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 651330 times)

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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3550 on: December 03, 2019, 12:56:20 am »
I had written TPI requesting the alignment procedure for the 194II, explaining what had happened to the meter.   They were able to supply me with everything I need.   

Points to TPI for customer service!!!!   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline Scottjd

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Re: Handheld meter electrical robustness testing.
« Reply #3551 on: December 03, 2019, 02:21:56 am »
I had written TPI requesting the alignment procedure for the 194II, explaining what had happened to the meter.   They were able to supply me with everything I need.   
Points to TPI for customer service!!!!   
Nice!  :clap: :-+
Please be sure to check out my YouTube channel and subscribe if you like the videos. https://www.youtube.com/c/GadgetReviewVideos

By people subscribing and giving thumbs up I know what I am doing is still wanted and adding value, then will continue to release new videos. Thank you for your support.
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3552 on: December 03, 2019, 02:38:48 am »
Waiting to see how your long term test results turn out Scott.   If you're able to replicate this problem, shoot me as much detail as you can and I will attempt to replicate it. 

From what I remember with that really old firmware, the meter would stop recording.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline Muttley Snickers

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Re: Handheld meter electrical robustness testing.
« Reply #3553 on: December 03, 2019, 02:51:01 am »
My parts made it in early, so I ran some tests for Muttley Snickers and finished things up.   

Many thanks Joe for your fine efforts.   :-+

In case people were wondering why I asked Joe to compare and show the auto hold feature it was because the only guide I had in regards to this meters ability was Scott's video where it failed miserably compared to other meters which incorporate auto hold.

In the comments section of the video linked below Scott declared that this problem has been addressed and resolved with later firmware and Joe's tests indicate that it is now working as expected and comparable with other similar meters with this feature.   


https://youtu.be/l7hBJh_NMOo
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3554 on: December 03, 2019, 03:25:31 am »
Glad to help.   Hope it covered what you wanted to see with the peak hold and min/max as well.    If not, I could try to add something to the next segment.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline Muttley Snickers

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Re: Handheld meter electrical robustness testing.
« Reply #3555 on: December 03, 2019, 03:35:35 am »
Other than a current craving for triple display meters all is good.   :-DMM :-DMM :-DMM
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3556 on: December 03, 2019, 05:14:54 am »
 :-DD   They are nice.   That $120 CEM meter was a deal.   Everytime I play with that UNI-T, I think where is the B model... If Brymen had made that meter to same level I have seen with their other products,  I think I would have a new all time favorite meter.     

After a third cleaning,  I aligned the DCV using my bench meter as a reference.  Shown looking at the output of my old Fluke standard.   The capacitance and ACV  ranges seem good.   The resistance could be improved but it's not horrible.   It's good to see it working again after 3 years.    If it wasn't such a odd ball design, I would attempt to harden the front end.  But it's similar to those cheap ANENG meters and would require a major effort to sort it out. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3557 on: December 08, 2019, 02:55:36 am »
I have started to work on part 6 and am now thinking that I may try and wrap it up with this video.  There is a fair amount of testing left to do, but most of these take longer to run than showing the results.  I'm sure very few want to see the meter switch cycling for days on end. 

It's going to require another week and the video will more than likely go long.   A couple of spoilers should tie you over.  I ran into a problem with the 121 that I have never seen before, even with the cheap ANENG meters!!    While running the temperature test today, I had the meter down at -10C and noticed that the internal temperature it was reporting was -17.2C.   I have a couple of cheap thermocouples in the box besides the platinum RTD to monitor other areas.  So I connected the Brymen to one.   Looking in the manual, they don't spec the accuracy of this ambient sensor but wow, that's a long way off.   

Stay tuned while I put Production2 to the test. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3558 on: December 08, 2019, 09:26:46 pm »
Sorry, no post post it notes to try and decode.  Just an HP bench meter reading good old resistance. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline floobydust

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Re: Handheld meter electrical robustness testing.
« Reply #3559 on: December 08, 2019, 10:33:01 pm »
Most thermocouples output a negative voltage at temperatures below freezing. The sign-change can flush out issues with firmware or the CJC. ANENG just uses a fixed room temp value for CJC, in EEPROM.

I made a battery powered reference+Wheatstone bridge, to generate stable (thermocouple) mV signals of either polarity and use that to test hardware.

edit: added schematic of the thermocouple simulator I made with junkbox parts, so it's not perfect. +/-100mV output.
« Last Edit: December 08, 2019, 11:53:17 pm by floobydust »
 
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3560 on: December 08, 2019, 10:49:14 pm »
Most thermocouples output a negative voltage at temperatures below freezing. The sign-change can flush out issues with firmware or the CJC. ANENG just uses a fixed room temp value for CJC, in EEPROM.

I made a battery powered reference+Wheatstone bridge, to generate stable (thermocouple) mV signals of either polarity and use that to test hardware.

In case the lack of the sign for the Celsius display causes confusion,   13.9F is -10C.  The Brymen also reads -10C.  The 121 is displaying -17.2C.   

I wonder if the 121 is using this reading as their cold junction compensation.  If so it's off by a mile. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline dcac

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Re: Handheld meter electrical robustness testing.
« Reply #3561 on: December 09, 2019, 05:47:22 pm »
As far as I can tell 121gw only has two temp sensors, one inside the hy3131 chipset and this one doesn't seem to be used at all, and then the smd NTC placed in the upper right corner looking from the PCB side. And this one is read by a rather crude low resolution routine and is used for showing the internal temperature of the meter.

So could they really be doing no cold junction compensation at all? The Temp mode really appears to just read the DCmV and translate this to temperature using a LUT, though a LUT that gives much more resolution than the one for the NTC sensor.
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3562 on: December 10, 2019, 12:55:05 am »
It would be easy enough to find out by testing it but Dave may be able to find out and add it to the manual.   

That switch has been cycling over 24 hours now.  I'm really curious to know what it looks like.

*****

I went back and watched the two shorter videos Dave made where he cycles the switch on the 121.   It's interesting that the switch that he tests has a different contact design than what was supplied in Production1.   I have yet to take Production2 apart but would assume these two are the same.    He had posted some graphs showing the contact resistance.  It appears they saw up to 2.5ohms once the shim had been installed.    The double dimple design Dave' shows are on the outside,  where mine are all single.   I wonder with the smaller surface area and higher travel speeds being on the outside, if it will wear the same.   

Where Dave had his apart at 1000, 11K, 25K and 51K half cycles,  I plan to leave this one together for all 100K half cycles and this is how I tested the other meters I have looked at.    It still has a good day to go but it's looking good for a weekend upload for Part 6.
« Last Edit: December 10, 2019, 04:55:51 am by joeqsmith »
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online HKJ

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Re: Handheld meter electrical robustness testing.
« Reply #3563 on: December 10, 2019, 05:23:23 am »
So could they really be doing no cold junction compensation at all? The Temp mode really appears to just read the DCmV and translate this to temperature using a LUT, though a LUT that gives much more resolution than the one for the NTC sensor.

The cold junction compensation done on multimeters is to add the ambient temperature to the thermocoupler temperature and the ambient is often measured inside the multimeter chip, i.e. a long way from the correct location. This also means a multimeter may need one to two hours at a specific temperature before the internal sensor matches the actual cold junction.
 
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Offline dcac

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Re: Handheld meter electrical robustness testing.
« Reply #3564 on: December 10, 2019, 09:41:39 pm »
I looked again at the code (the disassembled 1.02 FW) and found it this time, and yes they are loading a “cold junction” offset value based on the internal temperature taken from the NTC sensor. Ironically this sensor happens to be placed farthest away possible from the input jacks, but it would probably still be sufficient as long as the meter not recently been subjected to temperature changes, as HKJ suggested.
 

Offline dcac

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Re: Handheld meter electrical robustness testing.
« Reply #3565 on: December 10, 2019, 09:50:59 pm »
The Brymen also reads -10C.  The 121 is displaying -17.2C.

I wonder if the 121 is using this reading as their cold junction compensation.  If so it's off by a mile.

The 121 manual specifies operation temperature 0 - 50C, so -10C is outside this range. But the NTC sensor conversion routine seems to be limited to -25C to 85C so at least I hope it is reasonable accurate between 0 - 50C.
 

Offline darik

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Re: Handheld meter electrical robustness testing.
« Reply #3566 on: December 11, 2019, 12:21:37 am »
The 121 manual specifies operation temperature 0 - 50C, so -10C is outside this range. But the NTC sensor conversion routine seems to be limited to -25C to 85C so at least I hope it is reasonable accurate between 0 - 50C.

Wow, 0 C as a minimum operating temperature? That is extremely poor. I used to live in Canada, a meter that doesn't work below 0 C is garbage there, useless for anything but exclusively indoor work.

I looked up a Fluke 87 and they claim -20C as their minimum. That is reasonable, a lot of things start acting up at -20. But 0?????

I would imagine that most functions on the 121 work fine well below 0C, perhaps that figure is primarily because of this specific thing. But still, wow, that is a very limiting specification.

Now I'm interested in seeing what functions of the meter don't work at -20.
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3567 on: December 11, 2019, 01:45:24 pm »
Spoiler for the 121GW fanboys.   I just removed the meter from the jig and installed the batteries.  Both meters in parallel and attached to my 6.750VDC precision reference standard.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3568 on: December 12, 2019, 02:31:41 pm »
I have upgraded my 1950's Olympus since looking at the last DMM.   Button on my HP calculator.   We should get a decent view of the 121GW's internals. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline CDaniel

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Re: Handheld meter electrical robustness testing.
« Reply #3569 on: December 12, 2019, 04:47:20 pm »
Let's hope will remain unused and that the switch will be like brand new  >:D
« Last Edit: December 12, 2019, 08:02:00 pm by CDaniel »
 

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #3570 on: December 12, 2019, 07:25:01 pm »
I have upgraded my 1950's Olympus since looking at the last DMM.   Button on my HP calculator.

That's an easy one, it's an HP 20S.  :popcorn:
[attachimg=1]

nb.: Image resized for joe's sensibilities (it's his thread!)
« Last Edit: December 14, 2019, 02:39:17 am by Fungus »
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3571 on: December 13, 2019, 05:52:02 pm »
Let's hope will remain unused and that the switch will be like brand new  >:D

It won't be much longer now.  I finished up recording the final video.  Now I just have to edit 2 weeks of testing into an hour or so long video.    I had hoped UEi would release the new firmware before I finished.  I was wanted to look at the 1Meg range Dave mentioned and repeat the AC/DC waveform testing.   Oh well.  This video is going to be packed..

I have upgraded my 1950's Olympus since looking at the last DMM.   Button on my HP calculator.

That's an easy one, it's an HP 20S.  :popcorn:

Not only were you able to ID my calculator, you figured out how to make a picture take up a full page.  Nice job!

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

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #3572 on: December 13, 2019, 06:14:30 pm »
you figured out how to make a picture take up a full page.  Nice job!

You don't get many options with "copy URL", "paste URL". You can only make them expandable if it's one of your own attachments.
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #3573 on: December 13, 2019, 07:40:07 pm »
you figured out how to make a picture take up a full page.  Nice job!

You don't get many options with "copy URL", "paste URL". You can only make them expandable if it's one of your own attachments.

One option would be to DL the picture, then reupload under your account.  Or the simple option, don't link it at all.  After all it was only one previous post. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #3574 on: December 14, 2019, 02:35:31 am »
One option would be to DL the picture, then reupload under your account.  Or the simple option, don't link it at all.  After all it was only one previous post. 

I fixed it.

PS: The joke was that I know perfectly well what calculator you use, I've seen it in your videos. It's easy to remember because it's the same one I use. Thanks for derailing that.
« Last Edit: December 14, 2019, 02:40:25 am by Fungus »
 


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