Architecture comparison
| Family | Construction | Project strengths | Engineering checks |
|---|---|---|---|
| COG | Display integration using a glass substrate | Potential thin and high-density product architectures | Released drive method, substrate format, thermal path and replacement unit |
| COB | Bare LED dies bonded to a board before product-specific encapsulation | Potential fine-pitch and treated-surface product architectures | Encapsulation, reflection, protection evidence, service and calibration |
| SMD | Packaged LEDs mounted on a PCB | Multiple product-specific indoor and outdoor architectures | Package, mask, coating, scan, environmental boundary and service method |
The useful service question is not simply whether an LED product is COG, COB or SMD. It is what happens when one part fails: what can be replaced on site, which spare fits, which data must be restored, and whether the repaired area matches the rest of the wall.
Engineers discuss both colour differences between manufacturing batches and installations with almost no usable replacements. These are reported experiences, not comparative failure-rate data. They make a strong case for testing a spare before accepting the installation.
COG product
COB product
SMD productSeparate the construction label from the released product
SMD describes packaged emitters mounted to a board. COB generally describes bare LED dies bonded to a board before product-specific encapsulation. COG identifies a glass-substrate integration route. These labels do not by themselves specify field repair, calibration storage, environmental protection or camera performance.
BOE’s MLED platform includes multiple product architectures. Attribute active-matrix drive or a particular optical/thermal specification to the documented product, rather than extending it to every product sharing a label.
Ask for the replacement boundary
| Question | Evidence to put in the service record |
|---|---|
| What is replaced on site? | Exact module, cabinet, display unit, receiver or power-supply part number and revision |
| What must be repaired elsewhere? | Documented repair route, restrictions and expected return process |
| What makes a spare compatible? | Mechanical, electrical, driver/receiver, firmware and optical compatibility |
| Where is calibration stored? | Product-specific storage, backup and restoration procedure |
| When is service complete? | Function restored, configuration verified and visual match accepted |
“Front service” identifies the access direction. It does not specify tool clearance, isolation, access to electronics behind a module, or the method of restoring its appearance. Confirm these using the actual installation drawing.
Run a spare-module rehearsal
- Record the accepted wall at its working brightness using uniform fields, dark gradients and representative content.
- Identify the selected field-replaceable unit and spare. Save the system configuration and relevant calibration data using the supported procedure.
- Have qualified personnel perform the documented replacement and handling process.
- Apply the required configuration and calibration workflow for that product.
- Compare the repaired area from the agreed positions, under the same light and operating preset.
- Record access, replacement, restoration and verification time separately, along with tools and missing information.
A matching connector and pixel pitch are insufficient compatibility evidence. Nor should copying a configuration file be assumed to restore calibration: the storage and restoration paths are product-specific. A replacement can work electrically while remaining visibly different.
Do not diagnose every colour defect as calibration
In a reported green-artifact case, the author ultimately attributed the fault to defective controller HDMI inputs. Preserve the baseline and compare a known source, supported internal pattern, cable and input before changing calibration data. A single photograph rarely isolates the fault.
Compare lifecycle cost without inventing failure rates
Use a scenario worksheet: replacement parts + shipping/repair + access labour + configuration/calibration labour + the project’s downtime cost. Separate quoted costs from estimates. Without valid failure-rate evidence, do not present a precise lifetime total or claim one package family is inherently cheaper.
Agree the spare quantity, compatible revisions, storage conditions, inspection schedule and obsolescence response. Spares that have never been checked in the wall leave the most important question unanswered.
Keep optical and environmental checks alongside service
Evaluate the actual surface under room lighting, including off-state reflections and oblique viewing. Require named evidence for protection and cleaning claims. Encapsulation of the front does not establish protection of edges, connectors or the installed enclosure. Select the product whose documented service and performance fit the application.
Technical sources
- BOE: MLED product platform — primary examples of different product architectures
- Brompton: Dynamic Calibration — one manufacturer’s calibration architecture, not a generic restoration procedure
About this guide: Use these project checks with acceptance limits agreed for the supplied configuration. VITREVIA supplies and integrates display systems directly from Shenzhen, China.
Download the editable test record (.txt)
Project checklist
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