Buying a Used Monitor? Run These 3 Tests Before You Pay

Second-hand deals can hide defects that only appear on dark screens or at max brightness. Plug it in and visit our dead pixel tester before paying. Here’s a practical on-site checklist you can do in 5–10 minutes.

What to Bring

Your laptop and HDMI/DisplayPort cable.
Microfiber cloth (clean the panel first).
Phone flashlight for scratch inspection.
If possible, a quiet corner to dim lights briefly.

Step 1: Dead Pixel & Stuck Pixel Hunt (2 minutes)

Open the dead pixel tester and go fullscreen (F11).
Show White and Green: black dots = dead pixels.
Show Black: bright dots = stuck pixels.
Scan corners and edges carefully—sellers hope you only look at the center.
One edge pixel on a budget monitor might be tolerable; clusters or center defects are red flags.

Step 2: Backlight Bleed & IPS Glow (3 minutes)

Set brightness to 100%.
Show Black. Dim ambient light if possible.
Backlight bleed: patchy yellow/white flares from edges/corners that stay put.
IPS glow: a soft haze that shifts when you change viewing angle—normal to a degree.
Grade it: if bleed is obvious even in moderate light, walk away; mild corner glow is expected on IPS.

Step 3: Color/Uniformity Quick Check (1 minute)

Show 50% Gray and Red/Green/Blue.
Look for tinting (pink/green corners) or banding. Minor tint on cheap panels is common; strong unevenness is a warning.

Step 4: Physical Inspection (2 minutes)

Power off. Use phone flashlight at an angle to spot scratches on the coating.
Run a fingernail gently: if it catches, the scratch will remain visible lit.
Check bezel gaps, stand wobble, and ports (wiggle cable lightly).

Bonus: Motion & Port Sanity Check (1–2 minutes)

If it’s a high-refresh gaming monitor, quickly confirm max refresh in OS settings.
Wiggle cable/connectors to ensure stable signal—no flicker/dropouts.

Negotiation Tips

Document defects with a quick photo on white/black.
Use findings to negotiate or walk away. A cheap price isn’t worth a panel with severe bleed or center dead pixels.

Common Traps

“Refurb” units sold with 1–2 known dead pixels.
Panels with heavy backlight bleed sold in bright rooms so you can’t notice.
Scratches invisible when on, but glaring when off under light—always check powered off.

Keep-or-Walk Decision

Walk away: center dead/stuck pixels; large bleed patches; deep scratches; unstable ports.
Maybe keep: minor edge glow, tiny edge scratch, single edge pixel on a bargain unit—only if price justifies it.
Best: clean pixel check, minimal bleed, stable ports. Pay with confidence.

Next steps: Run the on-site checks with the Screen Test. If you spot defects, follow the Ultimate Guide to Monitor Quality Control and decide quickly within the return window. Need a structured checklist? Read How to Test Your Monitor Before the Return Period Ends.