Hitachi CL32W30TAN Wartungshandbuch Seite 69

supplied by a sawtooth waveform shaping circuit consists of D20, ZD9, R32, C44, D19, C43 & R30. Pin 3 is supplied by varying DC
levels via IC7 & R31. The 3V3 voltage rail is regulated by IC7.
Winding 8/14 provides 12V from D16, C35 & smoothing cap C39, also a 9V rail is provided by IC6 regulator.
SECONDARY PROTECTION: Provided via IC6 pin 7. Pin 6 of IC6 is set to a steady voltage level a round 3V, pin 5 used as the over
current sense point, D18, 25, 33 used to pull down pin 5 below pin 6 during over current in this state pin 7 is low which in turn
disables the feedback point pin 1 of IC10 shutting down the power supply.
FEEDBACK OPERATION
Increase in load demand by secondary rails results in higher voltage feedback on cathode of IC8 in turn rising the voltage on pin 1 of
IC10, this voltage is compared to the sawtooth generated on pin 4 via R76 & C95, this produces the gate drive square pulse with
larger off time therefore the larger the load demand the larger the duty cycle and vice versa.
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