Fault-finding
Lines, bands or noise across the picture
Rolling horizontal bands almost always mean electrical interference — a video cable running parallel to mains wiring, or a ground loop between two separately earthed buildings. Random grainy speckle is different: that points at a corroded connector or a failing camera. Which pattern you are seeing decides which fix applies.
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Note when the noise appears
Interference that starts when a generator, UPS, motor or welder switches on has named its own source. Plaza risers in Blue Area and the markaz blocks carry mains, generator changeover and camera cabling bundled together, and a video run pulled through the same trunking picks up all of it. Timing the fault against what else is running is the fastest diagnostic available, and it costs nothing but attention.
Separate the cable runs
Video and mains cable may cross at right angles but must not travel side by side. Re-routing the affected run — even a hand's width of separation helps — usually clears the bands permanently. Shielded cable is worth using near a source you cannot avoid, but distance does more than shielding ever will, so move the run first and keep the shielded cable for the one crossing you cannot design out.
Fit an isolation transformer for ground loops
A long analogue run between two buildings on different earths — a house and its gate cabin, a shop and its godown — circulates a small current through the video cable and draws slow bands up the screen. A ground-loop isolator fitted at the recorder end is inexpensive and cures it without rewiring anything. If the symptom is speckled noise instead, re-terminate the connectors before condemning the camera.
What causes rolling lines on a CCTV picture?
Why did lines appear after we installed a generator?
Changeover wiring is a strong interference source, and it often gets run beside existing camera cable. Re-route the video run away from the changeover panel and the bands normally disappear for good.
Does this happen on IP systems too?
Far less. Twisted-pair network cable rejects interference much better, and PoE removes the separate power runs. Persistent interference on an old analogue system is one honest argument for moving to IP.
Rather have it done?
Security camera repair covers black screens, recorders that stopped writing, lost phone access after an internet change, and footage that will not play back. Most faults trace to power, connectors or settings rather than a dead camera. Callout in Islamabad or Rawalpindi starts at PKR 3,000, with the full fix priced before any work.
Security camera repair in Islamabad — prices and scope