Handheld meter robustness testing

[AndrewBCN]

[...
Referring to your recent comment:

The UT61E has been discontinued, so your entire argument is moot.

In France, does the word discontinued mean something is no longer available for purchase?   Or are you just trolling him? 

In France, discontinued means exactly the same as in any part of the US or the UK:
discontinued
adjective
(of a product) no longer available or produced.

In any case, why bring a discontinued product with various versions into the discussion, when my comment was about the UT61E+ and its Intertek-certified version the UT161E and the negligible price difference between these two?

[Fungus]

The UT61E has been discontinued, so your entire argument is moot.

Huh? I can buy one right now from the Uni-T store on AliExpress. 

https://www.aliexpress.com/item/33006341055.html

Oh, and just a note: as usual, you post pictures from others without attribution or mention of their origin. That picture of two different UT61E DMMs is by user Nisei and comes from this thread:

Huh? The link to Nisei's post is right underneath the picture I posted. 

(...where it says "Ref:")

Joe, you are assuming Fungus actually owns or has access to a Fluke 101.  He really is the perfect armchair expert on DMMs that he has never even seen in person, much less taken apart.

That's three for three. Maybe you should take a break from posting. 

[bdunham7]

I am not sure what your point is exactly. UNI-T is certainly not the only manufacturer that changes the PCB of a product during its lifecycle, or that populates the PCB with different components from one production batch to another.
 referring to 3~4 years old pictures of a different, discontinued model seems to me a bit irrelevant and a distraction.

Your dismissive hand-waving is a worthy performance.  UNI-T should retain you.  But here is what I think happened:

1) At some point UNI-T, for whatever reason, had to actually produce a compliant meter and the TUV wasn't going to stand for any bullshit, so they added a whole pile of protection to the front end, upgraded the fuses and most importantly, reduced the claimed CAT ratings to CAT III/300 and CAT II/600--mind you those aren't unreasonable for an 'at-home' meter. 

2) Subsequently, UNI-T also released a version lacking a good portion of that protection and without certification, but printed higher CAT III/1000V and CAT IV/600v 'ratings' on the front.  They did label the fused current circuits as 250V, but whether that is allowed or not might be one of those things that jqs was referring to when he said different companies interpret the standards differently.  I think it defeats one of the major points of having CAT ratings in the first place.

What the current 'certified' version has in it's guts, I don't know.  Given the labelling on the front, it's pretty clear they didn't put 1000V fuses in it.  Perhaps they persuaded Intertek in China to adopt their interpretation of the CAT ratings standard.  But it is pretty clear that they are using different approaches depending on who is watching.  And that raises two disturbing non-technical conclusions, which are 1) UNI-T is untrustworthy, and 2) CAT ratings, even when 'certified', may not mean the same thing when comparing between manufacturers. 

So as a point of comparison, take the modest Fluke 115/116/117 series, which just have a CAT III/600V rating and no CAT IV.  They have 1000V fuses (except the 116 which has no fuse) and can withstand 600V (not just a transient) on any range or input combination without damage--and probably a lot more.  You'll also see that the 115 went all the way to the 12kV jqs^TM test without failing.  That is in line with my expectations of a CAT-rated device--and is what some companies deliver when they print a CAT-rating on their meter.

If the standards can legitimately be interpreted to allow what you get with the UT61E, certified or not, then those standards themselves are not useful to me as a point of comparison.  Here are the front sides of the UT-61E-GS and the 'regular' UT-61E.

[joeqsmith]

[...
Referring to your recent comment:

The UT61E has been discontinued, so your entire argument is moot.

In France, does the word discontinued mean something is no longer available for purchase?   Or are you just trolling him? 

In France, discontinued means exactly the same as in any part of the US or the UK:
discontinued
adjective
(of a product) no longer available or produced.

In any case, why bring a discontinued product with various versions into the discussion, when my comment was about the UT61E+ and its Intertek-certified version the UT161E and the negligible price difference between these two?

While the manufacturer may have discontinued the product,  it's certainly still available for purchase.  People can still choose it over other products.     

I often ask why people continue to discuss safety in a thread that has nothing to do with it. 

[Fungus]

In any case, why bring a discontinued product with various versions into the discussion, when my comment was about the UT61E+ and its Intertek-certified version the UT161E and the negligible price difference between these two?

The discussion wasn't about availability of the UT61E, it was about the value of an Intertek certificate.

[joeqsmith]

A) You removed the PTC and found the 101 could no longer read AC and/or DC voltages?
B)  You removed the PTC and found the 101 could still read AC and/or DC voltages but you don't want me to eat too much crow?
C) You want to continue to believe your original statements and are concerned they are wrong?  (burying your head in the sand rather than confronting it)
D) You lack the soldering skills to lift one pin or the 101 costs too much and you are concerned about damaging it?
E) You're too lazy and can't be bothered to test your theory?
F) I've burned myself too many times trying to solder and am scared to pick that thing up!!

Burning yourself with a soldering iron is nothing to be ashamed of.    

[bdunham7]

I found another meter that has a separate path for voltage that doesn't go via the surge resistor/PTC.
See, I'm not crazy! 

Crazy, no, but you may have jumped to a conclusion a bit early.

Have a look at the input diagram that I posted in response to Dave, then note that the 7 resistors you are referring to are 143K, so they add up to 1M.  Without tracing it out or finding a schematic I can't be 100% sure of the configuration, but the 87V/AN schematic I posted is fairly typical for contemporary Fluke designs.  As for others, it will be driven by the requirements of the chipset that they use.

[Fungus]

Have a look at the input diagram that I posted in response to Dave, then note that the 7 resistors you are referring to are 143K, so they add up to 1M.  Without tracing it out or finding a schematic I can't be 100% sure of the configuration, but the 87V/AN schematic I posted is fairly typical for contemporary Fluke designs.  As for others, it will be driven by the requirements of the chipset that they use.

Maybe that path is something to do with the IEC61010 requirement for the meter to still show hazardous voltages even if it's damaged. It could go directly to a comparator and show an indicator on screen or something like that. It would work in all ranges with no CPU required.

[Fungus]

A) You removed the PTC and found the 101 could no longer read AC and/or DC voltages?
B)  You removed the PTC and found the 101 could still read AC and/or DC voltages but you don't want me to eat too much crow?
C) You want to continue to believe your original statements and are concerned they are wrong?  (burying your head in the sand rather than confronting it)
D) You lack the soldering skills to lift one pin or the 101 costs too much and you are concerned about damaging it?
E) You're too lazy and can't be bothered to test your theory?
F) I've burned myself too many times trying to solder and am scared to pick that thing up!!

Burning yourself with a soldering iron is nothing to be ashamed of.   

G) You're in gloat mode and sound fairly sure of yourself so I'm guessing I'm wrong.

I don't mind being wrong, it's an excellent way to learn. I wish I could be wrong more often.

Right now I'm trying to think what it would be for if it's not for voltage measurement.

Crazy, no, but you may have jumped to a conclusion a bit early.

Have a look at the input diagram that I posted in response to Dave, then note that the 7 resistors you are referring to are 143K, so they add up to 1M.

OK, I wasn't paying attention here but I've got other meters with a resistor chain like that and they add up to 10M. I've measured it.

That's why I'm confused - there may still be meters that measure voltage that way even if the 101 doesn't.

[bdunham7]

Maybe that path is something to do with the IEC61010 requirement for the meter to still show hazardous voltages even if it's damaged. It could go directly to a comparator and show an indicator on screen or something like that. It would work in all ranges with no CPU required.

I don't think so.  I think the best way to comply with that requirement is to not let the meter become damaged!  These sections seem to be for ohms/capacitance/maybe other stuff.  If you look at meter designs, it is possible to construct an ohms source that is simply impervious to external voltage up to 1kV+ using just a diode and three transistors.  Then you use the normal high-impedance voltage circuit to measure.  However, if you want a meter that does capacitance, etcyou need to do things differently and these modern designs seem to rely on this 1M leg plus PTC protection of the other circuit.  I'm not saying they're all the same, just that the ones I have seen sort of all look like this.  I think if you pull one of those resistors, you'll see that the voltage ranges still work but OHM/CAP/DIODE will not.  If you pull the PTC, you likely won't get any voltage indication.

Right now I'm trying to think what it would be for if it's not for voltage measurement.

OK, I wasn't paying attention here but I've got other meters with a resistor chain like that and they add up to 10M. I've measured it.

Well, it is for voltage measurement, just not in the voltage ranges.

Other designs may work differently.  Were the ones with 10M in that spot Fluke or som'n else?

[floobydust]

[...] UNI-T is certainly not the only manufacturer that changes the PCB of a product during its lifecycle, or that populates the PCB with different components from one production batch to another.

UT61E there are least 15 PC board revisions! Did you end up with the kindergarten or junior-high version? Earlier ones were extra junky and ended up in landfill.
It's a bit ridiculous and I don't get a sense they know what they are doing. Seem to sell prototype builds off with fake regulatory claims and as they learn, for years.
And it's over $0.25 worth of parts savings for the boss's new Lambo 
The two schematics one has MOV's, they don't use Rev. #'s and SG4 (4th MOV)  at the current-shunts, appears useless.

Rev. 13(GS) has 4 MOV's, 3 PTC's, 600V fuses, rating Cat. III 300V, Cat. II 600V
Rev. 12  has 4 MOV's, 3 PTC's, 600V fuses, rating Cat. III 300V, Cat. II 600V
Rev. 9C  no MOV's, 3 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V;  SOT89 clamps
Rev. 9A  no MOV's, 2 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V
Rev. 8    no MOV's, 2 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V; SOT23 clamps

UT61E+
Rev. 3 has 3 MOV's, 4 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V
Rev. 2 looks the same, blue pcb

[AndrewBCN]

While the manufacturer may have discontinued the product,  it's certainly still available for purchase.  People can still choose it over other products.     

I never wrote that it was not available for purchase, I wrote that it was discontinued.

Clearly UNI-T have discontinued the UT61E (all variants): it states as much on their website. And I guess just like any discontinued product, it will still be available at various resellers "while stocks last".

In any case, it is completely irrelevant to what I posted, which was about the UT61E+ which you are testing these days, and the externally identical but Intertek-certified UT161E, which costs 2~3€ more.

Fungus made it a point to show a 4-year old picture of two different variants of the old UT61E and pointed the obvious: that they had different components. How is that relevant to the UT61E+ and its Intertek-certified version the UT161E? 

[bdunham7]

How is that relevant to the UT61E+ and its Intertek-certified version the UT161E?

OK, I see that the meter you referred to as 'externally identical' is actually the UT161E, which appears to me to be an entirely different meter.  So my fault for misreading and yours for saying they look the same or that the 161E is somehow a 'version' of the 61E.  It is, in fact labelled CAT III/1000V and CAT IV/600V with fuses listed as 1000V, which I'll presume reflects what is inside.  So we probably won't be able to proclaim noncompliance just by looking at it, or at least not as easily.  This appears to also be a more expensive meter, as you'd expect, but it is indeed available on Aliexpress for $73 shipped.  So if you like bargains, order one up and take it apart to show us its guts!

Edit: Never mind all that!  I see which meters are being referred to now...

[floobydust]

Uni-T is doing the PCB copy'n'paste between UT61E+ and UT161E. I see the larger fuses and PTC's, PTC's moved slightly but nothing significant.
Looks like they want to charge a premium for a real 61010 product. I'll bet the BBQ lighter still makes it crash lol.

[joeqsmith]

G) You're in gloat mode and sound fairly sure of yourself so I'm guessing I'm wrong.

I don't mind being wrong, it's an excellent way to learn. I wish I could be wrong more often.

I suggest taking the opportunity to try it for your self.  If it doesn't work as your first suggested, trace out the front end.  Learn where you made the mistake. 

Right now I'm trying to think what it would be for if it's not for voltage measurement.

It's easy enough to break the other circuit and see what the effects are.   

[joeqsmith]

While the manufacturer may have discontinued the product,  it's certainly still available for purchase.  People can still choose it over other products.     

I never wrote that it was not available for purchase, I wrote that it was discontinued.

I never suggested otherwise.

[joeqsmith]

Uni-T is doing the PCB copy'n'paste between UT61E+ and UT161E. I see the larger fuses and PTC's, PTC's moved slightly but nothing significant.
Looks like they want to charge a premium for a real 61010 product. I'll bet the BBQ lighter still makes it crash lol.

Maybe the BBQ lighter would damage them both.  Depending how the 61E+ holds up, I may have another look. 

[EEVblog]

[...] UNI-T is certainly not the only manufacturer that changes the PCB of a product during its lifecycle, or that populates the PCB with different components from one production batch to another.

UT61E there are least 15 PC board revisions! Did you end up with the kindergarten or junior-high version? Earlier ones were extra junky and ended up in landfill.
It's a bit ridiculous and I don't get a sense they know what they are doing. Seem to sell prototype builds off with fake regulatory claims and as they learn, for years.
And it's over $0.25 worth of parts savings for the boss's new Lambo 
The two schematics one has MOV's, they don't use Rev. #'s and SG4 (4th MOV)  at the current-shunts, appears useless.

Rev. 13(GS) has 4 MOV's, 3 PTC's, 600V fuses, rating Cat. III 300V, Cat. II 600V
Rev. 12  has 4 MOV's, 3 PTC's, 600V fuses, rating Cat. III 300V, Cat. II 600V
Rev. 9C  no MOV's, 3 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V;  SOT89 clamps
Rev. 9A  no MOV's, 2 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V
Rev. 8    no MOV's, 2 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V; SOT23 clamps

UT61E+
Rev. 3 has 3 MOV's, 4 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V
Rev. 2 looks the same, blue pcb

Where did you get the Uni-T schematics from?

[EEVblog]

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".

[bdunham7]

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

My reply #4203 has them.  The meter is still labelled UT61E, but has the "GS" mark and has different CAT ratings.

[gnavigator1007]

Fungus post #4172 has a pic of the meter opened up too

[bdunham7]

I often ask why people continue to discuss safety in a thread that has nothing to do with it.

One would need to reread the entire thread to see how that seeped in, but I suspect the similarities of your test transient levels to the ones specified for the CAT ratings are one factor.

Anyhow, by now I agree with you, if you are referring to safety as meters exploding or arc-flash type concerns.  My concerns are similar to what you have said about wanting meters to not die during normal, non-dangerous bench or other use.  Transients are one way to kill them of course, but accidental overvoltage is another.  I had one set of expectations about what a CAT-rating would mean about this, specifically that a meter with a CAT rating for any voltage--like a bench meter rated CAT I/1000V--would endure 1000VAC or 1000VDC on any range or input selection without damage.  There's also the expectation that after the transient tests, the meter works.  If those expectations on my part are wrong and the CAT ratings don't indicate performance in that regard across the board, or if different manufacturers have different standards regarding these issues, then the CAT ratings themselves are meaningless to me and of questionable value to anyone else, IMO. 

If anyone wants to comment on my assertion that a CAT x/1000V meter should withstand a full 1000V on any input setting or jack, I can see about setting up a test.

[EEVblog]

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

My reply #4203 has them.  The meter is still labelled UT61E, but has the "GS" mark and has different CAT ratings.

That's my point. The model number is exactly the same, yet the meter differs greatly in it's safety specs and ratings.
Why would anyone trust a company that sells the exact same model number meter in different markets with different safety/protection components?
At the very least give it another model number.

[bdunham7]

That's my point. The model number is exactly the same, yet the meter differs greatly in it's safety specs.

Yes, I suppose that's true if the '-GS' is just an internal designation and the model that it was marketed as is just UT61E.  So under the jurisdiction of the TUV, they sold one 'UT61E' with protection and lowered CAT ratings, elsewhere they depopulated the protection and increased the purported CAT ratings.  I think other companies in other areas may do similar things between markets, but CAT ratings are a globally harmonized standard (or so I thought) so it does seem quite slippery of them.

[gnavigator1007]

The Uni T equivalent of the Fluke Ex series meters