Epson PhotoPC 3000Z, Руководство по обслуживанию

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EPSON PhotoPC 3000Z Revision A
Operating Principles Circuit 47
SWITCHING CONTROLLER (IC501)
This is the basic circuit which is necessary for controlling the power supply
for a PWM-type switching regulator, and is provided with four built-in
channels, only CH1 (digital 5 V, analog system), CH3 (LCD system), CH2
(digital 2.5 V) and CH4 (digital 3.35) are used. Feedback from 5 V (D) (CH1), 2.5
V (D) (CH2), 3.7 V (L) (CH3) and 3.35 V (D) (CH4) power supply outputs are
received, and the PWM duty is varied so that each one is maintained at the
correct voltage setting level.
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Short-circuit protection circuit
If output is short-circuited for the length of time determined by the
condenser which is connected to Pin (17) of IC501, all output is turned
off. The control signal (P ON, P(A) ON and LCD ON) are recontrolled to
restore output.
DIGITAL 5 V AND ANALOG SYSTEM POWER OUTPUT
5.1 V (D), 15.1 V (A), -7.6 V (A) and 5.1 V (A) are output. Feedback for the 5.1 V
(D) is provided to the switching controller (Pins (29) of IC501) so that PWM
control can be carried out.
DIGITAL 2.5 V SYSTEM POWER OUTPUT
2.5 V (D) is output. Feedback is provided to the switching controller (Pin (26)
of IC501) so that PWM control can be carried out.
LCD SYSTEM POWER OUTPUT
3.7 V (L), 13.0 V (L) and 15.5 V (L) are output. Feedback for the 3.7 V (L) is
provided to the switching controller (Pin (11) of IC501) so that PWM control
can be carried out.
DIGITAL 3.35 V POWER OUTPUT
3.35 V (D) is output. Feedback is sent to pins (7) of the switching controller
(IC501) for PWM control to be carried out.
SWITCHING CONTROLLER (IC503)
This is the basic circuit which is necessary for controlling the power supply
for a PWM-type switching regulator, and is provided with one built-in
channel, the control of backlight power supply output to be carried out.
Feedback from 7 V (L) power supply outputs are received, and the PWM duty
is varied so that each one is maintained at the correct voltage setting level.
BACKLIGHT POWER SUPPLY OUTPUT
7 V (L) is output. Feedback is sent to pins (1) of the switching controller (IC503)
for PWM control to be carried out.
INVERTER CONTROL
The backlight uses a 1.8-inch flat picture tube, and is illuminated by
controlling T5003 with pulses which are driven by the inverter clock.
2.2.3.2 Strobe CIrcuit Description
The figure below is the strobe circuit block diagram.