Philips FL9.1, Technical Training Manual

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Power Supply (Figure 6)
AC is fed the line filters and bridge rectifier. RAW DC is fed to the Inverter via connector
CN602 on the power supply board and to transformer T601.
The switch mode supply consist of transistors Q601 and Q602. In standby, the power supply
is running in a low power pulsating mode controlled by Q634 on the secondary side.
When the set is turned On, the P-ON-H1 and P-ON-H2 lines goes High. P-ON-H2 changes
turns on transistor Q634 to change the bias of the feed back circuit switching the power sup-
ply to a full power mode. It also turns on transistors Q638, Q639 and Q637 to turn the P-ON-
3.3V supply On. The P-ON-H1 line switches Q207 and Q208. This switches Q210, Q201
and Q212 to switch the VGH voltages. Q211 is turned On switching the LCD-6.8V supply. It
also switches Q209 switching the LCD+16V supply. Q501 is switched to turn on the INV+16V
supply. Q642 is switched to produce the P-ON+9V supply.
Protect 1 (Figure 7)
Protect 1 is connected to all of the supplies via diodes. If any one of the supplies shorts, the
protect line will go Low causing the set to turn Off. The pull up voltage for Protect 1 is R401.
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P-ON+3V
P-ON+5V
AL+33V
P-ON+9V
TUNER+5V
D409
D414
D404
D416
D405
R408
10K
AL+13V
P-ON+3.3V
LCD+16V
INV+16V
LCD+24.5V
R412
10K
D406
15V
D411
D413
D412
D410
D415
AL+3.3V
R401
22K
D417
3.9V
PROTECT1
FIGURE 7 - PROTECT 1