Most no-signal calls are the wrong input, a bad cable, or a source device that is off or sending a format the TV can't show.
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Get lifetime accessOnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.
Component test · TVLED strips are wired in series strings and run from a constant-current driver at high DC voltage (often around 80-200 V total). One dead LED opens the string and the driver shuts down. Test LEDs with a backlight tester, not a meter diode range, and replace all strips as a set.
Component test · TVThe T-con converts video from the main board into the signals that drive the panel rows and columns. Loose ribbons, a blown T-con fuse or a failed T-con cause image faults; lines that stay fixed in the same place usually mean the panel itself.
Component test · TVThe power supply board makes a standby voltage that is always on, then switches on the main rails when the main board sends a power-on signal. Check standby, then the power-on signal, then main rails. The primary side holds a high-voltage charge.