Sony KDP-51WS550 Training Manual page 28

AX-1 5V Regulator and White Balance Protection Circuits
STBY
5V
HA BOARD
R0081
R0084
D0001
3.6V
CN0002
2 6
2 6
CN2003
O
IC6201
7V I
5V REG
G
A BOARD
(LOW B+ CIRCUIT)
FIGURE 4-6 - AX-1 5V REG AND WHITE BALANCE PROTECTION CIRCUITS
5V Regulated Protection Circuit
(Reference Figure 4-6)
The regulated 5V line is monitored using Q0008 and Zener diode D0001 (3.6V) on the MA-board. The output of
the 5V regulator IC6201 is applied to the emitter of Q0008. In normal operation, Q0008 is turned ON and D0001
is conducting, holding the base at 3.6V. Approximately 2.8V is applied to System Control IC0001/pin 43, indicating
proper level of the regulated 5V line.
If the 5V line falls below approximately 4.5V at the emitter of Q0008, D0001 will stop conducting, Q0008 will turn
OFF and a Low will be applied to IC2300/pin 43. IC0001/pin 69 will then turn OFF the AC relay.
The AC relay shuts down and the Stby/Timer LED flashes a 6X sequence.
White Balance Protection Circuit (IK Protection)
(Reference Figure 4-6)
The condition of each CRT cathode (RGB) must be monitored in order to maintain optimal white balance. Each
cathode has a separate driver (IC9101, 9201 and 9301) on the CR, CG and CB boards. Each driver IC9101/pin
O_STBY_LED
26 2 6
48
I_LB_ERR
43
2.5V
R0077
Q0008
R0082
C0036
O_AC_RELAY
IC0001
MAIN MICRO
IO_SDAT
31
4
IO_SDAT
IC0002
PF MICRO
IO_SDAT
31
52
SDA
IC0401
Y/C CRT DRIVE
IK_IN
24
CN0401
8
8
CN9103, CN9203, CN9303
R9133
R9132
R9134
Q9104
(CR BOARD)
Q9102 Q9202
11V
12V
7
IK
IC9101
RED
26
4. AX-1 Protection Circuits
AC RELAY
69 35 3 5
RY6000
MA BOARD
CR, CG, CB BOARDS
12V
(WHITE BALANCE PROT.)
Q9302
11V
12V 12V
7
IK
IC9201 IC9301
GREEN
A BOARD
11V
7
IK
BLUE
TVP16.4-6 1/13/04