Professional LED display sourcing for global B2B projects
Product Center
Premium large LED displays from top-tier brands, meticulously refurbished and tested to deliver uncompromised brilliance on every stage.
Our project case wall
From world tours to billboards and retail a look at the screens we helped bring to life.
6 Steps from Intake to Delivery
Every batch goes through a rigorous, documented process. No shortcuts, no exceptions.
1
Receiving & Intake
Incoming panels are verified against purchase orders — brand, model, pixel pitch, quantity, and physical condition. Every cabinet is photographed and logged into the batch record.
2
Inspection & Testing
Full electrical safety test, receiver card verification, module voltage check, and signal chain validation. Each panel is lit up for white, red, green, and blue uniformity testing.
3
Grading
Panels are graded A through E based on外观 condition and service age. Grading is transparent — you always know exactly which grade you’re purchasing.
4
Repair & Refurbishment
Every panel with functional issues is fully repaired using same-batch replacement parts. Dead LEDs, driver ICs, power supplies, and mask lenses are replaced as needed.
5
Burn-in Testing
Indoor panels: minimum 72 hours. Outdoor panels: minimum 96 hours. Continuous operation at full brightness with periodic inspections to catch early failures.
6
Final QC & Shipping
Pre-shipment visual re-inspection, quick power-on check, accessory verification, and professional packing. Each shipment includes a full test report.
Trusted by Global Partners
Building lasting relationships and driving shared success with clients worldwide.
About Stellux
LED stage screens are the most essential visual medium for concerts, exhibitions, and major events. When a show ends, many high-quality large screens are left idle or replaced — the hardware remains solid, and the value is never exhausted.
Stellux is dedicated to the stage-rental LED screen sector — we create no new waste, only reawaken old value. We know that stage equipment is more than just screens: it is the reputation of AV contractors, the visual quality of every show, and the confidence behind every client’s project.
With tight budgets in overseas markets, rental companies need mature large screens that combine great value with stable performance — Stellux lets every professional screen step back onto the stage and shine.
WHY CHOOSE STELLUX UESEDLED
Reliable LED Display Solutions from Project Planning to Long-Term Support
Engineering cases | Customer partnerships | 19 years of industry experience | Professional repair team
Top-Tier Brands · Assured Quality
- Absen · Benchmark of the global rental market
- Unilumin · Renowned for rock-solid stability
- GLOSHINE · Battle-tested on stage
- Lightlink · Exceptional color performance
Expertly Engineered · Pro Refurbished
- Module-level repair · Precise dead-pixel treatment
- System-level tuning · End-to-end optimization
- Color calibration · True-to-stage reproduction
- Structural overhaul · Mechanical strength testing
Standardized QC · Transparent & Trustworthy
- Visual inspection · Structural integrity
- Photometric testing · Uniform brightness / chromaticity
- 72h burn-in test · Stability verification
- Functional verification · Full-scenario simulation
Complete After-Sales · Long-Term Support
- 48h warranty response · Quick resolution
- Lifetime technical consultation · Support on demand
- Guaranteed spare parts · Long-term reliability
- Regular follow-up · Continuous improvement
Trusted by Global Partners
Building lasting relationships and driving shared success with clients worldwide.
What should I confirm before buying a used LED display?
Start with a complete equipment identity, not only a selling photo. Request the display model, pixel pitch, cabinet dimensions, indoor or outdoor classification, cabinet quantity, receiving-card model, power-supply model, controller, current software and available configuration files. Ask for front, rear, connector, label and powered-on test photos. A screen that can display an image in a warehouse may still have mixed batches, missing accessories, unstable power supplies or an unknown receiving-card configuration. Separate confirmed information from assumptions. The serial number, nameplate and original specification are evidence. A seller’s statement such as “same as P3.91” is only a lead until the physical pitch and model are checked. Also ask about previous use, rental frequency, repairs, water exposure, storage and the reason for sale. These details do not automatically reject the screen, but they help estimate risk. Before payment, agree on an acceptance checklist: image tests, cabinet quantity, accessories, packaging, configuration files, shipping condition and responsibility for missing items. If the screen is for a commercial installation, include a technical inspection or a sample-cabinet test before the full purchase. Do not assume that an old warranty, firmware package or spare part remains valid for a new project.
How do I verify the pixel pitch and cabinet size of a used screen?
Verify pixel pitch from more than one source. Check the original model label, module label, cabinet drawing and the physical distance between pixel centres. Do not identify pitch only from a front photograph because perspective, camera resolution and image processing can make different products look similar. If the cabinet is 640 × 640 mm, confirm whether that is the complete mechanical size, the LED face size or a nominal cabinet dimension with a frame. For planning, the approximate cabinet pixel count can be calculated as cabinet width in millimetres divided by the pitch, and the same for height. For example, a 640 mm P2.5 cabinet is approximately 256 pixels wide. This is a planning estimate, not a substitute for the manufacturer’s active-pixel drawing. Borders, module gaps, special cabinet structures and non-standard pitches can change the result. Measure several cabinets from different batches. A used inventory may contain visually similar cabinets with different pitches or resolutions. Photograph the labels and record cabinet numbers. If a screen is sold by square metre, also count the actual cabinets and verify that the quoted area matches the physical face, not the shipping or installation opening.
Why are serial numbers and production batches important in a used LED purchase?
Yes. Serial numbers and batch information support traceability. They can help identify the cabinet model, production period, module batch, warranty record, compatible receiving card and spare-part reference. Without this information, a screen may still work, but future repairs become slower and more expensive because engineers cannot tell whether a replacement belongs to the same system. Check labels on the cabinet, module, power supply and receiving card. Photograph the label in focus and link it to a cabinet number. If labels are missing or unreadable, mark that as an information gap rather than reconstructing a model from appearance. A batch difference does not automatically mean poor quality; it means that brightness, colour, calibration and mechanical parts should be compared before the cabinets are mixed. Ask the seller whether modules, power supplies or receiving cards have already been replaced. A repaired cabinet may contain a part from another batch. That is acceptable only when the replacement is compatible and the display passes a controlled test. Keep serial records with the purchase documents, inspection report and configuration backup. This is particularly valuable when the display will be shipped across borders or installed by a reseller who did not attend the original sale.
How many spare cabinets, modules and power supplies should I buy?
There is no universal spare percentage for every used display. The right quantity depends on screen size, age, rental frequency, operating environment, transport distance, product availability and the time required to obtain replacement parts. A small indoor fixed screen may need a different spare strategy from a large outdoor rental inventory used every weekend. At minimum, identify the parts that can stop a complete branch: receiving cards, power supplies, signal cables, power cables, HUB boards and matching modules. For rental systems, keep enough matching cabinets or modules to respond to damage during transport and installation. For an older product, consider buying additional modules and power supplies while the exact batch is still available. Mixed replacement parts may work electrically but create visible colour or brightness differences. The spare list should record model, pitch, cabinet size, connector type, receiving-card configuration and storage location. Do not buy a visually similar module without checking scan mode, driver IC, data interface and physical mounting. Store spares in a dry, labelled environment and test them periodically. A spare that has been stored for years without inspection should not be treated as confirmed good.
How can I tell whether a used LED cabinet is for indoor or outdoor use?
Do not decide from brightness or appearance alone. Check the model label, cabinet construction, sealing method, module protection, connector protection, cooling design and official environmental specification. Outdoor products may have higher brightness and weather protection, but an outdoor rating applies to a complete approved installation and defined test conditions. A bead of sealant or a rain hood does not automatically make an indoor cabinet suitable for outdoor use. Inspect gaskets, cabinet doors, screws, corrosion, water marks, cable glands and the condition of the rear panels. Ask where the cabinet was previously installed and whether it has been exposed to rain, salt air, dust or direct sun. An outdoor cabinet that has been stored badly may have hidden corrosion even if the LEDs still light. An indoor fine-pitch cabinet may look excellent but fail quickly in a wet or high-temperature location. The site also matters. Outdoor installation requires drainage, wind and structure review, protected power distribution, grounding, surge protection and maintenance access. Indoor installation still requires protection from condensation, roof leaks, cleaning liquid and air-conditioning discharge. Confirm the actual environment before ordering and record the limits in the acceptance document.
How should I evaluate used-screen brightness for the real viewing environment?
Brightness must be evaluated with the environment, content and viewing distance. A screen that looks bright in a dark warehouse may be weak behind glass or in direct sunlight. A screen that looks impressive at maximum brightness may be uncomfortable indoors and may create unnecessary heat. Ask for the model, rated condition, previous brightness setting and, where available, a factory or calibrated measurement. Test the screen with full white, mid-gray, black-background text, faces and moving content. Record the time, ambient light, camera exposure and viewing distance. Automatic phone exposure is not a brightness measurement. For transparent or grille displays, the background can reduce perceived contrast, so photograph the screen with its real background. For an outdoor screen, compare daytime, dusk and night modes rather than checking only at one time. Check whether the controller or receiving-card configuration is limiting brightness. A software value of 100% does not prove that the screen produces its rated nit value, and a dark image does not by itself prove that the wrong version was shipped. Temperature and long runtime can also reduce performance. If a customer suspects a delivered brightness mismatch, verify the serial or component reference with the supplier or factory instead of making an unsupported admission.
What is the correct way to inspect dead pixels and colour uniformity?
Use a repeatable test sequence rather than a single video. Display full white to reveal bright/dark pixels and overall uniformity. Display black to reveal unwanted light. Use red, green and blue fields to identify channel defects. Use gray steps and gradients to inspect low-gray behaviour, banding and uneven transitions. Add a grid, text and moving content to check mapping, sharpness and motion. Inspect the full wall from the normal viewing distance, then inspect individual cabinets from a closer but safe position. Record cabinet numbers and photograph every abnormal area. A defect that follows a cabinet boundary suggests a cabinet, receiver, power or signal issue. A defect that moves with a module may point to the module or its local connection. A colour difference that appears only through a camera may be related to shutter, refresh or moiré rather than a visible LED fault. For a used screen, test both cold start and stable operation. Some defects appear only after heat builds up. Keep brightness, content and camera settings constant so that before/after comparisons remain useful. If the seller changes configuration during the test, record the change and repeat the baseline pattern. Do not accept vague statements such as “a few pixels are normal” without agreeing on the applicable contract or acceptance standard.
How do I test grayscale, refresh behaviour and camera performance?
Camera performance cannot be confirmed by a normal viewing test alone. Use the actual camera, lens position, shutter, frame rate, exposure and intended content. Test gray gradients, faces, dark details, white transitions, fast motion and large areas of solid colour. Record the camera settings with the video. A phone’s rolling shutter can create bands on a screen that looks normal to the eye, while a real production camera may behave differently. Refresh rate is only one part of the result. Scan mode, driver configuration, synchronization, brightness, content frame rate and camera shutter also affect visible bands, flicker and motion. Do not promise that one refresh-rate setting will fix every camera. If the defect appears only on camera, compare another shutter and another camera before changing the receiving-card configuration. If the display flickers to the eye, continue checking power, signal, receiver parameters and internal connections. For a used-screen inspection, save the original configuration before changing refresh or grayscale settings. Test one known-good cabinet or receiver first, then compare the result. Keep the source file and test pattern available so the seller and buyer are looking at the same condition. Include a short camera clip, direct-view notes and the acceptance position in the report.
What should I inspect on the used cabinet structure, locks and connectors?
Inspect the cabinet as a structural and service product, not only as a display surface. Check frame flatness, corners, door panels, locks, handles, hanging points, support feet, alignment pins, screws and signs of deformation. For rental cabinets, operate every lock and confirm that it reaches the fully locked position. A narrow seam does not prove that the lock is engaged. Inspect power and signal connectors for cracks, looseness, corrosion, bent contacts and damaged locking shells. Check whether cables are pulled by their connectors or supported correctly. For outdoor cabinets, review gaskets, doors, drainage and water marks. For front-service cabinets, confirm that the specified service tool can reach the module without damaging the LED surface. For suspended systems, check the approved lifting points and secondary safety equipment; never infer load capacity from a photograph. Number each cabinet and photograph the rear, connectors and mechanical condition. A used cabinet with a cosmetic scratch may be acceptable, while a slightly bent frame or damaged lock can create alignment and safety problems across an entire wall. If the cabinet has been repaired, ask what was changed and whether the replacement parts match the system.
How do I check receiving cards, HUB boards and configuration files before purchase?
The receiving card, HUB board and configuration file determine how the cabinet actually displays pixels. Two cabinets with the same external size may use different scan modes, driver ICs, data groups, ribbon order or receiver firmware. If these details are unknown, the display may work during a simple demonstration but become difficult to repair or expand later. Record the receiving-card model, hardware revision, firmware, connector order and status indicators. Photograph the HUB board, ribbon cables, power input and signal IN/OUT. Ask the seller for the project-specific RCFGX or equivalent receiving-card configuration and the control-software version. The file should be linked to a cabinet type and screen zone, not simply labelled “LED configuration.” Before changing anything, export and save the original configuration. Never load a file from another display merely because the pixel pitch appears similar. If a receiving card is replaced, match the module structure, scan mode, data group, driver support and cabinet mapping. Test one known-good cabinet first and change one variable at a time. A successful software send message proves only that data was written; it does not prove that the parameters are correct.
How do I calculate the resolution and pixel load of a used LED screen?
Start with cabinet geometry. If a screen uses N cabinet columns and M rows, total cabinets equal N × M. Screen width and height come from the actual cabinet dimensions, while pixel resolution comes from the confirmed pixel count of one cabinet. For a 640 × 640 mm P2.5 cabinet, a planning estimate is about 256 × 256 pixels, but the manufacturer’s drawing and receiving-card data remain the final reference. Calculate each independent screen separately. A centre screen and two side screens may be controlled by one processor, but their windows, dimensions and pixel coordinates should not be treated as one simple rectangle. Add the pixel load of all zones for total capacity, then check each output port, maximum width/height, number of ports and any high-frame-rate or high-bit-depth limitations. Do not use a general “pixels per port” number from another controller. Confirm the exact processor or sending-card specification and operating mode. Also verify the source computer, content canvas and output resolution. A correct pixel calculation does not solve a wrong cascade, receiver configuration or poor signal link.
How do I confirm compatibility between a used screen and a video processor?
Pixel capacity is necessary but not sufficient. Confirm the processor’s input and output type, port count, maximum width and height, total pixel capacity, output format, refresh requirements and supported sending/receiving system. Then confirm the used cabinet’s receiving-card model, firmware, cabinet resolution, cascade method and configuration tool. A processor may have enough total pixels but still be unsuitable for the required three-screen layout or port distribution. Check whether the used screen is driven by the same control ecosystem or whether a compatible conversion path is documented. Do not assume that two RJ45 ports use the same LED data protocol, and do not treat a standard network switch as a universal solution. Optical links require matching SFP/fiber type, rate, wavelength and polarity. Create a signal schedule showing source, processor input, processor output, sending port, first cabinet, cascade direction and screen zone. Test one cabinet or one branch before connecting the complete used inventory. If the plan includes a different brand of receiving card or controller, request manufacturer confirmation and a test device rather than relying on an online comment.
How should I plan power for a used LED display?
Use the factory maximum power for final electrical design and distinguish it from average operating power. A used display may have changed power supplies, brightness settings or cabinet batches, so an old estimate should be checked against the actual nameplate and test condition. For planning, screen area multiplied by factory power per square metre can provide an estimate. Current then depends on voltage and the power arrangement, but a qualified electrician must approve the circuit. Draw the power tree: main distribution, zone circuits, cabinet groups, cable lengths, protection and phase allocation. Review voltage, frequency, cable size, connector rating, ambient temperature, generator capacity and shared loads. Do not copy the circuit count from a 220 V project to a 110 V site. Do not assume that one 16 A outlet can carry a fixed number of cabinets without the exact maximum power and installation conditions. Commission by zone. Inspect labels and connectors with power isolated, then energize one circuit at a time and record supply, protection, start-up result and abnormal heat. Run white and high-brightness content only within the approved test boundary. Repeatedly resetting a breaker is not troubleshooting.
What grounding, RCD and surge protection should a used LED screen have?
Yes. Reusing the display does not mean the new site’s electrical protection is automatically suitable. The cabinet, metal structure, controller rack, distribution board and building equipotential system need a reliable protective-earth path designed under local rules. Do not use a signal shield, a thin improvised jumper or a random screw as protective earth. PE and neutral have different functions and must not be joined inside the display without an approved design. Review RCD/RCBO selection, leakage current, circuit allocation and nuisance-trip risk. LED power supplies and long cable runs can create normal leakage, but a trip must never be solved by bypassing protection. Outdoor, temporary-event and long-distance power systems may need a surge-protection review. SPD selection, location, backup protection and earthing connection should be confirmed by the electrician. Keep evidence: distribution-board photos, earth-bonding photos, circuit labels and test records. Stop repeated resets after a protection event and record weather, recent work and the affected zone. Before any cabinet or internal connector work, fully isolate and verify power.
How do I choose RJ45 cable, fiber and SFP modules for a used LED system?
First identify the actual signal interfaces and distance. RJ45 may be the signal core, while EtherCON or an aviation-style shell may only add locking and protection. Confirm the connector before buying replacement cables. Check cable quality, category, length, shielding, route and resistance to interference. A dedicated LED data chain should not automatically pass through an ordinary Ethernet switch. For fiber, match single-mode or multimode type, optical rate, wavelength, connector, duplex direction, polarity, distance and optical power budget at both ends. A 10G SFP may fit physically but still be incompatible with a port, converter or fiber. Verify the exact CVT, processor, optical module and receiving equipment. Keep protective caps on unused fiber connectors, respect bend radius and never look into a fiber end. Commission with numbered links. Record source port, destination port, medium, length, SFP model, indicator status and test result. If one branch fails, use a known-good short link and replace one item at a time. If several cabinets disappear together, start with the upstream link; if one cabinet fails, inspect the local cascade and receiver.
What is the correct installation order for used LED cabinets?
Start with the approved layout, not with the nearest cabinet in the transport case. Check the screen orientation, cabinet numbers, columns, rows, maintenance direction and independent zones. Confirm the wall or structure, base level, anchors, support, lifting method and access route before placing cabinets. Used cabinets may have slightly different frames or locks, so inspect and group them before assembly. Install the mechanical structure and level the first reference row. Engage locks progressively and check seams, alignment pins and support. Keep the power and signal paths labelled. Connect the processor output to the first cabinet’s signal IN, then follow the approved IN-to-OUT cascade. Do not use a cabinet’s appearance to guess direction. Power circuits should remain separate from signal planning, and all electrical work should be completed by qualified personnel. After a small section is assembled, run grid, arrow, solid-colour and black-field tests. Confirm cabinet direction, mapping and receiver status before expanding. Photograph the reference row, connector labels and final topology. If the used cabinets come from different batches, keep them identified and plan uniformity checks before customer acceptance.
How should I install a used rental LED screen safely?
Rental screens need a repeatable process because they are assembled, transported and rebuilt frequently. Before opening the cases, group cabinets by product, pitch, batch, direction and event zone. Inspect locks, handles, connectors, modules, frames and labels. Keep spare and damaged cabinets separate. A cabinet that looks similar may have a different resolution or receiver configuration. For ground stacking, confirm the base, levelling, lateral support and top locking. For hanging, confirm the approved beam, lifting points, secondary safety, rated load, wind conditions and qualified crew. Every lock must be fully engaged; a narrow seam is not proof. Power distribution, protective earth and temporary-event circuits must be handled by qualified personnel. Keep signal cables labelled and protected from feet, water and sharp edges. Power up by zone and test one known-good cabinet before extending the cascade. Use grid, arrows, colours and black field to check direction and mapping. Prepare a replacement kit with matching cabinets/modules, receiver configuration, cables and tools. After replacing a cabinet, verify colour, mapping and stability, not only whether it lights. After the event, record damage, missing items, difficult cable routes and all temporary solutions before returning the cases to storage.
What must be checked when installing a used outdoor LED display?
The old cabinet arrangement is a reference, not an automatic approval for the new site. Review the cabinet condition, sealing, gaskets, doors, connectors, corrosion, drainage and rear ventilation. Ask whether the cabinets were previously exposed to rain, salt air, dust, snow or direct sunlight. Water marks or corrosion can remain hidden while the LEDs still work. The new site requires an independent structure and environment review. Confirm foundations, anchors, wind load, screen orientation, maintenance access, drainage, cable penetrations, distribution protection, grounding and surge protection with qualified local professionals. An IP rating applies to the approved product and test conditions; it does not approve a building opening, support steel or cable route. Test brightness at daytime, dusk and night if the project requires all three. Check temperature and airflow after a realistic operating period. Outdoor high-brightness content can create significant heat and power demand. Protect connectors, keep cables from standing water and label every power and signal zone. Before handover, document weatherproofing limits, cleaning, seal inspection and the emergency shutdown process. If the used cabinet cannot meet the site conditions, record the limitation and do not describe the installation as fully weatherproof without evidence.
How should I install a used fine-pitch screen indoors?
Fine-pitch indoor displays are often viewed close to the screen, so flatness, seam alignment, uniformity and low-gray performance become very visible. Start with a rigid, level wall or frame and confirm that the finished opening matches the cabinet layout. Do not force a cabinet into an opening that is too small or use excessive pressure to hide a structural error. Number the cabinets and keep their orientation consistent. Check alignment pins, locks, module surfaces and rear connections before closing the wall. Plan front or rear service access, power-supply replacement, receiver access and ventilation. Indoor conditions still require protection from condensation, roof leaks, cleaning liquid, sprinkler water and blocked air-conditioning discharge. Commission with grid, fine text, gray gradients, white, RGB and skin-tone content. Inspect from the customer’s closest normal viewing position and from the main audience position. If cabinets come from different batches, compare uniformity before final installation. A global brightness or colour adjustment should not be used to hide one local module or receiver fault. Keep the original configuration and calibration files. Fine-pitch screens are particularly sensitive to wrong scan mode, data group or module mapping. Complete a stable operating test before the final frame or decorative cover is installed.
What checklist should I follow before first power-on?
First confirm that installation is safe and complete. Check cabinet locks, support, lifting removal, protective barriers, cabinet direction, module condition, connector labels and maintenance access. Confirm that power circuits, protective earth, RCD/RCBO and upstream capacity have been reviewed by a qualified electrician. Do not energize a wet, damaged or mechanically unstable installation. Then review the signal chain: source, processor input, processor output, sending port, fiber/RJ45 link, first cabinet, cascade order and screen zone. Confirm that the receiving-card configuration has been backed up and that the correct file is identified. Check that no internal ribbon or power connector is loose, but require full isolation before any internal inspection. Power up one circuit or zone at a time. Observe indicators, start-up behaviour and any protection event. Display a low-risk test pattern first, then grid, arrows, black, white and RGB. Confirm that each independent screen is mapped correctly. Do not begin with a high-brightness full-white run before the power and thermal conditions are known. Record voltage, circuit, time, software/firmware, configuration file, test pattern and result. If anything trips, heats abnormally or behaves intermittently, stop repeated resets and investigate the relevant layer.
How do I configure a used screen with RCFGX and NovaLCT?
Begin by identifying the exact receiving-card model, hardware revision, module structure, driver IC, scan mode, cabinet resolution and project zone. Save the current configuration before editing. If the display is still working, preserve that working state and export the configuration with a clear project and date name. Use the project-specific RCFGX or equivalent file only after confirming that it matches the physical module and receiver. Do not use a file from another screen because the pitch or cabinet size looks similar. In NovaLCT, confirm the correct screen object, receiver selection, data group, mapping, brightness and refresh-related settings. Send the change to one known-good receiver or cabinet first, then test. Save to hardware only after the result is confirmed. Use grid, arrows, black, white, RGB, grayscale and text patterns after sending. If the image is distorted, mirrored, partially missing or colour-shifted, stop and restore the backup instead of making several changes together. Software version and controller/receiver firmware are separate; do not downgrade a working firmware package as a trial. Keep the original file, test file, final file, screenshots and result in the service record.
How do I map ports and cabinet cascades during commissioning?
A blank branch is often a mapping or topology problem rather than a dead display. Start with a physical cabinet map showing columns, rows, cabinet numbers, signal IN/OUT, receiver addresses, processor ports and screen zones. Use the actual viewing direction and maintenance orientation. Do not rely on a software rectangle that does not match the physical layout. Confirm that the processor output connects to the first cabinet’s signal IN and that each following cable uses the approved OUT-to-IN direction. Compare every cable label with the drawing. In the configuration software, confirm cabinet resolution, cascade order, port assignment, screen direction and total/port pixel loading. Irregular or independent screens should be mapped as approved zones, not improvised as one large rectangle. Test one known-good cabinet first, then add cabinets one at a time. Use a grid and arrows so that mirrored or reversed paths are obvious. If the fault appears when one cabinet is added, inspect that cabinet’s upstream/downstream cable, receiver address and configuration. Save the old mapping before sending a new one. After commissioning, photograph the sending device, first cabinet, mid-chain and final cabinet. Keep the final port map with the service documents.
How should I diagnose a black screen or “No Signal” message?
Define the scope first: whole system, one processor output, one network branch, one cabinet or one module. Ask whether the screen is fully black, showing black content, very dim or reporting “No Signal.” Record the last known-good time and recent changes such as a power event, input switch, software update, cable move or configuration change. Check in layers. Confirm upstream power and protection with qualified personnel. Check the source computer, input resolution, frame rate and processor preview. Then inspect processor output, port indicators, fiber/RJ45 link, SFP compatibility, cascade order and port mapping. If the signal reaches the cabinet, check receiver indicators, correct RCFGX, HUB, ribbon cables and module power under the isolation procedure. Use a known-good short cable or one known-good cabinet for a single-variable test. Do not replace the processor, cables and receiving card at the same time. Do not repeatedly reset a breaker or ask an unqualified person to measure live voltage. Save the current configuration before any parameter change. The service conclusion should state what is confirmed, what is likely and what still requires a site or factory test. A short video can show the symptom but cannot prove every internal condition.
How do I diagnose one faulty cabinet, row or column?
The shape of a local fault is evidence. A complete cabinet may point to its power, receiver, local signal or configuration. A row or column may point to a data path, HUB port, scan parameter, ribbon connection or module power. It is not automatically a module failure. Draw the fault on the cabinet map and record whether it is fixed or intermittent, visible to the eye or only to a camera, present at start-up or after running, and present during pure-colour tests. Inspect the upstream and downstream signal path, receiver status, HUB, ribbon direction and power input. If the fault follows a known-good cable or cabinet after a controlled swap, the location of the cause becomes clearer. Change only one item at a time and record the result. Before replacing a receiver, export its configuration and identify its address. Before touching a ribbon or internal connector, isolate and verify power. After a repair, repeat the original test pattern and compare the fault boundary; “the cabinet lights up” is not enough if the row or colour defect remains.
What should I check when a used screen flickers, ghosts or shows colour defects?
Describe the symptom precisely before changing parts. Flicker may be visible to the eye or only to a camera. Ghosting, trailing, colour cast, scan artefacts and pixel misalignment have different possible causes. Record the fault area, content, brightness, camera settings, time of occurrence and whether the issue appears during pure-colour and grayscale tests. Check the source and input format, then the processor output and signal link. Review cascade direction, port loading, fiber/SFP or RJ45 condition and power stability. Next verify the project-specific receiving-card configuration, scan mode, data group, driver support, refresh and brightness settings. Inspect HUB boards and ribbon cables only after power is isolated. If the problem is fixed at one cabinet boundary, the local cabinet path is more likely; if it moves with content or input, the source or processor needs attention. Use one known-good cabinet or cable for comparison. Do not change brightness, refresh, configuration and firmware together. A phone video with bands is not sufficient proof of a low-refresh fault; camera shutter and rolling shutter can create artefacts.
What should I do if the used screen is dim or has a brightness mismatch?
First separate a whole-screen brightness issue from a local mismatch. A whole-screen issue may involve ambient light, brightness mode, content, processor settings, receiving-card parameters, temperature or the delivered product specification. A local issue may involve calibration, module batch, power drop, receiver data or a damaged LED section. Test full white, gray, black-background text, faces and real customer content. Record ambient light, viewing distance, time, brightness setting and camera exposure. For transparent or outdoor screens, compare the real background and daytime environment. A software value of 100% is not a brightness measurement, and an automatic phone photo is not a calibrated result. Check the order model, serial number, component reference and factory record if the customer suspects the wrong brightness version. Preserve the configuration before adjusting brightness or calibration. If one cabinet changes after a controlled cable or receiver test, follow the fault boundary. If the issue appears only after long operation, check thermal conditions and power.
Why does a used LED screen restart or dim after running for a while?
Time-dependent failure often points to power, heat, signal stability or a component that changes behaviour as it warms. Record the start time, ambient temperature, brightness, white-content ratio, affected cabinet, circuit and exact recovery method. Compare cold start with stable operation. Do not assume that a software restart proves a software problem. Check the power tree with qualified personnel: supply stability, circuit protection, connector temperature, power-supply condition and zone allocation. Review cooling: rear clearance, blocked vents, fans, filters, glass cavities, decorative panels and direct sun. High brightness and white content create a higher thermal load, but the actual limit is model-specific. If only one branch is affected, inspect signal connectors, cascade order and receiver status. If the screen dims after high brightness but recovers after cooling, thermal protection is possible and requires site measurement. Do not hide a structural cooling problem by permanently reducing brightness without documenting the limitation. Run a controlled long-test with recorded content and conditions. Preserve configuration and change only one factor at a time.
How do I decide whether the problem is a module, receiving card, HUB or power supply?
Do not choose a part only from the visible symptom. Start with the affected scope and the fault boundary. A single LED or small module defect is more likely to involve the module, driver or local ribbon. A regular row/column defect may involve data group, HUB, scan configuration or ribbon order. A complete cabinet may involve power input, receiver, local cascade or configuration. Several downstream cabinets may point upstream to a sending port, fiber, RJ45 or processor output. Use a layered test: source and processor, signal path, receiver configuration, cabinet internals and then controlled hardware substitution. Export the original RCFGX before replacing a receiver. Isolate power before touching modules, HUB boards, ribbon cables or power supplies. Use a known-good, same-model part and change only one item. If the fault moves with the part, that is evidence; if it stays in the original position, investigate the path or configuration. After replacement, repeat the original symptom test, color tests, grid and a short stability run. Keep the removed part and label the test location until the result is confirmed.
What should be included in a professional used-LED repair service?
A professional repair service should begin with a case number and an evidence record. The technician defines the symptom, scope, operating condition and recent changes, then photographs the cabinet, labels, connectors and fault pattern. The original configuration is backed up before parameters are changed. This avoids replacing a visible part without understanding the cause. The repair may include module, ribbon, HUB, receiving card, power supply, connector, cabinet lock or signal-cable work, depending on evidence. Each replacement should use a compatible part and be recorded by model, serial or cabinet number where available. Internal power must be isolated and verified before opening or disconnecting anything. For a receiving-card change, the project-specific configuration must be checked before sending it to hardware. After the repair, the technician repeats the original test, then checks black, white, RGB, grayscale, grid, motion and a short operating run. The report should state what was confirmed, what was replaced, what remains pending and whether calibration or a wider inspection is recommended.
What does a professional used-LED quality inspection service include?
A quality inspection service should combine documentation, visual, mechanical, electrical and display testing. It begins with inventory: cabinet count, model, pitch, dimensions, serials, receiving cards, power supplies, cables, flight cases and spares. It then records the condition of frames, locks, doors, connectors, seals, corrosion, water marks and repair history. Display testing should include full white, black, red, green, blue, gray scale, gradients, grid, text and motion. The report should identify dead pixels, bright pixels, colour cast, row/column defects, flicker, ghosting, low-gray issues and cabinet-to-cabinet uniformity. Tests should be performed under a stated brightness, content, viewing distance and environment, with both cold-start and stable-operation observations when relevant. Control inspection checks the controller, sending device, receiving-card model, firmware, RCFGX/configuration backup and port map. Electrical and internal checks must be performed by qualified personnel with power isolated where required. The final report classifies items as pass, limited use, repair required, information pending or rejection risk.
