Part of the LED screen is dark: the boundary method
A black area with clean edges — a block of cabinets, half the screen, the whole bottom — is not an LED failure. It is a broken chain: data or power stops at a precise point, and that point always sits at the boundary between the lit and the dark part.
Why the geometry of the fault gives you the answer
LED cabinets are daisy-chained: data enters the first, exits to the second, and so on. When a link breaks, every cabinet after it goes dark at once.
A rectangular black area following the cabling order therefore means: cable, connector, power supply or receiving card at the first dark element. Never the LEDs themselves.
The step-by-step procedure
- Identify the boundary precisely: last lit cabinet, first dark cabinet, in cabling order.
- Swap the network cable between those two cabinets with a neighbouring working one. After transport this is cause number one.
- Inspect the connector: a broken RJ45 clip or a half-seated connector is enough.
- If the area stays dark, check the first dark cabinet's power: supply indicator, power connector, fuse if any.
- Still nothing? Swap the receiving card of the first dark cabinet with one from a healthy cabinet: if the fault follows the card, the card is to blame.
- Finally test the controller output port by moving the chain to another port.
After transport or installation
On rental walls and tours, nearly all dark areas come from connectors shaken loose. Check every connector lock during build-up, and keep two spare network cables in the flight case.
When to call an engineer
If the cable swap and power test change nothing, or several unrelated areas go dark at once (which points to the controller or mains power instead), get guided help before dismantling more.
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The right half of my wall is black since transport — is it serious?
Rarely. It is the textbook case of a data or power cable shaken loose. Swap the cable at the boundary between the two areas: in most cases the image comes straight back.
Can a dark area come from a cabinet itself?
Yes, through its receiving card or power supply, which then cuts the rest of the chain. That is why you test cable, power, then card, in that order, on the first dark cabinet.
My wall has redundancy — why didn't the area come back on its own?
With cabled, active redundancy a data break should be picked up by the backup path. If the area stays dark, redundancy may not be configured, or the failure is power, which data redundancy does not cover.
Can I finish my event with a dark area?
Yes, if power is not the cause and nothing is overheating. Reframe the content if possible and fix the fault after the show.