CST Maintenance and Troubleshooting 2 — Questions and Answers
Question 1: A PTZ camera stops responding to control commands but still displays video. What is the most likely cause?
- Faulty video encoder
- RS-485 communication failure (Correct answer)
- Blown camera fuse
- Incorrect frame rate setting
Correct answer: RS-485 communication failure
RS-485 is the standard control bus for PTZ cameras, and a failure on this bus would prevent control commands from reaching the camera while leaving video unaffected.
Question 2: When performing preventive maintenance on outdoor cameras, which environmental factor most commonly degrades image quality over time?
- Fluctuating frame rates
- Moisture and condensation inside the housing (Correct answer)
- Incorrect DNS settings
- DHCP lease expiration
Correct answer: Moisture and condensation inside the housing
Moisture infiltration into camera housings causes lens fogging, corrosion, and sensor damage, which are primary causes of outdoor camera degradation.
Question 3: A technician notices that a camera's image appears washed out during daytime but looks normal at night. What should be checked first?
- IR cut filter operation (Correct answer)
- NTP synchronization
- PoE wattage
- Video compression codec
Correct answer: IR cut filter operation
A stuck or malfunctioning IR cut filter can cause images to appear washed out in daylight because the filter is not blocking infrared light from the sensor.
Question 4: What tool is best suited for verifying that coaxial cable terminations have acceptable signal loss in an analog CCTV system?
- Multimeter
- Cable certifier or TDR (Correct answer)
- Oscilloscope
- Network analyzer
Correct answer: Cable certifier or TDR
A TDR (Time Domain Reflectometer) or cable certifier can pinpoint faults, measure impedance mismatches, and verify signal loss in coaxial cabling.
Question 5: A surveillance recorder's hard drive health check shows reallocated sector counts rising steadily. What action should be taken?
- Defragment the drive immediately
- Schedule a drive replacement before failure occurs (Correct answer)
- Lower the recording bitrate to reduce write cycles
- Reformat the drive in NTFS
Correct answer: Schedule a drive replacement before failure occurs
Rising reallocated sector counts indicate impending hard drive failure; proactive replacement prevents data loss and system downtime.
Question 6: After a power outage, an IP camera is unreachable on the network. The camera's link LED is solid green. What should the technician check next?
- Replace the camera lens
- Verify the camera's IP address for a conflict or DHCP change (Correct answer)
- Check the IR illuminator output
- Inspect the video analytics settings
Correct answer: Verify the camera's IP address for a conflict or DHCP change
A solid link LED confirms physical connectivity, so the issue is likely an IP address conflict or a DHCP-assigned address change after the power cycle.
Question 7: Which maintenance task helps prevent video loss caused by bit rot on surveillance hard drives?
- Increasing camera resolution
- Regularly running drive health diagnostics and replacing aging drives on schedule (Correct answer)
- Enabling motion-only recording
- Reducing the number of camera channels
Correct answer: Regularly running drive health diagnostics and replacing aging drives on schedule
Scheduled SMART diagnostics and timely drive replacement are the primary defenses against bit rot and unexpected drive failure in surveillance systems.
CST Maintenance and Troubleshooting 2
A PTZ camera stops responding to control commands but still displays video.
What is the most likely cause?