Brand:
LG
Category: Monitor
Document Type: Manual
Language: EN
Manual for 27GL850
Uploaded: Nov. 21, 2025, 7:30 p.m.
Manual Publish Date: 2019-03-29
Warranty Information
This manual does not contain specific warranty period information.
Safety Precautions:
- Always use an isolation transformer when servicing non-isolated chassis.
- Replace fuses with the specified type.
- Keep wires away from high voltage or high temperature parts.
- Perform AC leakage current checks before returning the unit to the customer.
- Specific checks for "Leakage Current Cold Check" and "Leakage Current Hot Check" are detailed, including test circuits and acceptable limits.
- Technicians should be protected from electrical shocks.
- Components can be protected from accidental shorts.
- High wattage resistors need to be kept a certain distance from the PCB.
- No Power: Steps involve checking voltage levels at various points (C701, IC701/702, IC703, IC705), checking the clock, and replacing components like IC701, 702, 703, 705, X100, or IC107.
- No Screen on: Checks include backlight status, panel power, eDP AUX, FFC cable, WLED_ENABLE signal, LED driver output, and potential replacement of IC700, P201, IC601/602, IC300/303, T-Con board, or the module itself.
- No Video – HDMI: Involves checking input signal format, HDMI cable, connector JK102, I2C signal (EDID), and AUX signals for IC102/IC103, with options to replace the connector, IC100, IC102, IC103, or the G-SYNC Module.
- No Video – DP: Similar to HDMI troubleshooting, it checks DP cable, connector JK101, AUX signals for IC101/IC103, with similar replacement options.
Troubleshooting and error codes
| Symptom | Check Point | Action |
|---|---|---|
| 1. No Power | Check C701 Voltage Level (19V) | Y: Proceed, N: Replace Adapter |
| Check IC701, 702 Output Voltage Level (5V) | Y: Proceed, N: Replace IC701, 702 & Recheck | |
| Check IC703 Output Voltage Level (3.3V) | Y: Proceed, N: Replace IC703 & Recheck | |
| Check IC705 Output Voltage Level (2.5V, 1.2V) | Y: Proceed, N: Replace IC705 & Recheck | |
| Check X100 Clock 27MHz | Y: Proceed, N: Replace X100 | |
| Check Power connector OK? | Y: Proceed, N: Replace Adapter | |
| Replace IC107 Flash Memory | N/A | |
| 2. No Screen on | Module Back Light On? | Y: Proceed, N: Check WLED_ENABLE High? |
| Check Panel Power 10V (L700) | Y: Proceed, N: Replace IC700 & Recheck | |
| Check IC700 Output 10V | Y: Proceed, N: Replace IC700 & Recheck | |
| Check Panel eDP AUX P300 (#9, 10, 36, 37) | Y: Proceed, N: Check IC300, IC303 Repair Main B/D | |
| Check FFC Cable for Damage or Open Conductors | Y: Proceed, N: Replace FFCable | |
| Check WLED_ENABLE High? (IC601, IC602 27pin) | Y: Proceed, N: Check P201 (PIN No.69) Replace G-SYNC Module | |
| Check LED Driver Output (P601, P602 - 1, 2, 5, 6) | Y: Proceed, N: Check IC601, IC602 Replace LED Driver IC | |
| Replace T-Con Board or Module | N/A | |
| 3. No Video – HDMI | Check input signal format Is it supported? | Y: Proceed, N: Replace the Connector |
| Check HDMI Cable for Damage or Open Connector | Y: Proceed, N: Replace the Connector | |
| Check JK102 for proper connection or Damage | Y: Proceed, N: Replace the IC100 | |
| Check I2C Signal (EDID) | Y: Proceed, N: Replace the IC102 | |
| Check IC102 AUX Signal (#J1,H1) | Y: Proceed, N: Replace the IC103 | |
| Check IC103 AUX Signal (#3,4) | Y: Proceed, N: Replace the IC103 | |
| Replace the G-SYNC Module | N/A | |
| 4. No Video – DP | Check input signal format Is it supported? | Y: Proceed, N: Replace the Connector |
| Check DP Cable for Damage or Open Connector | Y: Proceed, N: Replace the Connector | |
| Check JK101 for proper connection or Damage | Y: Proceed, N: Replace the IC101 | |
| Check IC101 AUX Signal (#29,30) | Y: Proceed, N: Replace the IC103 | |
| Check IC103 AUX Signal (#3,4) | Y: Replace the G-SYNC Module |