My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your
hand at it, but the other 2 now seem to be permanently illuminated. Does
this suggest faulty sensors? I imagine it would be a coincidence for
both to fail at the same time, especially as they appear to be on
separate cables. Could a fault elsewhere cause 2 out of 3 not to work?

Any advice welcome

"Stuart Noble" wrote in message
...
My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your hand
at it, but the other 2 now seem to be permanently illuminated. Does this
suggest faulty sensors? I imagine it would be a coincidence for both to
fail at the same time, especially as they appear to be on separate cables.
Could a fault elsewhere cause 2 out of 3 not to work?

Any advice welcome

I had a problem a couple of weeks ago where 2 PIR's failed. The LED
illuminated when it detected movement but it was not talking to the alarm.
After investigation, both the PIR's failed at roughly the same time.

"Stuart Noble" wrote

My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your hand
at it, but the other 2 now seem to be permanently illuminated. Does this
suggest faulty sensors? I imagine it would be a coincidence for both to
fail at the same time, especially as they appear to be on separate cables.
Could a fault elsewhere cause 2 out of 3 not to work?

Any advice welcome

Ask for her installation/instruction manual.
Somewhere in this you should find instructions on performing a "walk test".
This allows you to put the control panel into a mode whereby it bleeps or
buzzes each time it detects movement in a particular zone.
This will be as good a test as any of the passives.
Also in the instructions there will be details on how to omit zones.
If you find a particular passive faulty on the walk test, try omitting it
when setting the alarm and see if the false detections still occur.

HTH

Phil

In article ,
Stuart Noble writes:
My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your
hand at it, but the other 2 now seem to be permanently illuminated. Does
this suggest faulty sensors? I imagine it would be a coincidence for
both to fail at the same time, especially as they appear to be on
separate cables. Could a fault elsewhere cause 2 out of 3 not to work?

Any advice welcome

Possibly a nearby lightning event damaged a couple?
Some of the more expensive ones do self-tests and this
might be its way to indicate the self-test failed.
I noticed that one particular make I had used in a
couple of places had noticably dropped in sensitivity
and speed of response compared with the others which
were still behaving as they originally did, so they
don't all last forever. That's another reason to do
walk tests and replace weak units from time to time.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

TheScullster wrote:
"Stuart Noble" wrote

My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your hand
at it, but the other 2 now seem to be permanently illuminated. Does this
suggest faulty sensors? I imagine it would be a coincidence for both to
fail at the same time, especially as they appear to be on separate cables.
Could a fault elsewhere cause 2 out of 3 not to work?

Any advice welcome

Ask for her installation/instruction manual.
Somewhere in this you should find instructions on performing a "walk test".
This allows you to put the control panel into a mode whereby it bleeps or
buzzes each time it detects movement in a particular zone.
This will be as good a test as any of the passives.
Also in the instructions there will be details on how to omit zones.
If you find a particular passive faulty on the walk test, try omitting it
when setting the alarm and see if the false detections still occur.

HTH

Phil



Thanks. This is 20+ years old and activated with a key, so I doubt if
there's a walk test mode. Of course the manual is missing, and there's
nothing to indicate a manufacturer's name on the case.
Time for a new system maybe

On Mar 10, 5:06*pm, Stuart Noble
wrote:
TheScullster wrote:
"Stuart Noble" wrote

My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your hand
at it, but the other 2 now seem to be permanently illuminated. Does this
suggest faulty sensors? I imagine it would be a coincidence for both to
fail at the same time, especially as they appear to be on separate cables.
Could a fault elsewhere cause 2 out of 3 not to work?

Any advice welcome

Ask for her installation/instruction manual.
Somewhere in this you should find instructions on performing a "walk test".
This allows you to put the control panel into a mode whereby it bleeps or
buzzes each time it detects movement in a particular zone.
This will be as good a test as any of the passives.
Also in the instructions there will be details on how to omit zones.
If you find a particular passive faulty on the walk test, try omitting it
when setting the alarm and see if the false detections still occur.

HTH

Phil

Thanks. This is 20+ years old and activated with a key, so I doubt if
there's a walk test mode. Of course the manual is missing, and there's
nothing to indicate a manufacturer's name on the case.
Time for a new system maybe- Hide quoted text -

- Show quoted text -

Assuming all the wiring is OK, you're probably right to replace the
whole system.
B&Q are doing a multizone wired system for about £70 which includes:
Multi-zone panel (4 zone I think)
Alarm Bell
3 PIR sensors
2 door sensors
and a roll of cable.

Don't know if they're any good !!!
Anyone tries them ?

ac1951 wrote:
On Mar 10, 5:06 pm, Stuart Noble
wrote:
TheScullster wrote:
"Stuart Noble" wrote
My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your hand
at it, but the other 2 now seem to be permanently illuminated. Does this
suggest faulty sensors? I imagine it would be a coincidence for both to
fail at the same time, especially as they appear to be on separate cables.
Could a fault elsewhere cause 2 out of 3 not to work?
Any advice welcome
Ask for her installation/instruction manual.
Somewhere in this you should find instructions on performing a "walk test".
This allows you to put the control panel into a mode whereby it bleeps or
buzzes each time it detects movement in a particular zone.
This will be as good a test as any of the passives.
Also in the instructions there will be details on how to omit zones.
If you find a particular passive faulty on the walk test, try omitting it
when setting the alarm and see if the false detections still occur.
HTH
Phil
Thanks. This is 20+ years old and activated with a key, so I doubt if
there's a walk test mode. Of course the manual is missing, and there's
nothing to indicate a manufacturer's name on the case.
Time for a new system maybe- Hide quoted text -

- Show quoted text -

Assuming all the wiring is OK, you're probably right to replace the
whole system.
B&Q are doing a multizone wired system for about £70 which includes:
Multi-zone panel (4 zone I think)
Alarm Bell
3 PIR sensors
2 door sensors
and a roll of cable.

Don't know if they're any good !!!
Anyone tries them ?

I think I might try replacing the box and the sensors and leaving the
bell and original wiring intact. Quite how one would stop the thing
going off if it has its own battery I'm not sure

Hi
Most of the old keyswitch panels did have a walk test but not as we know it
now.
The key has 3 positions OFF TEST/MUTE ON.
Turn it test or mute and the zone light will show if the zone is clear
(usually red above green below)
As for the pir's change them all 20yrs is a good innings for any device and
at the cost these days cheeper than going back in a week or so to change the
one that works when it fails.

HTH

CJ

Stuart Noble wrote:
My neighbour's burglar alarm has suddenly taken to going off at random.
She has 3 IR sensors, one of which goes on and off when you wave your
hand at it, but the other 2 now seem to be permanently illuminated. Does
this suggest faulty sensors? I imagine it would be a coincidence for
both to fail at the same time, especially as they appear to be on
separate cables. Could a fault elsewhere cause 2 out of 3 not to work?

Any advice welcome

She hasn't just had a new carpet fitted has she?

My fitters nailed through the wires. To add insult to injury,I called
out an alarm repair man so I could send them the bill, and he reckoned
it was just chance. It was only when I was fitting the new one that I
found the short. (so I paid him for nothing) And the VCR failed at the
same time - expensive carpet that one

Andy

Andy Champ wrote:
Stuart Noble wrote:
My neighbour's burglar alarm has suddenly taken to going off at
random. She has 3 IR sensors, one of which goes on and off when you
wave your hand at it, but the other 2 now seem to be permanently
illuminated. Does this suggest faulty sensors? I imagine it would be a
coincidence for both to fail at the same time, especially as they
appear to be on separate cables. Could a fault elsewhere cause 2 out
of 3 not to work?

Any advice welcome

She hasn't just had a new carpet fitted has she?

My fitters nailed through the wires. To add insult to injury,I called
out an alarm repair man so I could send them the bill, and he reckoned
it was just chance. It was only when I was fitting the new one that I
found the short. (so I paid him for nothing) And the VCR failed at the
same time - expensive carpet that one

Andy

I think she has had a carpet fitted recently as it happens. I'll look
into that

cj wrote:
Hi
Most of the old keyswitch panels did have a walk test but not as we know it
now.
The key has 3 positions OFF TEST/MUTE ON.

I'll check again but I don't recall a test position.

Turn it test or mute and the zone light will show if the zone is clear
(usually red above green below)
As for the pir's change them all 20yrs is a good innings for any device and
at the cost these days cheeper than going back in a week or so to change the
one that works when it fails.


Hell, she's not short of money. I'm going to tell her to get a new
system installed, especially as I'm the one crawling out of bed in the
middle of the night when she's away.