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Maintenance Of Maintenance Problems Of LCD Power Bank And Backlight

In the LCD TV, LCD Power Bank and backlight failure rate is high, and most of the failure can be component-level maintenance, in which I provide some maintenance experience for reference.

After receiving the machine, look at the standby light is on, if not bright may fail in the power board, see whether the boot, can not boot,LCD Power Bank and the motherboard may be faulty, need to open the lid to check. Can boot, backlight light up on the issue, the problem may be in the backlight board or power board. There are backlight, a sound, the image is not normal, most of the failure and LCD Power Bank, backlight has nothing to do. Only after a rough estimate of the fault range, open the lid again.

First, troubleshooting steps

Step 1: Look. First look at whether the circuit board burning and ignition traces of whether the fuse is burning black, whether the drum package, resistance, such as whether the burn failure.

Step 2: Measure. Find the largest electrolytic capacitor (usually about 100μf / 450v), it is in front of a heat sink on the boost rectifier diode, first test whether the diode burned, if damaged to be removed, and then the diode as the dividing point Check.

If the short circuit will generally burn the insurance, and that the pfc circuit is faulty; look at the pfc field effect switch tube source (s pole) grounding the small resistance (close to 0ω) whether or not Blown, such as has been burned switch tube "in the catastrophe escape", pfc control chip mostly "glorious sacrifice". Such as a small resistance intact, and then test the switch is damaged (if damaged, remove the old pieces do not install new pieces). Such as switch tube is not bad, and then test the diode to the negative resistance to the ground, such as short-circuit after the switch LCD Power Bank failure.