G6 Board - Sony FWD-40LX2F Service Manual

3-4. G6 Board

AC input/rectification block
CN901 on the G6 board is connected to an AC inlet and
AC power is input from the AC inlet. The input AC power
is passed through an AC noise filter consisting of C910,
C901, C904, L901, L903, and L904 and bridge-rectified
using BD901.
PFC converter
AC power is rectified using BD901 and the power factor is
improved using a PFC converter consisting of Q911, IC911,
T911, D912, C920, and C921. Moreover, an output voltage
is increased and stabilized to 390 VDC. The smoothed
output voltage is supplied to a standby converter and main
converter.
Standby converter
5 V (5 VD and 5 VS) and 12 V are output from a switching
converter consisting of IC931 and T931. 5 VD is output
from CN931 (pins 2 to 4), and 5 VS is output from CN931
(pin 8). 12 V is output from CN950 (pins 6 and 7).
During standby, however, the output voltage that is not
increased, but smoothed is supplied from a PFC converter.
Main converter
17 V and 13 V are output from a switching converter
consisting of IC950, IC951, Q950, Q951, T950, and T913.
17 V is output from CN951 (pins 1 to 5), and 13 V is
output from CN950 (pins 2 and 3).
Main ON/OFF control
A PFC converter and main converter are turned on and off
by CN931 (pin 1) when a PS signal is set high and low
using a microcomputer. Q934 is turned on when a PS
signal is high. A PFC converter is turned on when Q931 is
turned on. A main converter is started when IC913 is
started after Q931 is turned on. Q934 is turned off when a
PS signal is low. A PFC converter and main converter
stop operation when Q931 is turned off and when IC913 is
stopped.
FWD-40LX2F
3-3
FWD-40LX2X