@ Joesmith
here is a teardown of my oldie, Motech MIC 2200 A, the pics aren't great quality, but I think you can have an idea, just tought you might be interested, ok? it probably wouldn't survive your tests lol
the only reference to the brand, but it's not the same meter, BKprecision got the multimeter part from Motech
I was about to start a thread about the UT-171B vs the Brymen 869S so I am glad I saw your posts on the UT-181A. I had fallen in love with the 181's huge easy-to-read screen but when I found out about the 2 update/sec rate I was so disappointed. Is the update rate really that bad for such a modern meter?
The 171B seems to be around 5/sec which is why I started looking at that meter as an alternative, but the niggly feeling that there is no such thing as a "high end UNI-T" remains...
@ Joesmith
here is a teardown of my oldie, Motech MIC 2200 A, the pics aren't great quality, but I think you can have an idea, just tought you might be interested, ok? it probably wouldn't survive your tests lol
the only reference to the brand, but it's not the same meter, BKprecision got the multimeter part from Motech
Thanks! I like looking at old equipment and how it was built. It's too bad that the LCD is cracked.
I saw an old 80's digital hand held for sale local but they wanted about $40 for it with unknown condition. Had the side slide switches.
it's not cracked, probably the seal failed, I tryed to seal it again with some vitral warnish, it's probably a manufacturing problem, never fell or anything like that, it works just fine, I don't have any precision reference, but I did compare it to the Digitek and it hasn't drifted to much, almost spot on
However, the point of the protective devices is to protect the user first, not the DMM, for the specific CAT rating of the meter.
I would guess that most of the safety in hand held meters comes from the mechanics. Things like spacing, wall thickness, double walled, etc. Things like the GDTs, MOVs, secondary clamps, PTCs are there to protect the meter so it does not need to be replaced or repaired. Maybe have a look at patents 5396168, 5606481, 5920188
I get feedback on some of my meter videos that talk about the testing not being real world and how meters would never see these sort of conditions. Recently, I had an opportunity to pull apart a power supply that had been hit with a real line transient. So to be clear, not to the IEC or any other standard. I then wondered what would happen if I ran the same power supply on my home made generators.
I don't think anyone on the net has demonstrated just what an impulse would do and compare it against other DMMs, than this series.
I get feedback on some of my meter videos that talk about the testing not being real world and how meters would never see these sort of conditions. Recently, I had an opportunity to pull apart a power supply that had been hit with a real line transient.
it's not cracked, probably the seal failed, I tryed to seal it again with some vitral warnish, it's probably a manufacturing problem, never fell or anything like that, it works just fine, I don't have any precision reference, but I did compare it to the Digitek and it hasn't drifted to much, almost spot on
That's great research, Joe. The Fluke patent is particularly interesting because that is now widely used by others, the plastic shields to supplement the creepage and clearances. As for the RS patents, in the early days of DMMs, input protection varied from maker to maker, but the prime focus was avoiding damage due to incorrect settings such as measuring voltages on ohms range. There was not much talk about impulses.
Once the IEC model for impulses on line voltage was agreed on, by 1992? CAT ratings were created, with a goal of user safety. I think only Fluke continues to state their meters survive the CAT rating impulse while the IEC criteria don't specify the device be functional after a successful test.
Today, I don't think any DMM can survive the required maximum impulse for its CAT rating without externally added impulse protective devices. However, your video series shows some DMMs can be designed to not only pass the CAT rating but also survive the rated impulses.
IIRC, some of your videos also show cheaper meters failing short of their CAT rating, while better brand meters being more consistent.
I think Joe is doing everyone a great service, not only does he have the skills to play with kV, he gives a superb post mortem, repairs the meter quickly [if possible?], then subject it to more impulses. Plus, more kudos for buying these meters himself to avoid patron bias, like a one man Consumer Report.
I don't think anyone on the net has demonstrated just what an impulse would do and compare it against other DMMs, than this series.
...
In Fluke promo video, they show the 87V failing at 17kV, but making it past 15kV [ but they do not show a full functional test between and the test is only done on the V scale.]
Joe I think you clearly show how to remediate this meter to make it a true CAT III, and thanks for ID the other protective devices. The Hioki is built very well, I just can't figure why they didn't go just a tiny bit more to give it the kind of impulse hardening you show can be done, fairly cheaply and easily too.
The office where my missus works recently had some sort of power surge. It left their telephone switching board looking a bit like the PCB in your video.
yes I intend to keep the oldie( it was a gift from somebody very close), but here in brazil it's probably impossible to find a replacement for this LCD, now they started to sell rebranded Brymens here, but they prices are ridiculous, I probably could get a fluke cheaper,but now I can't afford jack...I hope in the near future I'll get at least one real good meter, but...
I'll take a look at my stuff, to see if I can put something togheter
and your videos really do a good service, they are a good reference for people, and thanks to that guy who donated the meters for to testing, a real nice gesture
yes I intend to keep the oldie( it was a gift from somebody very close), but here in brazil it's probably impossible to find a replacement for this LCD, now they started to sell rebranded Brymens here, but they prices are ridiculous, I probably could get a fluke cheaper,but now I can't afford jack...I hope in the near future I'll get at least one real good meter, but...
I'll take a look at my stuff, to see if I can put something togheter
and your videos really do a good service, they are a good reference for people, and thanks to that guy who donated the meters for to testing, a real nice gesture
Wow, the Flukes are less expensive than Brymen! That's a twist!
It was a real nice gesture when 5ky (TechnologyCatalyst on youtube) agreed to donate those meters. I doubt very much I would have continued to test meters had it not been for that. It also forced me to come up with a better way to test them and to start publishing the results. It was a big win for the few people who are following along.
Weekend is here and I have a UNI-T calling my name.....
Thanks and glad your enjoying them. We can't forget about 5KY's contributions as well! Big thanks for giving me the opportunity to see just how much a Fluke 107 can take!!
Heh, the end of that is rather anticlimatic. It'd be really disappointing if that's all it takes to kill that meter. I'm hoping and guessing that it's the soft power feature that's causing the issue there (why do manufacturers feel they have to add soft power on high end meters?)
Btw, one thing you mention in nearly every video is the term FWHH, but I don't understand what that means. Maybe you explained it already somewhere, but I missed it? If not, maybe you could show a scope trace of what it means exactly if you find the time.
dead with one hit??? yeah that old saying is always right, when it looks too good... I'm really disapointed, I tought it would perform better tha that, but the video was excelent
The old Uni-T Achilles heel.