Sanyo DP42142 Service Manual page 3

Repair Flow Chart:Trouble Condition
Green Power is on, but LCD backlight is not on.
Backlight does not turn on, or only turns on and then off.
(TABLE *1.0) Main board: BL-SW Test Points
42" Models
P42142-00 Z5GH
P42142M-00 Z5GHM
P42142-02 Z5GK
P42142M-02 Z5GKM
(TABLE *2.0) Power board: BL-ERR Test Points
42" Models
P42142-00 Z5GH
P42142M-00 Z5GHM
P42142-02 Z5GK
P42142M-02 Z5GKM
Power LED turns ON,
but LCD backlight is not ON
or only turns ON and then
OFF.
For Main board:
No:0V
Is the "BL_SW" voltage (3.3V)
Supplied from "K8B Pin13"?
Yes:3.3V
For Power board:
No:over 0.8V
Is the 0V supplied from "K703 Pin13"
during LED on?
Yes:0V
No:0V
For Power board:
Is the 24V in "K703 Pin 1/2/3/4/5"
Yes:24V
For Power board:
No
Is the BL-SW voltage (3.3V) supplied
from "K703 Pin12"
Yes:3.3V
For Power board:
No
Is the BL-ADJ wave (PWM)from
"K703 Pin11" normally?
Yes
The Panel is broken.
Replace the "Panel".
BL-SW on Main board
Main K8B Pin13
BL-ERR on Power board
Power K703 Pin13
Main board can not work.
Replace "Main board".
The Panel is broken.
Replace "Panel".
Power board can not work.
Replace "Power board".
Confirm wire harness connection
between Main board and Power board.
Confirm wire harness connection
between Power board and Main board .
Confirmation Voltage
Confirmation Voltage
3.3V
0V
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