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 robustness testing  (Read 636951 times)

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Online joeqsmith

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Good info Pedro.   It's just a guess that it was re-branded. 

I was a bit surprised by the amount of sparks that came out of it.  I did not mention it during the video but I did check the leads after the last test and they were fine.  Held up better than the HF meter's leads.   

It would be good to know if the meter had a problem.  The continuity test threshold being so high and that the diode check did not work, I suspect there was a problem with the source.  The original owner told me he used used it for a volt meter only, so I doubt very much that these features are something that was ever used.   May have been bad from the factory.

The spreadsheet has been updated to include this meter.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline tautech

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Joe, after downloading your spreadsheet, it is not clear just what each of the cell pass/fails represent.  :-//
Does it need a tweak or must we refer to your vids to understand what each test is?

Members often ask of DMM recommendations, must they watch all your vids?
Maybe a short further vid in the OP to just explain your methodology and spreadsheet results.

Can I also say it seems obvious (at least to me) that the thread title has many overlook the excellent work you have done, but maybe not so with the addition of DMM in the title.  :-\

Tell me to F off if you must, it is YOUR thread.  ;)
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Online Fungus

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Joe, after downloading your spreadsheet, it is not clear just what each of the cell pass/fails represent.  :-//

"Fail" = Magic smoke escaped at the specified voltage.

Members often ask of DMM recommendations, must they watch all your vids?

You could try watching one of them...  :-//

PS: They're not 'recommendations'. It only measures one tiny aspect of a multimeter (resistance to sparks).
« Last Edit: December 21, 2015, 07:36:34 am by Fungus »
 

Offline tautech

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Joe, after downloading your spreadsheet, it is not clear just what each of the cell pass/fails represent.  :-//

"Fail" = Magic smoke escaped at the specified voltage.

Members often ask of DMM recommendations, must they watch all your vids?

You could try watching one of them...  :-//

PS: They're not 'recommendations'. It only measures one tiny aspect of a multimeter (resistance to sparks).
|O  :palm:
When I opened the spreadsheet FIRST time the Column titles DID NOT appear, hence the reason for my post.
All good now.  :-+

I've watched them ALL.
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Online Fungus

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|O  :palm:
When I opened the spreadsheet FIRST time the Column titles DID NOT appear, hence the reason for my post.
All good now.  :-+

 :-DD
 

Online joeqsmith

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 :-DD   Glad you figured it out. 

I will be the first to admit there may be a better way to present the data in the spreadsheet.    If anyone has a way to format it that they feel would make things more clear to the reader, feel free to post it.   I am not at all apposed to changing it.

I had though about moving the original round I tests to it's own page so the main page just has the format that I plan to use moving forward.

Can I also say it seems obvious (at least to me) that the thread title has many overlook the excellent work you have done, but maybe not so with the addition of DMM in the title.  :-\
This has came up from time to time but no one has offered what they feel is a better suited title. 


PS: They're not 'recommendations'. It only measures one tiny aspect of a multimeter (resistance to sparks).

One?

1) Continuity, short detection resistance
2) Continuity, open detection resistance
3) Continuity, short circuit current
4) Continuity, open circuit voltage
5) Continuity, max frequency using a 50% duty cycle before meter misses beats
6) Continuity, min pulse width the meter can detect
7) ESD, 5 +/- transients in each mode using a piezo grill ignitor
8) DC withstand voltage, meter is supplied its maximum specified DC voltage, sometimes higher  :-DD
9) 220 VAC line, meter is supplied with a full wave rectified 220V signal with the mode switch being rotated
10) Low voltage low energy surge test, up to 5KV 100us FWHH 2 ohm source, limited to less than 20J
11) High voltage low energy surge test, up to 12KV 50us FWHH 2 ohm source, limited to less than 20J

If I stay with the current format, there are other tests going on as well like basic accuracy, comparing them with other meters in their class or price range.   I showed the NCV feature of the UT139C for example.   If I continue to test meters, I am sure the test methods will improve along with the tests performed.     

And if that is not enough, now we get to see what can happen when some of these crappy meters breakdown with a higher energy source attached.  It does not answer the question if a meter is safe or not but for the people who post that the meters were not shown to be unsafe during the tests at sub 20 joules, it does give viewers some indication of what a small amount of energy could do to a meter.   

Just an FYI, testing one meter like the 115 where it survives takes about 10 hours not including the editing time.   :palm:   The Greenlee still took about 8 hours from start to finish. 

There are many tests others have done that really do not interest me.  Two tests I would like to run are DC temperature drift and RF susceptibility.  Both way outside of what I could do at home.   

This may help you with your counting skills


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

Offline tautech

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Joe, I thought just the addition of "DMM" would enable more hits from a forum search:

Hear kitty kitty kitty, nope not that kind of cat. CAT III handheld DMM surge tests.

Anyway, I'll butt out now, please carry on with what history will show as magnificent work.  :-+
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Online joeqsmith

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Joe, I thought just the addition of "DMM" would enable more hits from a forum search:

Hear kitty kitty kitty, nope not that kind of cat. CAT III handheld DMM surge tests.

Anyway, I'll butt out now, please carry on with what history will show as magnificent work.  :-+

 :-+

One member mentioned they could not read the entire title due to screen wraps.  I think I made it even longer when I added the DMM part.   We call that being customer led.  :-DD

A few people have asked about why it's not sticky and the fact that it is not I believe is the answer to how it is perceived.

Consider that even if the meters were being supplied to me for free (which thanks to 5ky / TechnologyCatalyst many were), they can not be resold after they are tested and have no value.  I would not even risk giving the working ones away after they have been stressed. 

So believe me, this has never been about making a profit!  :-DD   Even if I turned on the youtube ads, maybe I could buy a new Harbor Freight free meter?  :-DD   Its more been interesting for me to see just how wide of a spectrum there is in the robustness of the meters, even within the same brand.   

So don't look for it to go down in the history books unless you're looking on the basement floor in a back corner somewhere.  :-DD 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online joeqsmith

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After six years of use, my Mastech MS9508 / Cen-tech P37772 LCD was starting to become intermittent. 

Notice that the LCD is starting to pop out.  The On and Hold buttons are letting some photons escape.  Sparks are coming from the transistor test socket.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline tautech

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After six years of use, my Mastech MS9508 / Cen-tech P37772 LCD was starting to become intermittent. 

Notice that the LCD is starting to pop out.  The On and Hold buttons are letting some photons escape.  Sparks are coming from the transistor test socket.
:-DD
No holidays for you and your surge tester.  >:D
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Online joeqsmith

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:-DD
No holidays for you and your surge tester.  >:D

Consider the video a gift.

It's amazing just how complicated this meter is.  I got a lot of use out of this meter over the last six years and if the display wasn't becoming intermittent again,  I would have kept using it.   

It's a manual range meter and would take a fair amount of time to run a full test, so instead I just did a quick teardown, functional and hit it with the half cycle line simulator.   

What meter to fun first in 2016?   Would like to see that Keysight GDT protection in action

https://www.youtube.com/watch?v=NKgK8qbuREk&feature=youtu.be
« Last Edit: December 27, 2015, 03:58:47 am by joeqsmith »
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline rsjsouza

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joe, thanks for sharing - great christmas gift. One small detail that may increase your audience: on the video title, change the model of the meter from MS9508 to M9508.
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 Stupid Beard

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What meter to fun first in 2016?   Would like to see that Keysight GDT protection in action

Maybe not the first meter, but it'd be nice to see a BM257 run at some point. You've run a lot of lower end Flukes and compared them to your BM869 as a comparison to Brymen meters, but it seems to me that a BM257 or similar would be a fairer comparison in terms of price range / size / etc.

Thanks for the videos. I've been watching them from the beginning and it will be interesting to see what survives in 2016.
 

Offline Lightages

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I just was thinking that instead of blowiing up a bunch of more meters, why not run a video on the protection devices that can be found inside. Run a PTC or two, some MOVs, gas discharge tubes, etc. This would give easy subjects to video, and some fun fireworks perhaps. It would also be much cheaper and easier to video. This would help illustrate the actual safety of the safety devices themselves.
 

Offline SeanB

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I have a feeling the larger GDT devices will survive the test, but the other protective devices will certainly fail. The more common larger GDT devices will absorb enough energy to clamp a spike down to 1kV even if the spike is a direct lightning hit. The traces will vapourise, but the GDT will still be there unbroken in the carnage. Seen that in plenty of telecoms applications, where you find the green module blackened and burned, with nothing left of the incoming wiring, the IDC Krone socket, the PCB holding the GDT units or the earth wire, unless you used 10mm cable for it. About 10% chance the PBX after it has survived unscathed, they generally blow all the line cards, power supply and any extension card that ran into the incoming frame. The phones however typically will survive, unless they were in use when the lightning hit.
 

Online joeqsmith

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What meter to fun first in 2016?   Would like to see that Keysight GDT protection in action

Maybe not the first meter, but it'd be nice to see a BM257 run at some point. You've run a lot of lower end Flukes and compared them to your BM869 as a comparison to Brymen meters, but it seems to me that a BM257 or similar would be a fairer comparison in terms of price range / size / etc.

Thanks for the videos. I've been watching them from the beginning and it will be interesting to see what survives in 2016.

Brymen makes some nice looking meters.   I looked at the manual for this one.   It's not very expensive.     

I have a feeling the larger GDT devices will survive the test, but the other protective devices will certainly fail. The more common larger GDT devices will absorb enough energy to clamp a spike down to 1kV even if the spike is a direct lightning hit. The traces will vapourise, but the GDT will still be there unbroken in the carnage. Seen that in plenty of telecoms applications, where you find the green module blackened and burned, with nothing left of the incoming wiring, the IDC Krone socket, the PCB holding the GDT units or the earth wire, unless you used 10mm cable for it. About 10% chance the PBX after it has survived unscathed, they generally blow all the line cards, power supply and any extension card that ran into the incoming frame. The phones however typically will survive, unless they were in use when the lightning hit.

Looking at the Keysight, if the waveform has a fast leading edge, will it damage other components before the GDT responds?  I would have expected to see something like small MOVs or transorbs on the Keysight meter to handle this.  Maybe they are there or maybe they are not needed.   The other thing I don't like is how they latch until the energy dissipates.   In Dave's video (again hard to tell for sure) looked like they have two stages.   If the first R fails short and the GDT is tuned on we now have a very low impedance path.  All that energy from the line is would now be going through the meter and leads.   Once it starts to breakdown, seems like it could go bad fast.   Normally when I have damaged MOVs with a surge (not my toy setup) they will short, then open up.   :-//     Would really like to see a schematic of the front end and run it against the other meters. 

Keysight may not care if the meter is damaged as long as it does not present a hazard.   Personally, I would want the meter to survive the 6KV like all of the low cost Flukes, the Brymen BM769s and 5KYs Radioshack.   

I just was thinking that instead of blowiing up a bunch of more meters, why not run a video on the protection devices that can be found inside. Run a PTC or two, some MOVs, gas discharge tubes, etc. This would give easy subjects to video, and some fun fireworks perhaps. It would also be much cheaper and easier to video. This would help illustrate the actual safety of the safety devices themselves.


I am still open for ideas.   My response is below.   

no i dont have circuit in mind. its just an idea because the UNI-T PCB always come with unpopulated MOV. if say by putting in the MOV, and it can stand up to some more surge, it could be good news for some DIY-ers who are interested to mod it but do not know the result for a real surge.

There are a few things you should consider.....

There are many many different MOVs in the world.   I would doubt they put it right across the inputs for example.  So even if you knew the MFG and PN for the MOV, hooking it to the generator is not going to tell you much.   

Even if you traced out that part of the circuit of the meter you are wanting to test, clearances would not be the same if I just threw something together.  If your goal is to test a specific meter with some changes, I think to really know what is going to happen we would use the real meter.   

Next is your statement about "...DIY-ers who are interested to mod it but do not know the result for a real surge."
First, let's talk "real surge".   Let's just assume that the IEC standards represent a real surge.  I have been involved with these tests from time to time.  Believe me, if something goes wrong there it can be a real thrill.   Even my little half cycle line simulator does not come close to the amount of energy we test to.   And believe me, with all the comments people have talked about safety and how the meters have never been shown to be unsafe during my tests, the last thing you want is for someone who has no clue to modify their own meter and then think it would survive these tests or worse, somehow be safe.    None of us want that.   This is why there are real labs that run these tests.

Its fun to look at some of the mods people have done to their handheld meters.  Some of those rat nests would light up on a real test and worse, after cutting holes in the case, may actually come apart.   No thanks...

If the goal is to "harden" the meters front end, I tried to show how to make an attenuator for a meter.  Once again, people started talking about safety, which was never the goal.  It is a good way to protect the meters front end.  That may be a better approach. 

That said, believe me, I know what you are getting at and you are not the first person to ask me about this. My advice is just buy a better meter if you are concerned about it.
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Offline SeanB

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A little info on GDT and usage and turn on.

http://www.citel.us/gas_discharge_tubes_overview.html

Littelfuse datasheet, they are probably the devices installed.

http://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_gdt_catalog.pdf.pdf

they are rated to handle a pulse with a risetime of 1kV/us, so turn on is pretty fast. Failure is by going open circuit on the 2 terminal devices, though you do get safety ones that have a shorting bar that fails the device as a short circuit when it is ruptured.

Page 10 shows that it pretty much is turning on after around 300ns of the transient being applied, most of this probably due to lead inductance. They tend to stay on until the voltage drops below the holding voltage of around 140V, though they can easily clamp at over 1kV on a high energy pulse limiting the downstream side to that. Probably that is why they use 2 in series, so the voltage is clamped hard by the second stage to the breakover voltage of the second device.
« Last Edit: December 27, 2015, 06:04:42 pm by SeanB »
 

Online joeqsmith

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A little info on GDT and usage and turn on.

http://www.citel.us/gas_discharge_tubes_overview.html

Littelfuse datasheet, they are probably the devices installed.

http://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_gdt_catalog.pdf.pdf

they are rated to handle a pulse with a risetime of 1kV/us, so turn on is pretty fast. Failure is by going open circuit on the 2 terminal devices, though you do get safety ones that have a shorting bar that fails the device as a short circuit when it is ruptured.

Page 10 shows that it pretty much is turning on after around 300ns of the transient being applied, most of this probably due to lead inductance. They tend to stay on until the voltage drops below the holding voltage of around 140V, though they can easily clamp at over 1kV on a high energy pulse limiting the downstream side to that. Probably that is why they use 2 in series, so the voltage is clamped hard by the second stage to the breakover voltage of the second device.
:-+

Can't imagine having a GDT directly across the inputs of a handheld.   While many devices are rated to handle the surge test, you would need to look at the whole system not just one component.   In Dave's video on the Keysight meter, it looks like they have it in the divider as you would expect.    I have no idea what parts they used.  They may switch at under 100 volts for all I know.   While a  few hundred ns may not seem like a lot of time, consider what it takes to protect the down stream circuits.   One thing the GDTs have going for them is very low capacitance.   

While you are doing your research, you may want to have a look at the Bourns application notes as well for GDTs.  These are pretty good from what I remember.   

This paper gives some general information on protection. 
http://www.onsemi.com/pub_link/Collateral/TND335-D.PDF

Looking at the meters I have tested, the one thing you can't count on is the PCB.  I have seen a lot of what I would consider unintentional spark gaps in the layouts.  :-DD   Looking at 5ky's Innova, I doubt they ever thought about clearance from the circuitry on the PCB to the shield.   But, it seems like it could be important.   :-DD

https://www.youtube.com/watch?feature=player_detailpage&v=3fYVaXz8lVk#t=254

This was another one of 5ky's meters where the PCB was doing a very good job protecting some of the circuitry while I was testing at lower energy levels.   
https://www.youtube.com/watch?feature=player_detailpage&v=9ii55eHfUWY#t=378

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Offline SeanB

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The series resistance on the input does look like it will at least attenuate the pulse, though the survival of the resistor is not guaranteed, so it has a blast shield to keep the pieces more or less together. Then they cascade that again so it is likely it will safely absorb the pulse without blowing up, though the chances of it surviving are not that good it will at least absorb the test pulse. Low capacitance is a major advantage over a MOV, and the residual capacitance will likely help as well.
 

Online Fungus

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PS: They're not 'recommendations'. It only measures one tiny aspect of a multimeter (resistance to sparks).

One?

OK, more than one...  :-[
 

Online joeqsmith

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The series resistance on the input does look like it will at least attenuate the pulse, though the survival of the resistor is not guaranteed, so it has a blast shield to keep the pieces more or less together. Then they cascade that again so it is likely it will safely absorb the pulse without blowing up, though the chances of it surviving are not that good it will at least absorb the test pulse. Low capacitance is a major advantage over a MOV, and the residual capacitance will likely help as well.

Agree, it has to help.  At least it will limit the current.  I would have expected that second stage to have a small MOV.  My guess is they have some other clamps further down the chain to protect the sensitive parts.   

I thought about getting their low end U1232A.  It's CAT III 600 and I would hope would survive at least as well as the Brymen.  When you look at this review, they have some small package GDTs in there.   From all of my tests I have not seen an MOV fail however, some of the PTCs and in rare cases the high voltage resistors have.
I doubt these smaller package GDTs would fail.  My concern would be ICs, diodes, transistors that are down stream from it.

https://www.youtube.com/watch?feature=player_detailpage&v=RYFlHDNA1aA#t=1040

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Online joeqsmith

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PS: They're not 'recommendations'. It only measures one tiny aspect of a multimeter (resistance to sparks).

One?

OK, more than one...  :-[

Just having a little fun with you.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online joeqsmith

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Looking closer at Dave's video, I am not sure what the GDTs they used are.  Appear to be marked 2000 1411.  Littlefuse has a SL1411A series but they are not rated for the sort of voltage needed.  They also don't use blue lettering on white from what I have seen.   Maybe it's custom.   2000 maybe a 2KV breakdown.  This would be in the  ballpark.   Dave did a video showing a insulation tester.  He could use that to at least determine where the tube fires.   

Looks like two separate circuits.  Both use an R, PTC, GDT.   Makes sense.   Would really like to have some values for the R and PTC as well.   
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Online joeqsmith

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Video showing a simple protection circuit based on a production meter using a R, PTC and MOV.    The MOV is then replaced with a GDT.   

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

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I would guess they put in some secondary protection, to handle the initial pulse and either clip it using a series resistor further down, with a SMD MOV that is going to handle the limited energy easily, or a simple diode clamp to either a power rail or a zener clamp. Once the spike has been clamped the residual low voltage will be easy to handle.
 


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