How to Replace a Power Supply on LED Sign City Modular LED Signs

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LED signs are a crucial part of modern advertisement and informational display. LED Sign City modular LED signs are widely used due to their quality and reliability. However, like any technology, parts like power supplies may need replacing over time. This blog will walk you through the steps needed to replace a defective power supply in LED Sign City modular LED signs.

Diagnosing a Defective Power Supply

To identify a defective power supply, observe what your screen is doing. A power supply is connected to a series of modules; thus, if more than one module is out in a sequence, you should check your power supply. In LED Sign City modular LED signs, power supplies are typically located in the top second row for signs up to 3 feet tall and in the fourth row for 4-feet-tall signs. For larger signs, you can find your power supplies in every other row, starting from the second row.

Identifying the Issue

Our modular LED signs link a maximum of three modules to each power supply to maintain maximum capacity close to 80%. This precaution keeps power supplies cooler, reducing failures over time. If your sign has three modules in one column and 2-3 modules out in the top row, there is a good chance the issue is your power supply.

Step-by-Step Guide to Replacing the Power Supply

1. Unlock the Modules

Using a three-millimeter Allen wrench or hex key, identify the lock points on your module and make a counter-clockwise turn to unlock. Each module has two lock points in the center; the first about 2 inches from the top and the second is about 2 inches from the bottom. Here is a video showing you how to access and remove the modules:

2. Inspect the Power Supply

Next, inspect your power supply; a working power supply will have a solid green light in the top right/left corner. The light is not immediately obvious, so look closely. If the light is off, turn off the sign and replace the power supply.

If the light is on, use a multimeter to check the V+ and V- to verify that there is a constant output of 5V DC. If you are not familiar with measuring electrical current, consult a professional electrician to replace the power supply for you. If the current is less than 5V, turn off the sign and replace the power supply.

3. Removing the Defective Power Supply

  • Turn the sign off.
  • Remove the terminal cover and disconnect the power supply from the terminal, keeping a record or picture of where the cables are connected.
  • Remove the top screws from the power supply and loosen the bottom screws using a magnetic screwdriver. These screws are very small (M3/6 mm), and it’s crucial not to use any power tools when loosening or tightening these screws.

4. Installing the New Power Supply

  • Once you remove the power supplies, transfer the cables to the new power supply.
  • Reinstall the power supply, following the steps in reverse.
  • Reinstall your modules and then turn your screen on.

Your screen should now look as good as new. Here is a video walking you through the steps to replace your power supply:


Remember, safety first! Always ensure that the sign is turned off before attempting to replace the power supply and consult or hire a professional electrician if you're not comfortable or familiar with handling electrical components.

This guide should help in efficiently addressing and solving any power supply issues, ensuring that your LED Sign City modular LED signs continue to operate and display as intended!

If you need to order a replacement power supply, you can do so directly from here.

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