Quick answer
What this guide helps you determine
Prepare the screen, enter fullscreen and inspect user-controlled colors without flashing patterns.
Begin with the observable browser result, repeat it under the same conditions, and change one connection, setting or application at a time. A browser result narrows likely causes but does not certify hardware or decide a repair.
Scope of this check
A safe dead-pixel test uses user-controlled solid colors, normal brightness and a clean screen. It should include an obvious Exit control and never require rapid flashing. The goal is careful visual inspection, not an attempt to force a pixel to change.
Step-by-step method
- Use the display’s intended resolution and scaling, clean the surface and reduce glare. Enter full screen, note how to exit, and show black, white, red, green and blue backgrounds manually.
- Scan in a consistent pattern from one corner across rows rather than staring only at the center. Pause on each color and inspect suspected points from normal viewing distance, then slightly closer without touching the panel.
- Exit full screen and compare ordinary content. If documenting a repeatable defect, include the color backgrounds on which it appears and the approximate location, then review the manufacturer return or warranty policy.
What to check first
Use these checkpoints to keep the comparison focused. Record the visible behavior rather than assigning a fault label too early.
- Use normal brightness and low glare
- Advance colors manually
- Exit with Escape or the visible button
How to read what you see
| Observation | What it can suggest | Useful next check |
|---|---|---|
| A point changes normally across all colors | That location responds to the tested primary and neutral backgrounds. | Continue the scan. |
| A fixed point differs on multiple backgrounds | A pixel/subpixel defect is possible. | Rule out dust and document for support. |
| A faint shape matches previous content | Temporary retention or image persistence may be involved. | Return to varied normal content and follow manufacturer guidance. |
Common mistakes to avoid
- Do not stare at maximum brightness in a dark room.
- Do not touch or press suspected pixels.
- Do not use the test while driving, operating equipment or if visual patterns cause discomfort.
Build evidence another person can use
Write down the exact action, visible result and whether it repeats. Include the browser family, operating-system family, connection type and the single comparison that changed the result. Quote the observation directly—for example, “A point changes normally across all colors”—then add where it occurred and which comparison changed it.
Change one condition per comparison and return settings that have no effect. Follow model-specific manufacturer instructions before firmware changes, cleaning, disassembly or warranty action.
When to seek qualified support
If the same problem remains in multiple applications and on another compatible connection or computer, collect the repeatable observations and contact the manufacturer or a qualified technician. Stop using equipment that is physically damaged, unusually hot, wet, sparking or unsafe. Device Test Bench cannot inspect electrical condition or make a repair decision.
Privacy during testing
Our public tests process key events, pointer values, media streams and controller input locally. Do not send private recordings, complete typed text or device identifiers when asking for help. A short description of the behavior, browser and page URL is normally enough.
Questions readers ask
Why are several colors needed?
Different solid backgrounds reveal dark, bright and individual subpixel faults that one color can hide.
Should I test at maximum brightness?
No. Normal comfortable brightness is sufficient and better represents ordinary use.
Primary technical references
The following specifications define the browser APIs discussed in this guide. They are primary web-platform references, not product repair manuals.