If ENA and DIM signals are correct, hook an oscilloscope or a fast digital multimeter up to the gate of the Q50 MOSFET (PDR6912). Turn the monitor on. If you see exactly one brief voltage voltage pulse and then nothing, the DP860EGN chip is entering protection mode. 3. The "Single Pulse" Over-Voltage Protection (OVP) Loop
Always use an isolation transformer and safety glasses when probing a live, hot-side circuit. ilpi354 va schematic upd
Since "ILPI354" most likely refers to the (or similar LG UltraWide/4K monitor models that utilize the ILPI-354 power/LED driver board), and "UPD" refers to an update or revision, this blog post is drafted to target electronics repair technicians and DIY enthusiasts looking for schematic discrepancies or repair notes. If ENA and DIM signals are correct, hook
[ AC Mains Input ] ---> [ EMI/Hot Side Filter ] ---> [ Bridge Rectifier / Bulk Cap ] │ [ PWM Switching IC + MOSFET ] │ [ Main Transformer ] │ ┌─────────────────────────────────────────┴────────────────────────────────────────┐ ▼ ▼ [ Low Voltage Rectification ] [ High Voltage Backlight Section ] (Provides stable 5V / 12V DC rail) (Powers CCFL lamps or LED array strings) [ AC Mains Input ] ---> [ EMI/Hot
A common fault reported for this board involves the monitor displaying an image (visible with a flashlight) but no backlight illumination. This is often caused by the driver IC entering protection mode after a single initial pulse to the MOSFET. If the driver and MOSFET are replaced without success, the issue typically lies in: Faulty LED strips (open circuit).