32-inch Konka LCD TV cold boot protection without backlight, sound failure repair example - android - Phones Developers

LC03-3.3 SOP8 TVS Static Protection 3.3V

KKST patch plug-in active passive crystal oscillator hot sale 24.576000MHZ

Today, I received a 32-inch Konka LCD TV with a strange issue: it wouldn't boot properly and had no backlight or sound on the first attempt. Sometimes it would start after a second try, but not always. After discussing the price with the customer, we agreed to replace the power board (model 34006601). However, after some negotiation, the user decided to repair the board instead.

I started by disassembling the unit and checking the voltage levels. I wondered if there was interference causing the backlight to stay off. Then I came across a similar problem on a forum for the same model. I tried shorting resistor R773, but the issue remained. I also increased the capacity of capacitor C756, but that didn’t help either. The aluminum foil on the back of the logic board was still in place, and none of these steps fixed the problem.

Could it be a faulty power supply? I checked for any cold solder joints, but nothing obvious was found. At this point, I was feeling pretty discouraged. After two hours of troubleshooting, I accidentally noticed that the backlight flickered briefly before the system failed to boot. The screen was plastic, so I considered whether the internal aluminum foil might have been damaged. This reminded me of a similar Hisense TV repair I had done before.

I decided to take apart the screen. It was a real mess—there were over 10 broken pieces, and 6 of them were completely shattered. I carefully reattached the aluminum foil and added an extra vertical strip on both sides. After reassembling the screen, I tested the TV again, and the issue was gone! To be safe, I left it running for half an hour, and every time I checked, it worked perfectly. I finally felt relieved after a long day of work.

This kind of failure wasn’t fixable just by replacing parts. The only solution was to dismantle the screen and reattach the aluminum foil. It was a tough one, but after a full day of effort, I managed to solve it. Here are some photos from the process: