UN40F6300 backlight repair and LED current adjustment UN40F5500
45.7 هزار بار بازدید -
7 سال پیش
-
The video shows the process
The video shows the process of replacing single LEDs of the backlight in this Samsung Smart TV.
If you're not sure if your backlight is defective and don't have an oscilloscope the video will show you how and what voltage to apply to which pins in the backlight connector before opening it up in order to test them.
The power supply board (containing the LED driver) is the BN44-00645A. It uses 1 controller chip to drive two different branches of the backlight. One drives 3x13 LEDs, the other one 4x13 LEDs.
The LED current should be decreased after repair. This can be done by increasing two small 1W resistors from 3.6R to 4R7 or 5R6.
When just an LED is faulty without damage to the PCB it can simply be replaced. When the PCB is damaged/burned the whole LED strip can be replaced OR the damaged part can be isolated/cut out and replaced with a piece of another LED strip like in this video : Easy DIY LED TV backlight repair
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There are also 2 components in SOD323 packages on the LED strips. These are apparently TVS diodes, marked on the PCB as 12V and 24V.
They are in parallel with their respective LEDs, the larger part of the strip having a 12V and 24V (both in series then in parallel to the LEDs) and a single 24V diode for the shorter part of the strip. They should provide protection against transients to the LEDs. However, when one LED opens , the LED driver will try to increase the voltage (because there is no current) and that will burn these diodes. The 24V marked part starts conducting from 32V in both directions.
The BN44-00645D is slightly different from the "A". Increase the resistance of the 4 4R7 resistors in a 1206 package near the two LED driver chips in a SOIC8 package to lower the LED current. I replaced them with 8R2 resistors.
If you're not sure if your backlight is defective and don't have an oscilloscope the video will show you how and what voltage to apply to which pins in the backlight connector before opening it up in order to test them.
The power supply board (containing the LED driver) is the BN44-00645A. It uses 1 controller chip to drive two different branches of the backlight. One drives 3x13 LEDs, the other one 4x13 LEDs.
The LED current should be decreased after repair. This can be done by increasing two small 1W resistors from 3.6R to 4R7 or 5R6.
When just an LED is faulty without damage to the PCB it can simply be replaced. When the PCB is damaged/burned the whole LED strip can be replaced OR the damaged part can be isolated/cut out and replaced with a piece of another LED strip like in this video : Easy DIY LED TV backlight repair
-------------------------------------------------------------------------------------------------------
There are also 2 components in SOD323 packages on the LED strips. These are apparently TVS diodes, marked on the PCB as 12V and 24V.
They are in parallel with their respective LEDs, the larger part of the strip having a 12V and 24V (both in series then in parallel to the LEDs) and a single 24V diode for the shorter part of the strip. They should provide protection against transients to the LEDs. However, when one LED opens , the LED driver will try to increase the voltage (because there is no current) and that will burn these diodes. The 24V marked part starts conducting from 32V in both directions.
The BN44-00645D is slightly different from the "A". Increase the resistance of the 4 4R7 resistors in a 1206 package near the two LED driver chips in a SOIC8 package to lower the LED current. I replaced them with 8R2 resistors.
7 سال پیش
در تاریخ 1396/05/10 منتشر شده
است.
45,751
بـار بازدید شده