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How to use and interpret PC Problem Finder
Test your keyboard online: press any key and see it light up on the on-screen keyboard to find keys that do not register, repeat or stick. Works for full-size, TKL and laptop keyboards.
How to run the test
- Click the test area and press each key one by one.
- Watch the on-screen keyboard; every key you press should highlight.
- Note any key that does not light up or highlights twice.
- For a key that fails, clean it, try another USB port or keyboard, and check the layout or driver.
What this test checks
Checks whether physical key presses reach the browser and highlights missing or repeated input.
Press keys and get a missing-key report and health score.
How to interpret the result
Look for missed, repeated or unexpected input events and compare the behavior with another browser or device when possible.
Browser limitations
Browser focus, operating-system shortcuts, accessibility features, wireless interference and device firmware can affect input behavior.
How the key test works
The page listens to the browser's keyboard events and lights the matching on-screen key on every press. If a key lights up, the browser received it; if it does not, the signal never arrived or the operating system intercepted it first. The highest number of keys held at once appears under Max rollover, and the missing-key report lists keys you never pressed.
Full-size, TKL and laptop keyboards
Choose the keyboard type and layout (Turkish Q, Turkish F or QWERTY) above the keyboard. Laptops have no numeric keypad, so read the missing-key report against the right type. On a Turkish layout, also try the Ğ, Ü, Ş, İ, Ö and Ç keys.
Troubleshooting by symptom
- A key never lights upDust or dirt may be under the keycap. Turn the keyboard over and shake it gently, use compressed air, then try another USB port or computer. If it still fails elsewhere, the key is physically faulty.
- One press types the letter twiceThis is called chatter and is usually a worn switch or dirty contact. Press the key once; if the test shows two hits, it is hardware. Also check that Windows Filter Keys is off.
- Fn and media keys do not showOn most keyboards Fn is handled inside the keyboard and never sent to the computer, so it will not light up. Brightness and volume keys may also never reach the browser.
- The Windows key leaves the pageThe OS captures Win, Alt+Tab and Ctrl+Alt+Del before the browser. They cannot be tested in a web page; that is a limitation, not a faulty keyboard.
Frequently asked questions
How do I know which keyboard key is not working?
Press every key in the test; keys that never highlight are not reaching the browser. Test again after cleaning and on another device to separate hardware from software.
Why is only one key not working on my keyboard?
Common causes are dirt under the key, a worn switch or membrane, a loose laptop ribbon or a layout/driver issue. Try cleaning with compressed air and testing in another app.
Can this test detect ghosting?
Use the dedicated ghosting test to press several keys at once and see how many your keyboard registers.
Does the keyboard test measure input lag?
No. This tool shows whether each key is detected; it does not measure input latency in milliseconds. Use the keyboard diagnostic for delay or repeat symptoms.
How do I find how many keys my keyboard detects at once?
Hold several keys together and read Max rollover. The separate ghosting test gives a more detailed check.
Does Turkish Q vs F layout change the result?
Key events detect the physical key; the layout only changes the labels on screen. The hardware result is the same either way.
My wireless keyboard misses keys. Why?
Wireless connections can limit simultaneous keys, and a weak battery can drop signals. Connect by cable and repeat the test.
What does PC Problem Finder check?
Checks whether physical key presses reach the browser and highlights missing or repeated input.
Does a failed input mean the keyboard or mouse is broken?
Not necessarily. Re-test after checking focus, connection, batteries, another USB port or another browser before treating it as a hardware fault.
What should I do if the result looks bad?
Repeat the test under the same conditions, check the suggested next diagnostic and compare with another browser, connection or device where practical. Use the related guides for step-by-step troubleshooting.