Handheld meter robustness testing

[HalFET]

Your link did not work but item 32818141467 appears to be the UNI-T UT136B.   With as many UNI-T products I ran, I have never looked at this one. 

I have thought about making a small cooler for my cardboard/foam meat packing box.  This will be for fixed temperature testing.  I've ran some drift tests for people in the past where I set the box to an elevated temperature and hold it.   It would be nice to be able to run a sweep with it.  I have not thought about running any sort of controlled shock test.  Building some sort of dumbwaiter chamber would take far more effort than I would be willing to invest in a test like this.   

Good look testing.  As always, it will be interesting to see what you come up with.   


The Fluke was the forth meter I have attempted to measure the contact resistance with while life cycling the switch.  It has a long road ahead of it but I will say that the preliminary results are impressive.  Then again, it's being compared with a free meter, the ZT102/AN8002 and a blown up POS.      

My wife said I can't life cycle the original Fluke 101 I bought because it would be just wrong at this point.      It has survived everything I have thrown at it but I am still thinking to do some sort of high voltage shootout with the surviving meters at some point. Cycle testing this meter may damage it.  50,000 cycles takes days at the rate I am cycling them takes days, so there is plenty of time to decide.     

Well, I'm not quite willing to put up my ancient Fluke 73 (still has the gray bumper case even ), or the newer Keysight one up for this sort of testing. So went on aliexpress instead for now, I'll scour eBay for some main brand ones later maybe.

I ended up buying these two to begin with:
https://www.aliexpress.com/item/UNI-T-UT136B-Digital-Multimeter-Auto-Range-Tester-AC-DC-Voltage-Current-Ohm-Diode-Cap-Hz/32818141467.html
https://www.aliexpress.com/item/NEW-NK-51E-Multimeter-VS-UT136B-UT120C-MS8233D-With-2000uF-Capacitance-and-Frequncy-Measurement-Auto-Range/32757114149.html

The second I mostly wanted because it's pink, honestly who wouldn't want a pink multimeter! (Maybe we should all pitch in and buy one for Dave?)

Also have a couple of DT-830s hanging around that I've been meaning to blow up for months that I could include in the test. To be precise, I have an old capacitor bank laying around from an ill-advised railgun construction project ages ago, my main issue is that I can't find an affordable high voltage relay for it at the moment. Best one I could find on Farnell for a reasonable price arced internally, so planning to build my own transformer oil filled relay at one point or another.

But to get back to the subject at hand, the plan is to test the drift over the product lifetime by thermal cycling and ageing tests while I still have access to that climate chamber. After that I plan to just put them in water tight bags and expose them to some Belgian weather and see how long they last. Planning to verify drift and accuracy for voltage, current, diode, input impedance on volts, diode measurement current, and resistance measurements. For voltage, input impedance, and current I'll use a calibrated Keithley 2001 as reference. (If any of them would manage to go high input impedance I'll just pull out the 238 SMU and force the situation a bit ) For resistance I'll use some high precision wirewound resistors, and for diode I have some fun stuff laying around still that should be exceptionally stable.

Any remarks before I get started? 

[HalFET]

Heheh, it's almost begging to be tested isn't it? But it's soooo pretty, I don't want to destroy it.    I also love how they can't seem to decide on which batteries the thing uses, or how they show ceramic fuses next to it but never the portion of the PCB that contains said fuse. My money is on glass fuse with a cheap PTC in series. A MOV would certainly cost more than the 5 cents budget they had for the BOM.

Photonic Induction's cap is the real world equivalent from the average ACME weapon from Looney Tunes. But yeah, if you want to blow up meters, you got to do it properly! It'd also be fun to try to blow one up using induced currents when it's in ohms. (Make a coil out of copper tubing and discharge that cap bank through it.) I'm not quite sure what'd the use of that test would be, but I suppose it checks the resistance against externally induced electromagnetic noise? 

Actually we have a pile of UT61Es in the lab, we all bought them at the same time from the same supplier so it'd be funny to check if they still match up. These have seen a bit more (ab)use than yours I think considering the stupidity of some of my colleagues.

[joeqsmith]

The pink would go nice with that florescent green TPI meter I have.  Who knows, maybe the pink one will do great compared with the others you look at.  I run into all sorts of unexpected results.   

Looking at my cheat card,  I started collecting data for the UT61E on 11-21-16.   Looking at it today, it appears it has not budged.  Must be all the dope I used on it.    If there is ever a contest for the most chopped up handheld meter, I may have to enter this one.    

[stj]

about ut61e drift,

i suspect it was only voltage and related to rough handling.
the older ones had a 2k multi-turn pot, those things can move inside if you bang them hard enough.
the latest ones have a 1k pot and some different fixed resistors so the pot covers a smaller range.
so newer ones should be a lot better.

[Fungus]

The second I mostly wanted because it's pink, honestly who wouldn't want a pink multimeter! (Maybe we should all pitch in and buy one for Dave?)

Dave recommended that one in one of his videos (at the 1:07 mark):



Maybe he owns one in secret.

Full disclosure: I actually own one, for the stated reason.

I also love how they can't seem to decide on which batteries the thing uses, or how they show ceramic fuses next to it but never the portion of the PCB that contains said fuse. My money is on glass fuse with a cheap PTC in series. A MOV would certainly cost more than the 5 cents budget they had for the BOM.

Nope, ceramic fuses. Followed by a PTC and some MELF resistors.

The pink would go nice with that florescent green TPI meter I have.  Who knows, maybe the pink one will do great compared with the others you look at.

In real life it's more purple than pink. I'm saving it for a "gothic workbench" video.

[joeqsmith]

about ut61e drift,

i suspect it was only voltage and related to rough handling.
the older ones had a 2k multi-turn pot, those things can move inside if you bang them hard enough.
the latest ones have a 1k pot and some different fixed resistors so the pot covers a smaller range.
so newer ones should be a lot better.

Just to be clear for those that may read this and have not seen the videos where I chopped this meter to bits,  I had changed out the multi-turn trimmer in question when I had compensated the reference to a different value and brand.   

This is what not to do with your meter!     

[stj]

bourns - that wasnt cheap i'm sure.

[kalel]

Next up: Testing the input jacks.

No, it's not a real proposal of course, but that is the most vulnerable part in some DT models (similar to the free meter you mentioned). I have one and that's the first thing that broke (not counting the probes), so I soldered the broken metal tab connecting the input jacks to the PCB together used some epoxy so that there is no strain on the metal tabs keeping things connected. It may or may not have lost some accuracy, but it still works decently for continuity checks and some quick (low) voltage checks.

[rsjsouza]

The Fluke 17B+ has surpassed the free HF meter in cycles and there are no signs of anything going on with the switch.   So I think we can hang our hats on the fact that Fluke has a more reliable switch design than the Cen-tech.   The first useful bit of info... 

There is still a long way to go before we reach Kasuntest cycles....

If this little Fluke is able to go to 50k, that would be quite a safe and sturdy meter...

My wife is warming up to the idea of running the little 101. 

If the 101 goes to 50k, that would be an unbeatable price/durability point.

[HalFET]

Dave recommended that one in one of his videos (at the 1:07 mark):



Maybe he owns one in secret.

Full disclosure: I actually own one, for the stated reason.

Question is, would this one be banned in Russia?

Nope, ceramic fuses. Followed by a PTC and some MELF resistors.

Mhhh, it'd be interesting to see how it holds up if that's the case. Might have to run it through some careless probing.

[Fungus]

geonomad says:
July 17, 2017 at 3:07 am

The biggest problem I have had with the Chinese cheap meters has been the switch contacts.
If a reading appears wonky, I rotate the selector switch back and forth a few times to “clean”
the contacts and the readings come back to reasonable – sometimes. This is especially true if
the meter has been sitting in a drawer for a long time between uses.

I've been there too... Have you?

Yes.

I used to have a manual ranging meter that didn't work on the 20V range* without a bit of switch-jiggling. I eventually threw it out.

(*) ie. The range that gets used the most.

[Fungus]

Nope, ceramic fuses. Followed by a PTC and some MELF resistors.

Mhhh, it'd be interesting to see how it holds up if that's the case. Might have to run it through some careless probing.

I just dug it out to have a play using my new-found wisdom, gained on these forums.

It's not a great meter compared to this year's wave of ANENGs*, but it IS purple and would fit perfectly into a Hello Kitty themed workbench.

(*) Capacitance only goes down to 1uF, Ohms is slow, diode test can't light up an LED.

[rsjsouza]

geonomad says:
July 17, 2017 at 3:07 am

The biggest problem I have had with the Chinese cheap meters has been the switch contacts.
If a reading appears wonky, I rotate the selector switch back and forth a few times to “clean”
the contacts and the readings come back to reasonable – sometimes. This is especially true if
the meter has been sitting in a drawer for a long time between uses.

I've been there too... Have you?

Yes.

I used to have a manual ranging meter that didn't work on the 20V range* without a bit of switch-jiggling. I eventually threw it out.

(*) ie. The range that gets used the most.

Many times as well. A Uni-T UT55 (Triplett 9005) and older analog ones from Icel were always problematic.

This endurance test on the Fluke is more than enough evidence to completely obliterate an old suspicion of mine regards the durability of the "new" rotary switch versus the "old" ganged buttons of the older 80xx family.

[HalFET]

Nope, ceramic fuses. Followed by a PTC and some MELF resistors.

Mhhh, it'd be interesting to see how it holds up if that's the case. Might have to run it through some careless probing.

I just dug it out to have a play using my new-found wisdom, gained on these forums.

It's not a great meter compared to this year's wave of ANENGs*, but it IS purple and would fit perfectly into a Hello Kitty themed workbench.

(*) Capacitance only goes down to 1uF, Ohms is slow, diode test can't light up an LED.

Ah too bad, but we'll see how it fares. Planning to give it a run for its money in stability vs. a Weston cell reference 

[joeqsmith]

It was getting a bit long so I decided against running a forth meter.   This should give viewers some idea how I plan to proceed.

Looking at new meters, I think as long as I don't run them on the half cycle simulator, the switches will be fine to life cycle. 

Should have the video uploaded today.  In the meantime, here is a picture showing a worn through contact.  Yes, it's basically a hollowed out square dragging over the PCB.  Stay tuned to see the damage...

[HalFET]

Wish we could measure the hardness on these.

[joeqsmith]

You could determine the hardness, thickness of plating and materials used for both the contact as well as the PCB.  It's only money and time.  I look at it no different than the lube/dry contact.  I use the products, not design them.

I can see one argument from this video.  Say a high quality meter cost $130 and the low quality meter was $10.    That's 13 cheap meters I could buy for the price of one.  Seems like a great deal ... but ... if the high quality meter last 50 X longer than the low quality one,  to do the same job is 50 X $10 or $500 operating cost.   Not to mention the down time, and collecting bad data...

Maybe there are mid range meters that will perform as well as higher cost ones over the long run.  In the mean time, feel free to watch the first few meters.   There are only a few short clips of them cycling.  I can speed up the transient test but the time required to run this test is on a new scale.   

https://youtu.be/x_L6Z8BAXFQ

[kalel]

Useful results, but I think the argument for durability will depend on some factors.

If you're a professional, by all means you need a reliable durable meter and over time perhaps calibration for some work?

But as a beginner looking to do hobby electronics, unless you use the meter daily I believe even the cen-tech / DT800 series meters will last long enough, switch-wise.
That said, my first meter was about $10 and had issues with the range switch and probe contacts from the start, possibly just a bad unit, or maybe you will find meters that have less durable switches than even the free meter. Another weak point on some meters will be the probe inputs. These will definitely break faster on some meters than others.

Too bad you're not being paid for the tests.

[HalFET]

Useful results, but I think the argument for durability will depend on some factors.

If you're a professional, by all means you need a reliable durable meter and over time perhaps calibration for some work?

But as a beginner looking to do hobby electronics, unless you use the meter daily I believe even the cen-tech / DT800 series meters will last long enough, switch-wise.
That said, my first meter was about $10 and had issues with the range switch and probe contacts from the start, possibly just a bad unit, or maybe you will find meters that have less durable switches than even the free meter. Another weak point on some meters will be the probe inputs. These will definitely break faster on some meters than others.

Too bad you're not being paid for the tests.

At least spend the 20 bucks to get a uni-t or vichy vc97, or maybe that pinktacular thing I linked earlier. It ain't much more, but it will do fairly well compared to DT830s.

[kalel]

I got an ANENG 860B+ in the end and I'm really happy with it. The min, max and rel functions are all very useful.

I still use the DT for quick checks such as continuity (it is the non latched type, but it's also instant as well), battery level, etc.

[Cliff Matthews]

Before anyone beats me, congrats on passing 4K subscribers Joe! I enjoy your dedication sir.

[bitseeker]

You definitely beat me, Cliff.

Congrats, Joe!

[Fungus]

It's been a while since I saw the inside of a Fluke 17B+, I'd forgotten how well made they are. All the input jacks, input protection, PCB layout, etc. are orders of magnitude better than those $15 meters that are so fashionable.

[joeqsmith]

Before anyone beats me, congrats on passing 4K subscribers Joe! I enjoy your dedication sir.

You definitely beat me, Cliff.

Congrats, Joe!

Thank you for your support.  The channel is larger now than I ever expected it to get.   I've certainly learned a lot about handheld meters in the process and hope others have as well.   

Most recently I would say we learned that quality meters don't put vias in the function switch pads and don't route traces
between the pads where they may be damaged by the rotating contact.  Seem obvious afterwards.   

I'm sure I have upset countless people over the last few years presenting all this data.  A lot of meters were destroyed in the process and nobody likes seeing their meter fail.   

From my own perspective, I continue to look at them out of my own interest.  To be clear, I have no axe to grind with any company as some suggest.  Well, again I fully admit I was biased against Fluke from the start.  Damn you Fluke for making such robust products....      I still have no plans to use patreon or enable ads.  I appreciate those of you who have asked about sending me meters to run and such.  I have still not looked into a PO box.  The problem is really the lack of time to run them.   For those of you wanting to support the channel, your views and feedback are more than enough. 

[IanB]

Well, again I fully admit I was biased against Fluke from the start.  Damn you Fluke for making such robust products....

I think we'll only be sad if your Fluke 189 has displaced your BM869s as your go-to meter on the bench. For me, mainly because the 189 was discontinued shortly before I wanted to get one. So damn you Fluke for discontinuing the best meter you ever made...