Sharp AL-1000 Manual De Servicio página 90

AL-1000/1010
e. Control circuit
The secondary side outputs (24V series, 5V series) are
detected by the output voltage detecting circuit, and the
detected signal is fed-back through photo coupler PC1
to the control transistor Q2 to change the ON period of
FET Q1 in the primary side invertor circuit, stabilizing
the output voltage.
f. Series regulator circuit
This circuit stabilizes the output and protect against an
overcurrent by the series regulator. The 12V is com-
posed of IC51, the 5V is composed of IC52, the 3.3V is
composed of IC53.
(2) FW signal
The AC input voltage is full-wave rectified by D5 and D6.
When the voltage is divided by resistors R18, R19, and
R27 and decreased below 2.5V, the shunt regulator IC7 is
turned OFF to turn OFF photo coupler PC3, and turn ON
transistor Q3. LOW level output of FW signal is provided.
(3) Heater lamp drive circuit
(4) High voltage section
a. Invertor circuit
The 24V output of the main section is inverted by the
RCC system and the high frequency power is supplied
to the secondary side of high voltage transformer T101
and T102. The diode and the capacitor for rectifying
and smoothing are built in the secondary side of high
voltage transformer T101 and T102 to provide DC out-
puts of high voltage. MC is turned ON/OFF by MC IN
terminal, and TC is turned ON/OFF by TC IN terminal.
b. Series regulator
The GRID output of DV BIAS is applied from the MC
output and dropped by the series regulator.
DV BIAS is turned ON/OFF by BIAS terminal, and the
GRID voltage is switched by GRID L terminal.
c. Dividing circuit
BD OUT takes out a voltage from T102 and divides it
with the resistor and outputs it.
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