Sanyo VAR-G6E, Service Manual

Page: 5 / 49

– 5 –
1-3. PW1 POWER CIRCUIT and LENS DRIVE
BLOCK DESCRIPTION
1. Outline
This is the main power circuit, and is comprised of the follow-
ing blocks.
Switching power controller (IC501)
Analog and LCD system power output (Q5001, T5001)
Digital 1.85 V power output (Q5009, L5008)
Digital 3.35 V power output (Q5010, L5009)
Digital 3.35 V step-up power output (Q5011, L5010)
LED backlight power output (Q5012, L5011)
5 V system power output (Q5015, L5012)
2. Switching Controller
This is the basic circuit which is necessary for controlling the
power supply for a PWM-type switching regulator, and is pro-
vided with six built-in channels, only CH1 (analog and LCD
system power output), CH2 (digital 1.85 V system power out-
put), CH3 (digital 3.35 V system power output), CH4 (digital
3.35 V step-up power output), CH5 (LED back light power
output) and CH6 (5 V system power output) are used. Feed-
back from 15.0 V (A) (CH1), 1.85 V (D) (CH2), 3.35 V (D)
(CH3), 4.7 V (L) (CH4), LED backlight output (CH5) and 5 V
(CH6) power supply outputs are received, and the PWM duty
is varied so that each one is maintained at the correct voltage
setting level.
2-1. Short-circuit Protection
If output is short-circuited for the length of time determined
by the condenser which is connected to Pin (37) of IC501, all
output is turned off. The control signal (P ON) are recontrolled
to restore output.
3. Analog and LCD System Power Output
15.0 V (A), -7.5 V (A) and 9.6 V (L) are output. Feedback for
the 15.0 V (A) is provided to the switching controller (Pin (40)
of IC501) so that PWM control can be carried out.
4. Digital 1.85 V Power Output
1.85 V (D) is output. Feedback for the 1.85 V (D) is provided
to the switching controller (Pins (43) of IC501) so that PWM
control can be carried out.
5. Digital 3.35 V Power Output
3.35 V (D) is output. Feedback for the 3.35 V (D) is provided
to the swiching controller (Pin (45) of IC501) so that PWM
control can be carried out.
6. Digital 3.35 V Step-up Power Output
4.7 V is output. Feedback for the 4.7 V is provided to the
swiching controller (Pin (47) of IC501) so that PWM control
can be carried out.
7. LED Backlight Power Output
A constant current flows to the backlight LEDs. Feedback for
the voltage of R5098 is provided to the power controller (Pin
(2) of IC501) so that PWM control can be carried out.
8. 5 V System Power Output
5 V is output. Feedback for the 5 V is provided to the swiching
controller (Pin (4) of IC501) so that PWM control can be car-
ried out.
9. Lens drive block
9-1. Iris drive
When the drive signals (IRIS_A, IRIS_/A, IRIS_B and IRIS_/
B) which are output from the ASIC, the stepping motor is driven
by the driver (IC951), and are then used to drive the iris steps.
9-2. Focus drive
When the drive signals (FRSTB, FCW, FOEB and FCLK) which
are output from the ASIC, the focus stepping motor is sine-
wave driven by the micro-step motor driver (IC953). Detection
of the standard focusing positions is carried out by means of
the photointerruptor (FOCUS PI) inside the lens block.
9-3. Iris drive
The zoom DC motor drive signals (ZOOM_A and ZOOM_/A)
which are output from the ASIC are used to drive by the motor
driver (IC951). Detection of the zoom positions is carried out
by means of photointerruptor (ZOOM PI) inside the lens block.
9-4. Shutter drive
When the shutter drive signals (SHUT_A and SHUT_/A) which
are output from the ASIC, it is driven regular current by the
motor driver IC (IC951).