Old alarm system

[Timothy Murphy]

We used to have a service contract on our house alarm system, but that ended 15-20 years ago. (I think the alarm company went out of business.)

I'm wondering what the chances are of re-activating the alarm, either as a DIY job, or by finding a handyman that knows about these things? (My impression is that the large alarm companies are very expensive, and that one has to take out an annual contract.)

Any suggestions or advice gratefully received.

Incidentally, the alarm system is still alive, though set not to go off. How can one actually disable an alarm? I assume that if you just disconnect it, it will go off?

[Martin Brown]

It helps to know the model number and how you arm the alarm.

Very old ones use physical keys more modern ones keypad codes. The locks eventually wear out.

Set to daytime? Do you still know how to arm it?

Typically enter the engineering escape code and then do exactly the right sequence of dismantling it. There will be anti-tamper switches somewhere on each box if the design is even half decent.

More than likely the external bell box will have its own battery and ring until that runs out if you just try something crude. Cutting the cable will be interpreted as a hostile act. Best bet is find someone who knows how to service the model in question.

[Chris Bartram]

The bell box and any switches usually have an anti-tamper loop (and the box will have a microswitch on the cover), so just cutting wires will set it off. If you can't disable the alarm at the control, then start at the bell box, with ear defenders ;-), and work back to the control panel. They may have back-up batteries, but they'll probably not last long by now....

[NT]

If its had no maintenance in 15-20 years, the battery is quite likely dead.

NT

[ARWadsworth]

The engineers code will probably not be available to the OP if there was a service contract.

Even cheaper to do a DIY swap for a new one if needed.

[Martin Brown]

I agree, but I wouldn't want to put money on it and they are *VERY* noisy at point blank range. The OP needs to clarify what he wants to do

- bring the thing back into working order or remove it entirely. The optimum strategy is quite different in each case.

[Bill Wright]

A

15 years since a service? Kill the mains. The batteries will be shagged, so after a few days the thing will be dead. Open the control panel, it will try to sound, making a pathetic gurgle most likely. Cut the wire to the battery. If the bellbox keeps squawking chances are it will run out of steam after a few minutes. If not and it really bothers you get the ladder up and cut the battery wire. Best not do this late at night. Mid afternoon is best.

Bill

[Timothy Murphy]

Actually (as the OP), the alarm certainly does still work, so I assume it must work by mains power? Is there normally a battery backup?

[Alan]

There is normally a battery backup, in a control box. After a few years the battery may still have a terminal voltage of 12/4V as a result of the trickle charging. In my experience after a few years the battery fails to operate correctly. During a mains power cut the battery fails to provide enough "instantaneous" current to stop the alarm from triggering but it will provide enough current to maintain the alarm in its triggered state.

[ARWadsworth]

So what did do mean by "what the chances are of re-activating the alarm" in your first post?

If it's working then it does not need reactivating.

[ARWadsworth]

A couple of weeks ago I swapped my parents elderly but working bell boxes. I swap them every 10 years or so even if they work

My Dad was supposed to be footing the ladders. Halfway through swapping the first bell box he said "Sheff Wednesday have scored" and when I looked down the silly old git had wandered off as was watching the TV through the window.