Poll

How many cycles will the KeySight U1281A's detent spring last?

0-2000
7 (17.9%)
2k-4k
5 (12.8%)
4k-8k
14 (35.9%)
8k-16k
7 (17.9%)
>16k (most rubust meter ever made)
6 (15.4%)

Total Members Voted: 36

Author Topic: Handheld meter robustness testing  (Read 1145277 times)

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Offline joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4075 on: September 23, 2021, 01:01:58 pm »

Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4076 on: September 23, 2021, 01:53:22 pm »
.... If it were, we would all be experts at everything.  ...

We are! 

https://www.harvardmagazine.com/2018/03/death-of-expertise-by-tom-nichols

Very interesting article. So most of us are "armchair experts" (putting it kindly) and you know that!  >:D

On the other hand Joe, you have put > 6 years of effort into building your knowledge of "DMM robustness" as you modestly put it, have disassembled, destroyed and rebuilt countless DMMs, have designed and built your own test equipment, and have read and understood countless datasheets for components that are used in DMMs.

I had a friend who used to repair PC power supplies for a living, a dozen or more a day, and after years of the same routine he could usually diagnose the problem in less than 30 seconds (he had a PSU test rig which he had built himself), confirm his diagnosis with a $10 multimeter and unsolder the faulty components and resolder new ones in less than 5 minutes tops. I am not sure that made him an expert in PSU design or reliability, but on the other hand he never made any such claims. He spoke little and always worked in silence, actually.
 

Offline Fungus

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Re: Handheld meter robustness testing
« Reply #4077 on: September 23, 2021, 02:02:26 pm »
1. "one look at the PCB" is not enough for much. If it were, we would all be experts at everything. Ah, but I forgot: you are an (self-proclaimed) expert...  :-DD

I think I'm at the point now where I can follow a PCB trace.  :)

I also know that a genuine CAT rating includes all combinations of input jacks and switch positions and that Aneng fuses aren't 1000V rated.

You can actually see in that photo where it says 250V on both the fuse and the PCB:



2. What exactly do you claim is a lie?

See above^.

CAT II 1000V, CAT III 600V rated? Somebody's pants are on fire.

Is Uni-T/Intertek more reputable for $15? I'm not an expert but even I can see the lack of a surge-rated resistor.
« Last Edit: September 23, 2021, 02:16:39 pm by Fungus »
 

Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4078 on: September 23, 2021, 02:08:23 pm »
We are! 

https://www.harvardmagazine.com/2018/03/death-of-expertise-by-tom-nichols

There certainly are a frightening variety of mindsets out there and I'm often disturbed--but not longer surprised--by what 'normal' people are willing to believe at times.  However, I don't think any discussion of this issue is complete without the issue of experts losing their credibility due to them being wrong--overstating their knowledge, lying for various reasons and so on.  People may lack the basic education to even comprehend a subject that affects them--whether it is medical, electrical or financial--but if they become convinced, rightly or wrongly, that their experts have lied to them, what else do they have to go on?

 

A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4079 on: September 23, 2021, 02:26:34 pm »
Joe: If I'm reading it right this is a meter where the input goes directly from the volts jack to the IC with only R16 and R17 in between. The PTC is on a separate circuit (after going through the range switch!)

That appears correct and it's not uncommon.   

Running a meter like yours against my tests, the PTC would break down.  When that happens, they present a low impedance path to the low voltage clamp, which then opens up.  After this, the next device in the chain is the IC.   The only thing left to do after that is toss it. 

Yours may survive my ESD tests where the UT61E would not.   One difference between the UT61E and this meter is there's no high frequency compensation on the meter yours.     

An unhappy radio hobbyist.... excuse me... expert,  "reached out" to me about damaging the UT61E+.   I suspect the whole idea that the PTCs were capacitive at higher frequencies was totally lost on them.   Odd when you think their hobby is based on RF.   Then again, my wife uses her cell phone to also advance the art, with no understanding of how it works.  :-DD 

Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4080 on: September 23, 2021, 03:31:14 pm »
The fact that Intertek has certified the UNI-T UT125C is certainly relevant to the issue at hand. But the baseless or irrelevant dribble you posted certainly isn't.

Apart from your "anticipating being disappointed by the Intertek Shenzen (sic) branch", do you have anything to say based on facts relevant to the issue at hand?

Since you seem fascinated with English grammar and so forth, the typical word used in such a phrase is 'drivel' not 'dribble'.  I may in fact occasionally 'drivel', but I am neither so young or so old that I 'dribble' much.

Facts?  Multimeter input protection is not a new game and has been implemented, studied and improved for years.  The design, layout and components required to achieve certain levels of input protection are well known.  When lo-buck meter X arrives claiming a certain level of performance but obviously lacks components typically used in other similar products or uses components and designs that have been repeatedly shown to fail in other products, you are left to choose between believing either that Meter X company has ingeniously innovated by leveraging unique, newly differentiated synergies among select components to achieve unprecedented levels of excellence--or that they are full of shit.
Oh, and there's a pile of dead meters from Meter X companies previous attempts.

Quote
1. "one look at the PCB" is not enough for much. If it were, we would all be experts at everything. Ah, but I forgot: you are an (self-proclaimed) expert...

As long as there is a ruler or some method of determining scale in the picture--even a known SMD component will do--and you have a calibrated Mark VII eyeball, you can certainly spot creepage and clearance insufficiencies.  You can also follow circuit traces and get some idea of the input circuitry layout.  Admittedly, the UT125C appears to have more protection components and effort than I would have expected in a $16 device--at least they aren't so insulting as to have nothing at all and then claim that it has 'triode' protection (SMD transistor), as one other manufacturer did while back.  I'm still willing to bet $16 against it's survival.

I wish I had more facts.  I wish I had the complete standard used to look at to see what I might be missing.  I'm aware that I don't have the whole picture.  But that doesn't stop me or anyone from thinking about it.

Quote
perhaps refrain from the baseless claims and "anticipating being disappointed" sort of comments a little bit?

Sir, this is EEVBlog.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline Fungus

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Re: Handheld meter robustness testing
« Reply #4081 on: September 23, 2021, 03:34:38 pm »
Free meters!!!  It's been a while since anyone has "reached out" to me with such an offer. 

I'm torn. You could accept it and zap it.

Was it Dave or you that did a bad 'review' of something and the manufacturer put it on their web page anyway? I don't remember.  :-DD

(Bad meter! Bad!)

« Last Edit: September 23, 2021, 03:51:53 pm by Fungus »
 

Offline joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4082 on: September 23, 2021, 05:59:34 pm »
Quote
... you can certainly spot creepage and clearance insufficiencies.

Some of those last pictures looked tight.  They are all certified so I am sure they are fine to use in their rated environment.   


Free meters!!!  It's been a while since anyone has "reached out" to me with such an offer. 

I'm torn. You could accept it and zap it.

Was it Dave or you that did a bad 'review' of something and the manufacturer put it on their web page anyway? I don't remember.  :-DD

(Bad meter! Bad!)

It may have been one of Dave's.  My reviews are too boring to be use as an advertisement.   

HIOKI also "reached out" to me a while ago.   I use some of their equipment for industrial work.  I don't believe they are certified.  :scared:

Offline rsjsouza

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Re: Handheld meter robustness testing
« Reply #4083 on: September 25, 2021, 12:28:43 am »
Hioki and Sanwa are self-certified. Judging by the many decades on the market with good quality products (and still produce them), I think it is safe to say they are alright for the most part.
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

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...
 

Offline EEVblog

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Re: Handheld meter robustness testing
« Reply #4084 on: September 25, 2021, 04:20:39 am »
HIOKI also "reached out" to me a while ago.   I use some of their equipment for industrial work.  I don't believe they are certified.  :scared:

That's common for the Japanese meters, they do self certification to the standard.
[/quote]

I stand corrected.
I forgot that Sanwa do independent testing by SGS.
Not sure if that's for all meters, but if they go to the trouble for their pocket meter then I'd assume they do it for the bigger meters too.


« Last Edit: September 27, 2021, 12:49:41 am by EEVblog »
 

Offline joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4085 on: September 25, 2021, 08:21:53 am »
HIOKI also "reached out" to me a while ago.   I use some of their equipment for industrial work.  I don't believe they are certified.  :scared:

That's common for the Japanese meters, they do self certification to the standard.
But as opposed to the Chinse companies, the Japanese actually do do it and take it seriously.
And to be clear, you're suggesting that ALL of the Chinese do not? 

***
As long as we are making broad statements, I'm curious to know your opinion which is safer, a Chinese product certified by Intertek or a self certified Japanese product? 
« Last Edit: September 25, 2021, 03:58:28 pm by joeqsmith »
 

Offline floobydust

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Re: Handheld meter robustness testing
« Reply #4086 on: September 25, 2021, 08:08:17 pm »
HIOKI also "reached out" to me a while ago.   I use some of their equipment for industrial work.  I don't believe they are certified.  :scared:

That's common for the Japanese meters, they do self certification to the standard.
But as opposed to the Chinse companies, the Japanese actually do do it and take it seriously.

I'm not sure about that - I'd emailed Sanwa and Hioki asking for Certificate of Conformance or any proof about their multimeter 61010 claims.
One response was "Safety design in compliance with the IEC61010-1".  We all know "designed to" means only good intentions or "faith" an engineer has...

There are many ways to cheat and circumvent safety approvals, so I say real players can provide the cert or file number with an agency.
ANENG 61010 certificate is just for a 3V battery-powered device, no hazardous energy connected to it. chinese reports can be very hokey, skipping many tests.
Uni-T got real 61010 TUV for Germany but depopulated the MOV's for sales anywhere else. So I think they suck in terms of ethics and thankfully their meters are shit for robustness as they save $0.08 there.
 

Offline Fungus

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Re: Handheld meter robustness testing
« Reply #4087 on: September 26, 2021, 12:18:58 am »
That's common for the Japanese meters, they do self certification to the standard.
I'm not sure about that - I'd emailed Sanwa and Hioki asking for Certificate of Conformance or any proof about their multimeter 61010 claims.

The post you quoted literally says they don't do that, they only do internal conformance testing.

ANENG 61010 certificate is just for a 3V battery-powered device, no hazardous energy connected to it. chinese reports can be very hokey, skipping many tests.

Then you say you don't believe in certificates anyway.  :-//

PS: Yes, Aneng meters are 3V battery powered.

 

Offline floobydust

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Re: Handheld meter robustness testing
« Reply #4088 on: September 26, 2021, 01:09:07 am »
Claim your product complies with 61010, then back it up with the report and CofC. No need for secrecy.

If you have done independent 61010 compliance testing, it still can be by a hokey regulatory agency and misled into doing partial tests, i.e. as a 3V device. The "Cat. III 600V" claims are of course nothing but fake markings.

It's either no certificate, or a fudged certificate.

One product I delved into had electrical safety compliance done by Quality Assurance International (QAI). The largest organic food certifier. What could possibly go wrong lol.

"Internal conformance testing" just what is this exactly? The Honour System.
You can't self-declare compliance with safety standards, any more than Boeing lol.
Companies can't afford all the test equipment such as Transient generator, decoupling network, when it will be used just a handful of times a year. The calibration costs alone (50lbs shipping) are high. So it ends up cheaper to get UL/CSA etc. to do the tests in their labs.
CE-marking maybe worked long ago but china has exploited the fact nobody checks for compliance, and we allow fake or no safety approval products to enter the country.

Engineers can design to their heart's content and think it's all good- but testing is done to prove the PC board spacings are adequate, components etc. work and it stays reasonably safe.
 

Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4089 on: September 26, 2021, 06:05:37 am »
I guess when I posted that the 15€ UNI-T UT125C was certified by Intertek this sparked (hehe) a debate in this thread about the worth of independent certification.

Some here question the value of independent certification. The problem with this sentiment, if it becomes widespread, is that manufacturers of electronic test equipment will be tempted to entirely skip the certification process, since their marketing dept will just declare that it is a useless cost that is irrelevant to consumers and won't affect sales. In other words, this will discourage manufacturers from getting their products independently certified.

People here should realize that most consumers do not take apart their DMMs, etc when they get them to check the internals, they just use them as is. And almost all of us are totally incapable of judging the safety or robustness or standards compliance of a DMM, even when we have it taken apart in front of our eyes. And of course AFAIK only Joe has any real test equipment setup to actually test DMMs for their robustness. The rest of us are "armchair experts" i.e. total idiots, even if some believe otherwise.

Imo independent testing and certification is a valuable step in bringing a DMM or any piece of test equipment to market, and every DMM review should clearly state whether the device reviewed has been independently tested and certified or not, to what standards, and by which independent certification company. Whether this will actually encourage manufacturers to get their products certified is another question, but it would be a step, however small, in the right direction.

The blanket statement that independent certification is "worthless" is, imo, a step in the wrong direction. Also, any certificate can be "fudged", that applies to just about anything, from DMMs to diesel engines to jets. The question is whether it is worth it to "fudge" the certificate and risk being exposed. Personally I'll never buy another VW car or fly in a 737-MAX, but that's just me and it seems I am a rather rare case.

Just as a disclaimer, I am not connected to any independent certification company, my opinions are my own, etc.

Edit: Apparently some people here believe that the number of YouTube videos about a specific piece of test equipment is a better indicator of the safety standards compliance than an independent certification. This is actually quite a common phenomenon in modern marketing, where bloggers and vbloggers have become just another promotional tool - and the reason why Joe periodically gets called out by manufacturers to review their equipment, even though he makes clear that his channel was not created with that purpose.
 
« Last Edit: September 26, 2021, 05:37:33 pm by AndrewBCN »
 

Offline Fungus

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Re: Handheld meter robustness testing
« Reply #4090 on: September 26, 2021, 06:19:56 am »
Engineers can design to their heart's content and think it's all good- but testing is done to prove the PC board spacings are adequate, components etc. work and it stays reasonably safe.

You think Fluke engineers just design, cross their fingers, and send meters out to third party testers?

No, they have a room full of meter zapping equipment and test it themselves at every stage during development. Find the weak points and eliminate them. Third party testing only happens after the meter is fully production-ready.

Hioki just skips the last step.
 

Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4091 on: September 26, 2021, 06:27:51 am »
...
No, they have a room full of meter zapping equipment and test it themselves at every stage during development. Find the weak points and eliminate them. Third party testing only happens after the meter is fully production-ready.
Hioki just skips the last step.
You don't actually know that for sure, do you?  Unless you have worked with any DMM manufacturer development team at any point in your life, which I am certain you didn't...

 

Offline Fungus

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Re: Handheld meter robustness testing
« Reply #4092 on: September 26, 2021, 06:55:32 am »
...
No, they have a room full of meter zapping equipment and test it themselves at every stage during development. Find the weak points and eliminate them. Third party testing only happens after the meter is fully production-ready.
Hioki just skips the last step.
You don't actually know that for sure, do you?  Unless you have worked with any DMM manufacturer development team at any point in your life, which I am certain you didn't...

And you don't know for sure that they don't.

I choose to believe it because:
a) Hioki are reputable in the same way that Fluke/Brymen/Amprobe are reputable.
b) They don't sell meters for $25 on Aliexpress
c) I've seen Hioki Teardowns
d) Joe's zapped some Hiokis
e) Dave says Hioki do the internal testing

and finally...

f) Because it's not an unreasonable assertion. You seem to be demanding extraordinary evidence for something that doesn't really require it.

Yes, I know Joe has revealed some flaws in "serious" meters like Gossens but they weren't failures to meet basic CAT standards.
 

Online 2N3055

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Re: Handheld meter robustness testing
« Reply #4093 on: September 26, 2021, 07:51:31 am »

"Internal conformance testing" just what is this exactly? The Honour System.


"The Honor System." works if you have honor.

As it is now, I have much more trust in honor of a good Japanese company, than in USA safety certification agencies..

But that is just feelings.

Facts are, I know many companies that do internal testing, and do it well. Some products are hard to make compliant, and any precompliance must be done in full blown in house compliance lab during course of design. Once you have full lab, you might as well use it. They go independent party only if mandated. And since nobody wants liability and competition would  gladly crucify them, they do not only good job but make sure there is healthy reserve if possible...
Fluke does exactly that, and so do many others. OTOH, FLUKE does a lot of work with industries that have mandates for specific testing, so they go outside for those..

A good question would be: is there any verified information how many industrial accidents were caused by using UNI-T meters..?
A research, by numbers, how much more accidents happen by using UNI-T than Fluke?
I would like to see that information..

I still have UNI-T UT71C somewhere.  Worst part is that it worked very good as a electronics meter at desk, it was accurate up to specs for years, had very fast peak detect mode, and centered bar-graph mode, very accurate AC mV/V measurements with better than 100kHz bandwidth,  high Z mV DC mode, etc. etc..
It never got damaged. I didn't try to give it "Joe treatment" though, but in a controlled lab environment (with basic static control) it survived.
What was wrong with it was mechanically really cheap. Input jacks are some leftover pieces of sheet metal that look like someone bent them by hand, inserted into inner part of plastic socket. That makes it that thin plastic inner tube is holding all the inserted banana forces and they break in no time (and it wasn't fancy glass filled good plastic, but some cheap plastic). Meter was few months old when it started cracking. I had to find some thin brass tubes and remade those sockets, inserting tubes into plastic and fixing it with epoxy.  It was solid since.

It is like Joe said for UT181: it had all the potential to be great meter, they did many things right and then screwed up on   a bit of PCB layout, one resistor (mine is EU version with MOVs and big fuses), plating on a switch and better input sockets..
And for crying out loud, on UT181, use standard  Li-ion cells (like 18650 or whatnot), that can be replaced by user so you can also charge them outside..

 
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Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4094 on: September 26, 2021, 08:22:17 am »
...
A good question would be: is there any verified information how many industrial accidents were caused by using UNI-T meters..?
A research, by numbers, how much more accidents happen by using UNI-T than Fluke?
I would like to see that information..
...

In your dreams. Please be realistic, who would pay for such information to be researched and published, and in any case, how would you guarantee that the information wouldn't be "fudged"?

This is exactly why we have mandated safety standards and independent testing and certification companies. And it is also exactly why we, as consumers, should prefer products that are independently tested and certified vs. products that are not.

 

Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4095 on: September 26, 2021, 08:45:59 am »
...
I choose to believe it because:
a) Hioki are reputable in the same way that Fluke/Brymen/Amprobe are reputable.
b) They don't sell meters for $25 on Aliexpress
c) I've seen Hioki Teardowns
d) Joe's zapped some Hiokis
e) Dave says Hioki do the internal testing
...

 :-DD Thanks for a good laugh! c) above is absolutely priceless! d) and e) are good too.

From a), b), c), d) and e) I would assume that you don't own a Hioki DMM, and possibly have never laid your hands on one either. Note that neither do I, but I am not claiming anything about Hioki DMMs or the Hioki brand.
 

Offline AVGresponding

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Re: Handheld meter robustness testing
« Reply #4096 on: September 26, 2021, 09:03:33 am »
...
A good question would be: is there any verified information how many industrial accidents were caused by using UNI-T meters..?
A research, by numbers, how much more accidents happen by using UNI-T than Fluke?
I would like to see that information..
...

In your dreams. Please be realistic, who would pay for such information to be researched and published, and in any case, how would you guarantee that the information wouldn't be "fudged"?

This is exactly why we have mandated safety standards and independent testing and certification companies. And it is also exactly why we, as consumers, should prefer products that are independently tested and certified vs. products that are not.

Here in the UK the HSE collects such data, and the ONS will analyse it. I expect there are similar agencies in France and elsewhere around the world.

I'd be quite surprised to see anyone injured at work by using a Uni-T meter instead of a Fluke, as no serious electrician, electrical or electronics engineer that I have ever met would choose to use one in that setting.

I'm not a Uni-T hater either; I have a UT 139C and I like it. It's good at what it does. I would never use it at work, or for working with any high energy circuit at home, I have various Flukes, Agilents, Keithleys etc etc for that.

Information being "fudged" is exactly why independent testing isn't the panacea you seem to think it is. There are far too many examples of cheap meters with various test houses' marks on them that simply don't match up with those implied standards under closer scrutiny.
There may be several reasons for how and why this happens; one well known and well discussed route is to change the internal design post certification.

It doesn't get caught by national agencies responsible for checking these things because they just don't have the personnel or resources. Think about some of the plug-top usb chargers we've all seen videos of from the likes of Big Clive, utterly lethal in some not too improbable circumstances, and certainly the number of people thusly exposed will be higher than the number of hobbyists at risk from dodgy 61010 certs on cheap meters, and yet these things still make it into the hands and homes of consumers.
nuqDaq yuch Dapol?
Addiction count: Agilent-AVO-BlackStar-Brymen-Chauvin Arnoux-Fluke-GenRad-Hameg-HP-Keithley-IsoTech-Mastech-Megger-Metrix-Micronta-Racal-RFL-Siglent-Solartron-Tektronix-Thurlby-Time Electronics-TTi-UniT
 

Offline Fungus

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Re: Handheld meter robustness testing
« Reply #4097 on: September 26, 2021, 09:26:32 am »
:-DD Thanks for a good laugh! c) above is absolutely priceless!

Feel free to point out any safety issues:




« Last Edit: September 26, 2021, 09:31:22 am by Fungus »
 

Offline joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4098 on: September 26, 2021, 04:01:23 pm »
Feel free to point out any safety issues:
The batteries are a choking hazard and the supplied leads use probes that are very sharp.  They have fuses that can easily be jumped  out.  I also suspect they use materials known by the state of CA to cause cancer.   
 
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Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4099 on: September 26, 2021, 04:20:17 pm »
...
Feel free to point out any safety issues:
( links to two YouTube videos )

...
which is safer, a Chinese product certified by Intertek or a self certified Japanese product? 

Which is safer, a self-certified 200€ Japanese CAT IV 600V DMM that is the subject of two YouTube videos, or a 15€ Chinese CAT III 600V "YouTube-less" DMM certified by Intertek?

Which tastes better, a $20 orange with ten YouTube videos or a $1.50 apple with no YouTube videos?






 


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