Taxi Cab LED Sign – Power Supply Replacement Guide

This guide explains how to identify and replace the power supply in your LED taxi cab sign. It includes key safety steps and optional diagnostic testing for experienced users.

Tools and Materials

• Phillips-head screwdriver

• S2 TA (Triangle) screwdriver bit – for tamper-resistant screws on the housing

• Multimeter (optional)

• Protective gloves

• Clean work surface

• Zip ties (optional)

Safety Guidelines

1. Turn off all power to the sign. Unplug it from the power source or disconnect the battery.

2. Do not work on a live electrical circuit.

3. Only power the unit for testing when instructed and only if it is safe to do so.

4. Discharge static electricity by touching a grounded metal object before handling internal components.

Replacement Instructions

Step 1: Locate the Correct Side

Move to the side of the sign closest to the sensor light. This is the side that contains the power supplies.
If you open the opposite side, you will see the control board instead.

Step 2: Remove the Back Cover

Using a Phillips-head screwdriver, remove the five screws securing the back panel.
Lift off the panel and set the screws aside.

Step 3: Pull Out the Tray

Slide the internal tray outward carefully. You should now see two power supplies.

• The left power supply powers the left screen panel.

• The right power supply powers the right screen panel.

If you see a control board instead of power supplies, slide the tray back in and move to the opposite side of the sign. Repeat steps 2 and 3.

Step 4: Optional Voltage Testing (For Experienced Users Only)

If you have electrical experience and access to a multimeter:

1. Temporarily plug the sign back in with the tray extended.

2. Use a multimeter to check the output terminals of the power supply.

3. A functional power supply should output a steady 5V DC to the LED modules.

4. If no output or unstable voltage is detected, the power supply is likely faulty.

If you do not have electrical experience or tools, skip testing and proceed directly to replacement.

Step 5: Power Off Again

Fully unplug the sign again before proceeding with removal or installation of any component.

Step 6: Replace the Power Supply

1. Disconnect the input (AC) and output (DC) wires from the faulty power supply.

2. Remove any screws or clips securing the unit.

3. Install the replacement power supply in the same location.

4. Reconnect all wiring securely. Use zip ties as needed to organize cables.

Step 7: Reassemble and Final Test

1. Plug in the sign and verify that both screen panels power on.

2. If available, use a multimeter to confirm that each power supply is outputting 5V DC to its respective module.

3. Power off the sign.

4. Slide the tray back into the housing.

5. Reattach the back panel using all five screws.