Re: Alarm Stays On
On Jun 7, 9:30 pm, cl...@xxxxxxxxxxxx wrote:
On Thu, 07 Jun 2012 17:53:49 -0400, frank1492 <frank1...@xxxxxxxxxxx>
Here's a weird one. I have an old Ademco hard-wired alarm panel which
has been running well since 1985. Recently it went into alarm
condition but would not shut off. (For a momentary opening of the
closed loop, it's supposed to shut off after 12 minutes.
The closed loop contains a Dual Tec PIR/microwave combo unit
which has a very low false alarm rate. When it false alarmed recently,
I forgave it, but the alarm stayed on so I assumed it was "latching"
due to some failure and not shutting off. I replaced it with a second
unit, and watched the LED's carefully. The new one was clearly working
On testing the system, I simulated an alarm condition and
watched the LEDs turn on and off, so I knew the OC was momentary. I
even checked the output with a meter. The alarm did not turn off after
I then did a manual open and reclose of the loop with the Dual
Tec out of the circuit. The alarm cut off after 12 minutes.
What is going on here? The Ademco recognizes the opening of the
loop but does not recognize the closing, but *only* when the closing
is done by the Dual Tec and not manually.
Ideas? I'd say the relay on the DT is not re-closing properly
but the other unit apparently did the same thing. The panel must think
it sees something other than a closed loop!
A real hair tearer. (Thanks for help.)
P.S. The loop has a 2000 ohm terminating resistor.
Is it wired backwards, by chance? Removing the sensor and just
opening/closing the circuit makes the alarm work properly? Almost has
to be a sensoe related problem.- Hide quoted text -
- Show quoted text -
You think after 25 years it re-wired itself to be backwards?
For the OP, it might be time to consider a new
system. Anything electronic that is approaching 30
years of service is bound to have issues. Just simple
things like electolytic caps for example. Another
problem with a system of that vintage is that it's
probably going to be impossible to program if you
want to change anything, even
if you have the codes. My old one of that vintage
was programmed by blowing PROMS to set the
thing up. You can get a whole new panel kit for
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