LG LTRM1240SW Service Manual page 24

(3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD
The following symptoms indicate a defective circuit
board.
(1) The start function fails to operate but the high
voltage Systems, the interlock switches, the door
sensing and the relay check good.
(2) The unit with a normal relay continuously operates.
(3) The buzzer does not sound or continues to sound.
NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON.
(4) Some segments of one or more digits do not light up, or
they continue to light up, or segments light when they
should not.
(6) Wrong figures appear.
(7) The figures of all digits flicker.
(8) Some of the indicators do no light up.
(9) The clock does not keep time properly.
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