Fault Finding — Camera Image Problems

Purpose

This document covers how to systematically diagnose and resolve camera image faults — poor picture quality, no image, IR issues, colour problems, and focus faults. These are the most common CCTV service call types.

No Image — Black Screen or "No Signal"

The channel is showing a black screen, no video signal message, or a grey/blue screen.

Step 1 — Confirm which end the fault is at

On the DVR, check whether the channel LED is lit (on applicable models) or whether the DVR's channel input shows "Video Loss". If Video Loss, the DVR is receiving no signal from the camera.

Step 2 — Check the camera

Is the camera powered? Check the LED on the camera body (IR LEDs should be visible in the dark, or look for a power indicator on the housing)
For POC cameras: the DVR powers the camera through the coax — if the DVR channel shows video loss, the DVR is not getting signal back, which could also mean no power is reaching the camera
For PoE IP cameras: check the PoE switch or NVR port LED — it should show link/activity

Step 3 — Check the cable

For coax: check both BNC connectors at the DVR and at the camera end — are they secure? Is the BNC twisted fully and locked?
For coax: any sign of damage, kinks, or crushing along the cable run?
For Cat5/6: check RJ45 connectors are seated — swap for a known-good patch lead at the NVR end to eliminate the connector

Step 4 — Swap the channel

Connect the camera cable to a known-working channel on the DVR — does the camera appear on the other channel?

If yes: the original DVR channel input has failed — replace the DVR or use a spare channel
If still no image: the fault is with the camera or cable, not the DVR channel

Step 5 — Test the camera directly

For analogue: connect the camera cable directly to a portable monitor via BNC — does the image appear?
- If yes: DVR input fault
- If no: camera or cable fault — test with a short test cable from the camera direct
For IP: connect a laptop directly to the camera's RJ45 output with a PoE injector and access the camera via browser (default IP range 192.168.1.x)

Flickering or Unstable Image

The image flickers, rolls, or shows horizontal banding.

Symptom	Likely Cause
Regular horizontal banding	50/60Hz flicker from fluorescent or LED lighting — set anti-flicker to 50Hz in camera image settings
Intermittent flicker / loss	Loose BNC connector — press and re-twist BNC at both ends
Rolling image	Signal interference — check cable is not running alongside high-voltage cables or near motors
Intermittent on movement	Cable flexing — there's a break in the coax or a bad solder joint at the BNC

Check: Move the cable at both ends — if the image changes when you flex the cable, there's a break in the core wire or a short at the BNC crimp.

Image Too Dark

Camera is producing an image but it is underexposed and difficult to see detail.

Is it genuinely dark? Check the time — if this is night-time, is IR illumination working? Cover the lens to force night mode — do the IR LEDs or white light illuminate?
IR/White light not firing: Check the supplement light setting (Camera → Image → Light). Confirm the light mode is set correctly. If LEDs are not illuminating at all, the camera may have a hardware fault.
WDR fighting backlight: If the scene has a bright background (window, doorway facing bright light), WDR may be poorly configured. Try enabling or increasing WDR level.
Brightness setting too low: Check Camera → Image → Brightness — increase if needed.
Camera at the limit of its IR range: If the subject is too far from the camera, the IR cannot reach. Reposition or add supplemental lighting.

Image Too Bright / Overexposed

Common causes:

WDR too high — reduce WDR level in image settings
IR reflection: A wall, ceiling, or object very close to the camera is reflecting IR light back into the lens. This appears as a white haze or bright bloom covering part of the image. Reposition the camera or reduce IR intensity.
Facing into a light source: The camera is aimed at a bright window, sun, or artificial light. Reposition or enable WDR.
IR camera at short range: Reduce IR intensity.

IR Reflection / White Haze

A white or grey haze covers part or all of the image — most often visible at night in IR mode.

This is caused by IR light from the camera's own LEDs reflecting off a nearby surface back into the lens — typically a ceiling, soffit, gutter, wall bracket, or cable.

Fixes:

Reposition the camera so there is clear space in front of the lens
Check no cables or fixings are within ~20cm of the lens
Reduce IR intensity — Camera → Image → Light → IR Intensity
Use a lens hood or IR cut attachment to direct IR away from the nearby surface

No Colour / Black and White in Daylight

Camera is in black and white mode during the day.

Check:

Is the camera in forced Night mode? Camera → Image → Day/Night Switch — should be set to Auto
Has the camera been positioned where it receives very little daylight (deep overhang, north-facing internal wall)? In low ambient light, the sensor switches to night mode. Increase daylight to the lens or adjust the switch threshold.
On Smart Hybrid Light cameras: confirm supplement light mode is not forced to IR mode permanently.

Colour Tint / White Balance Problems

Image has an unnatural colour cast (purple, green, orange).

Common causes:

Mixed lighting: The scene has a mix of natural light and artificial lighting with very different colour temperatures. This confuses auto white balance.
Fluorescent lighting: Can produce green or pink casts. Try forcing white balance to the appropriate mode in camera image settings.
IR cut filter stuck: On auto day/night cameras, the IR cut filter switches position when changing modes. If stuck, the image will have an obvious colour cast in one mode.

Fix: Camera → Image → White Balance — try each mode (Indoor, Outdoor, Fluorescent, Manual) to find one that produces a natural image. If no white balance setting corrects it, the IR cut filter may be faulty — replace the camera.

Blurry or Out-of-Focus Image

Fixed lens cameras (4mm, 6mm): A blurry image on a fixed-lens camera usually means:

Condensation on the dome cover — clean and seal
Physical damage to the lens
Manufacturing fault — replace the camera

Varifocal cameras (motorised or manual zoom):

Motorised: use Camera → Lens → Focus in the DVR menu to adjust focus remotely — use the auto-focus function first, then fine-tune manually
Manual varifocal: adjust the physical focus ring on the lens barrel with the lens cover removed — lock with the locking ring when sharp

After adjusting zoom on a varifocal camera, the focus must always be reset — zoom and focus interact on these lenses.

Privacy Mask Covering Wrong Area

The black masked zone is covering part of the image you need to see.

Main Menu → Camera → Privacy Mask — select the channel and adjust or remove the mask rectangle.