Uni-T UT139c LCD biasing and other mods

[Kbird]

Been a while since I did the mod but I believe you are correct on all counts NiteC0re ,setting the value to 0 (00) should mean there is no time out , so both would become Manual.

There are other hacks you can do too , look for posts on DMM 660L Chipset DMM Hacking eg the Uni-t 210E has the same Chip and is also hackable..
https://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/msg1034969/#msg1034969

If you plan to use it for mains voltage testing it is recommended not to set it up any higher than a 8000 count meter though as it may read incorrectly especially at or above I think it is 200volts eg 220v or 240v.... there is more info in a post here about a Canadian Tire DMM with the same chip , commenting on this issue.

https://www.eevblog.com/forum/testgear/canadian-tire-mastercraft-dmm-new-and-old-revision-teardown/msg927276/#msg927276

KB

[Nitec0re]

Thank you for ur help

It worked 

Code: [Select]

DTM0660 EEPROM dumper and updater.
Waiting for DTM0660 POST and  i2c Bus to settle.
Scanning...

I2C device found at address 0x50
-- : 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00 : FF FF FF FF FF FF FF FF FF 52 00 2C 01 08 C8 03
10 : 10 27 38 18 4E 02 65 4B 3D 3D FF 3B 0A FF 40 FF
20 : 77 98 AF 81 FA 00 32 00 00 80 00 80 4B 7D DE BD
30 : 4E 02 09 25 03 09 62 FF 0A D7 13 0A AE 03 0A 00
40 : 00 01 00 01 00 07 98 00 64 00 64 00 64 00 00 00
50 : 00 80 00 80 00 80 00 80 00 80 00 80 00 80 00 80
60 : 97 7F 89 80 01 00 84 2A 00 00 00 00 00 00 00 00
70 : 61 7F 00 80 61 7E E0 7C 57 2B 00 00 00 00 00 00
80 : 00 00 00 0E 00 10 1E 18 00 00 0C 12 13 07 03 01
90 : 00 00 00 0F 00 11 00 19 00 00 0D 00 15 09 04 02
A0 : 00 00 00 00 00 00 00 00 00 00 00 00 00 0A 00 00
B0 : 00 00 00 00 00 00 00 00 00 00 00 00 00 0B 00 00
C0 : 0D 00 02 20 0D 00 03 20 20 00 03 20 20 00 03 10
D0 : 41 00 03 08 41 00 03 05 41 00 03 05 0D 00 02 20
E0 : E2 F1 0B 80 00 80 00 80 00 80 00 80 00 80 00 80
F0 : 00 80 00 80 00 80 00 80 5A C7 EC 0F 0F 80 00 00 
Setting LCD bias to 3.3V
Done
Extending Power On time
Done
Extending Backight On time
Done

Done.

[Kbird]

good news .......now you'll want a 210E to play with too

[Folxs]

The factory setting for my meters VLCD was 3.0V (taken from the memory dump). I reprogrammed it to 3.3V and the display is now pretty usable. For my taste, the contrast could still need a little bit more oomph, but I am not complaining. 3.3V is the maximum setting, as the DTM0660L datasheet indicates.

(...)

Anyone wanting more info on the issue, feel free to ask!

I assume that VLCD is contrast, but what does VDD does? Changes supplyment od all ICs?

Maybe it is possible to take VDD (3.6V) and short it to VLCD to gain better contrast? (just wondering if antyhin won't burn on PCB)

[UK]

Sorry for the upping such an old thread. But I have a newbie question, how do you guys think will these hacks work for a newer UT139E model?

[frozenfrogz]

Since I do not have one of those, I can not give a definite answer. However, my guess would be, that Uni-T did not opt for a different measuring IC on the updated version. There were no problems with the older models (that I know of) and completely reworking that series is not a thing that is easily done or financially justifiable. Hence, all the EEPROM modifications should work.

Someone having the E or S model would have to confirm though.

[UK]

Since I do not have one of those, I can not give a definite answer. However, my guess would be, that Uni-T did not opt for a different measuring IC on the updated version. There were no problems with the older models (that I know of) and completely reworking that series is not a thing that is easily done or financially justifiable. Hence, all the EEPROM modifications should work.

Someone having the E or S model would have to confirm though.

Thanks for your fast response! I will definitely try to apply these hacks my new UT139E.
Hope I will not brick it

[Folxs]

I have question - is it possible to activate RS232 on 139C? Datasheet says it is - but which pin is going to be responsible for communication? I wanted to add IR diode like in this video: https://youtu.be/8VPsWI963p8?t=7m21s

Can anyone help?

[frozenfrogz]

UART is on pins 20 / 21 of the DTM0660L as taken from: http://www.kerrywong.com/blog/wp-content/uploads/2016/04/DTM0660DataSheet.pdf

[Folxs]

UART is on pins 20 / 21 of the DTM0660L as taken from: http://www.kerrywong.com/blog/wp-content/uploads/2016/04/DTM0660DataSheet.pdf

Are You sure 100% about that?
I have seen that, but this is two way UART - so I thought this is UART between EEPROM and DTM0660.
Does that IR RS232 is two way communication somehow? It shouldn't be only one way?
Best way to find out is to check in other multimeter based on DTM0660 and see where that IR diode resistor is connected and how.

[nicstoun]

Hi, i  buy  139E but with these hack on FC address to 00 or 1E  blacklight time cant change i try everything. Backup eeprom,erase upload with changes. Not way only 15sec.
Any idea why multimer not read changes ?

 

[frozenfrogz]

Please re-check what you are doing. If I remenber correctly, byte 0xFB is where to change the power off time.

[nicstoun]

No, i talk for blacklight time..

[frozenfrogz]

Sorry, misread that on mobile.
Did you read back the value from the EEPROM after programming to check it has been written correctly?

[nicstoun]

Yes, all is correct but there on 139E  include another chip not only dmt006.. Not sure if keep some data from eeprom

[xeezawaki]

I tried to do this mod with a UT139C and it worked with almost no setup

I adjusted the LCD biasing and prevent the backlight to auto turn-off.

I soldered header pins on the board, connected pins to Arduino as shown by @KBird, read the sketch of @frozenfrogz , try to understand what was doing and what was going to happen, uploaded et voilà. Done.

I have a question as I'm quite new on this: the methods that do the bit write are into the loop(). I'm not sure if I did the correct thing, but I waited for two loops (one to see the dump before, and the next to see the dump after and check if bytes were written), and after all bitwrite functions executed i pulled out the 3v3. Did I act correctly or are there less agressive ways to break or stop the loop once everything is done?

Thanks to all people that investigated and made this possible, btw.  

[rogbese]

Hello!
I have the ut139c and I love it. I do electronics and basic electricals. I ordered the ch341a mini programmer and soic8 clip. I will be using the accompanying app. I have ZERO knowledge of hex bit I want to extend the power off time and set the backlight to manual.

I would really appreciate it if someone here could please tell me what addresses to look for and values to change to, to achieve this.

Thanks in advance all... 🙋🏾‍♂️

[Kbird]

See Reply No#25 , there are links to more info I used there ie to FlyWheelz Post.

WARNING : 

MAKE VERY SURE to save the Existing Hex dump in case you need to recalibrate the Meter in the future...this info is UNIQUE to YOUR METER....

[rogbese]

Hello again.

My test clip just arrived and the attached is what i got from the meter.
I just need manual backlight control.
Any help would be greatly appreciated.
And yes, I made a backup already!

Thanks in advance 

[rauldm]

Hi have a new revision of board for this meter, I like it, now multimeter chip and eeprom are located in rear circuit board,  only removed rear cap for access.

[kkontak]

My UT139C meter from work (bought in 2019) is also the new board revision with the eeprom at the back of the PCB, along with the main IC (wafer under blob).

I was able to read the 24C02 eeprom with my miniPRO, but it would not write.
The pins were:
8 V+
7 WP
6 SCL
5 SDA
4 VSS(gnd)

I resorted to desolder the eeprom and program the new BIN file directly with a SOIC8 adapter.

The changes I made were:

ADDRESS OLD -> NEW
8D 07 -> 09 (Mode1 Resistance -> Continuity)
9D 09 -> 0D (Mode2 Continuity -> Resistance)
FC 0F -> B4 (backlight 15s -> 180s)
FB 0F -> 1E (Auto Power OFF 15m -> 30m)

By default, the UT139C starts with DC on V/A modes, so I didn't need to change that, as opposed to the UT210E.

For some reason, the first 9 bytes were all FF, as per DTM0660 DataSheet. I haven't seen that at other's BINs. Even my UT210E had the first 5 bytes all FF.