Hey, have you also encountered this situation? I just took over a large LED screen and am anxious to change the content but can’t find it—where is the legendary control card hiding? Don't panic, today we are just like playing hide and seek, turning this little thing's hiding place upside down!

1. First understand what the control card looks like.

This thing is just like the chip in a mobile phone. Although it is small, it is the "brain" of the screen. ​ ​A standard control card is usually a palm-sized metal box​ ​, with seven or eight indicator lights and a bunch of interfaces. Last year I saw a transparent screen in a shopping mall. Its control card was actually the size of a USB flash drive and was inserted directly into the frame of the screen. Technology is developing really fast.

There are two common styles:

1. ​​Iron box type​ ​: Metal casing with heat sink, common in outdoor large screens
2. ​​card type​ ​: Bank card-sized plastic package, mostly used in rental screens

2. Revealing the secrets of the three major hiding places

​​First stop: the back of the screen​​
More than 70% of LED screens have control cards hidden here. You must first find the power cord of the splicing box and follow the cord to get it right. The most amazing thing I have ever seen is a certain stadium fence screen. The control card is actually disguised as a box lock, and it can only be opened with a special key.

​​Second stop: Side inspection port​​
Those ultra-thin creative screens love to play with this. Just like finding the air conditioner filter, you have to slide the side cover open. I once helped a businessman maintain a floor tile screen. The control card was hidden at the joints of four adjacent modules. You had to use a suction cup to pull up the module to see it.

​​Third stop: remote control box​​
Don't look for it when you encounter a very large screen. The control card may be installed separately in the power distribution room. I remember that in a commercial complex project, all the control cards for 48 screens were installed in an iron cabinet with a password lock, just like a safe in the movie.

3. Three Characteristics of Confirming Identity

1. ​​Look at the interface​ ​: A serious control card has at least a three-piece set of network port, HDMI port and power port.
2. ​​Touch temperature​ ​: It will get slightly hot under working conditions, but it should never be hot to the touch (there will be problems if it exceeds 55℃)
3. ​​Check the lights​ ​: The green light is always on during normal operation, and the red light flashes to indicate that data is being transmitted.

Last month I saw a high-end product. The control cassette LCD screen displays real-time parameters. The temperature, humidity, and voltage are clear at a glance, just like a car dashboard. This kind of smart control card is becoming more and more popular now.

4. Guide for beginners to avoid pitfalls

​​Don't do this! ​ ​
× Plug and unplug the data cable while the power is on (the same as unplugging a U disk without ejecting it)
× Wipe the control card with a damp cloth (static electricity will destroy the chip in minutes)
× Remove the casing yourself (if some seals are damaged, the warranty will be void)

The reliable approach is:

1. Operate after power off
2. Wear an anti-static bracelet
3. Take photos to record the wiring locations first

There is a real case where a guy at an exhibition site tried to save trouble and pulled the cable directly. As a result, the network port of the control card was torn. The entire screen was disgraced on the spot, and the project manager was so anxious that he jumped.

5. What to do if you encounter trouble

​​Situation 1: The control card cannot be found​​
→ Check the structure diagram in the product manual (the electronic version is usually stored in the USB flash drive attached to the screen)
→ Call the manufacturer’s 400 number for video guidance (all now support AR remote annotation and positioning)

​​Scenario 2: Control card strikes​​
→ First check the status of the indicator light: if it is all off, it may be a power problem, if it is all on, it will probably need to be repaired.
→ Prepare the spare card for hot swapping (remember to clone the system parameters in advance)

I heard that high-end screens now have dual control card redundancy designs, just like the dual engines of an airplane. If one of them breaks down, it will still run normally. This design is really user-friendly.

Let me tell you, finding a control card is like falling in love - you need to find out the other person's temperament. Nowadays, some smart screens can locate the control card via mobile APP and can remotely restart the device. Technology has indeed made life simpler. But having said that, no matter how good the technology is, it must be paired with reliable after-sales service. Don’t you think this is true?

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