Hisense LCD TV TLM32V76 black screen with sound repair - android - Phones Developers

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

MOS power IC full range

Photocoupler

I received a Hisense TLM32V76 TV with the issue of no sound at boot-up. The first thing I noticed was that the backlight wasn't working either. This model doesn’t use a separate high-voltage backlight system; instead, it uses a two-in-one LIPS power supply. After a quick inspection, I found that this isn’t just a simple transformer-based amplifier circuit. In short, the backlight power amplifier is powered by the 380V generated by the PFC boost circuit. When I checked the voltages, 12V and 5V were normal, but there was no flashing when the backlight was turned on. Normally, if the lamp itself was faulty, you would see some flashing. However, this isn’t always a rule—so don’t throw bricks at me, okay? 😄 So, I started by checking the circuitry. A quick test didn’t show any obvious issues. However, I noticed that the resistance from the gate of the power transistor to ground was too high. After removing the power field-effect transistor and retesting, the resistance still seemed abnormal, which pointed towards the push-pull transformer. Further testing revealed that the secondary side of the push-pull transformer had an open circuit. That was the main issue here. It’s frustrating when you have to dig deep into the circuit to find such a hidden problem. I can’t just rely on someone else's experience or "red grandfather" advice—I need to figure it out myself. Eventually, after replacing the faulty components, the TV worked perfectly again. Every time I fix something like this, it feels like a long and tiring process, but it's also rewarding in the end. 😊