Commax intercom repairs and installation

A Commax system has two halves joined by a cable: the door station on the gate pillar, with the call button, speaker and microphone (and a camera on video models), and the indoor unit, a handset or a monitor. A button on the indoor unit can open the gate when it's wired to the gate motor.

"1-to-1" means one door station and one indoor unit. Larger homes add a second handset or monitor upstairs or in a cottage.

• Completely dead: no ring, no screen, no sound. Usually the indoor unit's power supply or the plug point; sometimes the unit itself.
• The bell doesn't ring: a call button at the gate that's worn, stuck or full of water, or a break in the cable.
• Sound but no picture: on a video model, the camera in the door station, its cable, or the monitor.
• Only one side can hear, or there's a hum or crackle: the speaker or microphone at either end, or a poor connection. See intercom handset no sound.
• It talks but won't open the gate: the connection between the indoor unit and the gate motor, or the motor's trigger input.
• Storm damage: a door station that took water, or a system that died after lightning along the cable.

Door stations live outdoors on the pillar, in sun, rain and dust, so they wear out first. A cracked front, a sticky button or a fogged camera lens are signs it's on its way.

1. Power: is the indoor unit's adaptor plugged in and switched on, and does the plug point work?
2. The gate: does it open from a remote? If it does and the intercom button doesn't, the fault is the intercom's link to the motor, not the motor.
3. The door station: look for water inside the cover, a cracked lens or a button that stays pressed in.
4. Recent work: has anyone been digging, paving or gardening along the driveway? A cut cable is a common cause after building work.

Don't open the door station or the monitor; there's nothing inside that's safe to adjust without the maker's manual. The general checks for any make are on intercom not working.

People often ask how to connect a Commax intercom, or install one with a door lock. In principle:

• To the gate motor: the indoor unit's door-release output is wired to the gate motor's trigger input, so the button inside works like a remote.
• To a lock on a pedestrian gate or front door: an electric lock has its own power supply, switched by the intercom's release output.
• Between the gate and the house: the existing cable can often be reused for a new Commax, if it has enough cores and is in good condition.

We don't publish Commax wiring diagrams: without the maker's manual for your model, a wrong connection can damage the indoor unit or the gate motor's card. We wire and test it on site, from the button to the gate opening.

An intercom fault can sit at the gate, in the house or in the cable between, so we test the three halves separately rather than replacing parts until it works:

1. The indoor unit: its power supply and the voltage it sends down the cable.
2. The cable: continuity on each core from the pillar to the house, which shows a cut, a rodent bite or water in a joint.
3. The door station: the call button, speaker, microphone and, on video models, the camera.
4. The gate release: the signal from the indoor unit reaching the gate motor's trigger input, and the gate opening.

Once we know which part has failed, we quote for that part, and we tell you if a replacement Commax kit would cost little more than the repair.

If you're replacing an old system or fitting one for the first time, three questions decide which Commax suits you:

• Do you want to see who's at the gate? A video kit shows the visitor before you open; an audio kit relies on their voice. On a gate that faces a busy street, being able to see the visitor is worth the extra.
• Where will you answer? One handset or monitor by the kitchen is enough in a small home; a double storey or a home office usually needs a second indoor unit.
• What cable is already there? A sound existing cable keeps the job simple. If it's damaged, a new cable, or a wireless or GSM intercom from another maker, may be the better route: see intercoms.

Whatever you choose, place the door station at driver's-window height on the pillar, out of direct rain where possible: the gate station is the part that wears.

An intercom's cable runs from the gate pillar, outdoors, to inside the house, so a lightning strike nearby can travel along it and damage the indoor unit, the door station or both, and sometimes the gate motor's card at the same moment. Water in the door station after heavy rain can cause crackling, a bell that rings by itself, or no sound at all.

If your Commax failed during a storm, check whether the gate motor and electric fence survived too; when several things on the same cables died together, a surge is the likely cause. What storms do to the gate itself is in gate motor not working after rain or lightning.

In South African shops, a commax 1-to-1 audio kit sells for about R680 (Takealot), the Commax CDV-43K video kit for about R3 700 (Takealot) and the Commax 7-inch CDV-70N kit for about R4 700 (Takealot). Installed, a basic audio intercom typically costs R2 500–R5 000 (Kandua) and a video intercom R5 000–R15 000+ (Kandua). Prices checked October 2026.

So a repair makes sense when one part has failed, a door station or a power supply, and the rest is sound. When the indoor unit and door station are both old, or you'd like to see visitors, moving from audio to a Commax video kit on the same cable is often the better spend. More on intercom installation cost.

We repair and install Commax intercoms across Johannesburg, the East Rand and Centurion, along with Centurion, BPT, Zartek and Kocom systems, and the gate motors they open. All our spare parts are genuine, and every repair carries our six-month guarantee on our repairs. Your exact price is set in a free quote before any work starts. No call-out fee when we do the work. If no work is done, a R650 call-out fee applies.

Our intercom work is on intercoms, and the other brands on brands we work on. Repairs Plus is an independent installer and repairer. We are not the manufacturer.