Poll

Are you interested in seeing more handheld meters tested?

This testing is pointless! Please STOP damaging these meters!
3 (6.5%)
 Yes, I would like to more meters tested.
43 (93.5%)

Total Members Voted: 46

Author Topic: Handheld meter electrical robustness testing.  (Read 495267 times)

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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2950 on: October 28, 2018, 10:47:44 am »
Yes, you are missing something!! 
Uh... What exactly? The speed of the transient? I thought I had it covered on my post...
What does the speed, or better yet, let's say the rise time have to do with it?   What was it on the 61E that was damaged and why?
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2951 on: October 28, 2018, 11:03:33 am »
Just a quick update on my problems with the BM867S. I tried the same set up again and the display was 100% stable this time. I have no explanation of what the issue is. I even set the bench out as close to what I remember I had it set up as and documented in my notebook. Power out was within 5% of original. Frequency spot on.

I will put this one down to quantum bogodynamics as my other half was in last time and isn't this time. She may have high bogon emissions.

When I was a kid in my teens, one of my hobbies was amature radio.  I really didn't know a whole lot about anything back then but I had fun calculating my dipoles, hanging them up and then trimming them to the lowest possible SWR.   Our TV set, my scope, signal generator and even my meter was tube based.  So was my radio equipment.  There was a plate load and tune to set the power amplifier.    If the amplifier was not tuned correctly, I would get notice in the mail from some other amature who had heard my call sign on some other band that I wasn't even operating in.   Then I learned what harmonics and distortion are.   :-DD   I think my scope was good to a MHz, if that.   

Maybe your system was distorted enough that what you discovered is that the meter is actually sensitive in some other area.  Again, I swept the BM869s to 3GHz at 10V/meter and it was stable.  But you may have exceeded that by a fair amount.  If you run into it again and get a better idea of what is going on, just let me know and I can attempt to test it again over a wider frequency.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline Cliff Matthews

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Re: Handheld meter electrical robustness testing.
« Reply #2952 on: October 28, 2018, 12:57:45 pm »
FWIW, there's a short but entertaining new BM839 review from Marco Reps showing-off ugly soldering on their mezzanine board.
 
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2953 on: October 28, 2018, 11:49:17 pm »
Well about cheap it depends on which scale / type of the meter fits. The uni-t 181A is very similar to the fluke 287.. and the 287 costs a lot more, it is sluggish on plotting but it meets more safety then. Now the Keysight is not much cheap compared to equivalent meters , lets say fluke 115 / 117, [Edit the poor english, sorry ], the hioki ,brymen BM257s and fails so less value for the money.


The uni-t 181A heavly modified, with the software in labview over bluetooth must be something unique since it hasn't got a program for PC.

Now a different question. Did you perform a transient test after a drop on the aneng's?

I should have been more clear.  I was not inferring anything about the features, quality or value, only the cost.  For me, cheap is $50 USD and less.   I've stated numerous times that I had never paid more than $50 for a handheld before starting these tests.   These cheap meters were never used for anything beyond basic automotive use in the garage or if I needed something avoid risking my bench meters.  I have always considered them disposable.

That said, when I started running the first $50 meters it was clear that one company stood out, even at that level. 

I would not say my UT181A is heavily modified, at least not compared with that KASUNTEST ZT102 or even that analog meter I tested.     Now if we were discussing that UT61E, that's heavily modified!   :-DD  Possibly the first handheld meter ever with an auto back light control.   

If you go back and watch that video where I drop test the ANENG and the KASUNTEST, you will find both were damaged long before they were dropped.   I had put them back together to try to get a feel for how they would hold up.  I don't think I ever dropped a working one.   

Hello And thanks again for the clarification. For 50 "doll" mark it comes to the 101 or the Am510. I believe when you talked about the modifications about the ut61e you also mentioned the uni-t 181A and it sound  was more difficult on one of the videos :

https://youtu.be/cMutvk_6xhY?t=2541

The piezzo grill starter may have low energy but it is a ultra fast spike and the clamps must be prepared for it, if any...

My question about the drop is that my aneng has failed during monituring 230V AC isolated, due to droping from my TV stand to the floor (0.5m height) front facing which result in random mode changing / enter CAL mode when wake up from SEL button.

 
« Last Edit: October 29, 2018, 12:24:33 am by malagas_on_fire »
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2954 on: October 29, 2018, 01:14:37 am »
Well about cheap it depends on which scale / type of the meter fits. The uni-t 181A is very similar to the fluke 287.. and the 287 costs a lot more, it is sluggish on plotting but it meets more safety then. Now the Keysight is not much cheap compared to equivalent meters , lets say fluke 115 / 117, [Edit the poor english, sorry ], the hioki ,brymen BM257s and fails so less value for the money.


The uni-t 181A heavly modified, with the software in labview over bluetooth must be something unique since it hasn't got a program for PC.

Now a different question. Did you perform a transient test after a drop on the aneng's?

I should have been more clear.  I was not inferring anything about the features, quality or value, only the cost.  For me, cheap is $50 USD and less.   I've stated numerous times that I had never paid more than $50 for a handheld before starting these tests.   These cheap meters were never used for anything beyond basic automotive use in the garage or if I needed something avoid risking my bench meters.  I have always considered them disposable.

That said, when I started running the first $50 meters it was clear that one company stood out, even at that level. 

I would not say my UT181A is heavily modified, at least not compared with that KASUNTEST ZT102 or even that analog meter I tested.     Now if we were discussing that UT61E, that's heavily modified!   :-DD  Possibly the first handheld meter ever with an auto back light control.   

If you go back and watch that video where I drop test the ANENG and the KASUNTEST, you will find both were damaged long before they were dropped.   I had put them back together to try to get a feel for how they would hold up.  I don't think I ever dropped a working one.   

Hello And thanks again for the clarification. For 50 "doll" mark it comes to the 101 or the Am510. I believe when you talked about the modifications about the ut61e you also mentioned the uni-t 181A and it sound  was more difficult on one of the videos :

https://youtu.be/cMutvk_6xhY?t=2541

The piezzo grill starter may have low energy but it is a ultra fast spike and the clamps must be prepared for it, if any...

My question about the drop is that my aneng has failed during monituring 230V AC isolated, due to droping from my TV stand to the floor (0.5m height) front facing which result in random mode changing / enter CAL mode when wake up from SEL button.

If we talk about the changes made to the PCB just for the sake of getting the UT181A and the UT61E to pass me ESD test, then yes there  was a lot more involved in 181A.  As I said in the video the UT61E required a single cut to the PCB was all (again, just for the ESD. NOT for all of the other modifications I made to the meter).  Your original post is not specific to ESD.  It's a general statement about the "heavly modified" UT181A which when compared with the UT61E, is not. 

Yes, the gas grill starter is a fairly fast spike with very low energy compared with other transients that I expose these meters to.  I still have a hard time believing that it would damage ANY meter made today.

Your drop test does not explain that cracked transistor.  You may think it was random and had something to do with a calibration mode but I would put my money on the selector switch being in the wrong position and applying a high voltage.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2955 on: October 29, 2018, 09:23:12 am »
The 100mV means 1A on the plot?

The drop was an accident. I was checking the voltage on a SBC (Small Board Computer ) connected to TV, i pulled the leads a little bit and then it dropped in the floorr. The front panel got a scratc but nothing special. I tested the multimeter and it seemed fine. But sometimes in Volt mode and Sleeping, when i press SEL to wake up, sometimes it would go crazy jumping modes on it's one or going to CAL mode. If i press the multimeter it would switch more frequently.

The randomness i was talking is about the modes it would switch and would hang on CAL mode.

Eventually i  still kept using on a AC project and assume that it would only be tripped when in sleep mode, but it behave bad while measuring the AC Volts, then turned off and never came back again. I can open further if there was any damage on the contacts from the rotary switch, but it was all the time in Volts mode.
« Last Edit: October 29, 2018, 09:50:52 am by malagas_on_fire »
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2956 on: October 29, 2018, 09:45:22 am »
Here are some photos of the pads for the rotary switch with some sort of grease, also one trace in the middle is pretty scuffed. This is one year of use...
 Also the lens were scratch from the fall are available.

The spring contacs on the rotary switch are like brand new, without wear.
« Last Edit: October 29, 2018, 09:52:46 am by malagas_on_fire »
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2957 on: October 29, 2018, 09:53:13 am »
Here are some photos of the pads for the rotary switch with some sort of grease, also one trace in the middle is pretty scuffed. This is one year of use...
 Also the lens were scratch from the fall are available.

The spring contacs on the rotary switch are like brand new, without wear.

The image of the rotary switch...
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2958 on: October 29, 2018, 11:10:37 am »
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2959 on: October 29, 2018, 10:29:47 pm »
Thanks for refreshing the memory. That pulse is hard to capture on current measurement.
The ESD gun looks more harmfull than piezzo grill starter since it approaches the IEC test and again uni-t 61e modified passed that test. Maybe uni-t has corrected that in newer DMM's.

However the Amprobe pm55a, which i bet that would fail on that test, it ran without issues and got beyond the 6kv. By the way did you managed to produced the bug reported by True after the video?




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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2960 on: October 30, 2018, 03:43:05 am »
Thanks for refreshing the memory. That pulse is hard to capture on current measurement.
The ESD gun looks more harmfull than piezzo grill starter since it approaches the IEC test and again uni-t 61e modified passed that test. Maybe uni-t has corrected that in newer DMM's.

However the Amprobe pm55a, which i bet that would fail on that test, it ran without issues and got beyond the 6kv. By the way did you managed to produced the bug reported by True after the video?

I knew a guy who tried to measure the output of an ESD gun directly with a DSO.  It didn't work out so well.   :-DD The standards cover how to make the measurement.   

I've yet to have a Brymen product perform poorly against my tests so seeing the pocket meter not having any problems with the newer low voltage generator was not much of a surprise. 

I have continued to try other tests with the pocket meter but have yet to see a problem.  True talks about the low battery in all cases.  Maybe they installed LIRs to replace the CRs.   The manual clearly calls out CRs in numerous places but that doesn't mean that True followed the manual.   I don't know if the added voltage from an LIR could damage it or not.   The manual is just clear about what to use, not about what happens when you don't follow the instructions.   :-DD 

Maybe one day they will post again and we can get a few more details about what happened with all four of their meters. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2961 on: October 30, 2018, 04:55:08 am »
Wow nice detail on the battery , It's like installing lithium AA instead of the Alkaline or NIMH of this size, but the eevblog BM235 manual  calls out for that situation.

About my meter looks like one of my brothers use it to measure the voltage of the flyswatter and it said it was doing OL all the time and switched to other off position while the thing still on and leads plugged  :palm: . i. , before i ran the 230V ac test... I thought it was the fall but now i have the oportunity to offer one of my old meters, the uni-t 50b, teach more stuff. All bets are off for now.... :-DD





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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2962 on: October 30, 2018, 09:27:57 am »
I could try installing one and see if there are any long term effects.  If it damages the meter, it doesn't mean that's what happened with all four of True's meters.   It also doesn't mean there is anything wrong with the design.  I wouldn't expect to be able to use a different battery than the manufacture calls for without damage.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2963 on: October 30, 2018, 11:33:22 am »
Well there always the chance of flipping the polarity , but four in a row would be a bad play.  :-DD
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2964 on: October 30, 2018, 11:42:33 am »
Seems like Voltlog mentioned that it had reverse protection.  I think they shunt it with a diode.  Still I know I didn't test it.  It would be pretty bad though as the meter is marked in at least two places, plus the manual.  Still....  :-DD
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline stj

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Re: Handheld meter electrical robustness testing.
« Reply #2965 on: October 30, 2018, 10:19:46 pm »
About my meter looks like one of my brothers use it to measure the voltage of the flyswatter and it said it was doing OL all the time and switched to other off position while the thing still on and leads plugged  :palm: . i. , before i ran the 230V ac test... I thought it was the fall but now i have the oportunity to offer one of my old meters, the uni-t 50b, teach more stuff. All bets are off for now.... :-DD

on the left side of the battery holder is a supressor diode - see if it's shorted or try the meter without it.
i got an aneng from someone who did something stupid, and that was blown.
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2966 on: October 31, 2018, 04:00:23 am »
From what I remember, that TVS was for the current input and I thought it was on the backside of the switch.   :-//  I may have scribbled out that circuit when I made the video where I had modified the meter.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2967 on: October 31, 2018, 07:26:58 am »
Are you refering to the Q3 that was blown or the TVS on the current input? I can probe later the Q3 if it is shorted and maybe take it out.



Well i have probe Q3 and Q4 are shorted.... maybe i'll take out later and fingers crossed
« Last Edit: October 31, 2018, 07:33:26 am by malagas_on_fire »
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Offline stj

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Re: Handheld meter electrical robustness testing.
« Reply #2968 on: October 31, 2018, 07:51:59 am »
i was refering to the tvs,
people who dont read instructions dont know the current mode is limited to about 50v
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2969 on: October 31, 2018, 08:58:06 am »
Yes in most cheap meters its more or less 30 Vrms on the current side. I've removed the Q3 / Q4 and the TVS., plug the batteries, no meter.

The TVS shows no voltage in diode mode in both directions,  aka O.L. meanwhile i've ordered a replacement meter... one of the most cheapest true RMS meters for measuring voltages up to 600V, but i'm using max 230V. Bet you're guesses and it is similar to one that joe smith has tested :P
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Offline HKJ

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Re: Handheld meter electrical robustness testing.
« Reply #2970 on: October 31, 2018, 09:05:52 am »
Yes in most cheap meters its more or less 30 Vrms on the current side. I've removed the Q3 / Q4 and the TVS., plug the batteries, no meter.

There is no voltage limit when measuring current, even on cheap meters. The TVS diode is there to protect the current shunt during over current conditions until the fuse blows.
If the fuse blows it may not be able to break the current and higher voltage may damage the meter.
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2971 on: October 31, 2018, 09:27:00 am »
At least on the manual on the uni-t 50b it calls for 30Vrms maximum.input .. but this is a meter with unfused A and fused mA , so it gets even worse...
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2972 on: October 31, 2018, 10:58:36 am »
Demonstrating my software for the UEI / EEVBLOG 121GW and the UNI-T UT-181A.    This video also contains a test that 001 and Fungus had requested using high voltages, a spark gap and Vaseline.   :palm:   For future reference, that thread may be found here:

https://www.eevblog.com/forum/testgear/can-i-grease-my-dmm-selector-with-silicone-oil/


How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2973 on: October 31, 2018, 11:50:39 am »
Now it is using my old uni-t 50b and read the manual before using it. They are the acessible meters.
The one that i've got is the uni-t ut139A , the worst of the 139 line. At least it has ceramic fuses for the claimed voltage, it has enough grip and simple to use. It will be out of reach for modifications.
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Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #2974 on: October 31, 2018, 07:47:01 pm »
Just to be clear: I didn't request Vaseline, that was 001.  I just suggested the spark gap test.  :D

 
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