For Samsung split-type air conditioner, the whole machine does not start. Solution: After replacing with the same model power transformer, the Beijing Samsung air conditioner repair hotline was contacted, and the fault was eliminated. Fault phenomenon: Neither remote control nor manual emergency switch can turn on the machine, and there is no response from the buzzer or indicator lights. Article source: Beijing Samsung Air Conditioner Repair Hotline http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3908286.
Analysis and Maintenance: The 220V power supply of this unit goes through a fuse (3A) to the power transformer, which then outputs 9V and 13V AC voltages after transformation. These voltages are rectified and stabilized by three-terminal regulators 7805 and 7812, respectively outputting +5V and +12V. Among them, +5V supplies power to the microcomputer uPD75028 and the reset circuit, while +12V supplies power to the drive IC and relays. First, check that the 220V power supply is normal, and the 3A fuse is intact; then measure the +5V voltage of the chip as 0V, the three-terminal regulator 7805 has no +5V voltage output, and the secondary side of the power transformer has no voltage output, while the primary side has a 220V AC voltage input. Based on these observations, it is judged that the transformer is damaged.