Handheld meter robustness testing

[rsjsouza]

Well, the meter survived quite well the torture - thanks for doing this.

For a UNI-T product, overall, I couldn't agree more but not when compared with the better brands I have looked at. 

Then again, having the meter modified may have saved it from the total destruction we are use to seeing with this brand.  It's not good enough for me to want to invest more time into looking at the brand again.   After 13 products, I think we have learned our lesson.

Indeed. The transient test could have swayed you out of the switch test a lot earlier in the process. However, as we stand today, the state of the contacts and PCB held much better than the other single-test brands you did (apart from UEI, of course).

The break of the stands is an unfortunate event that muddles the waters, so it prevents us from saying one way or another: i.e., that UT61E+ has a crap switch or an "above average" one.

A few unknowns, especially due to the dramatic self-healing, but that happened with the other meters as well.

Well, let's be clear.  If we are talking about the contacts opening up (>1kohm) some meters have self healed.  Cycle3 shows the five worse meters I have looked at.  All of these went open before 7000 cycles.  It's good to see Keysight in the mix with UNI-T and the free HF meter.      

But consider the other five meters in Cycle4.  None of these meters ever opened up during the entire duration of the test.  Note that even Dave's 121GW with it's cobbled switch and countless contacts hung in there.    While Dave's test limited the measurement to 10 ohms, I like being able to see the higher values and trusting the HP bench meter.

Indeed they didn't open, although the cheapest of the bunch (17B+) was the only one completely unfazed during the test cycle. Also, they are Shift-left the price of an UT61E+ (apart from the Keysight, of course), so there is something to be said about bang per buck (something I also commented on Youtube - didn't read yet your reply there).

After 50k the status of its contacts and PCB are quite interesting. No way to compare with the 17B+, but still...

True but again, the wiper contacts were not locked to the knob.   How would the meter have held up had the pins not broke?  What if they hadn't spec'ed the frequency counter to 200MHz and the meter still had the original components?  Would a small ESE event have damaged it?

Yes, the breakoff was quite unfortunate and we don't know when this happened in the test. If they indeed copied Fluke's patent as mentioned by floobydust above, they skimped on materials or were incompetent in their redesign.

As for the other specs, that is my biggest beef with Uni-T, Aneng and others: they lie through their teeth with regards to CAT ratings (and, in this particular case of the Uni-T, specifications themselves). If they slap a CAT II 300V on their gear, I would have much more respect for them.

Full disclaimer, I have a Uni-T and a pair of Agilents and they are so far holding well while being used with certain regularity for the best part of five or six years - nowhere near 50k operations, obviously. As I mentioned many times before, the Fluke 87V and 179 rotary switches are kings to me: they are the sturdiest and most well put together that I have ever seen. Unfortunately I don't have the capex to put my Agilent meters through a similar torture contraption as I need them for various tasks and, as you could well see, youtube videos do not bring enough revenue to justify such adventure. 

Overall, thanks again for doing the test and publishing these results. That is a great advancement for the manufacturers.

[joeqsmith]

However, as we stand today, the state of the contacts and PCB held much better than the other single-test brands you did (apart from UEI, of course).

It's similar to how Fungus would comment how a meter that was tested at 1kV and survived but then failed it 20kV with no other data collected between, didn't fail until 20kV.   While technically true, it's very miss leading.    You are also 100% correct.  The switch broke early on in the testing.  We've seen the contacts open up and a broken detent spring but we've never seen a design so poor that the contacts fail to turn with the knob.  And yes, the PCB and contacts were spared.       

... as you could well see, youtube videos do not bring enough revenue to justify such adventure.

 
I have yet to beg for subscribers or $$$.   If we run another UNI-T, I may have to start a go fund me account.  Not to cover the cost of the meter or the time to run it but for pain and suffering.     

[rsjsouza]

However, as we stand today, the state of the contacts and PCB held much better than the other single-test brands you did (apart from UEI, of course).

It's similar to how Fungus would comment how a meter that was tested at 1kV and survived but then failed it 20kV with no other data collected between, didn't fail until 20kV.   While technically true, it's very miss leading.    You are also 100% correct.  The switch broke early on in the testing.  We've seen the contacts open up and a broken detent spring but we've never seen a design so poor that the contacts fail to turn with the knob.  And yes, the PCB and contacts were spared.

I suspect you understood my statement, but let me clarify anyways: I wasn't closing the case on the meter's quality, but only on the evidence we could gather from the (unfortunately) imprecise test.

Well, that and perhaps a way to tickle your nerve and see if you would be swayed to run another UT61E+ (or another meter from them) in the future. Judging by your next statement, I now know you have a price...  

... as you could well see, youtube videos do not bring enough revenue to justify such adventure.

 
I have yet to beg for subscribers or $$$.   If we run another UNI-T, I may have to start a go fund me account.  Not to cover the cost of the meter or the time to run it but for pain and suffering.   

Just to clarify, I have never asked to hit like or subscribe... Perhaps if I have done that (and created my videos in a language almost as common as Klingon) I could have made enough to splurge on another U1282A to be tortured. :-D

[joeqsmith]

I suspect you understood my statement, but let me clarify anyways: I wasn't closing the case on the meter's quality, but only on the evidence we could gather from the (unfortunately) imprecise test.

Well, that and perhaps a way to tickle your nerve and see if you would be swayed to run another UT61E+ (or another meter from them) in the future. Judging by your next statement, I now know you have a price...  

The only thing we learned from that test was the switch is poorly designed but expected based on the previous 12 products we looked at. 

I assumed my comment about a fund me would be understood as sarcastic.   I had no interest in looking at another UNI-T product but I caved to peer pressure of viewers.   

I may be persuaded to look at another UNI-T product in the future but there would be no reason to look at another 61E+ unless it was improved.   Had the two posts not snapped, I was going to get a second one to repeat the transient tests but like fungus, I think the meter has too many weak links in the design to make it worth spending any more resources on.       

Just to clarify, I have never asked to hit like or subscribe... Perhaps if I have done that (and created my videos in a language almost as common as Klingon) I could have made enough to splurge on another U1282A to be tortured. :-D

Don't forget the bell and turn on ads.   It all helps.    I would have to get the Fluke yellow Keysight meter. 

[Fungus]

It's better to just buy products that meet your needs.  This meter isn't something I would use but it could be a very good fit for someone else. 

The only thing I see this meter has going for it is the PC connection.

As a standalone meter? Nope. For the same money I can get a 20,000 count Aneng and a Fluke 101.

[Neutrion]

I am not a materials engineer and have no idea what they are using.  The Keysight appears to be a glass filled material. 

Its often marked on the plastic with a few letters, so you don't necessarily have to throw it into a gas chromatograph. Glass fibre in that arrangement, does not seems to be good idea anyway, but it did not got so far to rub off the plastic.

Joe, do you know which are the plastics paired in this meter? (The white spring, and the dark one it rubs on.)
And in the Keysight?
...

Like Joe, I am not a material/plastics engineeer, but I believe in the UT61E+ the white spring is nylon, whereas the dark plastic it rubs on is polycarbonate.

https://en.wikipedia.org/wiki/Nylon

https://en.wikipedia.org/wiki/Polycarbonate#Applications

The white stuff is usually POM. which stands probably for Polyoxymethylene Of Her Majesty.

I will check the Brymen later on, if it has letters on the parts.

Just wondering if any of the expensive meters are actually using teflon.

[joeqsmith]

Its often marked on the plastic with a few letters, so you don't necessarily have to throw it into a gas chromatograph. Glass fibre in that arrangement, does not seems to be good idea anyway, but it did not got so far to rub off the plastic.

I would imagine that if all four prongs of the Keysight meter's detent spring hadn't fractured, it would have eventually started to cut into the case.  But they broke really early on in the cycling. 

[AndrewBCN]

...
The white stuff is usually POM. which stands probably for Polyoxymethylene Of Her Majesty.
I will check the Brymen later on, if it has letters on the parts.
Just wondering if any of the expensive meters are actually using teflon.

I believe POM is too stiff to be used as a plastic "spring" part, but in any case, the only way to be 100% certain about what plastics are used for the various parts in any multimeter or electronic test equipment is to get the information straight from the manufacturer, iow next to impossible (unless there are markings on the case, as you suggested).

PTFE (one of the variants of Teflon) is a very good plastic for certain applications in electronic test equipment, but it is also very expensive. https://en.wikipedia.org/wiki/Polytetrafluoroethylene

About the symbols on plastic parts: https://en.wikipedia.org/wiki/Resin_identification_code

[Neutrion]

Its often marked on the plastic with a few letters, so you don't necessarily have to throw it into a gas chromatograph. Glass fibre in that arrangement, does not seems to be good idea anyway, but it did not got so far to rub off the plastic.

I would imagine that if all four prongs of the Keysight meter's detent spring hadn't fractured, it would have eventually started to cut into the case.  But they broke really early on in the cycling.

Possibly a very well designed safety feature from Keysight, which saves the case from being damaged.

Now I checked the Brymen 789: No markings on the plastic, except the upper case which is made of Policarbonate. On the lower case the letters are erased.
Interesting is, that now after not much usage, the wearmarks on the traces have a silverish colour. Checked your video again, but was unable to find out what the colour there was. It looks like as if wipers had some silverish material under the gold coloured.

For me by the way the rotary switch of the dt830 meters gives the best feeling, and if I consider the latching mechanism with the steel balls, I am quiet sure that this part of the mechanic would survive the torture test. Not necessarily the wipers of course.
Never felt the Gossen though...

[joeqsmith]

I had ran a that DT830 which of course had failed very early on.  It's the only meter that was so bad, I aborted the test. 

Somewhere there are pictures and a video showing how the ball had cut a deep grove into the case. 

[Neutrion]

I checked your youtube channel but found only short videos to the dt830. Is it one of them?

Anyway rather interesting, because in theory this construct should be quiet robust. With some non silicon grease I would have guessed it to outlast all the other meters. But maybe the plastic is so shitty that it's still not enough. Mine is also broken because of a very short fall.

Still the best switch-feeling to me.   

[joeqsmith]

Should be one of the very early ones.  The contacts opened up several traces and there was little left of the plastic.  I repaired the meter and used it for another test.   Maybe took it out with ESD.   

[Neutrion]

Found it.
Did you ever run the ut-210e with the generator, or the grill starter? Because the protection seems to be reasonable, at least compared with other Uni-t's.

[joeqsmith]

I've only looked at the meters included on the spreadsheet.  I would have no reason to plug the leads into the UT210E.  I kept it for that 1mADC resolution.       

There's not much room on the inside.  I would imagine it would do about as well as the other 13 UNI-T products I have looked at. 

[Fungus]

I would have no reason to plug the leads into the UT210E.

There's not much room on the inside. I would imagine it would do about as well as the other 13 UNI-T products I have looked at. 

This page has photos of the insides. Everything is very close together and there's still no surge resistor on the input.

https://lygte-info.dk/review/DMMUNI-TUT210E%20UK.html

It only claims CAT III 300V, CAT II 600V which is a very low standard. I guess it might meet those numbers.

the protection seems to be reasonable, at least compared with other Uni-t's.

If you're confident in the protection you can do a grill starter test at home. Grill starters are cheap and easy to find.

[joeqsmith]

....
Grill starters are cheap and easy to find.

But not all the same!!

[Fungus]

Maybe one of those electric fly swatters would be a good test, too. 

[joeqsmith]

Or just leave the probes out of it.  Of course, the switch will still fail.

[floobydust]

I don't like the UT61E+ LCD conking out with the BBQ lighter hits. I'd say it's got an EMC issue or the clamp-transistors have too high an avalanche voltage, usually around 7V some parts are even 12-25V. And what good are they anyhow if the IC is running off 3.6V, it's still getting nailed.

It would be interesting to compare the current of the BBQ lighter to 61000-4-2 ESD models, like the 150pF/330Ω  or 1,000pF hits.
Is the metal box (blast shield) earth grounded? I thought stray capacitance with the multimeter's foil shield could lessen the spike. Uni-T has no shield on the front side?

[Neutrion]

I would have no reason to plug the leads into the UT210E.

There's not much room on the inside. I would imagine it would do about as well as the other 13 UNI-T products I have looked at. 

This page has photos of the insides. Everything is very close together and there's still no surge resistor on the input.

https://lygte-info.dk/review/DMMUNI-TUT210E%20UK.html

It only claims CAT III 300V, CAT II 600V which is a very low standard. I guess it might meet those numbers.

the protection seems to be reasonable, at least compared with other Uni-t's.

If you're confident in the protection you can do a grill starter test at home. Grill starters are cheap and easy to find.

Not that confident, but still interested. Does it have protection diode clamps? If so I would bet it survives up till about ...4000V. But mabe not the grillstarter.
I "tested" it once with about 1000 V Dc , but it was only an insulation tester.

Joe in one thread you mentioned measuring a welding inverter with it, after which in was only reading OL.
Did you use the clamp to measure the amps? What exactly caused the damage?

[joeqsmith]

I would have no reason to plug the leads into the UT210E.

There's not much room on the inside. I would imagine it would do about as well as the other 13 UNI-T products I have looked at. 

Joe in one thread you mentioned measuring a welding inverter with it, after which in was only reading OL.
Did you use the clamp to measure the amps? What exactly caused the damage?

Read the following post:
https://www.eevblog.com/forum/testgear/over-current-in-clamp-meter/msg1996529/#msg1996529

[Neutrion]

Oh, thanks, this was also my first guess. Don't no if it is actually possible to damage the sensors on the clamp. Which according to a long youtube video of a german guy, are actually not hall sensors if I remember right. (In the two piece long videos about the calibration and working principles...)

[Nisei]

Also the pictures of the discontinued UT61E that Fungus posted are from another EEVblog forum member Nisei, who duly noted (as can be seen on the PCB silk screen) that the two UT61E DMMs that he owns are different variants of the UT61E - the model on the left is a UT61E-GS and indeed it has better input protection and larger fuses.

Show me a photo of a Uni-T meter, a manual, or a website link that actually has a meter labelled "UT61E-GS".

Sorry, just noticed this and feel like I have to step in to clarify the picture I've posted (even if it's been ages ago) which is being re-used in this thread.
Sucks when you don't get notified when people repost stuff but that's inevitable.
I have no time to read all the posts following that post but here's what was going on:
Reichelt (a German distributor) wanted to sell this meter in Europe but they knew the ratings were bogus so they asked Uni-T to alter some things and had it recertified.
Hence the input protection being beefed up and the CAT ratings being lowered.
Only then could it get a German GS rating.
I believe it was a one-off order of umpteen thousand and when they were sold that was it (no idea how many) because even when the regular 61E was in production they were already sold out.
I still haven't blown it up 

[cybercorfu]

I would like to ask the community I have UT181a not long but the battery drains very quick I measure the current when off to 18mA is this normal?

[joeqsmith]

I would like to ask the community I have UT181a not long but the battery drains very quick I measure the current when off to 18mA is this normal?

I've left the meter off for months at a time and haven't noticed a problem.   How did you measure the current?  If the meter is new, why didn't you return it under warranty?