Fault Phenomenon: Hongda HBT140 monitoring image is clear when cold. When the lens heats up (operating temperature), the monitoring picture becomes blurry, cannot focus, and eventually goes blind.

Troubleshooting Process:
– Checked lens cleanliness: lens clean.
– Checked video wiring: wiring normal.
– Checked host settings: settings correct.
– Measured internal temperature of the camera at operating temperature: found temperature too high.

Root Cause: Increased noise from the internal imaging sensor of the camera due to heat causes image blur.

Required Parts: Monitoring camera assembly.