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DP-4X STAND BY +5V POWER SUPPLY GENERATION EXPLANATION
STAND-BY +5V POWER SUPPLY GENERATION EXPLANATION:
The Stand By power supply operates anytime the set is plugged into an AC outlet. Shown
below in Figure 1 is the Stand By power supply. IC101 is the Driver IC for this supply. It's
a self contained Oscillator, Driver IC. It switches the primary of T101.
The secondary of T101 produces the SBY +5V via the rectifier D103 and filter C106. Then
the voltage is clamped by ZD101.
A feedback to IC101 is supplied by the photo coupler PC102 for regulation purposes.
IC102 works as a variable resistor attached to the cathode of the internal LED inside
•
IC102. As the SBY +5V changes so will the resistance of IC102. Voltage Up, Resis-
tance goes Down. As the Resistance goes down the Light emitted from the LED will in-
crease. As the Light increases from the LED, the receiver will conduct more heavily.
This decreases the voltage fed back to IC101 causing the internal circuits within IC101
to reduce the primary switching of T101 and reduce the SBY 5.7V line back to normal.
L102
F103
DS101
R110
-
+
C105
D102
IC101
C107
C110
D103
C106
C106
T101
PC102
R112
C109
IC102
Figure 1
SBY +5V
ZD101
R111
R113
R114
R115
PAGE 01-13
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