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Electronics => Projects, Designs, and Technical Stuff => Topic started by: hgg on February 11, 2017, 06:16:59 pm

Title: UNI-T UT61E Backlight mod with a twist...
Post by: hgg on February 11, 2017, 06:16:59 pm
Hi everybody,

Here is just another UT61E backlight mod but with a twist.
This is the usual obligatory modification for every UT61E owner.   :)

I had this project going for some months but never found the time to finish it.
The fact that I had to solder mod wires to the ES51922 was scary enough to stop me every time...
Finally I found the courage to do it and here is the finished product: (

I've designed the circuit and ended up with the following schematic and components :

( (

Then I placed an order with Elecrow which I highly recommend since they deliver very decent PCBs
with the lowest prices. 

( (

I started populating the PCB with all the components and then I remembered why SMD work is not my definition of fun...
Dimensions of the PCB are 2.7cm x 2cm

( (

Since I had to solder a single wire on the main IC, that was a nice opportunity to modify the factory disabled
sleep timer and RS232 functionality as well.  Which means two wires...

Nightmare!  I almost destroyed the multimeter!  I soldered two pins together and couldn't remove the solder,
twisted one pin.  These pins are extremely fragile!  After the proper prayers the mod wires were in place.   :phew:

( (

The RS232 pin had to be cut from the PCB trace:

( (

Below are some pictures with all the places I needed to connect all the mod wires:

RS232 connections:
( (

Ground for PCB and LEDs :
( (

Buzzer Pad :
( (

LED wires connected :
( (

LEDs were glued in place with Loctite Super Glue GEL.  The LEDs are underneath the wires.
(The Gel version is way better than the original.)

( (

RS232 wires and IR phototransistor in place :
(You also need to solder an IR Led and a resistor to the supplied serial cable PCB which already
has the options but were unpopulated).
( (

Buzzer wire :
( (

Populated PCB piggybacked on the main PCB:
You can also see the PCB VCC red wire connected to UT61E V+ which is live only when the unit is switched on.
( (

For the touchpad I used a small piece from a copper sheet 0.12mm :
( (

and below is the finished product :

( (

Power consumption of the piggyback PCB is 30nA when OFF and 8.8mA with both SMD LEDs ON.

Final power consumption of the UT61E now is:
2.38mA in Voltage mode,
2.47mA with RS232 ON,
10.6mA with LEDs ON and
178uA in sleep mode.

All in all I am very satisfied with the upgrade.

The only glitch that it has is, when the backlight is on and you turn the switch only counterclockwise,
it might get a false command and turn the backlight off. Maybe this is because I have not shielded
the purple wire that runs from the small PCB to the copper touch pad.


Title: Re: UNI-T UT61E Backlight mod with a twist...
Post by: JucaTec on October 17, 2018, 01:26:05 am

Can you recharge the circuit images?

Thank you.
Title: Re: UNI-T UT61E Backlight mod with a twist...
Post by: hgg on October 17, 2018, 04:27:42 am


Here is a link I've created with all the photos : (