Panasonic TH-42PX20U-P Service Manual page 386

PF
! !
AC CORD AC INLET
AC100V K2AH3H000028
K2CG3DH00034
AC120V
4
NEUTRAL
GND
1
LIVE
PF1
TH-42PX20U-P
PF-BOARD BLOCK Diagram
Tuner Power Board
D920
IC920
C920
POWER CONTROL
Latch-stop
-
+
comp
VUL
OVP
comp
+
R
-
VOVP
S
Thermal
Shutdown
R928 R927 Z/C
1
Zero Current
Detection
On Dead Timer
C926
Stand-By
Vref
IF/B
2
F/B
-
+
R934
R935
On Time Timer
C924 R929
C925
D926
!
T8AH 250V
F901
LF904
3 4
CF901
R901 C902
C901
2 1
! F900 T8AH 250V
HOT
S901
CF902
DC187V
D925
C922
C928
4 5
400V
Vcc D
Startup
UVLO
comp UVLO
+ + comp
- -
Vcc(start) Vcc(startup off)
/Vcc(stop) /Vcc(startup on)
Startup
Q
Peak Burst Peak
R924
C921
Current Current
Limit Limit
S
Soft
Q drive
R
S
L921
Restart
Timer
GND
3
D922
R925
R940
IC921
FEED BACK
4 1
3 2
LF911
!
F902
R904
K5D312BK0012
T3.15AL 250V
LF909 LF915
NEUTRAL
3 4 3 4
C915
C903
2 1 2 1
C910
C911
HOT
COLD
HOT COLD
C972
T920 14V(UN Reg)
18 P2
D971
C973
2
S3
3
S4
C970
21V(UN Reg)
14 P1 5
S1A
D970
6
S1B
7 C971
S2A
11 V2
8
S2B
10 V1
C914 R970
R972 C975
R976
C974
R974
R973
HOT COLD
3
1
REF_2.5V
R975
2
4 1
R971
IC970
2
3
ERROR
VOLTAGE
DET
STAND-BY 5V
RL901
C990
D990
Q990
POWER ON/OFF CTL.
R990
R992
HOT COLD
LIVE
TO PA10
PF10
1
2
5
7
9
TO P9
PF2
NEUTRAL
1
LIVE
4
TH-42PX20U-P
PF-BOARD BLOCK Diagram