Testing guides

Short, practical walkthroughs. Each one answers a single question and takes you to the test that answers it.

Display tests

  • How to test a new monitorTest a new monitor on day one, while it can still go back: set the native resolution, then check dead pixels, backlight bleed, uniformity, banding, gamma, refresh rate and ghosting in your browser. The whole check takes about 10 minutes.
  • Dead pixel vs stuck pixel vs hot pixel: what is the difference?A dead pixel stays black on every color, and no software can repair it. A stuck pixel stays lit in one color and a hot pixel stays white, both easiest to see on black; either can sometimes recover.
  • Dead pixel policy: how many faulty pixels each brand allowsMost monitor makers replace a screen only when faulty pixels pass a set limit, and they count bright faults more strictly than dark ones. Dell’s Premium Panel Exchange models and some premium lines from Lenovo, ASUS and Gigabyte are replaced for a single bright pixel; others accept a few. Count yours, then compare.
  • How to calibrate a monitor without a colorimeterWithout a colorimeter you can set four things by eye: brightness, so the darkest gray steps just separate from black; contrast, so the brightest stay distinct from white; gamma, to about 2.2; and white balance, until gray shows no tint. Color accuracy needs a colorimeter.
  • Why is my monitor flickering? How to find the cause and fix itScreen flicker usually comes from the display driver, an app, the cable or refresh rate, variable refresh in games, or PWM dimming at low brightness. On Windows, check Task Manager first: if it flickers along with everything else, fix the display driver; if it stays steady, an app is the likely cause.
  • IPS vs VA vs OLED: how monitor panel types differIPS keeps colors steady from wide angles but shows weaker blacks; VA has the most contrast of any LCD type; OLED lights each pixel itself, so black is truly black, but static images can cause burn-in. TN, the oldest type, is fast and affordable, with the narrowest viewing angles.
  • How to test a used laptop before you buy itCheck the case and hinges, then run the screen, keyboard, touchpad, speaker, microphone and webcam tests in the laptop’s own browser and try every port and the charger. Battery health and the serial number come from the operating system; allow about 15 minutes.

Audio tests

  • One earbud not working? How to fix sound from one sidePlay a left-right test to see which side fails. If one side is only quieter, check the balance setting and clean the mesh. If it is silent, check that mono audio is off, put both earbuds back in the case and reconnect, then reset or re-pair them the way the maker describes.

Camera tests

  • Camera or microphone blocked? How to allow accessAllow the site from your browser’s address bar or site settings, then check that Windows, macOS or your phone lets the browser itself use the camera and microphone. If it still fails, close other apps using the device and check shutters, mute keys and cables.
  • Camera or microphone blocked in an in-app browser? How to fix itApps such as Facebook, Instagram, Gmail and Telegram can open links in their own built-in browser. There the app, not your browser, decides whether a page may use the camera or microphone, and it may not pass access on. Open the page in your default browser, allow access when asked, then test it.
  • Webcam not working? How to fix it on Windows and MacOpen the privacy shutter, check any camera key or switch, and close other apps that may be using the camera. On Windows 11, run the camera troubleshooter, allow access in Privacy & security and check the driver; on a Mac, update macOS and check Screen Time and the camera privacy setting. Test after each step.

Device tools

  • How to check a used phone before you buy itBefore you pay, make sure the seller has removed their account: an Activation Locked iPhone, or an Android phone still tied to a Google Account, is not worth buying. Then check battery health and the repair history, and test the screen, touch, speakers, microphone and cameras in the phone’s own browser.