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

LED light-emitting diode

A Konka LED26F2200C liquid crystal appears backlight is not bright with sound, check is a three-in-one motherboard, backlight circuit boost diode, FET, chip and some chip resistors have burned the board heat black, has been repaired after the sale said must be changed Board, consider other parts no problem. Individual backlight problem should be able to take external backlight repair, so prepare to repair and repair the original backlight circuit, there are various general-purpose backlights on the Internet to buy, there are generally several types: one is low-voltage power supply, output The voltage is also relatively low, such as the power supply 24V output of about 80V, the constant current voltage of this board using low voltage power supply output is generally below 100V. The other type is a booster board that uses high-voltage power supply. The common one is about 100V. For example, many three-in-one boards are another set of 100V voltages dedicated to backlight boosting. The output voltage is generally relatively high, that is, LED strips. There are many series of lamp beads in series. Most of the output voltages are in the range of 100-200. The key is to look at the number structure of the lamp strips. Different machine voltages are different, but as long as the lamp bar voltage is clearly defined, Backlight boost power supply can be replaced, here is a common way to judge, look at the withstand voltage output of the constant current output filter capacitor can be judged, generally 100V is the low voltage light bar, the output capacitor is 250V is the high voltage This high voltage powered backlight is used. The output voltage no-load measurement can reach more than 200 points. The following maintenance examples and pictures are introduced:

This is the original three-in-one motherboard

Remove the damaged components of the booster part of the original machine, and the rest will not move.

Find 12V, 100V power supply and backlight control signal line connection


The original light bar is connected in series for two groups, keeping the performance of the original machine the same as that of the original machine, preventing the line from being damaged or connecting to the wrong one.

Connect all wiring correctly

Finally, the installation can be fixed. Measuring the operating voltage of the light bar is about 125V, and the backlight brightness varies slightly with different voltages.

Successfully lit, the effect is the same as the original machine
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