Sony KDP-51WS550 Training Manual page 26

(Reference Figure 4-4)
The HV level is monitored through the HV Regulator circuit IC8004. IC8004 and resistor network RV8002,
R8017, R8014 and R8015 are part of the HV regulation circuit (feedback path for IC8002 HV power supply
converter). A sample of the HV is output at FBT/pin 13 and is applied to IC8004/pin 5 (Buffer). Approximately
6.5V is produced at IC8004/pin 7, which is then applied to the resistor network (RV8002, R8017, R8014 and
R8015). Approximately 2.5V is developed at the junction of R8015 and R8017.
R8014 is the feedback path for IC8002 (HV Power Supply Converter IC) to keep the HV regulated.
R8025 is the path for the HV LVP circuit. The voltage at IC8004/pin2 is directly proportional to the HV; consequently
a decrease in HV will cause a decrease in voltage at IC8004/pin2. When the 2.5V at IC8004/pin2 decreases
below the reference voltage 2.2V at IC8006/pin3, a High will be output at IC8004/pin 1 (approximately 14V).
Zener diode D8027 (3V) will conduct and regulate the voltage applied to IC0001/pin52 to 3V.
A high at IC0001/pin52 (HV-Prot) will cause IC0001/pin69 to shut OFF the AC-Relay, turning OFF the unit. The
Stby/Timer LED will flash a 10X sequence.
AX-1 Excessive HV (HV OVP) and Horizontal Deflection (H-Prot) Protection Circuits
D-BOARD
SWITCHING
CONVERTER
(EXCESSIVE
HV PROTECTION)
2.4V
Q8004
C8007
+
D8024
6.2V
C8006
IC8001
R8011
0V
+
A
7
-
+
C8002
1 B
+
0V
C8021
IC8104
VREF.
NOTE:
HOT GROUND
SECTION
FIGURE 4-5 - AX-1 EXCESSIVE HV & HORIZONTAL DEFLECTION PROTECTION CIRCUITS
IC8002
Q8014
16
HV
12 Q8013
1
V-SENSE
R8001
2.4V
4
3
Q8003
D8072
D8001 R8078
C8041
2.2V
5
2.5V
6
R8046
-
2 2.5V
3
1.9V
R8052
3
2
H
DRIVE
1
Q5001
R8016
H-OUT
19V
FROM T6502/PIN 8
TO LOW HV
PROTECT
FBT
REF. FIG. 4-4
T8001
FOR DETAIL
PH8001
R8069
1 15V
2
R8072
IC8006
5
FBT
T8001
R8135
9V
R8136
TO
HORIZONTAL
DEFLECTION
YOKE
9V
Q5701
BUFFER
C5002
C5006
C5010
D5701
15V
24
4. AX-1 Protection Circuits
(HORIZONTAL
DEFLECTION
PROTECTION)
15V
7
-
+
6 5
2.2V 4.3V
R8137
D8140
12V
0.3Vpp
R5210
33.75KHz
0V
Q5202
Q5702 (BUFFER)
AC RELAY
RY6000
69
MAIN
MICRO
IC0001
31
4
IC0002
PF
DRIVE
31
52
IC0401
CRT
DRIVE
57
D5205
TVP16.4-5 11/4/03