Handheld meter robustness testing

[RobertoLG]

I am starting to suspect that even the Harbor freight stuff would fare better than these Uni-T meters...

and you could throw it in the trash without any remorse, and a top end meter that can't take some stress, as Dave sayid before and he is absolutely right,  what a waist of money...

[joeqsmith]

I am starting to suspect that even the Harbor freight stuff would fare better than these Uni-T meters...

I don't think I have ever tested the Harbor Freight meter with the grill starter.   Does make you wonder.   

and you could throw it in the trash without any remorse, and a top end meter that can't take some stress, as Dave sayid before and he is absolutely right,  what a waist of money...

I think I will pick another one (HF) up for the pocket meter testing.   Cause you know that there is going to be some carnage during that test!  Two of the meters are UNI-T.   Did you know that you can always download that spreadsheet from the first post rather than hunting through the videos?   

[RobertoLG]

I am starting to suspect that even the Harbor freight stuff would fare better than these Uni-T meters...

I don't think I have ever tested the Harbor Freight meter with the grill starter.   Does make you wonder.   

and you could throw it in the trash without any remorse, and a top end meter that can't take some stress, as Dave sayid before and he is absolutely right,  what a waist of money...

I think I will pick another one (HF) up for the pocket meter testing.   Cause you know that there is going to be some carnage during that test!  Two of the meters are UNI-T.   Did you know that you can always download that spreadsheet from the first post rather than hunting through the videos?

yes I know, but it's .xls format, I need to find a plugin or something like that for firefox to open it, most stuff on the net like manuals and other stuff is PDF format so I open it directly in firefox. and about hf meter, is this thing survives the test it would be hilarious, at least if it doesn't, won't be a big loss, I'm kinda curious if you can repair the uni t, it was looking good compared with the fluke, the menus and etc

[RobertoLG]

yes I know, but it's .xls format, I need to find a plugin or something like that for firefox to open it, most stuff on the net like manuals and other stuff is PDF format so I open it directly in firefox. and about hf meter, is this thing survives the test it would be hilarious, at least if it doesn't, won't be a big loss, I'm kinda curious if you can repair the uni t, it was looking good compared with the fluke, the menus and etc

I have uploaded the last data I collected that included the UT181A.  I also converted the data to PDF.

thank you very much Sir, much apreciated 

[ProBang2]

"yes I know, but it's .xls format, I need to find a plugin or something"

If you are using Windows, then there are 3 free solutions to look at .xls (Excel) files:

1) Download the free Excel-Viewer from Microsoft:
https://www.microsoft.com/pt-BR/download/details.aspx?id=10

2) Register in the free Microsoft Cloud (5GB free cloud-memory) and open (/work with) the downloaded file there:
https://products.office.com/pt-BR/office-online?legRedir=true&CorrelationId=4f3ee5d7-73f2-4bfa-bbb6-4a1e9b9da2ed

3) Download and install the open source freeware Office-Suite from "Libre-Office". (Full Office-Software: Writer, Calculation, Presentation, Math...)
https://www.libreoffice.org/download/libreoffice-still/?type=win-x86&version=&lang=pt-BR

Recommended: # 3

[rsjsouza]

I am starting to suspect that even the Harbor freight stuff would fare better than these Uni-T meters...

I don't think I have ever tested the Harbor Freight meter with the grill starter.   Does make you wonder.   

and you could throw it in the trash without any remorse, and a top end meter that can't take some stress, as Dave sayid before and he is absolutely right,  what a waist of money...

I think I will pick another one (HF) up for the pocket meter testing.   Cause you know that there is going to be some carnage during that test!  Two of the meters are UNI-T.   Did you know that you can always download that spreadsheet from the first post rather than hunting through the videos?

yes I know, but it's .xls format, I need to find a plugin or something like that for firefox to open it, most stuff on the net like manuals and other stuff is PDF format so I open it directly in firefox. and about hf meter, is this thing survives the test it would be hilarious, at least if it doesn't, won't be a big loss, I'm kinda curious if you can repair the uni t, it was looking good compared with the fluke, the menus and etc

Roberto, perhaps this?
https://addons.mozilla.org/en-us/firefox/addon/docs-online-viewer/

[RobertoLG]

thanks guys, I'll have a look at these

[joeqsmith]

The 181A is given a drink and bullet to bite down on..   The 210E knows from experience that this can't be good!

[Len]

The 181A is given a drink and bullet to bite down on..   The 210E knows from experience that this can't be good!

Tell me when it's over. I can't watch. 

[RobertoLG]

The 181A is given a drink and bullet to bite down on..   The 210E knows from experience that this can't be good!

damn, are going to use it for target practice???    with a bullet like that, there won't be much left, well at least it isn't an AAS50 rifle 

from Hateful Eight  "Y'all keep your mouth shut and do what I tell ya'. Anybody opens their mouth, gonna get a bullet. Anybody moves a little weird....little sudden--gonna get a bullet. Not a warning. Not a question; a bullet. Let me hear you say, 'I got it'. " 

[Muttley Snickers]

How big are those clamp meters ? 
If this listing below is any guide they must be huge, anyway race you to the rubbish bin....

[joeqsmith]

We all bleed red .....     
(Except UNI-T which bleeds Fluke yellow!)

[RobertoLG]

any survivors?  what's next?

[joeqsmith]

Spent the day with it.   Maybe in another day I will post part 2. 

I am still waiting on one of the pocket meters to show up before I do this review.   The 210E is getting no where.  The 181A is taking too much time.

any survivors?  what's next?

[RobertoLG]

when I saw the 181A with the bullet, I tought you would just trash it, I just asked because I tought that you really would targed practice on it

[joeqsmith]

I have done some pretty bad things to meters that were not worth the effort to repair.   High voltage with the Jacobs ladder, shot with arrows, dropped from the roof onto concrete, dremel tooled...   Shooting one is pretty high on the list but it will be a 12G at close range....   So stay tuned to see how it turns out..

when I saw the 181A with the bullet, I tought you would just trash it, I just asked because I tought that you really would targed practice on it

[joeqsmith]

Part 2 of my UNIT-T UT181A review. 

[RobertoLG]

Again an excellent video, glad you could get it working again, and now with some voodoo magic  and like you sayd it's not acceptable that a meter like that is so sensitive to ESD and cheaper meters do survive just fine, very informative 

[SeanB]

That DC DC converter likely failed because the ESD diodes to the ADC were feeding the pulse into the 3V3 rail, and this raised the output voltage of the regulator beyond what it could stand, or the internal ESD diodes avalanched and turned on the parasitic SCR inside it which killed it.  Easy to solve by simply having a small SMD diode to allow this energy to flow back to the battery across the converter ( it is step down so the diode will almost never be forward biased except in an ESD or overvoltage event), and add a little extra capacitance to the supply rails to tame the spike a little, just doubling the ceramic capacitors would do for this.

[saturation]

Great job remediating the problem. 

For other readers, a big difference between the tests is that static discharge waveforms are in nanoseconds while the impulse waveform are in microseconds.   So the energies involved relative to human injury is mJ for static versus J for impulses, but to high impedance electronics, its still deadly.  Why Uni-T didn't take it into account is puzzling given the effort to get ETL listed, typically the ETL consultant would have mentioned it.

[joeqsmith]

Thanks for the comments.   Just in case the UNI-T group ever visits,  if there is a rev B of this meter a few things I would like to see are:

Certify to EMC standard 61326.
Adapters for the European charger.
Offer a spare battery as an accessory.
Store the current settings on power down or function change (like the BM869s).
Better material for LCD cover (prone to scratching). 
When logging data with Windows, download the battery life.
Open source the interface or at least provide a communications library for it.

I am not sure how well this thing would  survive a drop test.  Maybe offer a slip on rubber sleeve as an accessory.

All in all, I really like the meter for hobby work but I would not recommend it with it being as susceptible as it is to static.

Today, I turned on the Fluke reference for an hour with it set to 1mv.  I then connected the Fluke to the UT181A (which was just sitting out in open air).  I then let it run for five and a half hours collecting the data.   Keep in mind the house temperature varies throughout the day.   It appears pretty stable.  Then again, they spec a temperature coefficient of 0.1 * +/-(0.025 +20 counts)/deg C.   

Plot is showing +/-3uV   

[Muttley Snickers]

Thanks Joe, this was an excellent effort on your part and it made for a great video, it clearly shows that improvements for reliability can be made to some meters and perhaps some manufacturers who see this may take it on board.

I did like the way you utilised the hold button on the first meter before switching to the second to retain the measured value for comparison, I wish others would do the same thing when comparing meters so we don’t have to remember what the previous meter displayed, this was a nice touch.

To sum up…….

[joeqsmith]

The meter goes into a low power mode when data logging.  I was hoping to finish off the battery this weekend but it still has a fair amount of charge left.   

I put the meter into my temperature chamber  (cardboard box with two layers of foam, fan and heater).   Normally I run this off a PC but for this, I just ran it open loop, using the Brymen to monitor the temperature next to the meter.

I started out at room temp (21.4C).   I then just set the heater to a fixed current.   At 18 minutes, it was at 32.2 C.   At 1 hour it reached 34.2 C.  At least a 10 deg rise.   

After three days of testing and around 30 hours of hard time, the last picture shows the battery remaining.   They do not talk about the battery life but I would guess based on my normal use, its about 40 hours between charges.   

[Maxlor]

That was interesting to watch, thank you for making the video. I'm a bit puzzled though by one thing: Obviously Uni-T put in some effort into making the meter robust to transients, so how could they miss the ESD susceptibility? Or rephrased, how would the meter survive transients, but not ESD events? Is this because of the (presumed, on my part) much smaller rise time of static discharges?

In any case, it feels like they're stepping up their game. If you look at what they've been doing so far, the next generation of meters in a couple of years will probably be hard to fault, but cost a third of what a Fluke costs. Which will hopefully make Fluke and others think about some strategic improvements as well. And your videos as well as those of your fellow videobloggers sure help with making issues more visible

[joeqsmith]

Thanks Joe, this was an excellent effort on your part and it made for a great video, it clearly shows that improvements for reliability can be made to some meters and perhaps some manufacturers who see this may take it on board.

I did like the way you utilised the hold button on the first meter before switching to the second to retain the measured value for comparison, I wish others would do the same thing when comparing meters so we don’t have to remember what the previous meter displayed, this was a nice touch.

To sum up…….

Using the hold was an excellent idea!   Thank you very much for that.

The video ran a little longer than I had hoped.  It's hard to condense three days into under an hour and know what to show.  Enough people had asked about the peak voltage that I thought it would be good to at least make an attempt to explain the standards and how the grill ignitor compared with it.   

I wanted to make sure people understood that the meter was fully functional after the repairs and that when I repeated the grill starter test that I was not holding back.   Adding the Harbor Freight meter at least gave some perspective that the grill starter would still damage a low end meter.   After running at 15KV, connecting the UT61E was just to show what sort of signal was coming out of the generator.   Still not a lot of energy but that has never been a goal. 

So thanks again for that little tip.   If anyone has a question about the meter or would like to see some other test ran on it, let me know and I will see what I can do.