is the only way to tell for sure what the CAT rating is. I wish IEC would stipulate that as a requirement, like they do for some other instruments. In the meantime, be safe and stay away from the meter if you have to test high energy circuits.
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #139 on: February 07, 2015, 08:51:38 pm »
The discussion about fuses is moot. If you're worried about glass fuses, buy the 1KV version. The real CAT rating is unknown; hopefully it is at least CAT II 600V, which would be sufficient for most of us. My Gossen has that rating and it doesn't even have a fuse on the mA range, just a polyswitch.
Independent testing is the only way to tell for sure what the CAT rating is. I wish IEC would stipulate that as a requirement, like they do for some other instruments. In the meantime, be safe and stay away from the meter if you have to test high energy circuits.

Isn't it also about the meters ability to protect itself (MOVs etc)?
Lightages found that his Uni-t couldn't and died, he made a vid about it.
 

Offline Wytnucls

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #140 on: February 07, 2015, 08:58:39 pm »
MOVs are not a requirement, although it is probably wise to install.
The 71E didn't die, the 61E did. But it wasn't a CAT rating test at all. By the way, it doesn't matter if the meter dies, as long as the damage is contained.
 

Offline electr_peter

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #141 on: February 07, 2015, 08:58:57 pm »
On the 71D, 10,000 data memory, accessible on the meter or the PC. 30,000 on my Gossen 30M, but I have to buy the Gossen cable and software to see any of it (350$). That's after you paid 900$ for the meter, 60$ for the bag and 140$ for the 5V wall wart, otherwise you have 16 hours of battery life. Oh, it's only CAT II 600V, with 100mA max. And it comes with a bodged cap on the DC to DC converter.
Gossen 30M with 1 200 000 counts, stable reference and 4 wire measurement is not in the same league for price comparison. It is like comparing rotten apples and gold plated oranges.
Agilent/Keysight sell IR->USB interface for ~30$ USD. UNI-T IR->USB adapter is the same for all their meters I thinks - same adapter for 61, 70, 81 series at least. Gossen are on very expensive side for some reason with their adapters and SW.
 

Offline IshtarTor

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #142 on: February 07, 2015, 09:04:00 pm »
It does not have "this is a dangerous piece of shit" written on the front does it?
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.

In any case, I would go for one of the newer models, which are both good value AND safe. And it's better if you buy it in Europe rather than in China, as chinese resellers may put crappy fuses instead of the correct ones. Or buy fuses as well.
« Last Edit: February 07, 2015, 09:16:18 pm by IshtarTor »
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #143 on: February 07, 2015, 09:10:06 pm »
MOVs are not a requirement, although it is probably wise to install.
The 71E didn't die, the 61E did. But it wasn't a CAT rating test at all. By the way, it doesn't matter if the meter dies, as long as the damage is contained.

Yes, sorry about the model confusion, confusing to say the least (though UniT are not alone here!).
Not a question of user safety, more a question of the value, if the meter is electrically "fragile", not so much a bargain if it "joins the choir invisible" when something nasty happens.
Every time it needs replacing it effectively doubles in cost (if replaced with the same model).
Again, this is not a point about user safety, and not about high energy circuits, just unexpected high volts or perhaps wrong range selected (charged cap when in ohms mode sort of thing).
 

Offline Wytnucls

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #144 on: February 07, 2015, 09:14:13 pm »
All ranges are protected by crowbar circuits up to 1000V.
 

Offline Candid

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #145 on: February 07, 2015, 09:20:15 pm »
There seeme to be many different board designs. These are some pictures of my 71E that I bought some weeks ago. Only the MOVs have been added by me the rest is original. The board was already designed for adding MOVs so I only had to solder them in.

I just removed the metal can so you can see what there is under it in the 71E with maybe the newest board design. I got it from reichelt.de in germany.
« Last Edit: February 07, 2015, 09:23:24 pm by Candid »
 

Offline Candid

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #146 on: February 07, 2015, 09:21:29 pm »
And under the metal can.
 

Offline Candid

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #147 on: February 07, 2015, 09:22:30 pm »
Last Picture.
 

Offline Yago

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #148 on: February 07, 2015, 09:24:59 pm »
All ranges are protected by crowbar circuits up to 1000V.

Thanks again Wyt!

Lights vid is unclear as it is after the fact, wonder what the threshold for damage is?
Not specifically UniT, and as suggested before, be nice to see a range of meters incrementally hit with high voltages.
Find out at what point the damage occurs for each model, as it is part of the bang for buck (ooo bad punnage).
Again, not high energy, just high volts (high energy is another type of issue and vid altogether!).
 

Offline Wytnucls

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #149 on: February 07, 2015, 09:28:48 pm »
Interesting. So, there have been a few changes under the can. Part of the resistor network has gone surface mount (resistor network, voltage divider). The 4x2.5MOhms resistors in series are still through hole.
« Last Edit: February 07, 2015, 09:35:17 pm by Wytnucls »
 


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