RANGER CompTIA A+ Core 1 (220-1201) · chapter 13 of 15
Week 13: Screens, projectors and phones
In this chapter Objectives 5.3, 5.4
Objective 5.3
Video, projector and display issues
Incorrect input source and cabling issues
"No signal" with a working display: check the input source (HDMI 1 vs. HDMI 2 vs. DisplayPort) first. Then cabling issues: loose or damaged cable, wrong port (onboard vs. GPU), bent VGA/DVI pins, an adapter that does not convert the signal, or a cable too long or too slow for the resolution/refresh rate.
Exam tip Monitor says "No signal"? Input source, then cable, then the PC.
Projector bulbs and shutdowns
Burnt-out bulb: lamp hours are finished, or the lamp LED is lit and no image. Replace with the exact lamp, let it cool first, do not touch the glass, and reset the lamp timer. Intermittent projector shutdown is usually overheating: clogged air filter, blocked vents, failed fan, or too hot a room. Clean the filter and give it space.
Exam tip Projector shuts off after 20-30 minutes = heat. Clean the filter and check the fan.
Fuzzy, distorted and sizing/orientation
Fuzzy image: resolution not set to the panel's native resolution, or an analog VGA link at high resolution. Distorted image: wrong aspect ratio or resolution, stretched output, or a projector with no keystone correction. Display sizing/orientation: wrong scaling %, overscan on TVs, or the orientation set to portrait/rotated (Ctrl+Alt+arrow hotkeys on some systems). Fix in Display settings.
Exam tip LCD looks soft? Set native resolution. Projector image a trapezoid? Keystone.
Burn-in, dead pixels and flashing
Display burn-in: a faint permanent ghost of a static image (logos, taskbars), mostly on OLED (and old plasma/CRT). Prevent with screen savers, auto-off and moving content. Dead pixels are always black; stuck pixels are stuck on one color. Within warranty, a panel with too many dead pixels is replaced. Flashing screen: loose cable, wrong refresh rate, a failing backlight or inverter, or a bad graphics driver.
Exam tip A pixel that is always black = dead. One bright color = stuck.
Color, dim image and audio
Incorrect color display: loose or bent-pin cable (a color channel missing, e.g. everything pink with VGA), wrong color profile, or display mode settings. Dim image: brightness/power-saving settings, ambient light sensor, failing backlight or inverter (CCFL), or an old projector lamp. Audio issues over HDMI/DisplayPort: wrong playback device selected, muted monitor/TV, or a VGA/DVI link that carries no audio.
Exam tip Whole image tinted one color on VGA = reseat or replace the cable (bent pin).
Check yourself 1The projector image is sharp, but it is shaped like a trapezoid: wider at the top than at the bottom. What should you adjust?
- The laptop's native resolution
- The keystone correction
- The input source
- The lamp timer
Show the answer
Answer: B. The keystone correction
A trapezoid image comes from the projector being angled at the screen. Keystone correction squares the image back up.
Objective 5.4
Mobile device issues
Battery health, swollen battery, charging
Poor battery health: short runtime; check battery health in settings, cut screen brightness and background apps, or replace. A swollen battery (bulging case, lifted screen) is a fire hazard: stop using it, power off, do not puncture or charge it, and send it for proper disposal. Improper charging: bad or underpowered cable/charger, dirty or damaged port, overheated battery, or a non-certified charger.
Exam tip Swollen battery: never "press it back in". Remove from service and recycle properly.
Broken screen and digitizer issues
A broken screen may crack only the glass, or the display and digitizer too. Back up data first, then replace the screen assembly. Digitizer issues: touch not working in one area, "ghost touches" or wrong taps. Try removing the screen protector/case, cleaning the screen, and restarting; if it persists, replace the digitizer/screen assembly.
Exam tip Display fine but touch dead in a strip = digitizer.
Cursor drift, calibration and stylus
Cursor drift/touch calibration: the pointer moves by itself or taps land off target. Clean the screen, update the OS/driver, and run the touch calibration tool (on Windows tablets: Tablet PC settings/Calibrate). Stylus not working: an active stylus needs charge and pairing (Bluetooth); check the tip, and confirm the device supports that stylus type.
Exam tip Active stylus = battery + pairing. Passive stylus works like a finger.
Connectivity, ports and liquid damage
Poor/no connectivity: airplane mode, Wi-Fi/Bluetooth off, out of range, wrong saved network, or carrier/SIM issue; toggle radios, forget and rejoin. Damaged ports: lint in the charging port (clean gently with non-metal tools), bent pins, or loose port. Liquid damage: power off at once, do not charge, dry it; check the liquid contact indicator (turns red). Corrosion may appear later.
Exam tip Phone won't charge? Look in the port for lint before replacing anything.
Overheating and degraded performance
Overheating: heavy apps or games, charging while running hard, direct sun, thick cases, a failing battery, or malware. Close apps, remove the case, let it cool. Degraded performance: low free storage, too many background apps, old OS, worn battery throttling the CPU, or overheating. Clear storage, update, restart, then factory reset as a last resort (back up first).
Exam tip Slow phone with storage 98% full: free up space first.
Malware and cannot install apps
Malware signs: pop-ups, fast battery drain, high data use, unknown apps, fake security alerts. Remove unknown apps (especially sideloaded ones or those with device admin rights), update, scan, and factory reset if needed. Cannot install apps: not enough storage, OS version too old, app not compatible, store account/payment issue, or MDM policy blocks it.
Exam tip Work phone refuses an app that installs on a personal phone? Check MDM restrictions.
Check yourself 2The conference room projector shows a good image but turns itself off after about 25 minutes, every time. What should the technician check FIRST?
- The HDMI cable for bent pins
- The air filter and fan for heat buildup
- The lamp hours counter
- The laptop's display resolution and refresh rate
Show the answer
Answer: B. The air filter and fan for heat buildup
Timed shutdowns after warm-up point to overheating. Clean the filter and confirm the fan works.
Practice questions
Answer in your head, then open the answer. Ranger's Help Desk has 436 questions like these for A+ Core 1, with mock exams.
Question 1A monitor shows "No signal," even though the PC is running and connected by HDMI to the HDMI 2 port. What should the technician check FIRST?
- The video card driver version
- The HDMI cable's length
- The monitor's input source setting
- The PC's power supply output
Show the answer
Answer: C. The monitor's input source setting
Monitors with several inputs show "No signal" when set to the wrong one. Select HDMI 2 with the monitor's input button.
Question 2A presenter connects a laptop to a conference room projector by HDMI. The projector is on the HDMI input, but only the laptop screen shows the desktop. What should the presenter do?
- Set the laptop to duplicate or extend
- Lower the laptop's refresh rate to 30 Hz
- Clean the projector's air filter
- Replace the projector lamp and reset its timer
Show the answer
Answer: A. Set the laptop to duplicate or extend
The laptop may be set to show on its own screen only. In Windows, Win+P switches to Duplicate or Extend.
Question 3A monitor connected by VGA shows a strong pink tint. Wiggling the cable makes the color flicker. What is the MOST likely cause?
- An unsupported refresh rate
- A loose cable or bent pin
- A cluster of dead pixels
- Display burn-in on the panel
Show the answer
Answer: B. A loose cable or bent pin
Analog VGA sends red, green and blue on separate pins. A loose connector or bent pin drops a color, which tints the image.
Question 4A projector's lamp indicator is lit, and the projector turns on but shows no image. The lamp has passed its rated hours. What should the technician do?
- Replace the lamp after it cools
- Change the input source to the other HDMI port
- Replace the HDMI cable to the laptop
- Adjust the keystone correction
Show the answer
Answer: A. Replace the lamp after it cools
A burnt-out bulb leaves the projector on with no light. Let the unit cool, then replace the lamp and reset its hour counter.
Question 5A technician is replacing a projector lamp. Which precaution is MOST important?
- Use any lamp of the same wattage
- Clean the new bulb's glass with a wet paper towel
- Let it cool and do not touch the bulb's glass
- Install the lamp while the projector is running
Show the answer
Answer: C. Let it cool and do not touch the bulb's glass
Projector lamps get very hot. Skin oils on the glass create hot spots that can make the bulb fail early.
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