Author Topic: Uni-T UT181A and calibration  (Read 11905 times)

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Offline JulienS

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Re: Uni-T UT181A and calibration
« Reply #25 on: February 25, 2024, 09:49:14 am »
I think I have found a door but we need the key ...
Keeping pressed F2 and F3 pres On/Off button.
And the screen with a 5 zeros appear . This can be modified with arrows to form a code . 00000 as to CEM is not working ...
I will search for key used in other uni-t dmms .
Hi everyone, better late than never ! the key code is 02089.
 
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Offline joeqsmith

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Re: Uni-T UT181A and calibration
« Reply #26 on: February 25, 2024, 04:19:42 pm »
I predict an increase in posts about how the UT181A is not accurate.  :-DD

Offline Bobson

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Re: Uni-T UT181A and calibration
« Reply #27 on: June 27, 2024, 05:50:02 am »
UT-171B to enter CAL mode turn on while pressing RANGE+STORE. Password is the same, 02089.
However, unlike UT-181A where you just type in proper values, UT-171B shows some CHANGING value at secondary readout, and it is unclear how to change primary value.
 
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Offline stj

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Re: Uni-T UT181A and calibration
« Reply #28 on: June 27, 2024, 12:52:32 pm »
lets apply some logic.

the meter is new.
it was probably calibrated on an automated system before being packed.
it has travelled a long way.

i would open it and look for bad soldering or other physical issues.
 

Offline Bobson

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Re: Uni-T UT181A and calibration
« Reply #29 on: June 27, 2024, 06:33:35 pm »
lets apply some logic.

the meter is new.
it was probably calibrated on an automated system before being packed.
it has travelled a long way.

i would open it and look for bad soldering or other physical issues.

How does it correspond to the adjustment protocol?
 

Offline stj

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Re: Uni-T UT181A and calibration
« Reply #30 on: June 29, 2024, 03:07:01 pm »
it doesnt have anything to do with ajustment protocol.
why would you mess up the calibration if it may just be a cracked solder joint?
changing the factory calibration should be the very last option, not the first!
 

Offline Bobson

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Re: Uni-T UT181A and calibration
« Reply #31 on: July 23, 2024, 03:39:20 am »
What made you believe it was the first option?
 

Offline stj

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Re: Uni-T UT181A and calibration
« Reply #32 on: July 24, 2024, 12:33:56 am »
it's the first thing people think of when they get something. :(
 

Offline sstenks

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Re: Uni-T UT181A and calibration
« Reply #33 on: August 28, 2024, 02:11:34 pm »
I have the same problem with UT181a with AC voltage it measures 205V on other multimeters 225V ..etc
I tried to calibrate the AC voltage but it does not accept the calibration, everything else works DC, A, mA ... how to solve this?
Thank you in advance
Everything that strives for perfection tends to self-destruction.
 

Offline sstenks

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Re: Uni-T UT181A and calibration
« Reply #34 on: August 31, 2024, 12:42:59 pm »
Hello,
Just to let you know that I found a way to successfully calibrate the AC voltage on the UT-181A I will post the details soon and hope it helps whoever needs it. I still can't calibrate the 1000V range but I'm working on it. Thank you all once again for the constructive consideration of the problem, they really complicated it 🙂😊😁
Everything that strives for perfection tends to self-destruction.
 

Offline janiorib

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Re: Uni-T UT181A and calibration
« Reply #35 on: September 01, 2024, 04:46:48 pm »
Mine on the 1000 vac scale measured 208 vac on a 220 vac reference, thanks, this post solved my problem, thank you.
 

Offline sstenks

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Re: Uni-T UT181A and calibration
« Reply #36 on: September 01, 2024, 08:08:32 pm »
Result of today, successfully calibrated range (1000V AC) but not finished it completely. Otherwise, let me say that the ut181a is calibrated at several different frequencies and goes up to 100KHz.

Just to add that you will need a function generator to calibrate the AC range, preferably with the highest possible output voltage, in my case it is 20V.
It is possible that you will need a function generator amplifier for this job since the sine signal drop quickly above 4Khz and that is only if you decide to go on this adventure.
What is important is that for everyday work it is possible to calibrate the AC voltage with the help of a small ordinary transformer using it as an amplifier of the AC signal.
To be honest, I doubt anyone will measure 1000V at 100KHz.
That's it for now, I'll look at making a little tutorial with pictures after the job is done to make it easier to set up.
« Last Edit: September 02, 2024, 03:39:31 am by sstenks »
Everything that strives for perfection tends to self-destruction.
 
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