Sony KDL-46HX750 Power Supply Repair
Recently, the Sony KDL-46HX750 LED TV arrived with a major problem: it was non-functional. Even the pilot light / standby light is was off, and the TV was not turn on. it was power supply problem.
When the TV arrived, it was completely dead—neither the screen nor the standby pilot light indicated any power. During the initial testing, it became evident that the 3.3V supply voltage was absent, which is required for the TV's starter circuit to function.
Problem Detection of Sony KDL-46HX750 SMPS
Step by step identification of the problemLets Check Fuse
The fuse on the power supply board was examined with a multimeter and determined to be functional.The 220V AC input was confirmed to reach the board.
Checking the Bulk Capacitor / Main Capacitor
The primary capacitor was examined and confirmed to be holding the right DC voltage, indicating that the rectification stage was functioning properly.Check the 3.3v Circuit
The circuit responsible for generating the 3.3V voltage has been examined. The MIP2H2 IC, which steps down and regulates the voltage to 3.3V, was tested and discovered to receive power from the main capacitor. All adjacent resistors and capacitors were checked for damage, but they were in fine working order. Confirming the Fault: The MIP2H2 IC failed to output the required 3.3V, despite sufficient input voltage and functional components. This confirmed that the IC itself was faulty and required replacement.d
Repair Process:
Replacing the Faulty MIP2H2 IC Once the fault was confirmed, The defective MIP2H2 IC was carefully de-soldered from the board to avoid damage to the PCB traces. Installing a New IC: To restore functionality, a brand-new, new MIP2H2 IC was soldered in place with exact connection.Testing the Board:
After replacing the IC, the power supply board was tested with a multimeter. The 3.3V output was successfully restored.The repaired power supply was reconnected to the TV, and the TV powered on normally.
Observations and Learnings
This repair highlights that the MIP2H2 IC is a common failure point in the Sony KDL-46HX750 power supply. Despite proper functioning of other components, the IC itself is prone to damage over time due to electrical and thermal stress. Regular maintenance and timely replacement of such components can help prevent extended downtime and further damage to other parts of the TV.Visual Reference
To help other technicians and customers understand the issue, here are detailed images of the process:Voltage Testing in the rectifier diode:
