Don't make it simple to complicate - Home Appliances

One-piece inductor

I was given a Konka LCD TV, 32 inches, LED model forgotten. The main issue is that there is sound and the remote control works, but the screen is dark and the image is barely visible in a dark room. The user mentioned that after a repair, the same problem returned within two days. He had to go through multiple repairs, and eventually cut off contact with the after-sales service. When he brought it back for testing, everything worked fine — so the user wasn’t lying. After checking, I initially suspected the backlight voltage was too low. Next step: talk to the user about the cost [omitted]. Coming home, I opened the unit and found it uses a three-in-one board. Power on, since the screen is dim, I measured the main voltage and skipped the smaller ones. The measured voltage was as follows: [image]. This 97V comes from the backlight boost circuit, which seems normal. But when I checked the voltage after boosting (the actual backlight LED power supply), it was only 105V — clearly abnormal. Normally, this should be around 135V–150V, depending on the model. [image]. Since the voltage is at 105V, the backlight circuit appears to be working. Turning the board over, I saw something strange — the legendary protection circuit. [image]. No matter what, I first restored the original look. Powered on again, the backlight LED power supply still showed 105V. Then I tested the filter electrolytic capacitor in the backlight LED power supply (22UF/250V). Measured in the forward direction, it showed a fixed resistance of about 7K, and in reverse, it didn't charge or discharge. Everything looked good. I removed the familiar 22UF/250V capacitor and replaced it with a new one. Here's the result: [image]. Compared with a new one: [image]. After replacing the capacitor, I powered it on again: [image]. Things are looking better now. The last picture shows the final result: [image]. Great success! If the above case was a simple fix, the next one could be more complicated. I'll take time to sort it out later. [images of other components: Psb (22), Psb (21), Psb (12), Psb (13), Psb (23)].