Introducere
Buying a replacement smartphone screen—whether for repair, resale, or personal use—can feel like a gamble. Some screens look fine at first glance but hide defects that will cause headaches later. The good news? You can spot most of these issues on the spot, before you ever hand over your money.
In this guide, we’ll walk through 4 screen features you must NEVER accept, along with simple on-site testing methods so you can return defective items immediately.
Let’s make sure you never get stuck with a bad screen again.
1. Yellow Corners When Displaying White (Backlight Aging)
What Yellow Corners Look Like
When you open a pure white image and notice that the corners appear yellowish or warm-tinted, that’s a red flag.
It usually looks like:
- The four corners are slightly “dirty”
- A warm halo, especially noticeable under bright light
- Uneven brightness levels
Why Backlight Aging Happens
This defect appears when the LCD’s backlight film has aged or overheated. It often indicates:
- The screen is not brand new
- The backlight has been replaced poorly
- The panel was previously used or refurbished
In short—yellow corners = old screen pretending to be new.
How to Test It On-Site
- Power on the screen
- Open a white background (camera app, browser, or test tool)
- Increase brightness to maximum
- Observe all four corners
If you see yellowing, even slightly, reject it immediately.
Why You Should Return It
Aging backlight continues to worsen. Today’s small yellow tint will soon become obvious discoloration. Performance and brightness will drop over time.
2. Water Ripple Effect When Slightly Pressed (Touch Layer Failure)
What “Water Ripple” Means
When you press the screen lightly and see ripples spreading like touching water, that’s a sign of touch layer instability.
A healthy screen should feel solid with no liquid-like distortion.
Causes of Touch Layer Separation
The ripple effect usually comes from:
- Weak bonding between the touch and display layers
- Poor lamination quality
- Panels damaged by heat or pressure during refurbishing
How to Test With Light Pressure
- Place the screen on a flat surface
- Lightly press around corners or the center
- Check for wavy distortions, rings, or liquid-like ripples
Long-Term Risks
A screen with this issue will:
- Lose touch accuracy
- Develop dead zones
- Show rainbow discoloration
- Eventually fail completely
This defect is an instant NO.
3. Green Spots on a Powered-Off Screen (OLED Burn-In)
How to Identify Green Patches
This defect appears even when the display is oprit.
Look for:
- Light green haze
- Irregular patches or dots
- Areas that stay green even when the screen is black
Why OLED Burn-In Happens
Burn-in occurs when OLED diodes wear unevenly due to long-term display of static images.
This means the screen is:
- Not new
- Previously used for long sessions
- Likely harvested from old devices
How to Test It Correctly
- Turn off the screen
- Tilt it under white lighting
- Inspect the black surface for greenish marks
If the green patches exist while the screen is off, run away.
Why This Is a Severe Defect
Burn-in is permanent and irreversible.
Once you install it, the issue becomes even more obvious. This is one of the worst defects you can receive.
4. Bent or Damaged Flex Cable Pins (Connector Defect)
What Bent or Missing Pins Look Like
Before installation, always check the connector.
Warning signs include:
- Bent pins
- Missing pins
- Misaligned gold contacts
- Murdărie, oxidation, or scratches
How Pin Issues Affect Installation
Damaged connectors can cause:
- No display
- Pâlpâind
- Touch failure
- Short circuits
- Permanent motherboard damage
How to Inspect the Connector Before Buying
- Hold the flex cable under strong light
- Look closely at every pin
- Ensure spacing, alignment, and glossiness are uniform
Why This Defect Is a Dealbreaker
Once installed, pin defects are irreversible.
You might even end up damaging the phone’s board—far more costly than the screen.
Never accept screens with connector problems.
How to Perform an On-Site Inspection Quickly
Step-by-Step Routine
- Check appearance (no scratches, glue marks, dust).
- Test brightness and white screen for yellow corners.
- Test touch pressure for ripple or separation.
- Inspect powered-off screen for green spots.
- Check flex cable pins for perfect alignment.
- Final full-function test (touch, color, luminozitate, camera hole alignment).
Tools You Should Bring
- Small LED flashlight
- Preloaded test images (white/black/red/green)
- Phone body or tester
- Microfiber cloth
Common Mistakes When Checking Screens
- Not viewing under strong light
- Only checking the display, not the flex cable
- Rushing the test because the seller is waiting
- Believing “it’s normal” excuses
If something looks off, it’s probably defective.
Why These 4 Defects Are Immediate Return Reasons
They Indicate Aging or Refurbished Parts
Most of these flaws appear in recycled or poorly refurbished screens.
High Risk of Installation Failure
Connector or touch defects often lead to installation issues or short-term failure.
Future Malfunction Almost Guaranteed
Even if the screen works today, these defects worsen over time.
Tips to Avoid Low-Quality Screens
Choose Reliable Suppliers
Look for suppliers with stable inventory and consistent quality.
Check Warranty Policies
A good supplier always offers clear replacement rules.
Understand Market Price Range
If a price is “too cheap,” the panel is likely refurbished or defective.
Concluzie
Buying a replacement screen doesn’t have to be risky. By learning how to identify these 4 critical defects—yellow corners, ripple effects, green burn-in, and damaged flex pins—you can avoid costly mistakes and ensure your repairs last longer.
Always test thoroughly on-site. A few minutes of inspection can save hours of frustration and prevent financial loss. Stay sharp, stay cautious, and never settle for a defective screen.
Întrebări frecvente
1. Are yellow corners always caused by backlight aging?
Da. This is the most common sign of an aged or refurbished backlight system.
2. Can OLED burn-in be repaired?
Nu. OLED burn-in is permanent and cannot be reversed.
3. Are water ripple effects normal on some screens?
Nu. A quality screen will not show ripple distortions under light pressure.
4. Should I refuse a screen even if only one pin is slightly bent?
Da. Even one damaged pin can cause boot failure or short circuits.
5. How long should an on-site inspection take?
A careful check typically takes 3 la 5 minutes once you know what to look for.
