KP-46WT520, KP-51WS520, KP-57WS520 (serv.man2) - Sony TV Service Manual (repair manual). Page 8

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KP-46WT520/51WS520/57WS520
KP-46WT520/51WS520/57WS520 
9
Self-Diagnosis Function Operation
+B overcurrent (OCP) 
Occurs when excessive current fl ows through R6812. The increase in voltage across Q6803 causes it to turn on which sends a high signal to the 
micro. 
+B overvoltage (OVP) 
IC6801 detects +B OVP condition and turns on Q6802. This sends a high signal to the micro and also shuts down the AC relay.
V-STOP 
Occurs when an absence of the vertical defl ection pulse is detected by pin 56 of IC452 (A Board). Power supply will shut down when waveform interval 
exceeds 2 seconds. 
White Balance Failure
If the RGB levels* do not balance within 2 seconds after the power is turned on, this error will be detected by IC452 (A Board). TV will stay on, but 
there will be no picture.
*(Refers to the RGB levels of the AKB detection Ref pulse that detects 1K).
Low B OCP/OVP
Occurs when set 5V is out.
     Also check for :  + 135V line shorted
 
  
+ 135V line is going over 145V
Horizontal Defl ection Stopped
Occurs when either: 
 
1) a +B overcurrent is detected (Q6803), or 
 
2) IC452 (A Board) is damaged.
Self-Diagnosis Block Diagram
3
1
2
R5104
R5105
R5125
Q5018
RY6000
Q6102
Q451
Q452
D452
D6803
D6505
D453
R6812
D6805
R6803
IC6801 
Q6802
1K-PROT2
+B OCP
+BVOP
5V 
+B OCP
2
1
3
4
IC5007
VDY-
CRT
IC452
Y/C JUNGLE
SCL
SDA
AKB
VPROT
HPROT
IC702
MAIN MICRO
A
CLKO
DATO
AC RLY
LOW B ERR
OVP
OCP
STR
STBY-LED
STBY-LED
P_SW(-)
IC303
5V
+B
+B
+B
BM
A
D
D
A
2
14
57
56
58
53
52
28
31
69
43
44
45
48
3
1
2
G
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