Author Topic: Did something really stupid; is my DMM a goner?  (Read 1843 times)

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Offline SilverSolder

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Re: Did something really stupid; is my DMM a goner?
« Reply #25 on: April 20, 2021, 02:09:16 pm »
 

Offline aqibi2000

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Re: Did something really stupid; is my DMM a goner?
« Reply #26 on: April 20, 2021, 02:20:26 pm »
List it on eBay as “untested”  :horse:
Tinkerer’
 

Offline cigmas

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Re: Did something really stupid; is my DMM a goner?
« Reply #27 on: April 22, 2021, 12:24:04 am »
The Thsinde is a good meter, provided you respect its limitations, which unfortunately you found in a not-so-ideal way. If you like it, by all means get another one.

Safer meters in more or less the price bracket of up to US$50 may come in the shape of a Klein MM400 or a Fluke 101. But they are less featured.
Thanks for the suggestions. I looked up the Klein MM400 (  https://data.kleintools.com/sites/all/product_assets/documents/instructions/klein/MM400_1390110ART_WEB.pdf) and it seems nice, but most of the range and accuracy specifications are less than the Thsinde, cost is about double, and it doesn't mention added input protection or safety. The capacitance max range of 200 uF is a bit of a bummer, as I've needed to measure 12 mF capacitors before which worked with the Thsinde's max 6000 uF range.

How useful is the NCV feature on multimeters? In particular, I foresee needing to drill into a wall and wondered if this would help avoid areas with wiring. That's mainly the reason I also looked at the HT118A https://www.manualslib.com/manual/1860345/Kaiweets-Ht118a.html?page=23#manual The measurement specifications are pretty similar to the Thsinde. I just wonder if its rather extensive feature set and appearance makes it more gimmicky, or if it adds decent value.

Unfortunately, $35 is in the "disposable" category of gadgets. At that price point you have to treat it as fragile and be really careful what you do with it.

Speak of the devil. Here's the only other DMM around here, taken out in its prime by a battery leak. Jealous of those abominable "leads"?  ;) The tips came off long ago, but not before having a chance to enjoy intermittent connections.



Can it work again? Maybe, sort of. Or not really..



It's dead, Jim.

Those bug zapper things produce quite substantial voltage, >1kV is typical. Always be aware of what you are trying to measure, even a good quality multimeter can be damaged by trying to probe something well beyond what it is rated to tolerate.
In hindsight it was such a stupid user error, but I still don't know what the voltage is on the zapper. Here's a video of its rather large and loud spark, which is even more so in person, just for fun: https://i.imgur.com/MvIFIot.mp4
 

Online IanB

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Re: Did something really stupid; is my DMM a goner?
« Reply #28 on: April 22, 2021, 12:48:16 am »
In hindsight it was such a stupid user error, but I still don't know what the voltage is on the zapper. Here's a video of its rather large and loud spark, which is even more so in person, just for fun:

Cool  :)  But the size of the bang does not tell you much about the voltage. I made enormous bangs as a child by shorting out an 18,000 µF capacitor charged up to only 12 V. And an accidental discharge of a 300 V photoflash capacitor nearly made me jump out of my seat.
I'm not an EE--what am I doing here?
 

Offline SilverSolder

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Re: Did something really stupid; is my DMM a goner?
« Reply #29 on: April 22, 2021, 12:49:00 am »
To measure such a high voltage, you need to divide it down by putting a whole bunch of resistors in series,  measure what happens on the last one, and multiply the number back up, if you see what I mean.

You need to use enough resistors that the spark can't just jump over all of them and blow the meter again!  :D
 

Offline cigmas

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Re: Did something really stupid; is my DMM a goner?
« Reply #30 on: April 22, 2021, 02:01:32 am »
Cool  :)  But the size of the bang does not tell you much about the voltage. I made enormous bangs as a child by shorting out an 18,000 µF capacitor charged up to only 12 V. And an accidental discharge of a 300 V photoflash capacitor nearly made me jump out of my seat.

True. I've shocked myself with ~18 kV by absentmindedly putting my thumb over the shielding and center pin of a BNC cable. :-[ That made no spark, but left my forearm tingly for a good 20 minutes. I wish I could say it happened only once...

As for capacitors, a lab tech once showed me a discharge of a nearly coke-can-sized capacitor whose capacity I don't remember. It was a frightful sound, and apparently could be quite dangerous.

To measure such a high voltage, you need to divide it down by putting a whole bunch of resistors in series,  measure what happens on the last one, and multiply the number back up, if you see what I mean.

You need to use enough resistors that the spark can't just jump over all of them and blow the meter again!  :D
Makes perfect sense, but I don't feel like risking it! haha
 

Offline rsjsouza

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Re: Did something really stupid; is my DMM a goner?
« Reply #31 on: April 22, 2021, 03:22:42 pm »
The Thsinde is a good meter, provided you respect its limitations, which unfortunately you found in a not-so-ideal way. If you like it, by all means get another one.

Safer meters in more or less the price bracket of up to US$50 may come in the shape of a Klein MM400 or a Fluke 101. But they are less featured.
Thanks for the suggestions. I looked up the Klein MM400
Yes, that is exactly what you are trading off: features and specs for safety. Klein is a brand used by people on the field and has great accountability with regards to safety - in other words, if it is shown their products claim safety but do not deliver, they will be sued pretty harshly. A completely different scenario when compared to a low cost Chinese brand.

Higher up in price and features are the Klein MM600 and MM700 with a bit higher capacitance and other features, but they will set you back somewhere closer to US$100, which takes them pretty close to EEVBlog's BM235 and Brymen's BM257.

Amprobe and Greenlee also have some interesting models as well (AM-560, DM210A), but the equation is the same: features versus safety.

Overall, you need to keep in mind that, when measuring higher voltages and spikes, any destructive accident can happen even if the meter or the voltage divider are sized for the voltage - inductive loads can cause several kV spikes.

How useful is the NCV feature on multimeters? In particular, I foresee needing to drill into a wall and wondered if this would help avoid areas with wiring. That's mainly the reason I also looked at the HT118A https://www.manualslib.com/manual/1860345/Kaiweets-Ht118a.html?page=23#manual The measurement specifications are pretty similar to the Thsinde. I just wonder if its rather extensive feature set and appearance makes it more gimmicky, or if it adds decent value.
The NCV is a useful feature but it is highly dependent on the use case. For example, the only meters I have used to "look through walls" are the U1282A and the Amprobe AM530, which can set their sensitivity. Others such as the Bside ZT-Y (Aneng SZ-18), the Richmeters 113D, the Richmeters RM219 (Aneng AN870) are less sensitive and can "see through" thin walls.

Also, keep in mind that some meters are designed for the Chinese market and can reliably detect only 240V, not the regular 120V here in North America.
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 rsjsouza

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Re: Did something really stupid; is my DMM a goner?
« Reply #32 on: April 22, 2021, 03:31:52 pm »
List it on eBay as “untested”  :horse:

Or: "Pulled from a working environment..."

(the environment was working, not the meter)  :-DD
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...
 
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Offline cigmas

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Re: Did something really stupid; is my DMM a goner?
« Reply #33 on: April 24, 2021, 12:38:17 am »
@rsjsouza Really appreciate the mention of so many models and how they compare. When you say safety do you mean the CAT II/II/IV ratings? Since I don't foresee use in high energy applications, I'm less concerned about those for now. I don't see any mentions of input protection of the type which could have prevented my DMMs untimely demise.

Maybe the best teardown review of the HT118A I've seen so far, by Kerry Wong: TL;DR: Seems good as far as cheap meters go, but nothing to write home about, and no input protection to speak of. Biggest downsides IMO are the omissions of the REL button and the big HRC fuse for the 10A jack when compared to the Thsinde.

Also from his general review, the NCV appears sensitive but it's doubtful if it would work through drywall distances: https://youtu.be/CxoAun4GRl8?t=771

Maybe it's worth trying out.
 

Offline rsjsouza

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Re: Did something really stupid; is my DMM a goner?
« Reply #34 on: April 24, 2021, 03:48:11 am »
@rsjsouza Really appreciate the mention of so many models and how they compare. When you say safety do you mean the CAT II/II/IV ratings? Since I don't foresee use in high energy applications, I'm less concerned about those for now. I don't see any mentions of input protection of the type which could have prevented my DMMs untimely demise.
Safety is usually tied to the CAT ratings; the meters that were tested for these ratings are usually sized to withstand voltage transients higher than their nominal rating while maintaining their integrity without harm to the operator. The fine print is that the meter does not need to survive - in other words, these ratings don't evaluate robustness but safety.

What does that tell you? Simple: if you still poke your meter -any meter- to a voltage source higher than its nominal rating (that is what bug zappers do), any outcome is fair game, as long as the meter does not explode in your hands (a bug zapper wouldn't have such energy).

With this in mind, the answer is: don't zap your meter. If you do, the chances (but not guarantees) of a properly rated meter to survive are much higher due to the better design and quality of its components.

As a side note, our regular meter zapper "joeqsmith" has an excellent channel and a very long thread in this forum about meter robustness. But even still, his tests are very controlled and limited to a short burst lasting only a cycle or two applied to a meter input - a zapper continuously generate these pilses and therefore with an increased chance of actually destroying something.

Maybe the best teardown review of the HT118A
(...)
TL;DR: Seems good as far as cheap meters go, but nothing to write home about, and no input protection to speak of. Biggest downsides IMO are the omissions of the REL button and the big HRC fuse for the 10A jack when compared to the Thsinde.
The Rel is a useful feature but, for your use in the lab, the HRC fuses are 100% optional. Worse, they cost more... Much more.

Again this is related to the safety: in case you are working on a circuit capable of delivering ten thousand Ampères, the HRC fuses are absolutely mandatory, as they are rated to quench the arc flash generated at those levels. In a lab or even around the outlets of the house you would be hard pressed to find such power - unless you do experiments à la Photoinduction.

Overall: get the Thsinde as it seems to work well for you and you like it. Just don't poke it on these zappers :)

Good luck in your quest!
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 cigmas

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Re: Did something really stupid; is my DMM a goner?
« Reply #35 on: April 24, 2021, 07:51:45 pm »
It makes sense that safety is priority, but it does seem strange to me to use that rating as an implicit correlatation to input protection instead of more concrete specifications of the limitations. Maybe it is difficult to guarantee.

Overall: get the Thsinde as it seems to work well for you and you like it. Just don't poke it on these zappers :)

Lesson learned. :) I'm curious, what is your reason to suggest the Thsinde over the HT118A?
 

Offline rsjsouza

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Re: Did something really stupid; is my DMM a goner?
« Reply #36 on: April 25, 2021, 01:13:12 am »
It makes sense that safety is priority, but it does seem strange to me to use that rating as an implicit correlatation to input protection instead of more concrete specifications of the limitations. Maybe it is difficult to guarantee.
You have a point but, whenever a specification is made in an industry consortium, many manufacturers chime in with their inputs. In this case, I suspect that someone like Fluke and their very generous price point would simply go over spec and keep their meters robust enough to withstand mistakes. Other companies could do "just enough" to cater to lower price points. The justification? You can't fully protect against stupidity. :-DD

Overall: get the Thsinde as it seems to work well for you and you like it. Just don't poke it on these zappers :)

Lesson learned. :) I'm curious, what is your reason to suggest the Thsinde over the HT118A?
Well, nothing in particular apart from the fact you really expressed your satisfaction with it in previous posts.

In my own opinion, the HT118A lacks the REL button. Also, IIRC its bargraph is not well implemented (too slow).

(Edit) part of a sentence disappeared
« Last Edit: April 25, 2021, 01:44:22 am by rsjsouza »
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 cigmas

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Re: Did something really stupid; is my DMM a goner?
« Reply #37 on: April 27, 2021, 03:47:22 am »
I see, thanks! I might just flip a coin to choose.. :-DMM

PS. Found this extensive filterable list of reviews and disassembled pictures of many DMMs: https://lygte-info.dk/info/DMMReviews.html
« Last Edit: April 27, 2021, 05:32:16 pm by cigmas »
 


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