Regulation - Sony CPD-420GS Training Manual

Regulation

Overall regulation is accomplished by varying the feedback voltage to
IC601/9 (FB). The secondary +16V DC supply via R631, D614 and R658
provide IC603/1 with a reference voltage. The secondary +180V DC sup-
ply is voltage divided by R659, R663 and R660 to provide IC652/1 (ER-
ROR AMP) with a sample of the +180V DC supply.
IC1001/7 (N Board) 'REMOTE ON/OFF' command is set H (+5V) which
turns Q656 ON and turns Q658 OFF, this allows IC652/3 to control feed-
back. IC652 is a shunt regulator and controls the current through IC603
pin 1 and pin 2. Any change in the B+ voltage will cause IC652 pin 3 to
vary in voltage inversely proportional to the B+.
IC601/6 PWM
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IC652/3 is applied to IC603/2 to control the feedback output of IC603/4
while maintaining electrical isolation between chassis ground and AC in-
put ground. The signal at IC603/4 is applied to IC601/9 (FB). As a result,
IC601/6 responds accordingly to adjust the duty cycle and frequency out-
put applied to Q602 by regulating the secondary B+ (+180V DC) voltage.
Q602/Drain