LG MAB745W 01 Service Manual - Page 14

MEASUREMENT OF MICROWAVE POWER OUTPUT • Microwave power output measurement is made with the microwave oven supplied at its rated voltage and operated at its maximum microwave power setting with a load of (1000±5) g of potable water. • The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of approximately 190mm. • The oven and the empty vessel are at ambient temperature prior to the start of the test. • The initial temperature (T1) of the water is (10±2)°C It is measured immediately before the water is added to the vessel. After addition of the water to the vessel, the load is immediately placed on the center of the turntable which is in thd lowest position and the microwave power switched on. • The time T for the temperature of the water to rise by a value ∆ T of (10±2)°K is measured, where T is the time in seconds and ∆T is the temperature rise. The initial and final water temperatures are selected so that the maximum difference between the final water temperature and the ambient temperature is 5°K. • The microwave power output P in watts is calculated from the following formula : 4187 x (∆T) P = T is measured while the microwave generator is operating at full power. Magnetron filament heat-up time is not included. (about 3 sec) • The water is stirred to equalize temperature throughout the vessel, prior to measuring the final water temperature. • Stirring devices and measuring instruments are selected in order to minimize addition or removal of heat. WATER LOAD TURNTABLE DISASSEMBLY AND ADJUSTMENT A. OUTER CASE REMOVAL 1) Disconnect the power supply cord from the outlet. 2) Remove the screws from the rear of the case. The outer case must be moved backward to be lifted off. B. POWER SUPPLY CORD 1) Remove the outer case. 2) Disconnect two terminals, and remove one screw of the ground terminal. Remove the screw securing screw C.CONTROL PANEL ASSEMBLY 1) Open the door. 2) Remove the screws for the ground and securing the control panel. 3) Disconnect the leadwire from RELAY(RY2) of the PCB SUB ASS'Y. 4) Lift up and pull out control panel assembly carefully from the cavity. 5) Disconnect the leadwire from connector(CN1) of the PCB SUB ASS'Y. Lift up and pull out control panel CAUTION: DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING (refer to page 2-1) 5-3