All Pir's Led's Permanently On

[Neilo]

Can anyone help?

I have a Scantronic 9452 (or rather my customer has) which was giving false alarms on one zone only. I checked the system was all as it should be (battery checks etc.) so figured that, failing any external influences on the zone, the detector was probably on it's way 'out'. I therefore installed a new cheapie Honeywell PIR in it's place which seemed to be working ok. I did a quick walk test and set the alarm and activated it in an armed situation. All as it should be.

However, and I didn't notice this but my customer rang me later tell me that all the LED's on ALL the PIR's except the one I 'd changed were permanently on. The new one was going on and off as expected. When I returned I did a full walk test and full armed and activated test and the system seems to work as it should do, although I haven't left it for any length of time becuase the owners are away and I have to liase with the next door neighbours for keys etc.

I have searched all the forum and can't find anything remotely like this fault listed. I've thought about powering down completely (mains off, battery disconnected) but don't want the system to go into default (I do have the installation/user manual).

Any ideas?

Thanks

[Chorlton]

Hi Neilo

I'm no help I'm afraid as I only do fire but other members may be along soon who can.

As this is a public forum the information provided will be limited to that we don't want falling into the wrong hands (burglars !!!)

If you are in the alarm/CCTV/fire industry have a look around make some more posts so you can get to know us and us you and once your post count is upto 10 you can apply (FOC) to access the trade side of the forum where alot more detailed information is available. Use the link below.

Take care,

C.

[antinode]

Sounds like a bizarre fault. Do any of the detectors in question have the latch wired up? I would try disconnecting the Aux supply to the detectors for a minute or two then power back up to see if that will clear it. Also may be worth checking any settings/links/DIP switches inside these detectors. Do you have a make/model or description of the PIR's in question?

[luggsey]

Sounds like a bizarre fault. Do any of the detectors in question have the latch wired up? I would try disconnecting the Aux supply to the detectors for a minute or two then power back up to see if that will clear it. Also may be worth checking any settings/links/DIP switches inside these detectors. Do you have a make/model or description of the PIR's in question?

Yep sounds like old latching PIR's, must have put the latch wire in the +ve by the sound of it.

Some were wired up cleverly to only flash when user code is entered and an output triggers so an output may be locked on as well.

[Wooly-bobs]

Last time i had that it was low AUX to the passives.

[morgan306]

As Chris says, some PIRs leds stay lit when the supply to them is low. They may still function normally though. What was the voltage at the detector?

[lawandorder]

As Chris says, some PIRs leds stay lit when the supply to them is low. They may still function normally though. What was the voltage at the detector?

First thing to check is supply voltage to detectors, many detectors will light up permanently if supply voltage is low.

Having said that most PIRs will go into alarm condition at this point so you would not have been able to set the system.

Check the wiring of the old PIRs, as already suggested look for a latch wire.

Are all the detectors powered from the same output on the panel?

[Neilo]

First thing to check is supply voltage to detectors, many detectors will light up permanently if supply voltage is low.

Having said that most PIRs will go into alarm condition at this point so you would not have been able to set the system.

Check the wiring of the old PIRs, as already suggested look for a latch wire.

Are all the detectors powered from the same output on the panel?

Many thanks to everyone who has replied so far.

Firstly I'm a Locksmith who occasionally gets asked to look at alarms so forgive me for being a tad naive! However, the system works as it should do, setting, activating, walk tests, the whole nine yards apart from the fact the LEDS on the old, existing detectors are permanently on. There were six wires, a + and - ; the two tamper wires; and NC and C. There wasn't a latch wire. I think I'll try to power down, disconnect the battery, leave for a while then see if the PIR's restore to normal.

Unfortunately I can't get in the house until the weekend but thanks once again for the posted replies so far and I will respond early next week to keep you posted.

[luggsey]

Many thanks to everyone who has replied so far.

Firstly I'm a Locksmith who occasionally gets asked to look at alarms so forgive me for being a tad naive! However, the system works as it should do, setting, activating, walk tests, the whole nine yards apart from the fact the LEDS on the old, existing detectors are permanently on. There were six wires, a + and - ; the two tamper wires; and NC and C. There wasn't a latch wire. I think I'll try to power down, disconnect the battery, leave for a while then see if the PIR's restore to normal.

Unfortunately I can't get in the house until the weekend but thanks once again for the posted replies so far and I will respond early next week to keep you posted.

If there is no latch wire then as mentioned start checking voltage to detectors and look for a possible high resistance connection.

[Neilo]

Hi,

Many thanks to everyone who gave me the benefit of their experience. I have just come back from the house having disconnected the mains and removing the battery and then reconnecting again and lo and behold the LEDS have gone off and are acting as LEDS should do (or LED's on PIR detectors anyway!).

All your replies were very gratefully received.

Rgds

Neilo