Products > Test Equipment
Uni-T UT181A and calibration
Thklinge:
--- Quote from: joeqsmith on March 29, 2020, 02:22:24 pm ---These are the specs from the manual I have for the 181A. So +/- 2.1 assuming they are running at 50/60Hz ish. What they are seeing is more like 22 volts off in this range.
--- Quote --- massively off, showing around 206 compared to 228(!!)
--- End quote ---
Granted, I assume they are talking volts and they are looking at their AC mains. Hard to believe that the alignment is not automated for these and one would get out not calibrated. Even the worse, bottom end meters I have looked at, all seem to meet their spec when I receive them. Maybe something else is going on.
One thing I find odd about the story is you spend say $300 - $400 USD on a brand new meter that doesn't work. Why would you even consider taking it apart? Why wouldn't you return it for a replacement? It's as odd as thinking you're going to align your own meter and not screw it up.
--- End quote ---
I too find it odd that it should be off that much, but compared to other DMMs (including a Fluke) it's way off.
I paid 275 usd directly from China. The store put their head in the sand so it's hard returning it. I sent an email to just about every email address on the Uni-T webpages and only the distributor in the Netherlands bothered to answer. They were oblivious to any calibration or service/support. As they said: "we only sell them". Found a re-seller in my country and they wouldn't help since it wasn't bought from them. They suggested a calibration institute so I contacted them and they wanted 100 usd to look at it, 117 usd per hour they work on it and had no idea if they would be able to calibrate it. If they fail they would still be paid.
So that leaves me one option: Fix it myself.
--- Quote from: skander36 on March 29, 2020, 08:10:47 pm ---@Thklinge - On CEM 9979 the calibration function was in menu (Setup) and can be performed with the arrow buttons. Maybe on UNI-T there is a secret combination that show calibration menu.
On board there are two ways to talk with the CPU (USB and JTAG) but I don't think that they can be used for calibration . External USB is through IR and I also don't see as a reliable way for calibration ...
So why I am thinking at a secret menu ...
--- End quote ---
I also think it would be software-based and in some service menu. I'd be happy to try it except I have no idea how to enter that menu if it exists.
skander36:
--- Quote from: joeqsmith on March 29, 2020, 10:47:05 pm ---
I would imagine for those buying the 289, they need the safety certification, or maybe they need a meter that is more electrically robust. After looking at so many UNI-T products, that's the one thing about them is they have not been very robust. The comments about lack of support from UNI-T may be another reason. For the 181A specifically, I can think of other reasons. Lack of standard batteries. When charging, meter is useless, mechanical parts are not the best quality. The screen is very easy to scratch. I could go on.
After seeing a their UT210E switch fail in the last couple of years, I wonder how the 181A's switch would hold up if I were using the meter.
Even with it's shortcomings, I do like the meter.
--- End quote ---
You are right ,
For companies that base their reputation and certified solutions on tools they used, the price of a Fluke 289 is not a problem . Not talking about of electrical security and serviceability .
But for hobbyists and home labs like me those meters offer best ratio value/performance .
joeqsmith:
--- Quote from: skander36 on March 30, 2020, 10:32:42 am ---
--- Quote from: joeqsmith on March 29, 2020, 10:47:05 pm ---
I would imagine for those buying the 289, they need the safety certification, or maybe they need a meter that is more electrically robust. After looking at so many UNI-T products, that's the one thing about them is they have not been very robust. The comments about lack of support from UNI-T may be another reason. For the 181A specifically, I can think of other reasons. Lack of standard batteries. When charging, meter is useless, mechanical parts are not the best quality. The screen is very easy to scratch. I could go on.
After seeing a their UT210E switch fail in the last couple of years, I wonder how the 181A's switch would hold up if I were using the meter.
Even with it's shortcomings, I do like the meter.
--- End quote ---
You are right ,
For companies that base their reputation and certified solutions on tools they used, the price of a Fluke 289 is not a problem . Not talking about of electrical security and serviceability .
But for hobbyists and home labs like me those meters offer best ratio value/performance .
--- End quote ---
If the switch fails after a couple of years of moderate use like what I am now seeing with the UT210E, $300 for 2-3 years of service is not a very good ratio. I would rather spend $900 and have something that will last 20 years and won't go intermittent. Switch aside, the battery pack which is some non-standard part will eventually fail. I have not been using mine enough to know what it's life will be. Will the hobbyist come up with creative and solutions? My guess is yes. Will some of these make for unsafe conditions? Again, my guess is yes.
While you may see it as a good long term investment, I don't.
skander36:
--- Quote from: joeqsmith on March 30, 2020, 12:10:43 pm ---If the switch fails after a couple of years of moderate use like what I am now seeing with the UT210E, $300 for 2-3 years of service is not a very good ratio. I would rather spend $900 and have something that will last 20 years and won't go intermittent. Switch aside, the battery pack which is some non-standard part will eventually fail. I have not been using mine enough to know what it's life will be. Will the hobbyist come up with creative and solutions? My guess is yes. Will some of these make for unsafe conditions? Again, my guess is yes.
While you may see it as a good long term investment, I don't.
--- End quote ---
You make assumptions based on analogies with other models . I also have a UT 61E that has never fail. I use it every day from years. Based on your model of judgement I can assume that UT 181A will last enough to get my money back on it . Also on the reverse I will not credit Fluke 289 based on the many display fading from 87V series for ex. .
It carry the Intertek sign so it can be an Intertek product with a higher quality than UT210E . Is about ETL certification fo US. I did not know about .
Also battery pack is an Intertek model so it must be found somewhere . But you can use any 7.2V Li-Ion pack of similar size that can be found on the market.
Switch seem to be very good built apart from other Uni-T models .
For me 20 years is to much for a tool of such complexity (for an axle , a hammer , maybe is useful) . If it will last 5-7 years is OK. Even it will last more, his place will be in personal museum. I like new technologies , new solutions so a long life for such tools is just for brand reputation ... :)
coromonadalix:
The OP need a way to calibrate his meter, its getting off topic ??
Maybe find other known meter calibration procedures " if any " with the same dmm chipset ???
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