Our home alarm system has sensors in 3 zones, the panel lights up if theres movement in any of the zones, preventing arming the alarm. We came home one day to find the alarm with all 3 zones lit up and a constant beep. The code was entered to stop it. However the 3 zones still show as detecting movement.

Ive been able to establish the alarm still works, that switching the power off for 30seconds (with the battery disconnected) then switching it back didnt help and the wiring to the sensors is ok (discovered this by trying to take a cover off one of the sensors and setting the alarm off), however there does not appear to be any movement detection happening on any of the sensors. Any ideas?

Im guessing theres no power getting through but not sure why, perhaps a blown fuse in the control box? i thought maybe it was fault PIR detectors but its strange they all went at the same time.

The alarm is a Sentinel 1 by National Fire & Security company (tried to google them but couldnt find anything)

Likely 1 fuse controls power to all PIR's so check the fuses first off but be sure to isolate mains power first - see my sig below1

Judging by the pic Id say that the panel has overheated due to lack of service. IMO you should call some local installers for quotes to repair and take on for maintenance.

Likely 1 fuse controls power to all PIR's so check the fuses first off but be sure to isolate mains power first - see my sig below1

thanks for that, i thought i had checked the fuses but apparently not close enough, one of them is blown, will replace ... thanks for your post

That panel is well old my friend...it sounds like a fuse, but it could be a good time to upgrade

It may be something more serious, the new fuse blew straight away so possibly a short circuit somewhere or maybe it is time to upgrade

any ideas on how i can find the source of the problem?

It may be something more serious, the new fuse blew straight away so possibly a short circuit somewhere or maybe it is time to upgrade

any ideas on how i can find the source of the problem?

If you have a meter check each cable's power cores to see if you can identify where the fault is and then investigate that cable and components connected to it - however I would suggest that all of the equipment would benefit from being replaced.