Five Most Common Reasons Alarms Develop Faults and How to Fix Them
You can guarantee that virtually every single time I am called out to repair a burglar alarm, it is one of five faults that usually occur, making it relatively easy for me to diagnose the problem in most cases.
I often think that rather than paying out for the call out fee if I could speak to the customers on the telephone I could talk them through their fault and the repair could be done within minutes and without any call-out fee. Of course this would be great for my business, but it just seems such a waste of time travelling to a house when the fault is such a minor repair.
I will go through the most common five faults that occur on hard-wired security alarms and explain how to repair the ones that occur most often.
When I go around to different buildings, I tend to see the same manufacturers and security alarm panels repeating themselves over and over again, there is a small number that tend to be used extensively.
Probably the biggest fault that you get on a security alarm which has been installed for over five years, or a system that has not had a service in that time, is the internal battery on the panel will be completely dead. Sometimes this has caused the 1.2 AMP on the circuit board which is in line with the trickle charger to blow. This means there is no rechargeable current going into the battery any more.
The battery needs replacing along with the fuse and it is worthwhile testing with a multimeter that you are getting approximately 12 to 14 V from the trickle charger again, so that the new battery will be topped up and stay that way.
The second biggest fault I would think is that the tamper circuit on the control panel has gone open-circuit. The Tampa circuit consists of a loop of wire that runs throughout all the passive infrareds, shock sensors and magnetic contacts in the building. It is one big series loop and this will often have gone open-circuit and this will cause the internal tamper sound to have occurred on the control panel. When the customer puts in their user number to stop the sound, it does extinguish the internal sound but it usually leaves an LED lit on the panel saying tamper and the system will not work again until this circuit has been closed.
All that is required is that all the sensors are checked to see if the lids are closed properly because there is a micro switch in each one which can go open-circuit. Alternatively it can be an actual break in the wiring, but that is less likely. If somebody is really having difficulty in finding the open-circuit in this tamper circuit, it is possible to put a small loop of wiring in the panel, bridging the tamper circuit terminals. You are effectively removing the tamper circuit from the buildings wiring and devices in total.
The only way to really find the actual open-circuit if it’s not a loose lid, is to go around each sensor and physically remove the wiring from the tamper circuit terminals in the device and then check to see if the open-circuit has disappeared. Obviously if that does happen on one sensor it’s a faulty micro switch on the device.
In reality the tamper circuit on the internal wiring is not that important in my opinion, because it is very unlikely that an intruder would damage these cables, because they would have to be physically inside the building with the alarm in activation to do so.
The third most likely fault is with the personal attack circuit which is once again a series loop of wiring that goes out to the siren box running through a micro switch that closes when the lid goes down on the self-acting siren box. The micro switch is sometimes faulty and with this circuit it’s like the tamper circuit but the difference being that when it goes open circuit it sets the full alarm system into activation rather than just the internal tamper sound. The repair is to replace the tamper switch in the siren box outside.
Once again a temporary measure repair could be as with the previously mentioned tamper circuit is to put a small group of wires across the panic attack terminals in the Control Panel, and these are usually marked Bell negative and tamper return.
Probably the fourth most recognisable fault with a burglar alarm system caused by the fact that the external self-acting siren box is mounted on the wall outside and exposed to the weathering elements. Inside the self-acting siren box there is a printed circuit board that in the older units could be affected by damp conditions after a number of years. In the new up-to-date units they usually enclosed this printed circuit board in its own self-contained plastic box to protect it from damp.
Because the siren box is self-acting with its own battery backup, it can go into alarm condition if the printed circuit board has been damaged to damp, but usually at this point there is no effect to the internal alarm system inside the building. Sometimes the self-acting siren box will not go into full alarm condition, but will omit the strange intermittent shrieking sound and this is always a sign that the siren box itself needs replacing. There will be no way to stop the external siren box from emitting its sound in this damaged condition without physically putting ladders up and disarming it.
The fifth reason that a hardwired security alarm system can stop working is quite simply because one of the various small 1.2 amp glass fuses on the main printed circuit board inside the control panel. You just need to physically check these, but it can be difficult to see if the very fine fuse wire is blown. Once again a multimeter with the continuity tester is the reliable way of checking.
A person with good do-it-yourself abilities could try to diagnose the hardwired security alarm problem themselves, but it is also advisable to call in a professional if there is any doubt.
Also it should be remembered that in a full security alarm service, there are other tests which have not been mentioned in this article and it’s always advisable to have your alarm serviced from time to time by a qualified engineer.