Poll

Are you interested in seeing more handheld meters tested?

This testing is pointless! Please STOP damaging these meters!
3 (6.4%)
 Yes, I would like to more meters tested.
44 (93.6%)

Total Members Voted: 47

Author Topic: Handheld meter electrical robustness testing.  (Read 502896 times)

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Online joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3250 on: March 31, 2019, 09:02:55 am »
So the 1.1M was replaced with a short... What could go wrong??!!  lol.   

I remember changing burned resistors on my old analog meter using parts I scavenged from old radios and TV sets.   

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 #3251 on: March 31, 2019, 09:50:20 am »
I still have a similar  model called protek a800, analog meter, but it is a pocket meter.



The battery left inside leaked a bit but didn't take much damaged on the spring contacs.
« Last Edit: March 31, 2019, 09:53:01 am by malagas_on_fire »
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Online joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3252 on: April 01, 2019, 01:15:31 am »
A real bandage!   I typically grab the closest tape I have which is normally electrical and some paper towel.    :-DD

Reviews claim the UNI-T is slow to settle.  How slow?  As bad as that Yokogawa? 
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 #3253 on: April 01, 2019, 02:52:11 am »
Got lucky on finding one bandage handy :P Jesus this uni-t 120c had some bad contacts on the battery terminals which would result on bad behaviour. I believe i have posted about freezing the display or turning off by its own  and it was due to this issue.

yeah it is very slow to read capacitors. i don't have  a 150pF cap but can check with a 10uF .
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3254 on: April 01, 2019, 03:15:08 am »
Here is a demo of a 10uF capacitor for comparisson.

https://youtu.be/ztD8GVa6tsI

Notice the 9.86nF offset capacitance. do they put a capacitor inside to mitigate the capacitance on the leads or force to rel always?
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Online joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3255 on: April 01, 2019, 10:58:48 am »
Does it ever become stable? Those are some big jumps. 

The leads will add capacitance.  Seen some that will read zero with the leads installed, like that Yokogawa for example.  Just depends on the meter.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Online rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #3256 on: April 01, 2019, 02:22:35 pm »
***
Watched his last video.  Would have liked to have seen the PCB removed so we could see the switch contacts.   I suspect it just uses the single PTC and some transistors for the clamp.  Maybe a TVS in there.  I doubt it would do very well in my transient testing.
Joe, I added the high resolution photos on the video's description, including the rotary switch.

As you imagined, it is an ordinary meter in terms of safety and rotary switch design.

The UT139C that I am still editing is much more promising. I know you tested it up to 5.1kV, which to me is quite impressive (similar to the much more expensive Keysight U1231A)
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Online joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3257 on: April 01, 2019, 09:35:03 pm »
Joe, I added the high resolution photos on the video's description, including the rotary switch.

As you imagined, it is an ordinary meter in terms of safety and rotary switch design.

The UT139C that I am still editing is much more promising. I know you tested it up to 5.1kV, which to me is quite impressive (similar to the much more expensive Keysight U1231A)
Thanks for adding them.   Looks like the same old problems we have come to expect.    The UT139C didn't make it as far in the transient tests as the Amprobe AM510, which is a bit strange as both are UNI-T products.  Still, it's more robust than most of their products and AT LEAST it survived that little grill starter that seems to be famous for damaging them.   The difference I see between the 139C and the 510 is that I damaged two 139Cs that could not be repaired.  In the case of the 510, I was able to repair it.   One goes to the recycle, the other lives to run another test. 
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 #3258 on: April 02, 2019, 12:00:43 am »
Does it ever become stable? Those are some big jumps. 

The leads will add capacitance.  Seen some that will read zero with the leads installed, like that Yokogawa for example.  Just depends on the meter.

Tested before shooting and it becomes stable at 10.47uF  . I let it sit for some seconds extra on the 10.47uF to reinforce that. It drops when i was to remove the leads. Yeah big capacitance leads.
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Online rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #3259 on: April 02, 2019, 12:50:26 am »
Joe, I added the high resolution photos on the video's description, including the rotary switch.

As you imagined, it is an ordinary meter in terms of safety and rotary switch design.

The UT139C that I am still editing is much more promising. I know you tested it up to 5.1kV, which to me is quite impressive (similar to the much more expensive Keysight U1231A)
Thanks for adding them.   Looks like the same old problems we have come to expect.    The UT139C didn't make it as far in the transient tests as the Amprobe AM510, which is a bit strange as both are UNI-T products.  Still, it's more robust than most of their products and AT LEAST it survived that little grill starter that seems to be famous for damaging them.   The difference I see between the 139C and the 510 is that I damaged two 139Cs that could not be repaired.  In the case of the 510, I was able to repair it.   One goes to the recycle, the other lives to run another test.
Quite interesting. I don't know the AM510, but the UT139C I have is an off-brand and seems to have a much heftier protection when compared to the Surpeer, the Mestek and my chinese-targeted UT-61E (the one with the PCB that looks like suitable for TÜV mark but has gobs of unpopulated MOVs and PTCs).

Despite the lack of input protection, which would never guarantee its status as a CAT III 600V, the Mestek is a very well rounded package IMO (thus the "Aneng killer" title). The NCV is quite useable, the autorange is quite fast (although the continuity is slow), the range distribution is very well rounded and, as malagas mentioned on the comments, the fuses are of a regular size - a much better offer when compared to the Anengs 8008/8009. 

*Please note that, as I mentioned at the end of the video, my opinion may have been biased due to "PTSD" caused by the Surpeer AV4 and its brokeness... :P
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3260 on: April 02, 2019, 02:43:30 am »
The uni-t ut139A which is the basic version of the ut139 line is very similar to amprobe am510 (sorry) functionalities except the true rms. I wounder if it is the 139A has .. needs a fuse inspection
« Last Edit: April 02, 2019, 10:38:03 am by malagas_on_fire »
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3261 on: April 02, 2019, 10:43:07 am »
Here are the inside of the meter uni-t ut139A.  it looks the similar to the uni-t 139C:

https://photos.app.goo.gl/aqgaqaD1kn51pPgTA

Fuses are according to the manual, but don't have any UL listeting ,... need to get better view


Edit: Mine has an extra PTC right above the 10A jack and MOV are placed different. The PTC's looks a bit bigger.

video for comparrisson:

https://youtu.be/zFvuigSS2Xk?t=296

« Last Edit: April 02, 2019, 10:54:56 am by malagas_on_fire »
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Online rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #3262 on: April 02, 2019, 01:30:23 pm »
Malagas, thanks for sharing! It is very similar to the UT139C.
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3263 on: April 03, 2019, 07:41:51 am »
i had mixed thoughts ...  was expecting to be the same board as the 139b and 139C less populaded and on the other hand it would be different since it is much more basic compared to its models, not too much cheaper although. Maybe this is a simplifed version and revision is also 2016, maybe more recent than the 139C which looks it is from 2012. :

https://youtu.be/zFvuigSS2Xk?t=292

i see a 190612 number above the ut139 marking. is this a date code?

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Online rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #3264 on: April 03, 2019, 08:22:08 am »
Yet another edit to my table at:
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg2100013/#msg2100013

Added the Mestek DM91A and the UT139C.

The UT139C comes really close to the ICL7106. Interestingly, the backlight of these two is really low power.
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3265 on: April 03, 2019, 09:02:20 am »
The backligh on the 139A it is a little dim :( even the ut 50b is brighter but yeah batteries last long on this meter. I didn't measure the cutoff from batteries because as soon as you open they are supposed to come on the compartiment or stay loose inside the meter. Also did an experiment with a NIMH battery which was almost discharged , putted two 390 ohms in pararell with it, leave for two hours and voltage was 1.72V. As soon as i removed from the resistors they instantly increased to 6.7V , which i wasn't aware before you all mentioned.. they do rebound indeed and quickly.

Edit; For now planing measure current draw using fully recharged batteries using better wiring than crocodile clips + thin wires :(
« Last Edit: April 03, 2019, 10:02:31 am by malagas_on_fire »
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Online windsmurf

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Re: Handheld meter electrical robustness testing.
« Reply #3266 on: April 03, 2019, 09:49:11 am »
Yet another edit to my table at:
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg2100013/#msg2100013

Added the Mestek DM91A and the UT139C.

The UT139C comes really close to the ICL7106. Interestingly, the backlight of these two is really low power.

Curious how nom. current was measured, as I noticed current draw varies by what measurement setting the multimeters is in, with highest draw usually happening in resistance, diode test or continuity modes.
 

Online rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #3267 on: April 03, 2019, 11:27:31 am »
Yet another edit to my table at:
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg2100013/#msg2100013

Added the Mestek DM91A and the UT139C.

The UT139C comes really close to the ICL7106. Interestingly, the backlight of these two is really low power.

Curious how nom. current was measured, as I noticed current draw varies by what measurement setting the multimeters is in, with highest draw usually happening in resistance, diode test or continuity modes.
This is mentioned at the bottom of the table
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3268 on: April 03, 2019, 09:16:10 pm »
Yet another edit to my table at:
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg2100013/#msg2100013

Added the Mestek DM91A and the UT139C.

The UT139C comes really close to the ICL7106. Interestingly, the backlight of these two is really low power.

There is another alternative to Mestek DM91A but with less resolution counts ( 6000) , the Uni-t 133A which is a compact true-rms meter witn NCV:

http://www.uni-trend.com/index.php?m=content&c=index&a=show&catid=172&id=192

It costs around 30E on local market with shipping + 2Y waranty and should be cheaper on other market platforrms

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Offline Cliff Matthews

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Re: Handheld meter electrical robustness testing.
« Reply #3269 on: April 03, 2019, 10:31:29 pm »
IMO, non-autoranger's need separate power switches. On the 133A, common functions are 4-6 clicks away from OFF.. FAIL!!
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3270 on: April 03, 2019, 11:56:35 pm »
IMO, non-autoranger's need separate power switches. On the 133A, common functions are 4-6 clicks away from OFF.. FAIL!!


That's the model 133B you're refering, the 133A is automatic.

https://www.batronix.com/shop/multimeter/multimeter-ut133b.html

https://toolboom.com/en/digital-multimeter-uni-t-ut133a/

From the official website:

http://www.uni-trend.com/html/product/General_Meters/Digital_Multimeters/UT133_Series/

I believe was my mistake on posting the wrong link , sorry

« Last Edit: April 03, 2019, 11:58:11 pm by malagas_on_fire »
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Online rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #3271 on: April 04, 2019, 01:43:41 am »
There is another alternative to Mestek DM91A but with less resolution counts ( 6000) , the Uni-t 133A which is a compact true-rms meter witn NCV:

http://www.uni-trend.com/index.php?m=content&c=index&a=show&catid=172&id=192

It costs around 30E on local market with shipping + 2Y waranty and should be cheaper on other market platforrms
What attracted me to the DM91A and made me call it "Aneng killer" was the price/feature ratio: at a sale on the Banggood site, it was US$16.00 with free shipping, which was less than the Aneng 8008/8009 and much better featured. However, we don't know how this trend will go, as the Anengs were also much less expensive than their current price when they were released (IIRC).

IMO, non-autoranger's need separate power switches. On the 133A, common functions are 4-6 clicks away from OFF.. FAIL!!
That's the model 133B you're refering, the 133A is automatic.
Stupid Uni-T does no favours in completely confusing their product families.

I have a UT136C which is a wonderful meter, compact and quite functional. Then, they release a UT136C+ that keeps the same counts, is much larger, conflates the mA with the V/Ω functions and adds a *ugh* transistor hfe tester.

The Uni-T UT-55 had a separate On/Off switch. Quite handy.
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #3272 on: April 04, 2019, 02:10:27 am »
Yeah in terms of price it is very good the DM91A and thought the ut133A would be in the same price range out of EU market, but it is 23 USD, having similar functions. About confusion just peak the ut204 and the ut204A  . one has true rms and other lot of features, not true rms. I bought the ut204A based on this website instead with has in the parameters true RMS.. opps :

https://www.uni-t.cz/en/p/clamp-multimeter-uni-t-ut204a


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Offline Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #3273 on: April 04, 2019, 04:27:09 am »
Stupid Uni-T does no favours in completely confusing their product families.

Agree.

That, plus the fact that they make some real stinkers and what you get one of their meters often depends on where you bought it.

How is anybody supposed to buy a Uni-T if they know that there's two or three identical-looking variants out there but some don't have any input protection inside?
 
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Online rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #3274 on: April 04, 2019, 05:44:33 am »
How is anybody supposed to buy a Uni-T if they know that there's two or three identical-looking variants out there but some don't have any input protection inside?
I agree, but I can tell the wide variance of quality and assembly across the Anengs, Mastechs, etc does not leave much to desire. Well, perhaps you could make the case these brands still actually mount the parts on the board, regardless of the Shenzhen sale of the week.

Despite this, I tend to recommend the UT61E for low voltage electronics as it is still a meter with good enough features for this usage and it sits at a good price range. There is some variability and there are certainly better models and more protected, but transients and sparks at low voltage systems are quite rare - just keep it away from those spark plugs! Another factor is that, at least for my channel, the vast majority of the watchers is cash strapped due to exchange rate and is subjected to severe import taxes.

(I can almost hear Joe's disheartened sigh... )

Joe, just because I can...
I took some photos of the UT136C's internals a long while back - however, the rotary switch was missing. Please see attached.

A few details about this meter:
- The grease of the ball bearings of the rotary switch (not seen, as they are in the front enclosure) seem to have seeped a bit into the contacts. This may or may not be dangerous, but at the voltage levels this meter is subjected, I don't see this as a problem.
- There are no vias on the path of the rotary switch blades. That may certainly help with the durability of the contacts
- The range switch feels very good, but I imagine how long the plastics would last in your torture tests.
- There is a single puny PTC at the input, together with clamp transistors and HV resistors. The PTC is in parallel with the V/Ω input.
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Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 


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