Read LG 50PT85-ZB (CHASSIS:PD74A) Service Manual online
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TROUBLE SHOOTING GUIDE
1. Power Board
1-1. The full flowchart for the voltage output
Start check
Manufacture’s model
passage
1. Check the Power Off
status.
Does the whole
screen appear?
screen appear?
Is it
identical to when the
power is off?
No
Yes
No
Yes
Yes
Yes
Yes
2. Check the Interface
signal status.
Is the Interface
signal operating?
Yes
3. Check the St-by 5V
signal circuit.
Does the
low pressure output
appear?
Does the
St-by 5V signal
appear?
No
No
Yes
4. Check the 5V Monitor
signal circuit.
Does the
5V Monitor signal
appear?
No
7. Check the VSC Vs-ON
signal
Does the
high tension output
appear?
Does the
VSC signal Vs-ON
appear?
No
No
Does the
high tension
output voltage
occur?
When
removing the Y B/D
Module input connector,
does output voltage
drop?
When the
Y, Z B/D Module
input connector, does Power
Board high tension
output voltage drop?
No
No
No
9. Check the Power
Board Output high
tension circuit
Yes
10. Check the Z B/D
Module output circuit
Yes
When
removing the Z B/D
Module input connector,
does output voltage
drop?
11. Check the Y B/D
Module output circuit
Yes
Yes
8. Check the Vs, Va
voltage output circuit.
Does the
Vs, Va voltage output
appear?
No
Yes
Yes
5. Check the VSC RL-ON
signal.
Does the
VSC signal RL-ON
appear?
No
6. Check the VSC low
pressure output
Does the
VSC low pressure
output appear?
No
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