Alarm Stays On

[frank1492]

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 properly. 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

12 minutes!!!!! 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.

[frank1492]

I should mention that without alarm condition, when the alarm is first set, the loop with the Dual Tec indicates that the loop is properly closed.

[G. Morgan]

Each time the sensor is tripped, a new alarm is generated - thus adding another 12 minutes. You probably have a Vista-10 or 4110XM both have an adjustable siren time-out. It also has a "runaway" feature so a faulty sensor with not alarm after "x" amount of triggers.

All this is done via the installer's level of programming. If your system is monitored, you should not attempt to program it or you may mess up something important. If you give me the exact model number (on the circuit board label) I'll shoot you an installer's manual. Hopefully the panel is not 'locked', so only the alarmco can access it. Most are not locked.

Also, you will need a 6160 or 6139 alpha keypad to see what you're doing while programming. Hopefully you already have one in the system, rather than the cheaper fixed-English display.

[clare]

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.

[frank1492]

Those must be much newer units. There is nothing digital in this one.' Ademco 1023-12 2/85..

[Evan]

Yeah, so its not like old age could be a part of it ?

Did you check the end-of-line resistor to see if it is still 2K ohms ?

[frank1492]

I am thinking I activated the Dual Tec then went outside to wait for the alarm to stop. It is possible that the DT kept reactivating (like its predecessor did) due to something that it actually sensed. I think I need to keep my eye on the LEDs during the initial alarm condition. Are you familiar with these combo PIR/microwave units. Anything you can think of that might cause repeated activations? Something in the house wiring, or outside the house or a reflection? The unit sits on a running refrigerator next to a microwave oven. The oven is off but plugged in. If this sounds suspicious, bear in mind that this never happened before since these were installed. the location was never changed. I'll unplug both the fridge and the microwave and try again, while watching the LEDs. Any PIRs that you like, minus the microwave?

[The Daring Dufas]

Mr Morgan knows his alarm systems, he does it for a living and I installed and serviced a lot of security systems back in the 80's. Most alarm systems are a hybrid of digital and analog electronics and the older systems have a higher parts count which can create more failure points making them less reliable. ^_^

TDD

[The Daring Dufas]

Evan is on to something but I would suspect that an electrolytic capacitor in the circuitry is out of spec due to age and repeated voltage spikes over the years can cause other parts to fail because the tiny damages add up over the years resulting in an eventual malfunction. If any of the electrolytic capacitors are swollen or leaking, that would be the place to look. ^_^

TDD

[frank1492]

Please remember that opening the loop momentarily without the DT in place caused the panel to perform normally. (Will attempt to replicate that several times.)

[trader4]

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 $150.

[clare]

Being obtuse again, eh?? The unit was replaced. Always possible the first one was defective and the new one reversed, no??

Stranger things have happened. Smartass.

By his description and basic analysis it would APPEAR to be a sensor related problem - either function or installation, or interference.

[G. Morgan]

Oh man... That is a dinosaur. You need a new panel and keypad(s).

There are no programmable anti-false alarm features in that one. No way to adjust response time for 'jigglers', or cross-zoning, or pulse count.

I would recommend another Ademco (Honeywell) panel, Vista-15P or

20P. You can get the best deals on eBay. Make sure at least one keypad is a 6160 alpha display. If you plan on adding wireless sensors get a 6160RF keypad, it acts as a transceiver as well as a keypad.

[G. Morgan]

Remember, microwaves will penetrate walls. If the sensor's PIR part is near a vent it may be the combination of heat change + something moving that the microwave (radar basically) detects. Any floating Mylar balloons, any moving apparatus at all in the detection area?

Have you tried to adjust the pulse count on the detector? Have you tried turning the trim-pot down on the microwave field that is emitted? Have you read the cut-sheet inside and out and understand how a dual-tech works?

Sure, but a dual-tech is nice for f/a reduction.

Do you have pets that may be setting it off?

The Honeywell Aurora series is a fine brand.

[G. Morgan]

The sensor was replaced, not the control panel. That is what needs to be upgraded.

Over 30 years, that thing has served it's purpose and was obsolete

20 years ago!

[clare]

Hey, I'm not saying NOT to check the resistors - but it APPEARS it is only the one sensor causing a problem, and if the sensor is removed from the circuit and a switch substituted, the system works as it is supposed to. This would lead ME to suspect it is an issue with the sensor.

Now,I don't pretend to know it all. However, many times, particularly with older tech solid state devices, reverse connections can have strange results, and unlike a simple switch type "sensor" like a door or window sensor, the microwave and PIR units ARE polarity sensitive.

ALSO

On any Honeywell Dual Tec I've seen there is a separate 7-16 (usually

12) volt power supply which is polarity sensitive, as well as the alarm contacts - which have 4 different programmable resistor values across the NC contacts if connected C to NC. and another 4 resistors across the NC tamper switch connections. On some you can connect C to EOL - I don't know what the rammifications would be if connected C to EOL.

Being Normally Closed contacts, if there is more than one sensor or switch on the loop, they are wired in series, with the EOL resistor across the terminals at the panel (generally) so with the whole string closed the resistance across the circuit is nominally ZERO ohms, and as soon as any contact is opened the panel sees the EOL resistance (in the OP's case, 2.2K ohms. If the sensor is installed jumpered to 2.2K ohms, the panel will see 4.4 k ohms with the sensor tripped - and the panel could "fault".

If he is using an external EOL resistor he needs to remove all of the jumpers.

If he has not removed the jumpers, it would very likely malfunction with the sensor connected, and work fine with it removed and replaced with a switch or jumper.

You can look for zebras and unicorns all day, but when you hear hoofbeats, it's much smarter to look for horses, ponies, or jack-asses first.

[G. Morgan]

LMFAO -- I don't think you have ever seen one based on this explanation of alarm system workings.

x-posted to ASA for a good laugh.

[clare]

I was not talking about the control panel - which appears to be working just fine, according to the OP's testing. Not saying replacing it might not be a good idea - but I doubt (not saying I know it definitely is not) it is the panel at fault.

My thought right now is that he has possibly not removed the jumpers on the integrated EOL resister pack on the new SENSOR.

That "dynosaur" panel is pretty simple, and pretty reliable. If the resistance is other than 2.2K ohms or zero (within tolerances) the panel "faults" and if the resistance is 2.2 K it alarms, and if it is zero it says "all's well". Basically a voltage devider circuit with a couple of comparators. If the resistance is too high, the voltage across the "reference" resistor goes too low. If the resistance of the string is too low, the voltage across the "reference" resistor goes high. Either condition trips the comparator If he has ANY jumpers installed the resistance will not be 2.2 K when the contacts open. And with the sensor removed and jumpered, the system will work just fine - as his does.

I believe I made one error on my last post. I believe I said if he had the sensor jumpered to 2.2K the panel would see 4.4K ohms with the contacts open. In this setup, it would see 1.1K ohms with the contact opened, because the resistors would be in PARALLEL, not series.

[G. Morgan]

Bwahahahahaha!!!

Why did you remove my x-post?

[clare]

I've installed a few. Some over 30 years ago, The last ones about 15 years ago - wired and wireless - and I've worked on one of the new ones within the last 2 years - a whole lot more complex - a whole computer packed into the box, with complex programming up the ying yang. Other than moving the control panel (keypad) and a few sensors, I said "get the alarm company - it'll be cheaper than paying my time to figure out how to program it".

There's more than just open and closed switches and resistors in the new digital jobs. The old analog or "2 bit digital" systems WERE simple. The 30 year old ones were a lot simpler than the 15 year old ones - which were not "leading edge" at the time.

But (at least most of) the sensors from the 30 year old system still work on the new systems, and many of the new sensors work on the 30 year old ones as well.