Rectifying Circuit And Standby Power Supply; Main Supply Circuit - Toshiba CN27E90 Technical Training Manual

2. RECTIFYING CIRCUIT AND STANDBY
POWER SUPPLY
Rectifying circuit is a circuit to generate dc from ac 120V.
D899 is a varistor to absorb surge (ex. lightning) arose
on ac line. When surge arises, the circuit let surge by-pass via
route shown in figure 13-2 to protect the following
circuit. C801 and T801 are a filter circuit to suppress
abnormal radiation. Degaussing circuit using thermistor is
equipped at after SR81 relay. R811 is a damping resistor to
remove light regulator noise. D801 is a bridge rectifier
F801 D899
Surge

3. MAIN SUPPLY CIRCUIT

This circuit is a current resonant switching power circuit
using hybrid IC Q801 (STR-Z3201). The current resonant
power supply realizes small, highly effective and low noise
power. Output of main supply are for H. deflection circuit
(+125V), for audio output circuit( +25V) and for signal
processing circuit (Low B, +12V). The supply (Low B,
+12V)
for signal processing circuit is equipped with 3 terminal
regulator and 4 terminal regulator with switch in the following
stage, to supply 9V-1, 9V-2, 5V-2 and 5V-3 to signal
processing circuit.
Audio output supply and signal processing circuit supply
lines are equipped with protecting fuses F899 (for audio
output line), F890 (for signal processing circuit line) which
breaks in circuit failure like short of load. And F860
breaks to protect the circuit in the failure of primary circuit
(break of Q801).
C801
THERMISTOR
T801
SR81
T840
Fig. 14-2 Rectifying circuit and standby power supply
diode and performs rectification and smoothing together
with C810. R801 is a resistor to regulate inrush current
and to suppress rush current in switch-on. T840 is standby
power transformer. D840 and C840 performs rectifying
and smoothing to make approx. 12V for relay driving, and
Q840 regulator makes +5V to supply to microcomputer
and also to output the reset signal of microcomputer.
L901
R811
D801
+3V-1
QB30
Q863
Q840
5
1
C840
2 4
3
D340
C843
100
Rectified
output
C810
R810
MICOM
POWER
+5V (to MICOM)
Reset
C842