Your intercom has stopped working.

First: how many units, and which ones

The call that reaches a building manager is almost always about one handset. A resident in unit 12-3 cannot hear the lobby, or presses the release and nothing happens. That report is true but it is not yet a diagnosis, and acting on it directly — by replacing the handset — is how buildings spend the same money twice.

Before anyone is called out, someone should establish how many units are affected and which ones they are. Not “a few on the upper floors”. Actual unit numbers. In a high-rise intercom the units are wired in a structure, and the shape of the failure follows that structure exactly. A committee that arrives at the first conversation with a list of unit numbers has already done the most valuable part of the diagnostic work, and it costs nothing but a knock on the doors either side.

The reason this works is set out at more length in the guide to a failing system: a high-rise intercom is mostly cable and mostly shared, so the visible device is the least likely thing to have failed.

One unit, one stack, one block: what each pattern means

There are only a few shapes a failure can take, and each one points at a different layer of the system. This is the table worth having in front of you while the complaints are still being collated.

The last two rows deserve attention. A whole-building failure sounds like the worst possible news and frequently is not — a head end that has lost power or locked up takes every unit down at once and may cost very little to put right. An intermittent fault affecting three units sounds minor and is often the expensive one, because nobody can reproduce it on the day of the visit.

The door station, and why it is rarely the cause

The panel at the lobby door is the part of the system everyone in the building touches, so it collects the blame. It is worth separating what a door station actually does from what is happening around it.

A door station calls a unit and passes audio and video. It does not, by itself, open the door. The release is a separate circuit — a lock, its power supply, and the wiring between them — and a very common report, the intercom rings but the door will not open, is usually a lock circuit fault sitting behind a perfectly healthy intercom. Replacing the door station in that situation changes nothing, and door stations are not cheap.

The other frequent report is one-way audio: the lobby can hear the unit but not the reverse, or the other way round. In a cabled intercom that is almost often a cable fault rather than a device fault: in a four-wire intercom the two directions travel on different conductors, so a break can take one without the other. (Two-wire systems carry both on one pair and fail differently, which is itself worth establishing.) A building with three lobbies has three door stations and often three separate runs, so establishing which entrance is as useful as establishing which unit.

Power, and the fault that comes back every few weeks

The most frustrating intercom fault is the one that clears itself. A stack goes dead on a Sunday evening, someone reports it on Monday, and by the time an engineer attends it is working again. Nothing is found, a visit is charged, and three weeks later it happens once more.

These faults usually live in power rather than in the intercom. The supply feeding a head end or a floor distribution point may share a circuit with something that draws heavily and intermittently. A backup battery aged past its useful life will hold up under normal conditions and collapse during a brief interruption, taking the system with it and restoring it when mains returns. Neither condition shows up as a fault at ten in the morning.

An engineer given four occurrences with times can look for a cause. An engineer given “it keeps happening” can only wait for it.

What to record before anyone attends

This is the whole preparation, and it is short enough to keep on one sheet at the management office. Whoever takes resident complaints should fill it in as the complaints arrive, rather than reconstructing it afterwards.

1. Unit numbers. Every affected unit, and ideally two or three neighbouring units confirmed as working.
2. Which entrance or lobby the problem involves.
3. What exactly fails — no call, no audio, audio one way, no video, or a call that connects but will not release the door.
4. When it started, and anything that happened around then: a power interruption, lift works, a renovation, a storm.
5. Constant or intermittent, and if intermittent, at what times.
6. What has already been done, by whom, and what was replaced.

That record is worth more than a photograph of the handset, and it is the beginning of the documentation a building should be keeping anyway.

What a diagnostic attendance should give you in writing

A committee is entitled to expect an attendance to end with a written position rather than a verbal impression. The useful output is short, and it is what makes the next quotation comparable to anything else.

That last line matters. An honest report saying a riser could not be inspected because the cupboard was inaccessible is more useful than a confident conclusion drawn without it.

When the answer is that the system has reached its end

Sometimes the diagnosis is not a fault at all. Recurring failures across different layers, parts that can no longer be obtained, and a system that has been repaired repeatedly are together a different finding: the installation has reached the end of its service life, and further repair is spending against an asset with no remaining life in it.

That is a legitimate outcome of a diagnostic visit and it should be stated plainly rather than discovered gradually across four more attendances. It also changes what the committee does next — not authorising a repair, but planning and funding a replacement, which is a different process with different approvals behind it. How long these systems actually last sets out the signals.

What it costs to find out

Occhio Tec does not publish a price for diagnostic attendance, because what the work involves depends on what is installed, how much of it can be reached, and how much documentation survives. A figure quoted before those are known would be a guess presented as a price.

What can be said is what the visit should produce: the layer identified, the correction described as work, and the wider condition noted. Occhio Tec has worked in high-end condominiums in the Mont Kiara, Bangsar and KLCC areas for service and maintenance, and intercom audio and video is one of the fourteen ELV services the company lists. The company was established in 2010.

The first step is a site survey. Related reading sits in Insights, and the wider diagnostic method is in the guide to a failing system.