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 an issue: no sound at boot-up. The first thing I noticed was that the backlight wasn't working properly. This model doesn't use a separate high-voltage backlight system; instead, it uses a two-in-one LIPS power supply. After opening the unit and inspecting the circuit, I realized it wasn't a simple transformer-based amplifier circuit. In short, the backlight power amplifier is powered by a 380V DC output from the PFC boost circuit. I measured the 12V and 5V rails, and they both looked normal. However, when the backlight was turned on, there was no flashing, which usually indicates a problem with the backlight board. If the lamp itself was faulty, it might flash, but this isn’t always the case. So, I decided to check the circuit first. After a quick inspection, I didn’t find any obvious issues. However, I noticed that the gate-to-ground resistance of one of the power transistors was unusually high. I removed the power field-effect transistor and retested, and the resistance value still seemed off—this pointed to a potential issue with the driver transformer. Further testing showed that the secondary winding of the driver transformer had an open circuit. That was the main culprit here. I couldn’t help but feel frustrated after spending so much time troubleshooting. It's not uncommon for these kinds of repairs to be tricky, especially when you're dealing with complex circuits like this. After replacing the faulty component, everything worked as expected. The TV started up normally, and the backlight functioned properly. It’s always a relief when you finally get it fixed, even though the process can be exhausting and a bit bitter.