Lift camera video flickers or drops when the lift moves
The four causes, in the order they are most likely, and the test for each.
A lift camera that is fine when the car is parked and bad when it moves is telling you exactly where the fault is: in the moving section. Work through these in order.
1. A conductor is cracking
The classic failure of round solid-core cable used as a travelling cable. The picture drops at the same point in the travel, gets worse over weeks, then stops. Test: wiggle the cable near the car-top clamp and watch the stream; continuity on a cable tester while flexing. Fix: replace the travelling section with a flat stranded cable — CC-8251G-90 for IP, CC-9511K-90 for HD.
2. Voltage drop on the power pair (HD cameras)
IR cameras draw more current when the LEDs switch on, and a long or thin 12 V run cannot hold the voltage. The picture rolls or reboots at night or when the car lights change. Test: measure DC volts at the camera with IR on; below about 11 V is the problem. Fix: shorten the run by powering from the car controller, or use the heavier power cores of the 2+2 Flat.
3. A loose connector
Twist-on BNCs and solid-rated RJ45 plugs both loosen under vibration. Test: touch the connector while the car moves. Fix: compression BNC; stranded-rated RJ45; a short service loop so the connector is not carrying the cable weight.
4. Drive noise
Lines across the picture that appear on acceleration and braking are the lift drive coupling into the cable. Test: does it correlate with the motor, not the position? Fix: separate the camera cable from the power travelling cable by a few centimetres, make sure it is not taped to it, and check the camera's and NVR's earthing. Twisted pairs (IP) are far more tolerant of this than coax (HD).
If none of that helps
Check the fixed section too — a poor punch-down at the junction box or a damaged cable in the machine room shows up as intermittent faults that only seem to follow the car.
