Acer AC501 AC501 Monitor Service Guide - Page 15

G. Under Voltage Protection When the line input voltage is below 75~85Vac range, the DC voltage on R983 which through R981, R982 is below 4.3V. Then Q981, Q982 turn on, the U901 pin3 immediately be lower at 0.2V and shut down the U901 and power. H. Degaussing CKT The DEGU signal which comes from u-p to control degauss coil act or not. When DEGU is high, Q950 will be saturated to make RL901 working, AC line provides a degaussing current to degauss coil. H-1. Block Diagram 15