TCL LCD TV L32W3212 open screen change lamp beads - Home Appliances

I had a TCL-L32W3212 LCD TV that wouldn’t turn on, showing a black screen. When I turned it on, the constant current drive board’s 24V power supply was normal, but the output voltage spiked over 40V and dropped back to 24V at startup. I tried connecting a 1K resistor across C808 to bypass the protection circuit, which made the screen bright for a moment but still remained black. I replaced the output filter with a 250V 22UF capacitor, but the chip capacitor failure wasn’t resolved. These methods were suggested in a forum, so I followed them. Another forum post mentioned that the lamp beads are prone to failure, so I decided to open the screen and replace them.

I started by removing the rear cover screws and placing the TV face up on a flat surface. I carefully removed the front case and took extra care not to let the screen fall, as that could easily damage it. Then I removed the LCD panel and placed it safely aside. Next, I took off the backlight board to expose the LED light bar. This model had 7 light bars. After checking each one, I found that six of the individual LEDs weren’t lighting up but weren’t completely dead. The bottom one had several LEDs in a breakdown state, so I decided to replace them.

This was my first time replacing such LED beads, and it took some trial and error. I asked other technicians for advice. They recommended using two soldering irons to remove the beads, which wasn’t easy. I had to remove the plastic cover first, then heat the area and carefully lift the beads. It was hard to get them off, so I used a hot air gun, which made the process much easier. I held the light bar in one hand and used the air gun in the other. The beads didn’t come off easily, so I used an old-style soldering iron, heated the area, and placed it on the table. Holding the light bar with one hand, I used a pair of tweezers to gently lift the beads. All the faulty ones were removed.

After that, I couldn’t find exact replacements, so I looked for a similar light bar from a previously discarded display. The length matched, though it was slightly wider, so I used it anyway. Once all the bad beads were replaced, I reassembled the unit and tested it. The voltage at the LED power supply terminal reached around 65V, and the image returned to normal. There was also a white strip attached to the light bar that I had originally planned to remove when taking out the LEDs. However, it became visible once the light bar was exposed. I simply cut it off and left the parts on the iron, which got burned and deformed. I don’t think it affected the performance much, so I just ignored it. Here are some photos for reference: