LED Black Screen: How to Locate and Solve Quickly?

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How to target the problems of LED black screen, and what are the methods for us to deal with it? There are some points you have to know before having the ability of locating such problems, and tackle with it. Now, let’s get start!

Warm up - Do You Remember the Structure of LED Control System?

Before we discussed today’s topic, let us review the basic structure of LED control system which we have introduced to readers in the previous article: LED Display Connection.

For the basic structure of LED control system, there are three parts: control computer, LED display screen and LED display controller.  

The control computer will be connected to the LED controller with USB cables or Ethernet cables for sending the control command. And signal cables such as HDMI will be used to connect to the controller so the video signals can be transmitted.

After this, there will be network cables connected to the LED display. Thus, we get our basic structure of LED control system.

Sometimes, there will involve LED display processor for dealing with the input source to let the screen can show the entire image, or achieve some effects such as rotation effects and scaling. Now, we can get a picture showed like below:

LED-display-control-systems structure

So, why do we cite this concept again? That is because that they all can be the factors resulting in screen blackout! So for the further discussion, we retrieve it again to prepare. Now, let us come straight to the point.

What Can LED Receiving Card Tell Us?

The receiving card will be equipped in the LED cabinet. Generally, one cabinet will equip with one receiving card. By noticing the states of LED receiving card, we can know the running statues of the screen. Let us take Novastar control card as the example: 

Please notice the green light indicator in the picture, it is the signal resource you can diagnose whether the receiving card is working normally or where is the problem. There are several situations for you to know:

(1) The indicator flashes once a second: in this case, the receiving card is working normally.

(2) The indicator flashes four times in half a second, and flashes four times again after half a second interval, meaning the receiving card is working normally but in the backup mode.

(3) The indicator flash slowly, only once for five seconds, and in this situation, there may be some problems with network cables.

(4) The indicator flash quickly, three times in half a second, that means there is no signal input. Therefore, maybe we need to change the signal cables or reconnect it.

After we know four conditions of LED receiver, we can come to the next chapter now.

LED Black Screen Troubleshooting

Types of LED Black Screen

There are two kinds of blackout of LED display screen including full-screen blackout and part of the screen blackout. 

And the part of screen blackout may happen on specific cabinet, specific LED display module, and specific sending card output area.

Why Dose LED Screen Go Black?

As we have mentioned before, any part of LED control system may be the reason for LED screen blackout. Here we list the reasons and corresponding solutions.

(1) Screen power

A. The screen is power-off.  Just power on the LED display, then the problem can be solved.

B. There is insufficient power supply. Please change the power supply to replace the power supply.

(2) Receiving card

A. The rcfgx file is wrong. Send the original rcfgx file or recreate the file and then send it.

B. The firmware is wrong. Please upgrade the correct firmware.

(3) Video source

A. Black source. Just check and change the video source.

B. Cables is disconnected, loose or bad. Please reconnect or change the cables.

C. The video source is not compatible with LED display. Please upgrade the correct firmware if there are something wrong with our sending card firmware program files.

Sometimes it comes from the wrong video source, so replace the right one.

(4) Sending card

A. The sending card is not powered on. Please power on the sending card.

B. Have selected wrong input. Please select the corresponding input source such as HDMI or DVI.

C. There are input source interface fault. Change another interface or change sending card.

(5) Brightness value

A. 0% Brightness. Please increase the brightness, and the value commonly is 50%.

B. The screen control is blackout. You can adjust the screen control to normal.

(6) Ethernet cable

The Ethernet cables may be loose or bad, then reconnect or change the Ethernet cables.

Now, we have known the points, let’s say the systematic methods now.

What If LED Full Screen Blackout?

We can make a preliminary judgement from the red indicator light of receiving card. 

led receiving card red indicator light

A. If the red indicator light is off, meaning there is no power supply. Then please check or replace the power supply.

B. If the red indicator light is on, then the problems may happen on other points. Check other possible reasons. 

If the situation is B, then go to check the green indicator light as we have talked about before.

A. If the green indicator light flashes slowly, only once for five seconds. Please check the sending card and Ethernet cables.

B. If the green indicator light flashes three times in half a second, and flashes three times again after 0.5 second interval, please check the video source input as there is no signal input.

C. If the green indicator light flashes once a second, meaning the receiving card is working normally, then please check the firmware program file of receiving card or rcfg file to see if there are something wrong with these two files. Besides, you can check whether the brightness value is set as 0 percent.

What If Part of LED Screen Black?

There are three kinds of part of LED screen black including specific module blackout, specific cabinet blackout and specific output port area blackout. 

(1) LED module level:

A. The LED display module power off. Change the power unit or power cable.

B. HUB board fault. Change to other connectors or change new hub board.

C. Flat cable is loose or fault. Please reconnect the flat cable or change it.

(2) LED cabinet level:

A. Power supply unit faults. Please replace the power supply unit.

B. Ethernet cable loose or fault. Just change a new Ethernet cable or reconnect it.

C. Something wrong with receiving card including wrong rcfg file, firmware and receiving card fault. 

Just do the corresponding fixing methods such as reading rcfg file from a normal receiving card and sending it to the receiving card.

For the wrong firmware, please upgrade the correct firmware. And the wrong receiving card can be dealt with by new LED receiving card.

D. HUB board fault. Please change a new hub board.

(3) LED sending card output level:

A. Ethernet cable is loose or fault. Just reconnect the Ethernet cable or change it.

B. The output port of LED sending card fault. Please change the sending card.

C. The LED screen power fault. Change the power supply or reconnect it.

Above are the potential reasons of LED black scree, and the methods to deal with them. If you occur any of them, just follow the advice to position the problem, and solve it quickly!

Reviews

Now, let us do the summary here.

First, we learned different conditions of green indicator light of receiving card. There are four situations we have to know.

(1) If the light flashes 1 time per second, meaning the card is working normally.

(2) If the light flashes 4 times at 0.5 second intervals quickly, then it is in the backup mode.

(3) If it flashes 1 time per 5 seconds, representing the network cable is disconnected.

(4) If the indicator light flashes 3 times at 0.5 second, meaning there is no signal input.

Then, we talked about today’s topic – LED black screen. It can be divided into two situations including full LED screen black and part of the screen blackout.

For the full black LED display, please check the red indicator light of receiving card at first to make sure that it is powering-on. If yes, go to check other points we have mentioned above according to conditions of green indicator lights such as Ethernet cable and receiving card files.

Moreover, for the part of LED screen black, there are three levels including LED module level, LED cabinet level and output port level. Please troubleshoot the problems based on the contents we listed above.

Conclusions

In this article, we discussed a common issue that confuses users and technicians of LED display screen – LED black screen. We discussed the way of justifying the conditions of receiving card as the information we get from it can tell us many clues. And then we introduced to you two situations of screen blackout including full LED screen blackout and part of the screen blackout and the solutions!