[ AC Input: 100V-240V ] │ ▼ [ EMI Filter & Rectifier ] ──► [ 450V Main Filter Cap ] │ ▼ [ Low Voltage Logic Out ] ◄── [ PWM Switcher & Transformer ] ──► [ LED Backlight Driver ]
I can provide more detailed circuit breakdowns based on your focus.
A network of medium-voltage electrolytic capacitors (typically 10V to 25V ratings) eliminates high-frequency ripples, outputting pure lines to the logic array.
In Rev 1.0 boards, they were 0805 size. In Rev 2.0 boards, they are 1206. If your ILPI354 gets hot but you have 19V on pin 17, replace these resistors even if they measure fine. They develop micro-cracks. Use 1.5-ohm to 2.2-ohm as a modern substitute. ilpi354 va schematic updated
The schematic shows a split-rail design:
This board integrates the AC-to-DC power converter and the LED backlight driver circuit. AliExpress 2. Visual Inspection Checklist
If open, test the Bridge Rectifier and Main MOSFET for shorts. [ AC Input: 100V-240V ] │ ▼ [
If you repair monitors, all-in-one PCs, or BenQ/LG displays, you’ve likely crossed paths with the power/LED driver board. Good news for the repair community: a major update to the schematic diagram has just been released.
If blown, do not simply replace it. Check the bridge rectifier and the main switching MOSFET (Q101) for a collector-to-emitter or drain-to-source short circuit.
If the power LED turns on but the screen remains dark, the LED driver section of the ILPI-354 may have failed. 4. Where to Find Schematics and Parts In Rev 2
Replace capacitors C611, C612 (usually 10V or 16V 1000uF) on the secondary side, even if they look fine. Voltage Stability: Measure 12V and 5V under load. 3. Backlight Failure Check LED Connector: Ensure pins are not corroded.
An updated schematic mapping of the ILPI-354 V.A divides the board into four prominent electrical environments:
The high operating temperature of the inverter transformers degrades factory solder over time. Clean old solder away and re-solder the pins using leaded solder for better mechanical durability.
Ensure the logic board sends a 3.3V or 5V signal to the inverter IC when the power button is pressed. Without this signal, the backlights will never turn on. 5. Modifications and Reliable Repair Practices