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 1149609 times)

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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2900 on: October 19, 2018, 07:52:01 pm »
Joe, something you might want to look into with the bigger Brymens and maybe other meters too:


Also found another issue with the BM867s. If it’s sitting in series with the PA monitoring current it goes bloody mental when you key down. Fluke, fine. Keysight, fine. Hmm. This is why I haven’t dropped my review yet. I still like it but not for that.

Not sure what you've got to replicate RF keying or if you even want to give yourself a slight RF fry up.  :-\

What's this about?   I do normally sweep them to see if there are areas they are sensitive at.  Post a link or details about exactly what they are doing, their test setup, modulation....

I played around with a few of my meters once I picked up that Gossen at 10V/m, swept to a GHz. 
https://youtu.be/wYuzFtoHMqg?list=PLZSS2ajxhiQBTCU8Mq_i9jidT024A0dV6&t=840

I still have my old Vibroplex
https://youtu.be/QBho9XD7VPQ?t=79
« Last Edit: October 19, 2018, 08:01:11 pm by joeqsmith »
 

Online tautech

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Re: Handheld meter electrical robustness testing.
« Reply #2901 on: October 19, 2018, 07:58:53 pm »
Joe, something you might want to look into with the bigger Brymens and maybe other meters too:


Also found another issue with the BM867s. If it’s sitting in series with the PA monitoring current it goes bloody mental when you key down. Fluke, fine. Keysight, fine. Hmm. This is why I haven’t dropped my review yet. I still like it but not for that.

Not sure what you've got to replicate RF keying or if you even want to give yourself a slight RF fry up.  :-\

What's this about?   I do normally sweep them to see if there are areas they are sensitive at.  Post a link or details about exactly what they are doing, their test setup, modulation....

I played around with a few of my meters once I picked up that Gossen at 10V/m, swept to a GHz. 
https://youtu.be/wYuzFtoHMqg?list=PLZSS2ajxhiQBTCU8Mq_i9jidT024A0dV6&t=840
I know and watched all you did with the Gossen to get it immune to the near field and magnetiser sensitivity.
You can glean a little more about the circumstances here:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1898834/#msg1898834
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2902 on: October 19, 2018, 08:15:17 pm »
Hummm.  I have no idea what they are doing.  You don't think they stuck the meter between the output and the load at 7MHz do you?   :-DD  I am guessing they are looking at the DC supply side but I can't find where they show a lot of details.  Maybe they will write something up and post some pictures. 

I'm sure I could come up with 7MHz at 25W. 
 
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Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #2903 on: October 19, 2018, 08:26:19 pm »
If you feel the SANWA can survive to even higher levels than the Brymen, are you thinking it's in Fluke 101/107 territory? 
I really don't know. I suspect both would be equivalent (I hope I don't eat my hat if you happen to test the PM300 in the future).

What do you feel is a mechanical flaw with the Brymen?   There is something I really don't like about the mechanics but I doubt it's the same problem.   Because often I run these meters to failure and I try to analyze why they fail, I want to be able to run the PCB open case.  The way the LCD, switch and battery are mounted to the case, it would make it difficult to work on.   I'm sure we will find out just how difficult.
In the original shootout video from Dave, he found out that twisting the Brymen was wreaking all sorts of crap on its screen. But perhaps it was a different model (so many OEMs/rebrands)
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2904 on: October 19, 2018, 08:43:19 pm »
Ah, the twist test.   I showed my wife one of Dave's reviews and when he starts to twists the meter she busted out laughing.  It must have made an impression because months later when I told her I was planning to run one of Dave's production meters, the first thing she asked is if I was going to twist test it.    I need to start weight training.   :-DD

It seems very subjective. 

Offline IanB

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Re: Handheld meter electrical robustness testing.
« Reply #2905 on: October 19, 2018, 09:35:54 pm »
Ah, the twist test.

It beats me how people manage to put their phones in the back pocket of their jeans and then sit on them without breaking them.

When people do that with wallets all their credit cards come out bent.
 

Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #2906 on: October 19, 2018, 10:09:58 pm »
Take your best guess where you feel the Brymen will fail. 
I forgot about this question. IIRC from your tests, the well built meters tend to have the point of failure around the clamp diodes/transistors. Obviously that may change to the rotary switch due to the sheer space constraints.
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2907 on: October 19, 2018, 10:31:04 pm »
You have learned well.  :-DD   I have yet to damage a MOV with all the testing I have done.  I don't think I have ever damaged a surge rated resistor.   It's almost without failure the high high speed clamps that fail in the higher class meters.   Diodes, transistors, etc.  In the cheap meters, the piss ant  PTCs will commonly fail.  That's if the meter even has them.  Mostly its the main IC that does them in.

Dave's little UEI meter is a bit of an odd ball with that 15V diode check seeming to be the weak point when I looked at it.  A couple of KV will take the MUX first.  The UNI-T UT181A is just a bad layout which is really too bad.

Then we have that UNI-T UT90A.  That meter has more lives than a cat.  There's not enough clearances to things just break down and save the meter.   I have done everything I could to finish that meter off shy of building a higher powered generator.   

This little Brymen has the basics.  PTC, spark gaps, clamps, lots of slots in the PCB.  Yet True damaged four of them.   Something is very strange.. 
 
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2908 on: October 20, 2018, 02:22:43 am »
Joe, something you might want to look into with the bigger Brymens and maybe other meters too:


Also found another issue with the BM867s. If it’s sitting in series with the PA monitoring current it goes bloody mental when you key down. Fluke, fine. Keysight, fine. Hmm. This is why I haven’t dropped my review yet. I still like it but not for that.

Not sure what you've got to replicate RF keying or if you even want to give yourself a slight RF fry up.  :-\

What's this about?   I do normally sweep them to see if there are areas they are sensitive at.  Post a link or details about exactly what they are doing, their test setup, modulation.... 

I played around with a few of my meters once I picked up that Gossen at 10V/m, swept to a GHz. 
https://youtu.be/wYuzFtoHMqg?list=PLZSS2ajxhiQBTCU8Mq_i9jidT024A0dV6&t=840
I know and watched all you did with the Gossen to get it immune to the near field and magnetiser sensitivity.
You can glean a little more about the circumstances here:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1898834/#msg1898834

First, I don't recommend anyone ever try this at home with a meter they value.  Obviously, I have no way of knowing what they were doing. So let me try and set up a VERY bad and stupid thing to do.    :-DD

The Brymen BM869s was set to Amps and the signal generator set to 7MHz.   The meter placed DIRECTLY IN SERIES with a 50 ohm load.  The load has a tap going back to the DSO to monitor power.

The DSO is showing 746mV which is well over 100 Watts. Yes the load was HOT in short time.  :-DD

Of course I am not expecting the Brymen to throw up any useful data.   "If it’s sitting in series with the PA monitoring current it goes bloody mental when you key down."  What bloody mental means is anyone's guess.   The meter didn't reset,  show random data, power down and it didn't smoke. 

Maybe this is what damaged True's meters!
« Last Edit: October 20, 2018, 02:24:53 am by joeqsmith »
 
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Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2909 on: October 20, 2018, 11:53:36 am »
It is useful when people  mention issues with meters and at least give the test conditions.
The uni-t 90A is the one have "fusible" tracks ?

About the Little Brymen, even it has the components and layout, does it have enought to withstand a ESD event?

The Amprobe functional test either it could be related to a batch issue, improper use of the meter, so you could get one good batch, do a proper use of the meter and get a different result from the test.


[Edit]

The Brymen in case is the BM27s and it is similar to the Ambrobe PM55A, but the supplied leads are different, and brymen has protective caps on the leads. Doesn't change the test but changes the aspect in terms of trying to do it more safe to hands... yeah...



« Last Edit: October 20, 2018, 12:17:21 pm by malagas_on_fire »
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Offline Housedad

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Re: Handheld meter electrical robustness testing.
« Reply #2910 on: October 20, 2018, 12:11:10 pm »
Ah, the twist test.

It beats me how people manage to put their phones in the back pocket of their jeans and then sit on them without breaking them.

When people do that with wallets all their credit cards come out bent.

Oh they do get bent. and cracked. and twisted. and dropped.  Don't let anyone fool you.

I have two daughters now in their early 20's. Add in my wife, and my sister.   I hate thinking about how many tablet,  Samsung phones and Iphone backs and screens I've replaced over the years or had to reform the corners and backs.  Off the top of my head, I think I have about 5 back straightener dies and the same # of corner straighteners in my 'phone box' of tools.  They can be rough on them sometimes.  I got tired of fixing them and their tablets all the time and told them to just pay for the insurance plan when they hit 20 years old.  They end up replacing them at least once a year on the plans.  Freedom is bliss.

The worse ones of all was the early Apple tablet about 6-7 years ago.  Seems that the ribbon cable connector on the main board to the screen would come off if you just looked at it.  I did not have hot air tools for reflow back then so I had to farm it out when it happened.  PITA.
« Last Edit: October 20, 2018, 12:17:22 pm by Housedad »
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Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #2911 on: October 20, 2018, 02:05:28 pm »
I was going to mention that as well. Cracked screens is a very common thing. When Apple released their slender phone (iPhone 6S, IIRC) the overall reaction was very negative with the bent phones. That's when people realized the blatantly obvious fact that putting a phone on the back pocket and sitting on it was actually a bad idea.

Fortunately for me, my wife is careful with her phone - although her last phone had a cracked screen, it only happened after many years of use and quite understandable as handling three year old twins is not an easy thing to do - an accident was bound to happen.
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2912 on: October 20, 2018, 02:54:35 pm »
Because BD139 mentions using a BM867s, which I don't have,  I thought I would try this same test with a couple of other Brymen meters I have.   

The second one I looked at was the BM839.  Using the same setup, again the readings appear stable.   There was no power cycling or what I would consider "mental" behavior. 

***

Also, I should mention that the Brymen on the left is measuring the temperature of the 50 ohm load in the center of the heatsink.  There is a lot of air flow, but during short runs it will reach 100C.   
« Last Edit: October 20, 2018, 04:04:38 pm by joeqsmith »
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2913 on: October 20, 2018, 03:43:44 pm »
The uni-t 90A is the one have "fusible" tracks ?

It seems so.

https://youtu.be/aRuI_q_K5RY?t=411

Wow they really blew out of sight. I have now my anenginsh gone ... and it was related to a fall that it had ( 0.5 meter to floor). If you leave in the volt's position, let it power off ( at least its high impedance) and power on, if i push the box it would go crazy showing all segments or enter CAL mode :S It did that when i was performing some measurements on 230V isolated and puff..  I blame myself for using this meter on wood surface and not providing enoughtgrip... of course the there i grip in other meters...

[Edit]

Q3 blew up and and doesn't power on :(

« Last Edit: October 20, 2018, 03:48:19 pm by malagas_on_fire »
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2914 on: October 20, 2018, 03:56:01 pm »
That's a bit odd as that clamp is not normally engaged.   Did you attempt to read the resistance of the 220V?   :-DD 

Actually, even if you did, I would have not expected it to fail like this.  All the ANENGs I looked at survived with that full rectified 220VAC line supplied to the meters while in each mode.   They actually held up better than many meters I have looked at.   

So what exactly did you do that caused this clamp to fail?
« Last Edit: October 20, 2018, 04:06:28 pm by joeqsmith »
 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2915 on: October 20, 2018, 04:03:22 pm »
I repeated the 7MHz RF test on Dave's rebranded Brymen BM235.  What was interesting is as I increased the power level, the contrast changes to the point it washes out.   The readings were stable and there was no damage to the meter.    The last picture was just under 110 Watts at the load.    I changed over to DC current using my bench supply for a comparison.   

AGAIN, this is NOT something I would ever expect anyone to do.  I do not see this as a weakness of the BM235.  It's interesting to see how the meters behave but IMO there is little value in a test like this. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2916 on: October 20, 2018, 04:16:13 pm »
Just a closeup of how washed out the BM235 is compared with the BM869s.   If you watched some of the videos where I was testing a few automotive meters, I had attempted to use both the BM869s as well as the BM235 to measure RPM with the meters located very close to the test jig.   The BM869s was pretty solid throughout that test.   These are some pretty harsh tests.  We don't just hook a meter to a 9V battery and a 1K resistor and call that a review!   :-DD

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2917 on: October 20, 2018, 06:34:47 pm »
That's a bit odd as that clamp is not normally engaged.   Did you attempt to read the resistance of the 220V?   :-DD 

Actually, even if you did, I would have not expected it to fail like this.  All the ANENGs I looked at survived with that full rectified 220VAC line supplied to the meters while in each mode.   They actually held up better than many meters I have looked at.   

So what exactly did you do that caused this clamp to fail?

As i mentioned before i droped the meter some months ago from about 0.5m from the TV to the floor.   Since then when it was in sleep mode, in the Volts mode, if i awake with Select button it would do random stuff, like beeping, changing the decimal point, turning all digits and sometimes the backlit and CAL on display. Today i was performing some measurement on a 230V circuit isolated from mains and then the meter suddenly do random stuff and turns off.

I wish i was measuring resistance in the 230V so i could least have my punishment with precision, not with random stuff.   :palm:

I believe the fall must done something to the meter, on the PCB. There is a scrach on the lenses.  Anyway i assume the random bug was occuring in sleep mode circunstances and proceed with experiences , so ... i still blame myself 



100W and 7Mhz???? Is that an induction heater? Does the user was measuring an induction heater=
« Last Edit: October 20, 2018, 06:36:23 pm by malagas_on_fire »
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Offline bd139

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Re: Handheld meter electrical robustness testing.
« Reply #2918 on: October 20, 2018, 07:11:38 pm »
Tautech mentioned the RF issue I encountered being analysed in here. Some additional info:

1. PA was open board prototype.
2. BM867S was used to measure current hitting the drain of a FET through a 50uH loaf I nductor. Connected via Pomona banana leads. Mode Amps DC.
3. There was supposed to be a decoupling cap or two on the top end of the inductor. This was missoldered.
4. PA was delivering 25W out at the time.
5. “Mental” was weird readings and eventually it froze and had to be turned off.
6. My BM867S has crashed twice since I got it so this may be a problem with this meter.
7. Issue went away when I fixed decoupling, added Pi network LPF and Hammond enclosure.

I also found the PA was oscillating at around 120MHz as well as 7Mhz. This was resolved with a 10 ohm resistor in series with gate.

I didn’t delve too much further into this as I was more interested in building the PA at the time.

I suspect that there were extremely large voltage spikes (think SMPS) at the top of the inductor here.

Really I think this is a faulty unit at this point based on this behaviour and the other crashes.
« Last Edit: October 20, 2018, 07:16:05 pm by bd139 »
 
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2919 on: October 20, 2018, 08:36:47 pm »
Tautech mentioned the RF issue I encountered being analysed in here. Some additional info:

1. PA was open board prototype.
2. BM867S was used to measure current hitting the drain of a FET through a 50uH loaf I nductor. Connected via Pomona banana leads. Mode Amps DC.
3. There was supposed to be a decoupling cap or two on the top end of the inductor. This was missoldered.
4. PA was delivering 25W out at the time.
5. “Mental” was weird readings and eventually it froze and had to be turned off.
6. My BM867S has crashed twice since I got it so this may be a problem with this meter.
7. Issue went away when I fixed decoupling, added Pi network LPF and Hammond enclosure.

I also found the PA was oscillating at around 120MHz as well as 7Mhz. This was resolved with a 10 ohm resistor in series with gate.

I didn’t delve too much further into this as I was more interested in building the PA at the time.

I suspect that there were extremely large voltage spikes (think SMPS) at the top of the inductor here.

Really I think this is a faulty unit at this point based on this behaviour and the other crashes.

Thanks for the added details about your setup.   That other amplifier that I show is something I had put together from a kit can easily run up at 120MHz with more than 25W into a 50 ohm load.   The problem I see is that I don't have the exact same meter you have.   I tested the BM869s all the way up to 3GHz at 10V/m and it was very stable but that doesn't mean the BM867s doesn't have a design problem.   

If there is some other test you would like me try, feel free to ask.   

Offline bd139

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Re: Handheld meter electrical robustness testing.
« Reply #2920 on: October 20, 2018, 08:49:06 pm »
Please excuse the horrible typos in the previous post by me - damned iOS!

Thanks for testing this by the way. I'm not sure any further testing would be conclusive.

Out of interest I have another PA prototype in development which should kick out 50W this time. When I get to the same state of the build I will try again and see if I can isolate a cause.

Honestly though I'm not surprised if there are problems in these situations as they are mostly well outside what would be considered normal EMC situations. I certainly am not annoyed by the meter. On that front at least. It has a couple of annoying misfeatures.
 

Offline malagas_on_fire

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Re: Handheld meter electrical robustness testing.
« Reply #2921 on: October 20, 2018, 09:02:55 pm »
Hi there

Here is a photo of my setup test and the uni-t 50b , brymen bm235 are quite happy

But fortunally i got another unhappy meter about low battery. It just hanged :P with no reaction to buttons :P The uni-t ut-120c pocket meter that was offered in a workshop. Maybe it is in draining battery mode ...

https://youtu.be/GNOx79hEHmo

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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2922 on: October 20, 2018, 09:38:09 pm »
Please excuse the horrible typos in the previous post by me - damned iOS!

Thanks for testing this by the way. I'm not sure any further testing would be conclusive.

Out of interest I have another PA prototype in development which should kick out 50W this time. When I get to the same state of the build I will try again and see if I can isolate a cause.

Honestly though I'm not surprised if there are problems in these situations as they are mostly well outside what would be considered normal EMC situations. I certainly am not annoyed by the meter. On that front at least. It has a couple of annoying misfeatures.

My spelling and grammar are both poor.  I typically won't take the time to proof read anything I post and only have myself to blame.  No big deal. 

I really don't know what a normal use case would be.  One reason I post my testing of handheld meters is because I'm sure I am not to only one who's electronic hobby extends past digital logic and 12V batteries. 

Let me know if you get a replacement meter and if it works any better or if you find the problem.

Offline bd139

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Re: Handheld meter electrical robustness testing.
« Reply #2923 on: October 20, 2018, 09:48:35 pm »
Will do. I'll post back here right away. Hopefully in the next couple of weeks.

If I find the same problem again I'll record all the details, stick it on youtube and talk to Telonic to get a replacement unit and see if that has the same "feature".
 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2924 on: October 20, 2018, 10:03:48 pm »
This video is for our long lost member True.   

https://youtu.be/0D_6uOFSgyY


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