Electronic Alarms and Home Security Devices - Window Bug Circuit Test

I have an older Ademco system with 20 Window Bugs on one zone for perimeter protection. The circuit is shorting out which probably indicates one of the 20+ year old Window Bugs (WB) is failing.

The wiring does not allow me to easily test the WB’s at the alarm box or where they are all connected in series in the basement. Groups of windows were tied in series behind the window moulding, and then a single wire run to the basement to tie into the rest of the window groups (approx 8).

Question #1: Is there some way to test individual WB’s at the window that does not include cutting and re-splicing the wires?

Question #2: I would like to put all of the junction wires in the basement on to some sort of buss bar setup that would allow easier testing in the future. Right now it is a tangle of wires & tape. Are there some sort of buss bars that are designed to link a series of wires and is there any to illuminate each circuit to easily see which has shorted?

All guidance greatly appreciated.

The truth of the matter is that 20 of these on a single alarm zone is actually a _lot_. I'm surprised you have had as few problems as you have. Each window bug adds to the resistance of the circuit and pushes it closer to the alarm trigger point. Most systems will only tolerate 8-10 on a single loop.

That said: The way I usually test window bugs is to turn on the chime function on the system then sharply rap the window frame next to the device using the handle of a screwdriver. It the shock sensor is working correctly, you should hear a chime. It may take a couple of shots to get a feel for how hard to rap.

When I use terminal strips I favor this style:

connex-electronics.com online industrial distribution. (http://www.connex-electronics.com/?url=/html/products/prodtermblockpower.html)

You can usually find them at places like Radio Shack (at least those that still have component drawers)

are these the round ones, wire exiting the side with a screw in the middle???

if so- there is not much to them- 20 years ago, it was the cat's ass vers foil.

to set them properly, you need to turn them until the zone is cleared- clockwise... etc.

1 or more may have rotated over time- cleaning windows... etc.


they contained mercury- not used today.


had a glass bulb containing the mercury in them, any sudden rap would cause the mercury to make or break the circuit, causing an alarm

if the window was tilted or glass broken- it too would cause an alarm

how old is the panel? you may not have such a chime feature

Thanks-

- I do not have a chime feature on the alarm.

- Have purchased the necessary terminal strips from RS, but hoping to not have to tear it all apart for one bad WB.

- My system requires a 600 ohm (Ademco #600) End Of Line resistor at the end of the wiring run before it attaches to the zone 1 control box post. Maybe that allows a greater number of WB’s in the circuit?

- Since the system is presently shorted (circuit open), tapping or otherwise trying to trigger can’t work- it is already in the alarm state. Need to find a way to close the circuit on the offending bug. Am trying to turn the WB’s to less sensitivity, one at a time, to see if that has any effect- none so far.

- Believe that 7:00 wire position is for greatest sensitivity. (Current model also at max sensitivity at 11:00) Do not know what position will provide the least sensitivity. Suggestions?

- Have not been able to find working drawings for the older WB’s that would show the position / shape of the “glass bulb”. Any leads?

-Is there any sort of meter or inductive reader that can test at the window without cutting the wires?

Thank you so much.

That's not a short circuit, that's an open circuit; both very different electrical concepts. The resistor is in the loop because the system is designed to look for that resistance on it's protection loops. It has nothing to do with how many devices may be on the loop.

What model is the alarm system? This is a lot easier when we know what commands and features you have to work with.

Alarms nearly always use a normally closed loop. Each window bug should test as closed switch/very low resistance. If you have easy access to the connections where the window bugs are wired into the alarm loop, all you have to do is test for an open device with your continuity tester (a cheap multimeter will work), but you have to disconnect it from the loop.

The low tech trick is to simply jumper each pair of wires at the device, one by one, until your zone closes. The last one you jumper that closes the loop is your bad shock sensor.

Sorry for the “short” vs “open” terminology.

System is Ademco #1023.

My problem is that there is no easy access to the WB circuits. All 20+ are connected in series behind window moldings in various locations, with just the two leads for the completed series of 20+ available at the control station.

To test at the individual devices with jumpers, the only way I see (plan Z) is to start cutting every WB wire lead, one at a time, and test until I find the bad / open device.

I am searching for a solution that avoids cutting most of the device leads. Something like an inductive tester?

THANK YOU

Sorry, for this type of configuration, there is no special gadget for the job. Since they all home run, the best you can do is identify the open pair at the head end, cut it loose from the loop there, use a wire tracer to determine the specific window.

That's as good as it gets.

Appreciate the follow up. Not good news, but at least now I can stop the research and get down to cutting wires with no second guesses.

Thanks,
Bob