Diamond View DV154, Service Manual

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DV154/154B LCD Monitor Service Guide
Circuit operation theory
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3.2 Royer Circuit
Fig. 9
Royer circuit use the characteristic of transformer saturation to oscillate. When the DC power inject, Q739 or Q740 will turns on,
and the current Ic increases. After a period, the transistor will leave the saturation status and Vce increase. The result cause the
voltage of primary coil get lower . Finally the transistor turn off , and another transistor turn on. These status are repeated and
the pin7 and pin8 of T752 will get a Sin Wave to turn on CCFL.
3.3 Feed-back Circuit
Fig. 10
Fig. 10 is the feedback circuit of inverter. It get the voltage of Lamp-Current to be the feedback signal and PWM IC
( IC751 ) will adjust the duty-cycle according to the signal to control the lamp brightness.