This old Skyworth LCD TV again

DIAG

This old Skyworth LCD TV again [Copy link]

It’s still the old 32 Skyworth LCD TV, with simple functions, suitable for my grandma. The auxiliary 5V power supply was repaired once at the end of 2016, but it broke again after more than two years of use. Now I can occasionally see the boot screen, and then there are "three noes". When I shine a flashlight on the LCD panel, there is no image. It is not a backlight problem. I think it is a power supply problem. After disassembling it, I found that the capacitor was swollen. I won’t talk about the heat dissipation design problem here. It’s meaningless after all, the TV has been used for ten years. I think Skyworth is still conscientious! I also want to thank Teacher Maychang for giving me the electronic components that helped me repair the TV!

懒猫爱飞

Capacitor aging

dcexpert

Such large capacitors are rarely used nowadays.

okhxyyo

The quality is still good. My Xaxin TV started to break down within a year after I bought it, and it broke completely after two years. I bought a new one later. I feel that the quality of early products is still good.

DIAG

dcexpert Published on 2019-3-25 09:26 Such large capacitors are rarely used nowadays

Those with higher power still need larger capacitors, and those who play audio have even larger capacitors!

DIAG

okhxyyo posted on 2019-3-25 11:08 The quality is still good. My Xiaxin TV started to have problems within less than a year after I bought it. It was completely broken after two years. Then I bought a new one. It still feels like the early Dong...

Yes, I have always bought Skyworth TVs, Huawei phones, and Changan cars.

qwqwqw2088

I didn't see clearly that these capacitors are 1000uF, how many V should they be? It's not cheap to buy a few.

DIAG

It was still the old Skyworth TV. The fault phenomenon was that it could start up normally and the TV programs would turn off automatically after a few minutes. There was no fault and the power indicator light was not on. After a few minutes, the program could be automatically restored. It was judged to be a power supply problem. The 5V power supply was only about 3.4V after disassembling the machine and measuring it online. It was only about 4.5V under normal circumstances. After replacing the bulging capacitor, the fault still existed. In the end, it would not start up at all.
The power board was repaired offline. The 5V power supply chip was P1014AP10. I forgot whether pin 1 supplied 7.8V or 8.8V. I then looked for the TL431 chip and found the sampling resistor between pins 1 and 2 and the output power supply. I found that the resistance of R664 had changed (the board was not tested and was full of white glue. It was more than ten kilo-ohms after being removed). The silk screen was 242 (chip). The voltage divider resistor was R660, and the silk screen was 2491 (about 2.5K measured online). Fixed resistors plus adjustable resistors, adjust the output voltage, remove and measure the resistance value,

Discrete components are spliced with a close resistor,

After installation, it is OK.
Note: It is best to add an isolated power supply when repairing the power board! ! !

When I searched for the fault online, I found that the circuit diagram of the power board was quoted from the home appliance repair information website.