A look at the Uni-T UT210E

[SkyMaster]

My UT210E reads about 60 mA DC before I zero it. Then by rotating it I saw up to +/- 36 mA, but +/- 20 mA seems to be more typical.

[bitseeker]

I just grabbed mine. On the 2A range, it showed 3 mA when turned on. After zeroing, moving it around indicated a maximum of 20 mA and a minimum of -9 mA. After setting it down for about a minute in the same location and orientation as when I zeroed it, it now reads -2 mA.

[thisguy]

7 pages is a lot to read.  Pg 4 post 96 may be of interest.

I ended up sending it back.  Even when I was careful, as often as not it would read out of spec when measuring low DC current. If I understand your post 96, I may have been able to tweak the trimpots to bring the offset down and reduce the variability by adjusting the null, but after doing this the 'range calibration ratio' may have still been off, and I don't see how to adjust that yet. Today was the last day I could send it back. If I had more time I might have tried adjusting the trim-pots. I'll order another and see if it behaves a better.

[bitseeker]

Last day! Yeah, good thing you sent it back. No need to mess with it if you can get it exchanged. Hopefully, the replacement will be fine. Let us know.

[joeqsmith]

Degauss, null, set offset.    No need to turn off something you want to measure.  Position probe, null, clamp and measure.   TC is not a problem for me as it is rare I have it on for more than a half minute or so.   Been using the one a fair amount and been pretty happy with it.   Still need to make a better degauss for it.  Time to time, I do something stupid and can't null it.   For the price, I just can't complain.  It does a good job. 

7 pages is a lot to read.  Pg 4 post 96 may be of interest.

I ended up sending it back.  Even when I was careful, as often as not it would read out of spec when measuring low DC current. If I understand your post 96, I may have been able to tweak the trimpots to bring the offset down and reduce the variability by adjusting the null, but after doing this the 'range calibration ratio' may have still been off, and I don't see how to adjust that yet. Today was the last day I could send it back. If I had more time I might have tried adjusting the trim-pots. I'll order another and see if it behaves a better.

[fedcas]

Hi everyone,
today I tried reading a AC current, specifically the output from this kind of 12 V AC switching power supply with a halogen bulb attached:



The clamp meter shows a few mA reading, while my normal multimeter set on AC current shows over 3A... how is that possible? Somehow the output must not be a sinewave, but I thought that didn't matter since it is true RMS.

For instance, the same bulb attached to a 12 V toroidal transformer correctly showed the current reading with the clamp meter.

[bitseeker]

Was the clamp across one output wire or both output wires?

[Circlotron]

Those things are a switch mode power supply with no output rectifier or filter capacitor. They output a square kind of AC wave at maybe 50-100kHz so probably the meter cannot respond to this high frequency.

[bitseeker]

Woah, yeah, if the frequency is that high, it's going to look like near-zero DC.

[fedcas]

Those things are a switch mode power supply with no output rectifier or filter capacitor. They output a square kind of AC wave at maybe 50-100kHz so probably the meter cannot respond to this high frequency.

thanks after I posted i was thinking over the fact that the output is AC and I was suspecting something like that... after all the input is rectified at first, so no 50 Hz after that.

[tronde]

Seems like our friends in Russia have more to tell:

NCV added substate level in millivolts - 9Ch = 02h !!!
NCV mode can now operate as a voltmeter electromagnetic field without sound, can now be more accurately find a wire in the wall. In normal mode, the maximum beeps and can not see how to change values ??after pinning. This feature is found by chance in the search for the frequency!


http://kazus.ru/forums/showthread.php?t=112135&page=62
Scroll down and use google translate.

[thisguy]

Last day! Yeah, good thing you sent it back. No need to mess with it if you can get it exchanged. Hopefully, the replacement will be fine. Let us know.

My replacement ut210e got here. It's better than the one I returned, but still varies quite a bit more that yours. I set it for 2A DC and zeroed the meter. Rotating it up and down by 180 deg can still cause the reading to vary by 145mA. That's two different meters from two different vendors, so I'll assume that this amount of variation is typical, and I'll just ignore the least significant digit when reading in the DC mA range.

[flywheelz]

Finally I cracked open my ut210e to mod the eeprom.  I am using Arduino wired directly to the header next to the chip.  At first the chip would not respond.  I then disconnected the WP pin 7 from GND and now I can dump the eeprom.  But as soon as WP is grounded the chip will not respond.  I noticed when WP is grounded the SCL and SDA drop to ~2.5volts. 

Any ideas?

here is data from my eeprom

Code: [Select]

FF FF FF FF FF 00 80 E8 03 E8 03 FA 00 00 BE 03
70 17 98 08 BE 00 3D 3D 3C 3C FF FF 0A FF 40 FF
7A 98 06 81 64 00 96 00 00 80 17 80 FB 7E 38 75
4E 02 09 5A 02 09 A0 FF 0A 3D 13 0A 5D 03 0A 00
00 01 00 01 00 07 98 00 64 00 64 00 64 00 00 00
83 75 EC 70 00 80 00 80 00 00 00 00 01 00 00 00
E3 7F 48 7E 01 00 BA 2A 00 00 00 00 00 00 00 00
C2 7F 00 80 0A 80 E0 7C 07 06 00 00 00 00 00 00
00 00 00 00 00 00 00 17 00 00 00 19 1E 1B 04 07
00 00 00 00 00 00 00 16 00 00 00 18 00 1A 05 09
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0A
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0B
0D 00 02 30 0D 00 03 20 20 00 03 20 20 00 03 10
41 00 03 08 41 00 03 05 41 00 03 05 0D 00 02 30
00 80 00 80 00 80 00 80 00 80 49 02 E5 03 59 05
4A 02 EB 03 6E 05 00 80 5A C7 EF 0F 0F 80 00 00

[stj]

read the datasheet, WP wont stop you reading it.

your problem is something else is using the serial bus - try grounding / shorting the crystal to stop the cpu.

[bitseeker]

Finally I cracked open my ut210e to mod the eeprom.  I am using Arduino wired directly to the header next to the chip.  At first the chip would not respond.  I then disconnected the WP pin 7 from GND and now I can dump the eeprom.  But as soon as WP is grounded the chip will not respond.  I noticed when WP is grounded the SCL and SDA drop to ~2.5volts. 

Any ideas?

Did you set the mode selector knob to a position other than Off?

https://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/msg924060/#msg924060

[flywheelz]

I can read the eeprom just fine as long as WP is not grounded.  The ut210e circuit design pulls WP high through 10k. 

Trouble starts when I ground the WP, then I can't read or write.  Maybe I need to remove the 10k on the pcb?  But others did not need to do that.

I am reading Kerry's blog, http://www.kerrywong.com/2016/03/19/hacking-dtm0660l-based-multimeters/

With WP not grounded I get:

Code: [Select]

VCC=4.90V
WP=4.90V
SCL=4.70V
SDA=4.85V
With WP grounded I get:

Code: [Select]

VCC=4.84V
WP=0.01V
SCL=2.34V
SDA=2.40V
So I am why grounding WP also pulls down SCL and SDA to ~2.4volts.

I did move the Selector from Off.

Update: Removed the WP pull-up 10k but the problem still there    Also, I noticed with WP not connected the meter beeps twice but with WP grounded it makes two cracking sound, weird.

[bitseeker]

Something very odd going on there. First I've heard of this.

[flywheelz]

Something very odd going on there. First I've heard of this.

I tried adding a pair of external 10k resistors for SCL and SDA but they are still at around 2.37volts.  Its as if the chip (maybe bad) or meter clamping down as soon as I ground the WP (WP pull-up 10K resistor already removed).  I think WP should be isolated from the rest of PCB without the pull-up.  Next step will be to try lifting pins.

I don't see any solder bridges or shorts.  I am wondering if the paper behind the LCD is conductive?  Its possible the pins I have soldered in are touching the paper.

The good thing is I was able to get a good original eeprom dump.  I could also install a new chip.

[flywheelz]

Looks like the eeprom's WP pin (2nd from bottom) is connected on top side of pcb to the proccessor.  I wonder why?

Update:

The WP is connected to DTM0660 [Pin 13] (PT2.3, TMCK1, LVDIN, Data input/output. RC clock input, LVD external input).  It might not be happy to be grounded on this pin.

[flywheelz]

*SUCCESS*   Man, I like this UT210E so much more now with these mods.  It defaults to DC(v)(a), 6000 count, 3min backlight, 30min Power-off, full 6000 count 2A Dotless mode and NCV extra readings, WoW 

Got up this morning with fresh mind and a set of rested eyes and had another go at it.  First I tried grounding the XTAL as stj suggested but it did not help.

I was going to lift WP pin or cut traces but decided to first try grounding the processors RESET pin like seen in this video
https://youtu.be/el3rW7O27IQ

However, I could not find the RST pad on my UT210E   Opened up the DTM0660 datasheet and found the RST is on pin 55.  Looking at PCB I found a Cap I could easily attach the ground to to set RST low.

Here is how I did it with Arduino UNO.  I've attached the sketch I used based on Kerry's D source with additions. 

I just wired it up as shown in the diagram.

I held a grounded jumper wire on the side of the capacitor shown in diagram. No need to solder to it.  It only takes 3 seconds to dump/flash.

Switch UT210E to ~V mode then plug in Arduino into the USB.  Open the attached i2cArduino210E.ino sketch in Arduino IDE.  Open Serial Monitor window (CTRL+SHIFT+M).  Now upload the sketch.  You should see your eeprom dump in Serial Monitor window.  You better Copy/Paste it for backup. 

Now you must edit line 9 and 10 by using data from your dump.

Code: [Select]

 
  //Dotless mode calibration data, copied from 0x50, 0x51
  writeByte(I2C_ADDR, 0x56, (byte) 0x83);
  writeByte(I2C_ADDR, 0x57, (byte) 0x75);
If all good, you can edit MODeeprom() as you like, uncomment the //MODeeprom() inside setup() function and Re-Upload to Arduino.  Arduino will reset and flash the eeprom.  You will see ...Flashing EEPROM... between Before/After dumps in the Serial Monitor window.  I hope others will find this useful.

Thank you everyone!

The changes I've done to my eeprom so far:

ADDR   |  OLD  | NEW
6200 Count

Code: [Select]

12: 98 38
13: 08 18
All Alarms disabled

Code: [Select]

16: 3D FF
17: 3D FF
18: 3C FF
19: 3C FF
1C: 0A FF
2A Dotless mode calibration data device specific, copy yours from 0x50 to 0x56, 0x51 to 0x57.  Required if you enable Dotless 2A mode.

Code: [Select]

56: 00 ??
57: 80 ??

2A modes: 1. Dotless DCA, 2. Dotless ACA, 3. Dot DCA, 4. Dot ACA

Code: [Select]

87: 17 1C
97: 16 1D
A7: 00 16
 B7: 00 17
20A modes: 1 Dot DCA, 2. Dot ACA

Code: [Select]

8B: 19 18
9B: 18 19
100A modes: 1 Dot DCA, 2. Dot ACA

Code: [Select]

8D: 1B 1A
9D: 1A 1B

V modes: 1. DCV, 2. ACV, 3. DCmV, 4. ACmV

Code: [Select]

8E: 04 03
9E: 05 04
AE: 00 05
BE: 00 06
NCV, NCV mV

Code: [Select]

9C: 00 02
AC: 00 1D
30 min Auto power off

Code: [Select]

FB: 0F 1E
3 min Backlight off

Code: [Select]

FC: 0F B4
credits:  People in this thread and on Russian and Chinese forums.

[bitseeker]

Wow, flywheelz, you've been busy. Good to see you've had success. Has this not come up before or do I just not recall it? It makes sense, though, as putting processors into reset is a common method for freeing up a bus when snooping.

[flywheelz]

Wow, flywheelz, you've been busy. Good to see you've had success. Has this not come up before or do I just not recall it? It makes sense, though, as putting processors into reset is a common method for freeing up a bus when snooping.

I don't remember anyone mentioning about RESET as a required step on here.  Maybe I missed it while being occupied with the Transistor Tester  . 

I first saw about it on the Russian site  Then I found the youtube video that I linked above.  Without grounding RESET and WP grounded the meter flashes "ErrE" once then goes blank, speaker crackles twice and it locks up the serial bus.

Btw, just fyi, I also ran across some custom flash for USBasp that supposedly adds supports for reading 24's, 25's eeproms.  Link Link2

[flywheelz]

Anyone willing to test two new eeprom mods?  It gives two new functions in 2A mode.  Its reported on the Russian site that these functions still have the full count even after zeroing out (i.e. doesn't go back to 2000).  The LCD does not show a "." in the read out.

Update:  Tested the DCA 0000 function in 2A and it truly works even after zeroing out. 

Code: [Select]

       old      new
 A7: 00 1C - DCA 0000 in 2A mode / SELECT slot 3
 B7: 00 1D - ACA 0000 in 2A mode / SELECT slot 4

[flywheelz]

Another interesting mod is at address 19h.  It turns on beeping warning alarm when you hit 60x.x volts on display (default 3C value = 60). 

I've changed it to 0B which is 11x and now it starts beeping when checking mains voltage   One negative side affect is its starts beeping in 2A 0000 function when it reads 11xx.  Oh well.

Code: [Select]

       old     new
 19: 3C 0B

[bitseeker]

Update:  Tested the DCA 0000 function in 2A and it truly works even after zeroing out. 

What does that function do?