Samsung PN19LT/LO, Service Manual

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5 Troubleshooting
PN19LT/LO/JT/JO 5-7
5-1-13 High Voltage Failure
IC401 Pin 6 OSC pulse exists?
Q402 Gate driving pulse exists?
Check and replace Q401,
Q423, Q424, and Q425.
Yes
Yes
No
Check and replace IC401
and +12 V line.
No
Q402 Drain pulse exists?
Check and replace
Q403, Q404, D401, D432, and L402.
Yes
No
Done
WAVEFORMS
10
3
10 2.00 V (Q402, Gate)
CH1 P-P = 2.00 V CH1 RMS = 7.692V
3 2.00 V (IC401, #6)
CH1 P-P = 2.00 V CH1 RMS = 5.868 V
11 50.0 V (Q402, Drain)
CH1 P-P = 50.0 V CH1 RMS = 73.7V
IC101 Pin 8 input exists and
varies with different patterns?
Check and replace IC101.
Input full white pattern to monitor.
No
Yes
No
T501 Pin 8 output exists?
Check and replace T501.
Yes
No
IC201 Pin 26 output exists and
varies with different patterns?
Check and replace IC201.
Check and replace some parts
around T501.
Yes
No
Done
Check CN102.
5-1-14 ABL Failure
11