Author Topic: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)  (Read 157223 times)

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Offline jancumps

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #250 on: February 08, 2015, 10:43:49 pm »
At least they are protected by your mains fuse. The UNI-T is supposed to work upstream of that tripper, where there is no fuse to protect you from harm :)
 

Offline Corporate666

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #251 on: February 08, 2015, 11:24:56 pm »
A fool and his life are soon parted with?  Darwin award?  Who in their right mind would work with +300V from a Chinese multimeter?  Granted, in the US, we only really have 120, so for us, it's really not much of an issue.   :bullshit:

Fluke meters are made in China too.  And I don't think "Uni-T" is a particularly Chinese sounding name... certainly not like Tenma or the ones that don't even have a name on them.

And I don't think it's unreasonable to expect something labeled to a spec to meet that spec - it's a foundation of marketing and truth in advertising.

In cases where something doesn't meet its spec or isn't of the quality the name or price suggest, how does the consumer find out about that?  They either open it up themselves (in which case they have already purchased it, likely can't then return it and may not be qualified to know what they are looking at).  Or they look to a reviewer who does know what he/she is talking about to review the product.

Sort of like Dave.  :o
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Offline Hydrawerk

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #252 on: February 09, 2015, 12:52:40 am »
UT70A is quite OK for me. It was designed in 2002 or so. But it has some minor problems. https://www.eevblog.com/forum/testgear/uni-t-ut70a-gone-weird/msg255397/#msg255397

Also if you want to replace battery, you have to loosen three screws. For changing the fuse you must loosen seven screws. It is badly designed. The input protection is also rather poor.
« Last Edit: February 09, 2015, 01:06:06 am by Hydrawerk »
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Offline DanielS

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #253 on: February 09, 2015, 01:00:04 am »
I thought the traditional 'fix' was a .22 bullet ... they're about the same size as a standard fuse.
You would have a hard time replacing one of these:
http://uk.farnell.com/cooper-bussmann/non-100/fuse-100a-250v-one-time/dp/2112064
with a bullet - the gap between terminals for the 100A/250V type is almost 6" / 15cm.
 

Online Monkeh

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #254 on: February 09, 2015, 01:10:02 am »
I thought the traditional 'fix' was a .22 bullet ... they're about the same size as a standard fuse.
You would have a hard time replacing one of these:
http://uk.farnell.com/cooper-bussmann/non-100/fuse-100a-250v-one-time/dp/2112064
with a bullet - the gap between terminals for the 100A/250V type is almost 6" / 15cm.

In Soviet Russia, bullet much bigger than fuse. 12.7mm and 14.5mm rounds aren't that uncommon.
 

Offline Muttley Snickers

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #255 on: February 09, 2015, 04:15:44 am »
These are safer once calibrated, I have the required tool.   :-DD


Muttley
 

Offline Smokey

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #256 on: February 09, 2015, 05:34:53 am »
My point is if it can be done in a shoddy manner, it will be. China as of late the greatest offender. At least there's a remedy for it in the AFCI. :blah:


That is a serious Violation!!  That rock isn't approved to be used as a chair!!  That rock is going to give that guy back problems!!
 

Online Wytnucls

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #257 on: February 09, 2015, 05:42:23 am »
One major flaw of the 71E, which was overlooked until recently, is the lack of an intermediate amps range (4A).
The true RMS converter doesn't work properly under 10% of range, which means there is a dead zone between 400mA and 1A on this meter. It overreads by 10~15% of measurement.
That's a show stopper on a meter where AC current and power measurement is a major feature.
If the majority of your AC measurements are under 400mA or above 1A, you're OK, otherwise buy something else.
All meters in the 71 range are affected and so is the 61E, with an even larger dead zone of 220mA~1A AC.
Sadly, the new UT181A probably also has a dead zone between 600mA and 1A. UT171 models are OK.

I'm surprised that 71E owners didn't pick this up sooner.
« Last Edit: February 09, 2015, 07:14:58 am by Wytnucls »
 

Offline DanielS

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #258 on: February 09, 2015, 07:10:39 am »
I'm surprised that 71E owners didn't pick this up sooner.
As others have said: if Uni-T is willing to fool around something as serious as safety ratings on a meter that is clearly intended to be connected directly to mains, what else might they be less than honest, if not outright liars, about?

People who buy "inexpensive" Uni-T meters might not have something significantly better or more reputable to compare against. My UT61E is currently my "best" meter and my only True (?) RMS one. One of the first things I did when I got my DS1054Z was a sanity check on that: see if I could get them to agree on the RMS value of voltage across a 0.1 ohm low-side sense resistor powering a 23W CFL lamp, a PC power supply, other stuff I had lying around and a mix of them to produce oddball current waveforms. I could get them to agree within 1% by changing the sampling rate and memory depth on the scope, which is about as good as it is going to be with the DS1000z's DC offset issue.
 

Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #259 on: February 09, 2015, 08:19:48 am »
There are other "more reputable" meters that have blindspots in their ranges too - Agilent U1232A is one.
 

Offline G7PSK

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #260 on: February 09, 2015, 09:22:39 am »
I thought the traditional 'fix' was a .22 bullet ... they're about the same size as a standard fuse.
You would have a hard time replacing one of these:
http://uk.farnell.com/cooper-bussmann/non-100/fuse-100a-250v-one-time/dp/2112064
with a bullet - the gap between terminals for the 100A/250V type is almost 6" / 15cm.
That is a 20mm cannon shell size fuse.
 

Offline Maister

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #261 on: February 09, 2015, 09:23:35 am »
This is really interseting:
I have the UT61E which you are showing towards the end of the video. Mine is only rated 300V CAT III and not 600V CAT IV.
Despite that mine has a better input protection: A bigger HRC fuse for the 10 amps (690V, I1=80kA), 4 MOVs, and 3 PTCs.

Here are the photos of my UT61E:
https://dl.dropboxusercontent.com/u/11083462/DSCN1240.JPG
https://dl.dropboxusercontent.com/u/11083462/DSCN1241.JPG
Professional electronics design engineer living in Hannover, Germany.
 

Offline Stonent

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #262 on: February 09, 2015, 09:28:21 am »
Um, how has no-one noticed the trace going nowhere? 5:44 in the video. Unless this board has plugged vias, which I seriously doubt. Or my eyes are deceiving me, which is more likely.

It's also visible in other peoples pictures in this thread.

They put in an antenna for better Dave reception.  It didn't work.
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Online Wytnucls

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #263 on: February 09, 2015, 09:36:50 am »
There are other "more reputable" meters that have blindspots in their ranges too - Agilent U1232A is one.
That's pretty obvious with the lack of a mA range on the meter and plenty warning text : 'DC/AC current range of 0.6 mA to 300 mA is not measureable on the U1232A and U1233A models'.
More insidious on the 71E. Even Dave, with his vast experience, didn't latch onto that. Mentions of glass fuses always elicit more gasps from the audience.
 

Offline EEVblog

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #264 on: February 09, 2015, 09:38:47 am »
More insidious on the 71E. Even Dave, with his vast experience, didn't latch onto that. Mentions of glass fuses always elicit more gasps from the audience.

I wasn't reviewing the meter, it was a teardown. I had barely touched it.
 

Offline Stonent

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Offline EEVblog

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #266 on: February 09, 2015, 09:43:42 am »
This is really interseting:
I have the UT61E which you are showing towards the end of the video. Mine is only rated 300V CAT III and not 600V CAT IV.
Despite that mine has a better input protection: A bigger HRC fuse for the 10 amps (690V, I1=80kA), 4 MOVs, and 3 PTCs.
Here are the photos of my UT61E:
https://dl.dropboxusercontent.com/u/11083462/DSCN1240.JPG
https://dl.dropboxusercontent.com/u/11083462/DSCN1241.JPG

That goes to show the insane variability in Uni-T products. Madness.
Shame, because your meter is very decent indeed.
 

Offline EEVblog

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #267 on: February 09, 2015, 09:45:33 am »
http://www.brymen.com.tw/product-html/index.html
The Byrmen homepage is straight out of 1996, complete with the animated Under Construction man digging.

They must spend their money UL testing instead of a web designer.
 

Offline rob77

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #268 on: February 09, 2015, 09:47:43 am »
That goes to show the insane variability in Uni-T products. Madness.

couldn't it be that we have fake UNI-T meters out there ?  :-// or did just UNI-T hired a new management pushing the costs down heavily ?
 

Online Wytnucls

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #269 on: February 09, 2015, 09:54:12 am »
No fake meters, just some safer versions for specific markets, under pressure from importers.
The company went public recently, is probably flush with cash and is upping their game a bit, with proper independent testing and safer meters in the works. But China is China, so there is always someone on the line looking for shortcuts to save some pennies (fens).
 

Offline Stonent

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #270 on: February 09, 2015, 10:06:04 am »
http://www.brymen.com.tw/product-html/index.html
The Byrmen homepage is straight out of 1996, complete with the animated Under Construction man digging.

They must spend their money UL testing instead of a web designer.

I just looked at the source code to their page, and it really is about that level of skill, including BLINK tags.  Those were deprecated back in Internet Explorer 4 I think.
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Offline gildasd

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #271 on: February 09, 2015, 10:55:27 am »
Just opened my UT61B bought for 58€ in a brick and mortar shop (40 less than the next cheapest: the Brymen i really wanted including postage) last northern hemisphere summer.
I seems to have the input protection and proper fusing. It's quite ok and well built for the price.
And if the 61B(GS) 200107-7 code mean that the PCB was designed then? If that's the case, they've been able to do so since at least 2001!

Ah well, i'll get a Fluke when I grow up.
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Offline TMM

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #272 on: February 09, 2015, 11:06:04 am »
There are other "more reputable" meters that have blindspots in their ranges too - Agilent U1232A is one.
That's pretty obvious with the lack of a mA range on the meter and plenty warning text : 'DC/AC current range of 0.6 mA to 300 mA is not measureable on the U1232A and U1233A models'.
More insidious on the 71E. Even Dave, with his vast experience, didn't latch onto that. Mentions of glass fuses always elicit more gasps from the audience.
Does it say that anywhere other than buried deep within the Users Guide? I could forgive someone for thinking that a U1232A would have a decent mA range contained within the A range just as it has mV ranges contained within it's V range.
 

Offline Tepe

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #273 on: February 09, 2015, 11:07:49 am »
I have the UT61E which you are showing towards the end of the video. Mine is only rated 300V CAT III and not 600V CAT IV.
Despite that mine has a better input protection: A bigger HRC fuse for the 10 amps (690V, I1=80kA), 4 MOVs, and 3 PTCs.
Where did you buy it?
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Online Fungus

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Re: EEVblog #712 - Uni-T UT71E Multimeter (Why Uni-T Meters Suck)
« Reply #274 on: February 09, 2015, 11:21:59 am »
It's quite ok and well built for the price.
And if the 61B(GS) 200107-7 code mean that the PCB was designed then? If that's the case, they've been able to do so since at least 2001!

The problem is that the management of that company feel it's OK to lie to customers and rip them off.

There's alternatives out there. Uni-T don't really deserve anybody's business until there's nothing but well built meters in their lineup and they've recalled all the bad ones from stores.

OK, they're not going to do that but they should at the very least remove the CAT-IV labels and market them for what they are.

Plus HRC fuses and proper track clearances aren't that expensive to do. That's pretty much all it would take to bump the safety up by an order of magnitude.

 


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