Tp.ms3458.pc757 Service Manual |link| ⇒

If you are replacing a mainboard, ensure you have disconnected the TV from the mains power and waited several minutes for capacitors to discharge before handling the internal components.

HAIER 75UF5550 CHASSIS MSD3458 Service Manual download, schematics, eeprom, repair info for electronics experts. Elektrotanya LED TV SERVICE MANUAL - iFixit