False Alarm triggered by Window Shocks.. No Gross or Pulse

Jimbob1977

Hi there,

We came home to a ringing alarm on the Aritech CS350.

The zone is a Window Shock Sensor zone. It's not a door contact sensor.

There was no Gross nor Pulse in the log message. It was simply that the zone was triggered three times in an hour. The windows were firmly shut, so it's a false alarm.

The sensors are really old... like 16 years.

In the past week, I was doing a normal set and the zone was showing as 'Open'. Ten minutes later, it was showing as fine for a textbook Normal Set. I didn't mess around with anything. It came good.

There are four shocks in the zone. I guess my question is:

1. Without having a multimeter, is there a way to identify the dodgy sensor... bearing in mind that I can't replicate the issue every time?

2. Should I replace all the sensors at this stage. The remainder of the house is covered with new HKC types.

Thanks in advance.

davidconroy46

You say it did not say gross or pulse counts. If it told you its an alarm type on log then more than lightly you have a faulty sensor. Like some people might think its the door like you in your case.it all depends how it was named in the zone. It could be say back door kitchen, there could be a window on same zone. Will need to be checked with meter. You could set the alarm and tap one sensor open door at a time etc and that will tell you which zone they are on.

Jimbob1977

davidconroy46 wrote: »

You say it did not say gross or pulse counts. If it told you its an alarm type on log then more than lightly you have a faulty sensor. Like some people might think its the door like you in your case.it all depends how it was named in the zone. It could be say back door kitchen, there could be a window on same zone. Will need to be checked with meter. You could set the alarm and tap one sensor open door at a time etc and that will tell you which zone they are on.

Hi David,

Thanks for your reply. A few years ago, we went through the entire house and wrote down the Zones in detail. It's definitely a window shock.

The triggered zone is 03.

Our door sensors (we only have three doors) are Zones 02 and 06. So it's definitely the back windows shocks of the house.

If I got my hands on a multimeter, what would I be setting it to..... and what is the desired average reading?

KoolKid

A multi meter would make finding the device much easier.

Disconnect the zone from the panel & remove the end of line resistor,
Set you meter to continuity and connect the pair to the 2 meter leads.
on a lenght of cable long enough to reach all your windows on zone 3.
Make a note of the reading in ohms. One by one tap every sensor & open and close every contact. After a tap or an open close the resistance should return to the around the same value. If it does not disconnect that device , close of the pair wired into it & move on. Replace any that you had to close off.

Jimbob1977

Hi,

I got a multimeter and followed some good advice from davidconroy46.

I think I gave a problem with two sensors, per the testing below.

Steps undertaken:

1. Removed the four shock sensors from their windows

2. Slotted them back in their outer plastic casing (to replicate a real life mounting)

3. Set the multimeter to its lowest setting (200 ohms)

4. Applied the red and black probes to the sensor metal ends

5. Tapped the sensor (surrounded by its casing). Took a few samples to validate.

Results:

o Sensor A and Sensor B returned to 0.2 ohms within a second. I believe that's a good thing.

o Sensor C took a few seconds to settle at approx 2.5 ohms. High side of bad?

o Sensor D was in a constant state of flux and never settled down. It kept hovering between 7 and 8 ohms forever.

Do you think it's fair to say that Sensor C and Sensor D are not 'fit for purpose' and should be replaced? I assume the alarm system is picking up a false breach due to their condition

KoolKid

I would replace those 2 yes.
However testing that way does not diagnose an issues with connections or the cable on the entire zone.
If , after replacing those ,you have any further issues I would recommend testing the entire zone as I described.

davidconroy46

Hi you, ve done it write, so replace sensors D for sure, sensor C 2.5 omhs . Sometimes you will get away with that. Change both and that should do you. Good diy man, fair play to you.

mfceiling

You're sure that nobody "tried" the window from outside to check your alarm?

Jimbob1977

mfceiling wrote: »

You're sure that nobody "tried" the window from outside to check your alarm?

Good question. But I'd expect a Gross and/or Pulse should have registered on the keypad display if the force was sufficient to trigger the alarm.

There was no Gross or Pulse message, just the Zone ID flashing up. And the alarm blaring