CPI Troubleshooting & Fault Diagnosis 3 — Questions and Answers
Question 1: A wireless microphone system experiences dropouts only when the presenter moves to one side of the stage. What is the most likely cause?
- Incorrect frequency selection
- RF antenna shadowing or multipath interference in that zone (Correct answer)
- Low transmitter battery
- Gain structure set too high
Correct answer: RF antenna shadowing or multipath interference in that zone
Dropouts localized to a specific area indicate RF dead zones caused by antenna placement, shadowing, or multipath reflections.
Question 2: A PoE IP camera powers on but the image is extremely dark even in daylight. What should be investigated first?
- Camera's iris/exposure settings or lens cap still in place (Correct answer)
- Switch PoE budget exceeded
- Incorrect VLAN assignment
- Firmware version mismatch
Correct answer: Camera's iris/exposure settings or lens cap still in place
An extremely dark image in adequate lighting is most commonly caused by incorrect exposure settings or a protective lens cover that was not removed.
Question 3: A digital signage player outputs video but text on screen appears pixelated and blurry. The display is 4K capable. What is the likely cause?
- The player's output resolution is set below the display's native resolution (Correct answer)
- The HDMI cable is too long
- The display brightness is too high
- The signage software needs updating
Correct answer: The player's output resolution is set below the display's native resolution
Pixelation and blur on a 4K display is typically caused by the source device outputting at a lower resolution that the display is scaling up.
Question 4: After installing a fiber optic cable run, optical power meter readings are 6 dB below the calculated link budget. What fault should be suspected?
- Excessive bend radius violating minimum bend specs or a dirty/damaged connector (Correct answer)
- Wrong fiber color jacket selected
- Incompatible wavelength on the SFP
- Incorrect cable reel labeling
Correct answer: Excessive bend radius violating minimum bend specs or a dirty/damaged connector
A 6 dB loss significantly above the budget points to physical impairment such as tight bends, dirty connectors, or a damaged splice.
Question 5: A ceiling speaker emits distorted audio at all volume levels, even at very low settings. The amplifier channel tests normal with a different speaker. What is the fault?
- Damaged or torn speaker cone/voice coil (Correct answer)
- Incorrect crossover frequency setting
- Amplifier clipping
- Impedance mismatch at the amplifier output
Correct answer: Damaged or torn speaker cone/voice coil
Distortion present even at low levels that is isolated to one speaker indicates a physical defect in that speaker, such as a damaged voice coil or torn cone.
Question 6: A video conferencing system shows the remote participants with a green tint. Local video appears normal. What should be checked first?
- Network bandwidth to the remote site
- White balance or color profile settings on the remote camera (Correct answer)
- The local display's color temperature
- HDCP compliance of the codec
Correct answer: White balance or color profile settings on the remote camera
A color cast visible only on the remote video feed points to an incorrect white balance or color space setting on the remote site's camera.
Question 7: An access control reader flashes red and beeps three times when a valid credential is presented. What does this behavior typically indicate?
- The credential is not enrolled in the system or is outside its time schedule (Correct answer)
- The door strike is faulty
- The reader needs firmware update
- The credential battery is low
Correct answer: The credential is not enrolled in the system or is outside its time schedule
Three red flashes with a beep is a standard reader response for an unrecognized credential or one that falls outside an active access schedule.
CPI Troubleshooting & Fault Diagnosis 3
A wireless microphone system experiences dropouts only when the presenter moves to one side of the stage.
What is the most likely cause?