LVDS Display Not Turning On: Troubleshooting Guide & Solutions

Application Note — Issue 1

LVDS Display Not Turning On:

Troubleshooting Guide & Solutions

Applicable Board: PCM-ADP351 | Document Version: V1.1 | Last Updated: April 2026

LVDS (Low-Voltage Differential Signaling) is widely used to drive LCD panels in industrial control and commercial display applications. However, issues such as "black screen", "no backlight", or "abnormal display" are among the most frequently reported problems during integration and commissioning. This guide covers four key diagnostic areas specific to the PCM-ADP351 motherboard, along with a six-step self-check checklist to help you identify and resolve the issue quickly.

 Quick Diagnostic Priority Reference

Follow this priority order. The majority of cases are resolved within the first two steps:

 Check Area 1: Verify Panel Operating Voltages

An LCD panel requires two supply voltages to operate: the panel drive voltage (VCC) and the backlight voltage (BKL). A mismatch between the board output and panel requirements will prevent the display from turning on — and in severe cases, may damage the panel permanently. This is the single most common root cause.

1. Voltage Jumper Quick Reference

First, consult your LCD panel datasheet to confirm the required drive voltage and backlight voltage. Then set the jumpers according to the table below:

2. How to Tell If the Backlight Is the Issue

If the screen appears to have a very faint image visible only when illuminated with a flashlight, the video signal is present but the backlight is not on. In this case, check the PWR_BKL jumper setting before anything else.

 Check Area 2: Verify Critical Pin Connections

The LVDS connector (DF13 2x20Pin) has 40 pins. Incorrect wiring is the second most common cause of a blank display.

1. Critical Detail: PIN 39 Must Be Connected to GND

• Confirm that PIN 39 of the FFC/FPC cable is connected to GND.

• If using a custom-made cable, specify PIN 39 grounding when placing the order.

2. Prevent Reversed Cable Insertion (Locating Pin 1)

With densely packed pins, a reversed cable shifts all signals and will guarantee a non-functioning display. To verify the correct orientation:

• Locate the orientation marker on the board near the LVDS connector.

• A square pad, the number "1", or a triangle "\u25b3" symbol marks Pin 1.

• Align the Pin 1 conductor of your cable with this marker before inserting. The connector should seat fully with a light click.

 Check Area 3: Verify Signal Type (LVDS vs. eDP)

The PCM-ADP351 outputs LVDS signals by default, but can be factory-configured to output eDP. If an eDP panel is connected to an LVDS output — or vice versa — the display will never turn on regardless of jumper or BIOS settings.

• If you need eDP output, request factory customization or signal switching when ordering the board.

• Do not attempt to modify the board hardware to change signal type.

 Check Area 4: Verify BIOS Resolution & Channel Settings

Once hardware connections are correct, BIOS configuration is the final step. The PCM-ADP351 supports 18-bit and 24-bit, single-channel and dual-channel LVDS. These parameters must exactly match the panel datasheet.

Step-by-Step BIOS Configuration:

• Press Del or F2 during POST to enter the BIOS setup utility.

• Navigate to the Display / Graphics settings section.

• Set the LVDS panel resolution to exactly match the physical resolution in the panel datasheet (e.g., 1024×768, 1920×1080).

• Set the channel mode: Single or Dual channel.

• Set the color depth: 18-bit or 24-bit, as specified in the panel datasheet.

• Press F10 to save and exit, then observe whether the display turns on.

 Six-Step Self-Check Checklist

Complete all items below before contacting technical support. Most issues can be resolved without escalation.

☐ Power Off Confirmed: System is fully powered off before handling cables or jumpers.

☐ Cable Orientation Confirmed: Pin 1 marker located on the connector; cable is not reversed.

☐ Voltage Jumpers Confirmed: PWR_LCD and PWR_BKL jumpers are set to match panel datasheet voltages.

☐ PIN 39 Confirmed: PIN 39 of the LVDS cable is correctly connected to GND.

☐ Signal Type Confirmed: Board output signal type (LVDS or eDP) matches the panel interface type.

☐ BIOS Settings Confirmed: Resolution, channel (Single/Dual), and bit-depth (18/24-bit) match the panel datasheet exactly.

 Still Not Working? Contact Our Technical Team

If the display is still not turning on after completing all six steps, the issue may involve a hardware defect, panel damage, or a special customization requirement. Please contact our technical support team with the following information to expedite resolution:

• Motherboard model and serial number (label on the back of the board)

• LCD panel model number and datasheet (especially interface type, resolution, drive voltage, and backlight voltage)

• Description of the symptom (fully black, faint image visible with flashlight, distorted display, etc.)

• Diagnostic steps already attempted and their results

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