UNI-T UT71D review

[deadshort]

Have just brought a UT71D very pleased with it. In the box is a note

       "Manual Amendment in order to meet new CE standards, the following amendments are made:
         Alligator clamp - removed
         Safety clamp - removed"

Their are no Alligator clip to go on the test leads/probes and no short test leads with alligator clip. Their is 2 covers that fit on the test probes so that only about 2mm of probe protrude. The fuses are still 250volt!

[Wytnucls]

If your meter came with the latest PCB revision, it would be quite easy to install the required 1000V fuses and clips yourself.
If you're only going to use it on low power circuits, don't bother with an upgrade, as the glass fuses are much cheaper to replace.
Too bad the short croc test leads aren't included anymore, they are quite useful.

[torr032]

Can the continuity on UT71 series meter be modded to be fast, unlatched. I prefer unlatched continuity over latched one, for the electronic use unlatched is far more useful as it can reveal contact quality.

[Lightages]

No it can't be modified. You can use the hack that Wytnucls has discovered for improving the pseed. If you want unlatched you would need to add a separate continuity tester circuit and hack it in somehow.

[torr032]

No it can't be modified. You can use the hack that Wytnucls has discovered for improving the pseed. If you want unlatched you would need to add a separate continuity tester circuit and hack it in somehow.

No, latched continuity doesn't suit me at all, fast or slow doesn't matter since it lie about contact quality.. I am looking for a good quality dmm with an unlatched continuity and with a dual display and ac+dc simultaneous voltage measurement.

[Lightages]

Perhaps it is better to start a new thread asking for such a recommendation instead of hijacking this thread.

[WackyGerman]

Even this multimeter may be ok for electronic hobbyists who use it only with low voltage , this multimeter is a dangerously piece of shit with whimpy fucking glass fuses and non effective overload protection , marked with a cat rating which is light-years far away from the reality . Normally this crap has no place on the market and has to be removed from the market and annihilated at the expense of the manufacturer . It s a rip off and playing with the life of the customer with a wrong marking of the cat rating is not excuseable . Please don t support this crap companies and buy a decent multimeter from a good reliable company

[Wytnucls]

Calm down, not everybody can afford a 700 Euros Gossen DMM to use on their electronic projects.
The requirement for HRC fuses only came in force with the latest regulations and only applies to Europe, at the moment.
Uni-T is upgrading their meters to comply and is sending the newly developed ones, like the UT-181, for independent testing in the USA.

[Lightages]

It is still a good meter for the bench and electronics! But I am looking forward to seeing the new series.

[Wytnucls]

Had a quick play with Franky's UT-181. It has all the bells and whistles with big improvements all round, but it won't be cheap, at just under $300,00.
Would be keen to order one, but I need another meter like I need a hole in the head!

[Lightages]

I think the new UT171X series might be more in line with normal price levels, especially the UT171B. If it is all that it appears t could be then it will become a real competitor to the major brands. As it is, the 181 looks really nice but we are waiting on Franky to show us more!

As far as the UT71D goes, it is still a great meter for electronics, except for the really bad continuity test.  I have yet to hear a problem with a UT71D, but I now know I am not the only one who has a received a UT71E way out of specification as I have heard of another. Maybe it was a bad calibration run on a batch.

[Wytnucls]

To illustrate the fast transient capture of the 71D, I fed it a 3V 10uS pulse at 50Hz from a function generator. The meter easily registers the pulses and displays the pulse voltage in 'Peak Hold' mode, all the way down to 100mVpp.
Most meters need a minimum repetitive pulse duration of 250uS for proper capture.
Peak Hold data can be logged to the computer in real time, at 15 samples per second.

[sbose]

@Wytnucls
does UT71D has overshoot issue like the UT61E?

edit : fixed the model name

[Wytnucls]

Namaste,
No overshoot noticed when tested between 5V and 35V DC, in 5V increments with auto ranging.
Fairly large overshoot and settling time on 220V AC, due to slow auto ranging. No overshoot or display delay when on proper manual range selection.
I did the same test on 220V AC with a Fluke 185, which had no overshoot on auto ranging.

[sbose]

Nomoshkar,
and thanks for the information  .

[teslafan]

Wytnucls,
"16.   Conclusion
I never regretted buying these two meters and although I have acquired a few more ‘respectable’ ones since then, I still reach for the 71s on a regular basis."  Is the 71s a typo? S/B 71d? I don't see that model in the multimeter spreadsheet, if legit, will it be in a future update?
Fantastastic info, xclnt job!
Thanks

[DanielS]

Wytnucls,
"16.   Conclusion
I never regretted buying these two meters and although I have acquired a few more ‘respectable’ ones since then, I still reach for the 71s on a regular basis."  Is the 71s a typo? S/B 71d? I don't see that model in the multimeter spreadsheet, if legit, will it be in a future update?

It is not a typo: it is simply plural for referring to whatever flavors of the 71 he has access to if he has more than one and possibly different variants.

[teslafan]

 

[Wytnucls]

Something peculiar was brought to my attention recently:
AC current measurement, because of the true RMS converter limitation of 10% of range, is tricky. There is a zone between 400mA and 1A, where measurements are not to be trusted. Ideally, the meter should have had a 4A extra range, to cover the dead zone. DC current measurements are not affected.
Check your equipment, as all true RMS meters which lack an intermediate A range could be affected.
The Fluke has a 5A range and the Gossen a 3A range.

[DBoulanger]

Good day,

I clearly understand that this topic, the "UNI-T UT71D review", has been created and posted a little while ago, nevertheless I would like to take a moment and thank Wytnucls for his great and pretty much indepth review of this DMM.

I do have one on my workbench, for over 2 years now, and it does a good job for me.  As previously stated, there are quite a few nice features for the price.  For an electronic hobbyist like me, this is an adequate tool.  I rarely use it for main voltage.  I used it a few times to troubleshoot some electrical wiring in the breaker panel, but these times were really the exception to the rule.

One feature, that I somehow consider as poorly designed, is the SEND function, used for pre-recorded readings.  For example, while doing some experiment with solar cells, batteries and LEDs, I used my DMM to take readings every minute and let it go for 12 hours or so.

What I disliked about the overall thing is that when time came to send the data back to the computer, the program didn't take into consideration my interval setting of 60 seconds between each reading.  It actually took the current computer's clock time and used that as the timestamp.  Since the unit is sending roughly 15-16 entries per second to the computer, I ended up with time intervals averaging 65ms instead of the 60 seconds I initially set it at the beginning.

Fortunate enough each entry have its own number, incrementing by 1, so I used that to recalculate the adequate timestamps.  This is not a catastrophic issue but when you're not prepared for that, it surely takes you by surprise and "Plan B" must show up quickly if you want to resume your work.

Despite that little misadventure, overall I'm really satisfied with this DMM.  Great deal for the features and the price was right for an hobbyist like me with a somehow limited hobby budget.

Thank you again Wytnucls for posting this extended review.

[Wytnucls]

Glad you appreciate the effort.
To register the correct time stamp, the meter would need an internal clock, which the UT71 series doesn't have. Very few meters have one and they generally tend to be on the expensive side. The new UT171C and UT181A have an internal time reference and should be able to spit out the data with proper time stamps.
It doesn't always make sense: My old Gossen 26S has a clock and a stopwatch, but no internal memory (except for the 26M), whereas the expensive Gossen 30M has 30,000 registers, but no real time reference either.
Fortunately, as you pointed out, this is easily corrected after transfer to PC memory.
On some meters, the captured data is not accessible on the screen. It has to be transferred to the PC for final viewing, forcing you to buy their pricy IR cable and software. Thankfully, this is not the case on the UT71D.

[Wytnucls]

A new member sent me this cryptic message (machine translation). I gather he is concerned about the last digit repeatability and stability of the UT71 when measuring DC volt in an average circuit.
I shot a video of a power supply measurement on the mV DC range, compared to a Keithley 2000, to show that the last significant digit is reliable. (Accuracy on DC mV range is 0.025%+5)

When measuring the voltage reference, and will be, as shown in surveys range UT71s. And it will match the specifications ± 5 LSD.
But we use the meter in different schemes. We have little interest or ideal conditions ideal solution calibrator more 10MOhm.
What in actual measurements? Performing the measurement in real circuits will be the behavior of a meter - it is necessary to carry out 3-4 times a single point measurement.
In the course of 3-4 measurements will be shown on the display various figures around exactly about 0,01V. And if again to make 3-4 metering numbers may be repeated in exactly four bars, but the average from this, there will be more precise 0,01V.
Thoughts:
a) Vref can not be so quickly drift back and forth.
b) C-integr - adsorption? But in other schemes meter measures according to the specification.
in) Bugs MCU?
d) Eureka! This behavior is a meter in different schemes with different total resistance. At the measuring point it can reach tens of radioactive elements.

Please, you are faced with the phenomenon of line UT71s? How can I explain? 3-4 times in one measuring point - different values around 0,01-0,02V.
On what basis can we assert that the accuracy and resolution in millivolts 0,005V, if the inaccuracy and uncertainty of the real measurement is much worse? (Not taking into account the thermal instability and rounding rules).
1) How do you personally consider this strange behavior and the real meter accuracy is more accurate 3 1/2?
2) Only Conrad points to the newest multimeters +10 LSD. What does this mean? It exists closer to the real.
3) We have the resolution bench UT71s - 10mV. In fact, it is not feasible for the same reason - a large uncertainty and inaccuracy of the far-right digit.

[measurementpoint]

Machine translation. Important precision of thought.
Talking about the behavior of the Meter is not in the tests. There Multimeter conforms to the specification.
Talk about practical applications. In most real in-circuit measurement - at one point - measuring cycles 3-4 times - the display will show around 0.01V.
Thus, taking the average, we can not follow exactly the best 0,01V.


Excuse me, I am now corrected.

Excuse me, did not clarify earlier. My observations and speech in the range of 39,999 - as the main series of stabilized voltage will lie here 5-6-8-9-12-24. The illustrated display in the cycle 3-4 times measuring one point - about around 0,01V. And never close to exactly 0,005V

[gamarilla]

My UT71D meter has very high current consumption when it auto-powered off. I couldn't measure it yet but it drains the battery overnight if I forget to power it off.

Is it a problem with my unit or is a design flaw? Do you guys have this issue?

[retiredcaps]

My UT71D meter has very high current consumption when it auto-powered off. I couldn't measure it yet but it drains the battery overnight if I forget to power it off.

In Martin's video at 26:15, he measures the current consumption.  At off, it s 0.0mA.  The others varies from 3.5mA to 9mA depending on the function you use. 14mA for backlight.



If you assume a 9V battery is 500mA and you left it on for 12 hours assuming auto power-off works, that implies it is drawing roughly 41mA in auto power-off.  I would say your meter has a problem.