Author Topic: UNI-T UT61E Multimeter teardown photos.  (Read 534345 times)

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Online mariush

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #450 on: November 22, 2012, 05:29:45 pm »
The manual says that if the input voltage is high enough, it will try to play the waveform on the internal piezo speakers.

The manual also says you SHOULD NOT use the Hz position with more than 30V rms, but this is for safety reasons.  It doesn't say the meter will fail.

Martin tested the meter on his Youtube channel and tested the Hz on mains 240v AC and it didn't die, but naturally it doesn't like it, that switch position is for low voltage stuff.  To measure AC frequency, you go to V and press the yellow button.

Martin's review is below.. bear with him as he does some minor mistakes but he corrects himself in the following videos. He did these reviews straight as he gets the meter without checking the manual, so some things were confusing to him.
I personally like this style, but some may not be very patient.


Part 1  design, lcd screen, dc voltage, resistors, diodes, capacitors etc



Part 2  data logging (own software and ultradmm) , ac voltage, frequency voltage



Part 3 Insides, battery consumption



Part 4  Cold / Hot tests (how stable and accurate remains when outside the specified operating temperature) ,  calibration




Really, you guys should read the manual.. it's mixed with information for the other meters in the series but it's not that hard to read and understand. You can get the English version from uni-t's site: http://www.uni-trend.com/manual2/UT61English.pdf
« Last Edit: November 22, 2012, 05:33:53 pm by mariush »
 

Online Monkeh

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #451 on: November 22, 2012, 05:41:00 pm »
The manual also says you SHOULD NOT use the Hz position with more than 30V rms, but this is for safety reasons.  It doesn't say the meter will fail.

It will damage components if you leave it connected to that high a voltage for long. Check the schematic. Far as I'm aware, that will break either the capacitors or the chip itself in pretty short order.
« Last Edit: November 22, 2012, 06:03:25 pm by Monkeh »
 

Offline dimitrioptimus

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #452 on: November 22, 2012, 07:50:07 pm »
Welcome to the horror that unleaded solder is !  ;)

Unleaded solder can look very dull and almost a 'dry joint' in its appearance. I still use 2% silver loaded leaded 60/40 solder and always have nice shiny joints. Don't worry about the dull look in your meter, it is normal unleaded ROHS compliant (read 'crap') solder and should be OK. Rosin will not help as teh solder is the problem not the flux.

Kind Regards

Fraser

thanks for the response

"read crap" did U meant real,l in place of r ? :-//

so its relieving that its normal to see nonshiny surface for unleaded solder.
 

Offline T4P

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #453 on: November 23, 2012, 05:43:46 am »
Anyone who does that when the manual clearly states not to be used above 30V deserves to get blown up  :-+
 

Offline bitwelder

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #454 on: November 23, 2012, 09:29:15 am »
It will damage components if you leave it connected to that high a voltage for long. Check the schematic. Far as I'm aware, that will break either the capacitors or the chip itself in pretty short order.
Can you guesstimate what that 'short order' would be? Few seconds? Minutes? More?
 

Offline dr_p

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #455 on: November 23, 2012, 11:06:41 am »
Anyone who does that when the manual clearly states not to be used above 30V deserves to get blown up  :-+

   Yes, it's written in the manual, also (probably) written in the manual is that you should not measure Voltage when the probes are inserted into the Amps jacks. But despite that, a good meter should have proper input protection and save the user's ass if he mistakenly does that.
   The two Hz positions are obviously a cause of confusion, even if you have read the manual. For instance if you have multiple meters and are used to measuring frequency "the-bad-UNIT-way", on the separate Hz position.

   I think the manufacturer should put a "max 30V " next to the Hz position on the meter's front panel.
 

Offline torr032

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #456 on: November 23, 2012, 11:43:02 am »
It will damage components if you leave it connected to that high a voltage for long. Check the schematic. Far as I'm aware, that will break either the capacitors or the chip itself in pretty short order.
Can you guesstimate what that 'short order' would be? Few seconds? Minutes? More?

Mine is working fine. It was connected for maybe one second, it started to buzzing immediately after connecting and I disconnected it immediately. On the warranty card there is a date 18 jul 2012. I bought in on taobao and the manual is only in chinese.

Thanks for the videos mariush I watched them all :)
 

Online Monkeh

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #457 on: November 23, 2012, 02:48:29 pm »
It will damage components if you leave it connected to that high a voltage for long. Check the schematic. Far as I'm aware, that will break either the capacitors or the chip itself in pretty short order.
Can you guesstimate what that 'short order' would be? Few seconds? Minutes? More?

Low tens of seconds.
 

Offline rr100

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #458 on: November 23, 2012, 04:02:12 pm »
   I think the manufacturer should put a "max 30V " next to the Hz position on the meter's front panel.

That CERTAINLY should be the case, especially if it says 300V or 1000V beside the probe connectors.
In fact I strongly suspect this is the Voltcraft (VC) 820 (UT 60A clone) I mentioned in another thread is acting funny, I did measure Hz on mains. And YES, I did check the manual and it says 1000V on Hz.
 

Offline Lightages

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #459 on: November 23, 2012, 04:17:17 pm »
Be aware that the UT61E has a different version available in Europe. It did not pass the labelled CATIV/600V CATIII/1000V ratings. The revised version is now rated at CATII/600V and CATIII/300V and has upgraded fuses and more input protection.

So regardless of what the manual says for the non-GS approved model, it is not safe for 1000V in any way. Without the modifications that are in the GS approved model, who really knows what the safe rating for the "standard" model is as it must be worse than CATII/600V and CATIII/300V.
 

Offline M. András

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #460 on: November 23, 2012, 10:12:08 pm »
not any higher then the battery inside the meter? :)
 

Online mariush

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #461 on: November 23, 2012, 10:55:06 pm »
So regardless of what the manual says for the non-GS approved model, it is not safe for 1000V in any way. Without the modifications that are in the GS approved model, who really knows what the safe rating for the "standard" model is as it must be worse than CATII/600V and CATIII/300V.

There's no way you'd know it's WORSE, you're not an expert and you shouldn't make any assumptions.

Maybe it only did well at up to 800v or something like that, so they had to bring it down to whatever "level" is below 800v, which happens to be CAT II / 600v.
Maybe the meter could only handle 5000v transient voltage, less than the 6000v needed for CATIII 600v, so they had to list it as CAT III 300v which only demands 4000v transient test voltage.

Either way, you guys are blowing this out of proportion. It's a f**king 55$ multimeter, nobody's gonna climb the pole outside his house to measure the transformer, 99.5% or more will probably use it at best to measure switching power supplies voltages (400v or thereabouts).

Same with the fuse talk ... complaining it's a 250v rated fuse... duh, that's what it says on the front, current measurements 250v max.

It's really annoying... Take for example Extech ex330, the winner of Dave's 50$ meter shootout :



Yeah, I'm sure it's Cat III - 600V  and CAT II - 1000V ... with cheapo glass fuses (and ALSO 250v rated maximum, while it says 600v on the front), less internal protections... But no, let's all piss on the Uni-T meter because it's not Fluke or some other brand name.
« Last Edit: November 23, 2012, 11:10:17 pm by mariush »
 

Offline torr032

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #462 on: November 23, 2012, 11:12:26 pm »
Be aware that the UT61E has a different version available in Europe. It did not pass the labelled CATIV/600V CATIII/1000V ratings. The revised version is now rated at CATII/600V and CATIII/300V and has upgraded fuses and more input protection.

So regardless of what the manual says for the non-GS approved model, it is not safe for 1000V in any way. Without the modifications that are in the GS approved model, who really knows what the safe rating for the "standard" model is as it must be worse than CATII/600V and CATIII/300V.

I'm in hart of Europe, Bosnia and Herzegovina and it is impossible to buy this meter anywhere here. I had to buy it on the internet, taobao is the cheapest.
 

Offline Lightages

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #463 on: November 23, 2012, 11:25:15 pm »
There's no way you'd know it's WORSE, you're not an expert and you shouldn't make any assumptions.

The GS approved revision has better fuses and improved input protection to make it meet CATII/600V and CATIII/300V. Therefore it is easy to deduce that the original model did not meet CATII/600V and CATIII/300V without these modifications, never mind the CATIII/1000V and CATIV/600V rating it claims to have. It is merely a logical deduction from the facts. No one needs to be an expert in anything other than logic.

And this is about the safety of the human holding the meter hen that human assumes that the company is being honest about their safety ratings, it has nothing to do with the price. If Uni-T labels something as safe for a purpose then it should be so. That is why I started the suspect meter thread so that people can see the problems with the claimed ratings.

I piss on all meters that lie about their safety ratings, not just the "poor" UT61E.

If you want a safe, well built and safe multimeter for $55, get an Amprobe AM220.
« Last Edit: November 23, 2012, 11:29:15 pm by Lightages »
 

alm

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #464 on: November 23, 2012, 11:59:56 pm »
Anyone who does that when the manual clearly states not to be used above 30V deserves to get blown up  :-+
Isn't this in direct violation of IEC61010 that states that the meter should be fine at any range/function with the max rated input voltage applied? Is it really stupid to apply 1000 V to an input labeled 'CAT III 1000V'? Any decent meter will survive the max rated voltage on the resistance ranges, so why shouldn't the same apply to the frequency counter range? We're not talking about GHz BW spectrum analyzer inputs that are hard to protect.

There's no way you'd know it's WORSE, you're not an expert and you shouldn't make any assumptions.
There's no way you'd have any knowledge about the expertise of other forum members. Please don't make assumptions.

Either way, you guys are blowing this out of proportion. It's a f**king 55$ multimeter, nobody's gonna climb the pole outside his house to measure the transformer, 99.5% or more will probably use it at best to measure switching power supplies voltages (400v or thereabouts).
Nobody would complain if it was labeled CAT I 300V/CAT II 200V. CAT IV 600 V should be suitable for industrial and power distribution circuits (up to 600 V).

Same with the fuse talk ... complaining it's a 250v rated fuse... duh, that's what it says on the front, current measurements 250v max.
Fuses are often blown when people try to measure voltage with the meter/leads in the current position. If you're not looking at the lead connection, than fine print near the sockets isn't going to help either. Products should be safe by design, not safe by fine print.

Take for example Extech ex330, the winner of Dave's 50$ meter shootout :
[...]
Yeah, I'm sure it's Cat III - 600V  and CAT II - 1000V ... with cheapo glass fuses (and ALSO 250v rated maximum, while it says 600v on the front), less internal protections... But no, let's all piss on the Uni-T meter because it's not Fluke or some other brand name.
The ex330 is rarely discussed, and so are its bad points.

If Fluke would make a meter like this, there would be a lot more complaints. Of course, based on past (and current) performance, people would be more skeptical about Uni-T safety testing than Fluke safety testing.
 

Offline Wytnucls

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #465 on: November 24, 2012, 12:15:41 am »
The problem for manufacturers is that the CE Cat ratings testing directives have changed, about 6 months ago.
Meters with a 1000V rating are now subjected to a 2000 volt input on the amps jacks, with blown fuses in place, to check for arcing inside the meter. (1000V before)
The fuses voltage rating  must now match the meter CAT voltage rating and must be ceramic HRC and fast blow. (new requirement)
All other meter inputs must survive high voltage transients, whose strength varies according to the CAT rating applied for.
The meter CAT rating is downgraded until it passes all the required tests.
So, the old UT61E doesn't comply with the new regulations, at least because of the 250V fuses and is unlikely to comply with the GS TUV approved CAT rating, without some PCB modifications.
« Last Edit: November 24, 2012, 12:17:42 am by Wytnucls »
 

Offline Salas

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #466 on: December 11, 2012, 04:52:15 pm »
Does anybody know a way to tweak the mA range? I tested a 15.25mA current flow arrangement with Fluke 87V in Hi Res and Mastech 8218 agreeing, while Fluke 17B was showing 15.15mA, but the 61E ~13.5mA only! Fail for selecting JFETs IDSS to my circuits spec for instance!
 

Offline Salas

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #467 on: December 11, 2012, 05:03:18 pm »
P.S. I used the same TL175 leads in all cases to avoid uncertainties due to cabling between meter tests in series mode.
 

Offline Salas

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #468 on: December 11, 2012, 05:22:17 pm »
In another test with 10X the voltage source and a higher resistor load of the previous so to minimize different between meters burden voltage effect, the 87V was 10.05mA while the 61E 9.945mA by the way. While F17B at 10.03mA.
« Last Edit: December 11, 2012, 05:27:14 pm by Salas »
 

Online Monkeh

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #469 on: December 11, 2012, 05:24:25 pm »
In another test with 10X the voltage of the previous to minimize burden voltage effect, the 87V was 10.05mA while the 61E 9.945mA by the way.

And there you go. Burden voltage; you can't use the 61E for low-voltage mA/uA measurements.
 

Offline Salas

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #470 on: December 11, 2012, 05:33:10 pm »
Still the 17B showing much closer while quoted 1.5% and 61E quoted 0.5% at that mA range when I used ~10V source and 1K 1% resistor.
 

Offline T4P

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #471 on: December 11, 2012, 06:41:28 pm »
This is not a issue about accuracy more likely it's the burden voltage. Must be nuts to think it's the accuracy and the dropout voltage has always been a big problem for the UT61E
 

Offline Salas

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #472 on: December 11, 2012, 06:59:43 pm »
Will test at 20V source and 2K resistance against 87V and let you know. Still if going that high is necessary, then the 61E is no good for mA in many many situations due to excess burden, and its an  issue to be well pointed out.
 

Offline Salas

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #473 on: December 11, 2012, 07:06:46 pm »
Test done. 87V 10.00mA, 61E 9.950mA, 17B 9.98mA.
 

alm

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #474 on: December 11, 2012, 07:12:49 pm »
Try putting all three meters in series (connect common terminal of the first to mA terminal of the second, and so on) with the current source. Then the current through the meters should be identical (Kirchoff's current law), so burden voltage will not introduce any errors.
 


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