Samsung TV repair case: After turning on, the TV shows three no's (no picture, no sound, no power), but the power indicator light is on. Beijing Konka TV Repair Center.
Analysis and inspection: After disassembling the TV, it was found that the main fuse F802 (2A) of the power supply had blown. A static check was performed on the resistance value between the c~e poles of the switch tube Q823 in the power circuit. The reverse resistance value was measured to be close to 0Ω. Further inspection revealed that Q823 (2SD4706) and the zener diode D836 (6V) were both damaged. Continuing to check other components, it was found that the main filter capacitor C809 (220uF/400V) had lost its capacity.
Solution: After replacing Q823, D836, and C809 respectively, the fault was eliminated. Beijing TCL TV Repair Center confirmed the fix.
Data provided by the Samsung TV after-sales service hotline in Beijing.