LG 42LS3400 - No power
Hoping you guys could help me diagnose this LCD TV. Standby light is solid red when unit is plugged it. On power-on, the standby light flashes 3 times and then stays off. No visible damage, caps look ok, and fuses check out ok (shorted).
Attached is the service manual and some pics of the boards.
Here are the voltages I'm getting off of the pins when the unit is "on". The low voltages seem to be in spec, but nothing on 12 or 24v.
P201:
Left row, top to bottom (see pic for V reference)
--------
87.3 mV
87.3 mV
87.3 mV
0 V
3.576 V
3.576 V
G
G
2.2 mV
3.444 V
Right row, top to bottom
-----------
V bouncing
1.152 V
V bouncing
3.248 V
3.575 V
3.575 V
G
G
2.2 mV
2.2 mV
P203:
Top to bottom, pins 14 to 1
1.152 V
~140 mV
3.248 V
90 mV
G
G
G
G
G
2.2 mV
2.2 mV
2.2 mV
2.2 mV
2.2 mV
In the troubleshooting section, it says to test voltages and to "Check short of Main B/D". How would one go about checking for a short of the main? Not sure I understand this.
Any direction would be wonderful!! Thanks!
Attached is the service manual and some pics of the boards.
Here are the voltages I'm getting off of the pins when the unit is "on". The low voltages seem to be in spec, but nothing on 12 or 24v.
P201:
Left row, top to bottom (see pic for V reference)
--------
87.3 mV
87.3 mV
87.3 mV
0 V
3.576 V
3.576 V
G
G
2.2 mV
3.444 V
Right row, top to bottom
-----------
V bouncing
1.152 V
V bouncing
3.248 V
3.575 V
3.575 V
G
G
2.2 mV
2.2 mV
P203:
Top to bottom, pins 14 to 1
1.152 V
~140 mV
3.248 V
90 mV
G
G
G
G
G
2.2 mV
2.2 mV
2.2 mV
2.2 mV
2.2 mV
In the troubleshooting section, it says to test voltages and to "Check short of Main B/D". How would one go about checking for a short of the main? Not sure I understand this.
Any direction would be wonderful!! Thanks!
Attached Files
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