A look at the Uni-T UT210E

[RoGeorge]

-0.014 ... -0.070 Amps [DC] depends on orientation in the space
I demagnetized it last time about 2 or 3 months ago

Thank you, mine was way off the scale.

I did just now the self calibration described in

I recorded video of process of resetting to zero of the current indications in the DC mode at UT210E. This method allows to reduce residual indications in the mode of measurement of a direct current (DC 2A Dotless, 2A,20A,100A) without the need for EEPROM correction without the programmator. Thanks of kDnZP from a Russian-speaking forum!

ATTENTION! To do only if there is a backup copy of EEPROM!

1. To switch off device.
2. To clamp HOLD+SELECT and to switch to the "resistance, ring-up, diode, condenser" mode.
3. To see a text of "CAL", to release the HOLD+SELECT buttons
4. To wait. To wait long and not to hurry. To wait so far there will pass all self-tests until squeaks, then still to wait and wait for the moment when there are changing indications of the millivoltmeter. I.e. when the self-test will be completely passable, it will take ~ 2-3 minutes.
5. Further it is possible to switch the selector on 20A, to press the ZERO button and to nullify indications. At the same time the instrument in hand not to hold, give time for that that indications calmed down, to place the instrument where least of all el./magn. noises and the more so far away from magnets.
6. To switch the selector on 2A and to repeat the same as in point 5.
7. If necessary it is possible to modify values on other interesting ranges
8. On the end of calibration - to transfer the selector to "OFF"
9. To switch on ut201e and to check indications, if necessary - to repeat.

The link to video which explains this process.
https://yadi.sk/i/bu8eS8uF3ZfK3E

and shown in the linked Russian video (self calibration without a programmer and without opening it, only buttons pressing):
https://disk.yandex.ru/i/bu8eS8uF3ZfK3E

After self-calibrating as shown in the video, my -12.59 A DC offset was removed, but I couldn't reset it for the 100A DC range.  It can be zeroed on 2 and on 20A DC, but on 100A DC the zero only set it to 3 instead of 0.   

Will try again a self-calibration after properly demagnetizing it first.

[Kean]

Can you tell what offset (in DC Amps) your UT210E Pro displays before pressing zero on the DC 2A current range, and no wires, please?

I have three UT210E's.  DC offset on them currently is (depends on orientation)
1: 40mA to 126mA
2: 71mA to 100mA
3: -183mA to -158mA

I haven't demagnetized them recently.  I'll give that a go and see how much these change.

Ediited to add:

After demag I got the following
1: -15mA to 48mA
2: 3mA to 36mA
3: -271mA to -230mA and I can't improve it

[Neutrion]

Did you try this manual calibration method?
In the long video about calibration on youtube it is also explained why this kind offset can be caused by not being calibrated well. So it is not just abut zeroing the offset, or having the correct readout values.

[Neutrion]

So it seems that I have a contact problem with the selector switch. Did not use the meter too much, almost no sign of wear on the traces. Cleaned up the grease a bit, which made it a bit better, but not really perefect. Is any kind of proven method aviable to solve this? Not much info on this forum about this, so maybe I am the only one affected?

Another question is the new version which according to this topic appeared at least around 2019 with new MCU and a new Gainsil  branded op amp, which have slightly different parameters than the original TI part. So I just wonder whether anyone compared the the two versions especially in low amps modes?
Did it get different? More or less drift in the last digits?
Still switches back to the 2000 count mode after being hacked and zeroing it? (Or was it something similar...)

[joeqsmith]

So it seems that I have a contact problem with the selector switch. Did not use the meter too much, almost no sign of wear on the traces. Cleaned up the grease a bit, which made it a bit better, but not really perefect. Is any kind of proven method aviable to solve this? Not much info on this forum about this, so maybe I am the only one affected?

I know several people using them and the switch failure is certainly a common problem with this particular meter.   

[RoGeorge]

Mine was almost never used, the switch is still OK, but the clamp doesn't measure any more. 

I suspect I might have damaged the Hall sensor or its input stage because of a too bigger field during de-magnetizing the UT210E.  Didn't attempt to repair it yet, so I don't know for sure what happened.

[Neutrion]

I would check the flex cables first.

I cleaned the grease properly with isopropyl alcohol. Not sure it was a grease meant to be
on the contact surfaces or whether it migrated down from the plastic mechanism.
But it seems that I solved the problem, now I can push the switch around in all the different modes
without causing contact problems. Hopefully it stays so.
Would be nice to know whether  new meters come with or without grease.

And by the way the main chip on this 2013 modell is marked both with the Hycon sign and the letters j200 and the Dreamtech logo and dtm0660l. This is the VC330 Version from Voltcraft.

Also would be nice to know if the new ones got fast protection diodes, becose these old ones don't seem to have it, so it might wouldnt survive the grillstarter. Not sure about the other generators though.

[BillyO]

I've had no trouble with mine.  I only use it for non-contact current measurement and voltage detection.  Nothing else, but it has been exemplary at doing that (so far).  The sad thing is, you won't get any support from UNI-T.  You can certainly try asking them, but I don't personally know anyone that has gotten a response from them.  My policy with UNI-T, after buying a scope that had minor issues but no updates or fixes or support response, is don't buy anything over $50 from them.  This unit falls into that category.  It's too bad you got little use out of it.

Open it up to see if it's anything obvious.  Perhaps a wire or other component was badly soldered. 

[apelly]

Would be nice to know whether  new meters come with or without grease.

Just got one. I see some sort of grease. See pic.

Also would be nice to know if the new ones got fast protection diodes, becose these old ones don't seem to have it, so it might wouldnt survive the grillstarter. Not sure about the other generators though.

Ha! Hadn't read this far when I had mine open. Can't be arsed opening it again, sorry.

[Neutrion]

Thanks for checking it! It seems to be deliberately greased, just like mine. My idea is,
that this grease looses some of its properties on the longer term and that is what causing the problems.
Because there is really hardly any wearmark visible on the traces if anything at all.
With mine it was like it started to drift around both in ac and dc amps mode, sometimes it was resetting
itself when pusing some buttons or turning the wheel, or not measuring anything at all.Luckily it's all gone now.

Other interesting note: In mine, the iron clamp core doesn't seems to be made of trafo plates. Is it the same with the new ones? Could that be the reason, why Joe was not able to get it to an even higher frequency? How is that made with higher bandwith current scope probes?

[Neutrion]

So meter is still fine.

On the other hand: DC amp in the lower ranges are quiet good but it is linearly getting worse as I am measuring higher amps with like hundreds of mA off at the end of 20 Amp range.
DC offset is 85mA, so I don't think that it is the root cause.

Are there still no argument to not to use the calibration procedure with the buttons?

In one of the longer YT videos from a german guy mentioned not to use the button method but I still couldn't find any info why it would pose a problem. But also not many people in this forum were trying it either.

[andyB2022]

Is there a full guide with all the possbile modifications? Like a PDF file or something? Thanks.

[BillyO]

On the other hand: DC amp in the lower ranges are quiet good but it is linearly getting worse as I am measuring higher amps with like hundreds of mA off at the end of 20 Amp range.

Odd.  Mine actually measures low in the sub 200ma range.

DC offset is 85mA, so I don't think that it is the root cause.

Pressing the "Zero" button should get rid of any offset.  Offset could be due to magnetized jaws or a prevalent magnetic field in your area.  Does changing the orientation of the meter change the offset?

[Evgeniy]

Hi everybody.
Have a clamps UT213C, very similar in schematic with UT210.
By negligence, was measured the voltage on a high-current capacitor in a microwave. The device immediately passed out and does not turn on anymore, in all modes it writes "ErrE", if you press SELECT, then in all (except A) it writes "----".
There are no obvious burned-out elements on the board.
The first thing that came to my mind was the varistors at the input and the posistors, soldered the new varistors - it didn’t help, replaced the posistors (although when measured -+ it matches the nominal value of 15kOhm) with a resistance of 15kOhm, it also didn’t help, the protective resistor at the input, according to the measurement, matches the marking ...
I removed the EEPROM, the data is being read, but I tried to write others, when I read it again, it writes again as it was before... (maybe it's the case?)
Where to dig further, tell me, please.

[Evgeniy]

One more picture.

[Neutrion]

On the other hand: DC amp in the lower ranges are quiet good but it is linearly getting worse as I am measuring higher amps with like hundreds of mA off at the end of 20 Amp range.

Odd.  Mine actually measures low in the sub 200ma range.

DC offset is 85mA, so I don't think that it is the root cause.

Pressing the "Zero" button should get rid of any offset.  Offset could be due to magnetized jaws or a prevalent magnetic field in your area.  Does changing the orientation of the meter change the offset?

Did you try the "button calibration"?

Well, I mean't the offset is not so huge, that some nonlinearity of the sensor in higher range should cause any problem. (As it theoretically could happen when zeroing only in SW.) But don't know which hal sensor is used.

[joeqsmith]

Could that be the reason, why Joe was not able to get it to an even higher frequency? How is that made with higher bandwith current scope probes?

Back in 2016 when I attempted to hack that meter for higher BW, the goal was to see if my troll friend from Czechia would step up and show me some of their engineering skills.  Seemed like a simple enough project for any EE to tackle.     
https://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/msg1048470/#msg1048470

Yes, the core material was a limiting factor.  Some time ago I demonstrated a simple clamp made from a standard split core that was based on the following article.  Maybe you will find it useful. 

http://interferencetechnology.com/the-hf-current-probe-theory-and-application/
   

[Neutrion]

Thanks for the link.
So it seems that a simple monolith ferrit core would do it up to 1GHz. But I suppose it was not only the core which was limiting your frequency.
But I took another look at my meter now, and it seems that I was wrong. The jaw seems to be made of transformator plates, but at the part where it is openly visible, it is polished, so one has to take a loupe to be sure.
But you see it is good to know that with a bit trolling you can get motivated to do such great stuff, next time instead of arguing with you for some high voltage experiment, I will have to try this method.

[joeqsmith]

If the meter had used better materials, yes, I could have pushed it up higher.   Better jaw, MHz for sure.

When trolling the troll, I never released any details about the mods I made.  After all, the goal was to show them up.  While they seemed to have left the group, I figured one of the hobbyist here would at least make an attempt.  It was a very low cost meter after all so there was little investment and it's not like it was a difficult project.  I had some fun with it.   

[Neutrion]

Hi everybody.
Have a clamps UT213C, very similar in schematic with UT210.
By negligence, was measured the voltage on a high-current capacitor in a microwave. The device immediately passed out and does not turn on anymore, in all modes it writes "ErrE", if you press SELECT, then in all (except A) it writes "----".
There are no obvious burned-out elements on the board.
The first thing that came to my mind was the varistors at the input and the posistors, soldered the new varistors - it didn’t help, replaced the posistors (although when measured -+ it matches the nominal value of 15kOhm) with a resistance of 15kOhm, it also didn’t help, the protective resistor at the input, according to the measurement, matches the marking ...
I removed the EEPROM, the data is being read, but I tried to write others, when I read it again, it writes again as it was before... (maybe it's the case?)
Where to dig further, tell me, please.

I can not not help either, but only ask you: What do you think the voltage was about what you tried to measure?
Are the V sense input pins of the micro a dead short or what is the resistance?

Unfortunately as I see it, these meters do not have fast clamping diodes, so generally not so well protected, but unfortunately Joe did not do the torture test on them to know their limits.

[Evgeniy]

What do you think the voltage was about what you tried to measure?

I think approx 2kV.

Are the V sense input pins of the micro a dead short or what is the resistance?

[Neutrion]

I mean the microcontrollers pins directly after the MOVs and PTC's. But actually what you just measured is also strange, as in voltage mode the resistance should be around 10 Mega Ohm.
And of course I suppose the micro is the same as in the ut210-e.

[Evgeniy]

I mean the microcontrollers pins directly after the MOVs and PTC's. But actually what you just measured is also strange, as in voltage mode the resistance should be around 10 Mega Ohm.
And of course I suppose the micro is the same as in the ut210-e.

Ouh, can you tell me the pin on micro?

[Neutrion]

I don't have your meter, but if you follow the trace through the protection devices you will end up at the input pins of the microcontroller where it senses the voltage. If it is zapped I suppose some change of its input resistance there.(I can check it on mine a bit later) IF it is the same micro but I suppose it is. What's written on it?

[Evgeniy]

I don't have your meter, but if you follow the trace through the protection devices you will end up at the input pins of the microcontroller where it senses the voltage. If it is zapped I suppose some change of its input resistance there.(I can check it on mine a bit later) IF it is the same micro but I suppose it is. What's written on it?

Micro is same DTM0660.