CT-34WDM60 — Panasonic TV Service Manual (repair manual). Page 6

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Switching po
w
er supply (T802)
+23 V output
+5 V output
+3.3 V output
IC3101
IC3106
IC3105
To each module
E-Board    F-Board
E-Board    F-Board
E-Board    L-Board
To L-Board
E-Board    A-Board
To each module
To each module
To each module
D3039 D3040
D3050 D3051
D3035 D3036
R6841
D6837
R6836
D6835
R6840
R6843
D6838
D6841
R6834
R6835
R6838
R6839
Q6831
Q6832
Q3017
R6831
R6832
R888
R833
R832
R887
R6833
Q879
D6833
D888
R890
Q890
D899
D890
D832
Q831
R835
R836
D831
BS +15 V output
+12 V output
+6 V output
IC3110
IC3109
+6 V output
IC881
+5 V output
IC3107
T3001
(BT +30 V output)
Switching
transformer
D3011 D3038
Audio +23 V
+15 V
+140 V
-15 V
+23 V
Switching pulse
TV 
+23 V
TV 
+208 V
TV 
+130 V
To L-Board
(heater voltage)
f
b
c
g
TV
+208 V
constant
voltage
IC891
TV
+130 V
error
detection
IC871
R831
E-Board  
    
F-Board
 
35
27
28
23
A20
Standby
microcomputer
Main
microcomputer
1
F6
25
40
41
U-Module
F-Board
Standby +5 V output
IC3111
Standby +B
a
e
d
 
L-Board
Self-check for the power supply system
(1)Block diagram of the power supply system
This unit is equipped with a protector circuit for the case when the +B line on the secondary side of the switching power supply
is short-circuited at all times.
Abnormalities are detected for seven +B lines per switching power supply.
Operation for detection of abnormalities
(1) Lines  
 ,  
  ,  
  , and 
  in the above figure
The collector of each transistor for detection of abnormalities becomes "H", and a voltage of about 2.5 V or about 5.0 V is
impressed to the microcomputer.
(2) Line 
 in the above figure
Abnormality detection for each regulator output voltage is performed by Zener diode and protection ON/OFF diode.
When the regulator output voltage rises, the withstand voltage fault voltage is applied to the Zener diode, the protection ON/
OFF diode is switched to ON by this fault detection, and a voltage of about 5.0 V is impressed to the microcomputer.
(3) Lines 
 and 
 in the above figure
The lines 
 and 
 both are the reset input voltage for the standby microcomputer, and when this input voltage is not pro-
vided as input to the standby microcomputer, the fault detection operates.
When fault detection operates, the microcomputer switches the relay of the switching power supply to OFF.
When the power has been cut off by the power supply protector (or by detection of abnormal high voltage), the "Power supply/
function standby/video reception" LED at the front of the unit flashes one to seven times at the time of power supply protector
operation (detection of abnormal high voltage) to facilitate discrimination of the fault location.
a
b
c
g
d
e
f
e
f
!"#$
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