Panasonic TH-P42X30K Plasma TV Power Board Fix

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.

Will try to find the actual component soon (B3100) for replacement.

Lab Power Supply

Description and Circuit

Make your own lab power supply complete with adjustable voltage and constant current source.

Using single IC (LM324)

Here is the circuit.




Strip Board Layout.

Part List

1 LM324 Opamp

1 Ammeter 100 µA 1k ohm

1 Voltmeter

6 IN4001

1 Zener Diode 9.1V

1 Full-Wave Bridge Rectifier

1 LED

2 NPN Transistor, 2N3055

1 NPN Transistor, BC109C

1 Transformer

2 E-Capacitor 2200µF

1 Potentiometer 5k ohm linear

1 Potentiometer 10k ohm linear

1 Resistor 500 ohm

2 Resistor 2.2k ohm

1 Resistor 560 ohm

1 Resistor 6.2k ohm

2 Resistor 68k ohm

1 Resistor 0.22 ohm

4 Resistor 4.7k ohm

Component Image.

LM324

2N3055

Some Pictures.