This is my own Plasma TV. Symptom, sudden power cut off. Power LED not lit at all when the side power button switched on. According to the service manual [ th_p42x30d_g_k_m_p_s_v_1.pdf ] , this is Power Board issue.
Trace further and narrow down the search to standby power section. Standby voltage (5V) is totally down.
| B159-003 Power Board Block Diagram |
This section on the B159-002 power board, component side.
| B159-002 Power Board Component Side |
This diode fails become short circuit, part of the secondary side of the transformer that feedback to FAN6754 PWM controller pin 2 (FB)
| FAN6754 Typical Application schematics, not the actual schematics |
It is B3100 diode that should be able to withstand 100V peak and 70V RMS reverse voltage
| 3.0A HIGH VOLTAGE SCHOTTKY BARRIER RECTIFIER |
Replace this FML-G22S, the best I have currently, salvage from old PCB.
It can withstand 200V peak.
Now, I can see the 5V standby voltage. Put everything back together and test.
