LED backlight universal board replacement method example [Kangjia three-in-one board backlight transformation] - Home Appliances

LED light-emitting diode

A Konka LED26F2200C LCD TV was brought in with a problem where the backlight wasn’t bright, but there was sound. Upon inspection, it turned out to be a three-in-one motherboard. The backlight circuit components such as the boost diode, FET, and some resistors were burned, causing the board to appear blackened from heat. After repair, the seller recommended replacing the entire board, though other parts seemed fine. Since the issue was likely isolated to the backlight, I decided to try fixing the original circuit instead of replacing the whole board. There are several options for external backlight solutions available online. One common type is a low-voltage power supply, which typically outputs around 24V and provides a constant current below 100V. Another option is a high-voltage booster board, often using around 100V to drive the LED strips. These boards usually have higher output voltages, ranging from 100V to 200V, depending on how many LED beads are connected in series. To determine the right replacement, I looked at the voltage rating of the filter capacitor on the original board. If it was rated at 100V, that indicated a low-voltage LED strip. A 250V-rated capacitor, on the other hand, suggested a high-voltage setup. Measuring the no-load output voltage could also help—some high-voltage boards can reach over 200V. Below are the steps I took during the repair process:
This is the original three-in-one motherboard.

Removed the damaged components from the backlight booster section; the rest of the board remained untouched.

Located the 12V, 100V power supply lines and the backlight control signal connections.

Identified key ICs used in the backlight control circuit.

Connected the appropriate signals for the new backlight system.

The original LED strip was connected in two series groups to maintain the same performance as the original.

Ensured all wiring was correctly connected to avoid short circuits or incorrect polarity.

After installation, the operating voltage of the LED strip was measured at about 125V. The brightness varied slightly depending on the voltage level.
The TV successfully lit up, and the display quality matched the original unit. [attach]421519[/attach][attach]421518[/attach][attach]421517[/attach]