backlight repair / custom led-strip: 3 steps (with pictures)

by:LCD Mall     2020-09-01
Oscilloscope is an indispensable device in electronic products.
Unfortunately, this is not very useful for a broken backlight.
In this instructable I will show you how I can fix the backlight of the oscilloscope & how to make custom led-strip.
The LCD screen consists of several parts: LCD panel, backlight and diffuser (
The layer behind the LCD panel, you guessed it, it will spread the light).
Backlight is a small TL bulb with an inverter (
This will convert the power of the bulb).
I could have bought a replacement, but I chose to make my own backlight.
This also gives me the chance to try SMD welding. Let\'s begin! Since the led-
The strip needs a specific size, starting with measuring the space in which the TL bulb is located.
The mine is 160 × 4mm and the maximum thickness is about 4mm.
Another parameter is the voltage to the inverter.
My range wrote voltage and maximum current near the connector: 8. 4 V, 2.
5 A respectively.
Also verify the voltage with a multimeter.
Based on these measurements, we can choose the number of led and the total amount of led we will be in series.
The white LEDs need about 3v each, so I chose to connect two in series with resistors.
The current of the resistance can then be calculated to be about 15 mA, so I chose 150 ohms :(8. 4 V-6 V)
/15 mA = 150 ohms.
They are placed in my very beautiful paintings (
The Black part is resistance and the orange part is led)
: The number of Pled depends on the available space, the size of the led and the resistance you want to use.
I used a resistance of 0406 size, which is the smallest size I would personally use.
We need custom pcb before we weld anything.
I first cut the pcb to the right size and then print out the template.
I use the toner transfer method to transfer the design and etching the circuit board with iron chloride.
There are a lot of guides here on how to do this.
Once our pcb is ready, it\'s time to weld the resistors and LEDs.
It\'s a tedious job, so you have to take the time to wait patiently.
In addition, make sure to test the polarity of the led before welding.
I used some blue light.
Fix the small pieces in the appropriate position when welding.
As you can see in the photo, led-
The belt is very bright.
Now our led
We can install it on the oscilloscope.
For installation, first disconnect the power supply of the inverter and check the polarity of its wires.
By connecting these wires to your led-strip. Place the led-
Peel off in the display component and make sure it stays in place.
I added some paper to the back of the strap and attached it to the diffuser.
Pass the cable through the hole and close the display assembly.
Connect all the other cables you may disconnect and test them!
Your display should light up if everything goes well.
Due to the large number of led, the brightness of the screen is very uniform and very bright.
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