ADT zone fault

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  #1  
Old 07-15-06, 11:03 AM
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Question ADT zone fault

I recently replaced the backup battery in my unmonitored ADT hardwired home alarm system (1A910-50 is the label on the board within the control panel but I don't know if that is the relevant information to provide). After resetting the system, one of the zones now shows as being open and prevents the arming of the system. The system can be armed if the zone in question is bypassed. I've checked the sensors in the windows/doors in question but don't see any obvious problems. The zone in question worked fine prior to the battery replacement (the system was down for several days waiting for the battery to be shipped).

Any ideas as to the likely source of the problem? Any help/recommendations you can provide are greatly appreciated.

-CL
 
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Old 07-15-06, 01:11 PM
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If you are reading model numbers off of the keypad, the information is not really the whole story. The information that comes out of the main system box where the backup battery resides is the ideal. (not picking on you, but there have been a lot of posts with keypad models, lately, so I'm reenforcing the concept, right now)

That said, it sounds like you may have the the old (very old) Safewatch/Entrepreneur system, which is a modified Moose Z900 system.

Do you know what devices are on the zone in question? Since it's a single zone, it's very likely that it's either an aged set of contacts, a missing magnet, or simply a door/window that you didn't realize was part of the system.
 
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Old 07-16-06, 06:50 PM
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Smile ADT Zone Fault follow-up

Hi and thanks for the quick reply. The model number mentioned in the initial post was from the board inside the control panel and a further inspection just now revealed that it is indeed a Safewatch/Entrepreneur system. From a small sticker attached to one of the capacitors on that board, I gather the system was installed in Dec '93 so I would agree with your assessment of its age.

The zone in question has two windows and one door on it. I don't think there are any other protected units on this zone as we've used the system for some time and not found any other "beeping" units as we've opened other windows in the house. All the other doors are protected on other zones so I know it wouldn't be any of them. The three protected units also match the zone description posted inside the control box.

There are no missing magnets or sensors in any of the three locations but I suppose any of them could certainly be damaged. Based on this info, what would you recommend as a next step to work on? It occurs to me that I also never unplugged AC power on the control panel to reset it after replacing the battery. As all the other zones work as normal, I guess that doesn't likely matter but thought I would mention it inmm the event that you thought doing that might be useful.

Thanks again for all your help.

-CL
 
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Old 07-16-06, 08:54 PM
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The battery change was likely simple coincidence. You don't have to power down after a battery replacement.

If you have it narrowed to 3 contacts, start with the simple trick of giving each a sharp rap with the handle of a screwdriver, one by one, checking to see if the zone closes. They some times stick (test the door first if the windows are seldom opened). If that doesn't work, then you can try bridging the wires at each contact in turn.

If you have a multimeter, and all of the contacts are home run to the panel, you can jumper each pair there, and see if the zone closes. (sorry, this is one of those things that's harder to describe than to do)
 
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Old 07-17-06, 03:23 PM
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ADT Zone Fault follow-up

I gave the sharp rap idea a try on each of the sensors but didn't get any response. I don't have a multimeter but can get one at work and give that a try. I know it's a little tough to describe how I should evaluate the sensors for each window or door at the control panel but any additional description you can provide would be helpful as I don't do this very often.

Thanks again for your help.

-CL
 
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Old 07-17-06, 04:18 PM
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A lot depends on how your zones were hardwired. if they brought a pair of wires back from each opening to the system can, then the testing is pretty easy and you don't even need a meter to do it.

The three loops will be connected together in series. All you have to do is short across each pair of wires until your zone closes, then test the openings. The one that doesn't respond when opened is the bad one. The acid test is to short the wires at the contact end. If the zone closes, then bingo, there's your bad contact. If the zone doesn't close when the suspect contact is shorted around, but does when shorted at the head end, then you have an in wall wiring problem.

My bet is still on the door contact, especially if its one of the press fit types. Doors get cycled a lot, and the wood around one of those press in contacts sometimes swells in damper weather and crushes the contact.

Testing with a meter is a little more effecient. Disconnect one of the leads for that zone from the zone terminal. Then simply check each loop pair for continuity. When you find the open one, short the pair reconnect the zone input and test as above.

The process isn't difficult, but you do have to be logical, methodical and patient.
 
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