BenQ Q7T4-FP71G, Service Manual

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Q7T4-FP71G LCD Monitor Service Guide
Circuit Operation Theory
11
Confidential
3.3 Oscillator Circuit
Royer circuit uses the characteristic of transformer saturation to oscillate. When the DC power inject,
Q808 or Q809 will turns on, and the current Ic increases. After a period, the transistor will leave the
saturation status and Vce increase. The result causes the voltage of primary coil get lower. Finally the
transistor turn off, and another transistor turn on. These statuses are repeated and the pin7 and pin8 of
T801 will get a sine wave to turn on CCFL.