Samsung plasma TV S42AX-YD05 (W3) secondary boot protection fault repair - android - Phones Developers

LC03-3.3 SOP8 TVS Static Protection 3.3V

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Samsung S42AX-YD05 (W3) plasma screen can not open the machine indicator light secondary open source board protection According to the initial phenomenon of fault phenomenon, the fault point is roughly on the power board, remove the power board to let it work alone (single work only need to ground PS-ON , VS-ON connected to D5V), protected when powered. Then it is judged that the power board is faulty.
According to the fault phenomenon, the indicator light is on, indicating that the 5VSB circuit works normally. The fault point may be in the VAMPA12VGDSV voltage forming circuit and the PFC circuit and the VS and VA voltage forming circuits. Disengage all short contacts and measure 5VSB to 5.2V.
normal. Short the PS-ON to the ground. Power-on measurement PFC voltage is about 360V, then protect, re-energize to measure VAMP voltage, the voltage is protected to about 10V. Then judge the fault point in the VAMPA12VGD5V voltage forming circuit and the corresponding protection circuit.
The VAMPA12VGD5V voltage was measured at the moment of power-on, and the DSV voltage was found to rise to 5.6V and then protected. The description is that the D5V feedback detection loop has a problem that causes the D5V voltage to run out of control. The DSV feedback detection loop consists of R8321, R8322, and R8320. From the circuit analysis. Only R8321, R8322 open circuit or R8320 leakage may cause this fault. The measurement R8321, R8322 has no open circuit. Check R8320fl inch and find that there is rust under R8320. It is suspected that the leakage is here. Remove the R8320 and measure the resistance value. After the board is installed, the R8320 is powered on and the fault is eliminated.