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Author Topic: DS10A False Positives  (Read 10349 times)

jpeckiii

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DS10A False Positives
« on: March 07, 2009, 02:11:25 AM »

Hi all,
Have recently developed a problem on my DS7000 system with a DS10A randomly and frequently reporting false positives to the system. The DS10A is on a back door, and has been working fine for nearly a year other than battery replacement needed. I had an issue with a false positive setting off an alarm at night, but replacing batteries seemed to fix the problem for several months. Now it is sending false positives all the time randomly. I can watch the sensor do it and it is flashing a open zone. I have tried wiggling the sensor contacts back around and even moving the door some and that doesen't set it off. In fact have to open the door a good inch or so of separation before triggering occurs. That means its not wind related or anything like that. I have watched it trigger, and there was absolutley no movement of the contacts. Also have tried jiggling the leads on the contacts and sensor with no trigger occuring. Is there something else to try short of replacing the sensor? If I do replace the sensor, my understanding is to wait four hours until a trouble code appears, move to install mode, and the system will place the new sensor into the troubled zone without having to do a full reinstall. Is this correct?

Also have always had a strange issue with the DS7000 interfering with hardwired X10 dimmer switches. When I have the DS7000 on the same house code as these dimmers, they do not respond to X10 signals. They will still work fine as a regular light switch. When I change the house code on the DS7000 to B instead of A the dimmers work great. Any insight into this problem? Since I have to keep the DS7000 on a separate house code, it won't flash all of my lights like it is supposed to. This has occured in several different apartments and houses I have set the system up in through the years.

Thanks in advance!
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BVD

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Re: DS10A False Positives
« Reply #1 on: March 07, 2009, 10:58:44 AM »

Hi Jpeckiii,
A quote from your message and a question.
Now it is sending false positives all the time randomly. I can watch the sensor do it and it is flashing a open zone.

Where are you watching the sensor do it? On the DS700 or in a activity monitor. Are you using AHP software?
There are two possibilities 1. The DS10 is bad or has a loose connection on the RF circuit board possibly a clod solder joint. Do you have radical temperature changes when this problem occurs most frequently? 2. The DS7000 is possibly picking up stray noise (RF) of some kind and setting it off its self without ever getting a signal from the DS10A.

I will be awaiting your reply and try to help you more.
Till Later,
Bob
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jpeckiii

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Re: DS10A False Positives
« Reply #2 on: March 07, 2009, 12:41:37 PM »

I have witnessed this from both ends. Obviously I have the chime on the system so I hear it whenever it triggers, but have also been standing right by the sensor and seen it actually trigger with the flashing light on the sensor. So the sensor is definately sending the signals, its not stray signals. I suppose it could be cold solder problems. This sensor is in an unheated garage, and yes, I suppose the activity does coincide with a recent warm front that has come through where the temps are now in the 80's instead of the 40's. I suppose this would also line up with another sensor on a window where it stopped registering the contacts for awhile (but would still send a signal with the test button), but when I slightly squeezed the body of the unit it started working normally again. I wonder if I have gotten a few out of a bad batch?

I do have AHP software. Got so frustrated with it I gave up for awhile, because it keeps crashing and had major reception issues. It would never read or register this particular sensor, the very one I'm having problems with although the DS7000 gets the signal twice the distance away. I suppose the long metal antenna helps versus the little plastic one. So I don't have an activity log. I know this would be helpful in diagnosing the time the problem occurs.
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BVD

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Re: DS10A False Positives
« Reply #3 on: March 08, 2009, 08:28:55 PM »

Hi jpeckiii,
If it would be possible for you to give me a call I would like to discuss this problem a little further. My number is 740-862-2616 Baltimore, Ohio. Hope to hear from you. If this is long distance for you, email me you number at w8rvd@columbus.rr.com as I can call anywhere in the US & Canada.

Till Later,
Bob
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Jsnlong

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Re: DS10A False Positives
« Reply #4 on: March 08, 2009, 09:07:12 PM »

Have you started using cheaper battries?  Or maybe the cold is effecting it? When you said 80's to 40's is that a day time temp or is it getting colder then that at night.


Anyone know what the operating Temp of a DS10 is?


Jpeckiii.... Your right on the ds7000 having better RF range. The cm15a with Active home Pro Rf ranges sucks. but there are alot post on here to improve it with Antenna mods.
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jpeckiii

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Re: DS10A False Positives
« Reply #5 on: March 09, 2009, 12:24:54 AM »

Thanks for the info everyone. Jsnlong... I do use cheap batteries, but I've been using them pretty much all along. Yes, the temps I gave are daytime highs. It is getting much colder at night. The trend overall is warmer temps though. The problem seems to have surfaced during the warmer temps. We just got a little bit of a cold front and the problem has nearly disappeared for the time being. I don't think the issue is operating temps, because it has worked fine on this door for over a year in near freezing to well over 90. I also mentioned the one other problem sensor that is indoors in the heated space. It showed the problem of the contacts not seeming to be connected to the sensor last night in that it did not respond to the window being opened or closed, but tonight it began working again with no problem when I opened the window. This is a little confusing, because I was under the impression that these normally closed sensors would transmit an open status if there was a problem with the wiring from the contacts to the sensor, but in this case, it just transmits a closed status even though it does not register contacts opening and closing. It will even return to a closed status if you press the test button. That means you could have a contact failure and not know it had occured, unless you happened to open that particular window. It seems that the sensor does not monitor whether the contacts are closed on a constant basis, but only registers a change in state. I guess the other possibility is the problem is not in the sensor body itself as in a solder connection on the circuit board, but might be in the contact end. Is there some malfuntion of the contact itself that could make it tell the sensor it is closed when in fact it isn't?
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spam4us

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Re: DS10A False Positives
« Reply #6 on: March 09, 2009, 12:43:19 AM »

     Had the same problem on 3 ds10a's mounted at 3 different locations.  What finally solved it for me was to take the batteries out; stretch the little springs that the battery makes contact with on the +/- side that hold the battery in place.  Haven't had a problem since.

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jpeckiii

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Re: DS10A False Positives
« Reply #7 on: March 10, 2009, 01:26:15 AM »

Just an update on the original sensor on the back door. The contacts have now totally failed just like the sensor on the inside window. The sensor still has power and will trasmit with the test button, but the contacts do not register the door opening or closing at all. Just like the indoor sensor, it transmits a closed status to the DS7000 console even though the contacts are apparently dead. Still don't know if the problem is the solder connections on the board inside the sensor or some malfuntion with the contact itself. I will do some exploratory surgery and post the results.
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BVD

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Re: DS10A False Positives
« Reply #8 on: March 10, 2009, 10:53:44 AM »

Hi Jpeckiii,
Here is something to try before surgery if you haven't started withe scalpel yet. Disconnect the two wires connected to the sensor momentarily and see if it triggers open. Then touch the two wires together manually and see if it triggers closed. If so the reed switch in that little device is bad. Replace that little reed switch enclosure with another one if you have one. That should let you keep the same security code as before as it is held in the window sensor box. Reed switches are delicate little devices and if you got that many years out of it before having problems you should count yourself very lucky. A reed switch is hermetically sealed device. Operation of this switch in the conditions you described could have broken the seal or cracked the glass on the switch. Depending on what the contact areas are plated with could oxidize and cause the switch to malfunction.

FYI I put an Ohm meter on the door/window sensors that I have and the contacts show open when the magnet is away from the switch and closed when the magnet is close to the switch. This would indicate that the reed switch is a normally open switch. Therefore if you are getting a constant closed reading the contacts are either welded closed, (very doubtful), or the switch is broken and the contacts are touching each other.

If it works with the test button, chances are that the transmitter is OK and all you have to replace is the little reed switch holder at the end of the wires.

Let me know if you try this and it works. I only worked with reed switches for about 15 years so I know very little about them......

Till Later,
Bob
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jpeckiii

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Re: DS10A False Positives
« Reply #9 on: March 27, 2009, 02:27:12 AM »

Ordered a bag of 10 normally closed contacts for less than $10 on ebay. Replaced the contacts on the back door sending the false positives as well as the window that was not registering being opened. Things are working great now. I noticed when I removed the old contact from the door that there was no back on the contact leaving it open to the air (I guess the actual reed switch was hermetically sealed, but had a yellowish appearance, possibly oxidation from the air?). Needless to say things are working perfectly now. The new contacts I bought are advertised to be hermetically sealed, and indeed the units are solid pieces of plastic unlike the ones from x10 that have backing that can be removed or come loose with any flexing etc. Also the backing seems to come off if they are stuck on the surface with double sided foam tape and you pull them off the surface (that stuff is REALLY sticky!) A bonus is the new contacts are about a 1/4 the thickness of the old contacts therefore are less noticeable/eye sore.

Now if I can just get any ideas on the dimmer switches not responding to commands while the DS7000 is on the same house code. Perhaps I should repost that as a seperate question?

Thanks for everyones help on this! No more false alarms in the middle of the night to scare the wife to death ;-)
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BVD

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Re: DS10A False Positives
« Reply #10 on: March 27, 2009, 10:42:16 AM »

Ordered a bag of 10 normally closed contacts for less than $10 on ebay. Replaced the contacts on the back door sending the false positives as well as the window that was not registering being opened. Things are working great now. I noticed when I removed the old contact from the door that there was no back on the contact leaving it open to the air (I guess the actual reed switch was hermetically sealed, but had a yellowish appearance, possibly oxidation from the air?). Needless to say things are working perfectly now. The new contacts I bought are advertised to be hermetically sealed, and indeed the units are solid pieces of plastic unlike the ones from x10 that have backing that can be removed or come loose with any flexing etc. Also the backing seems to come off if they are stuck on the surface with double sided foam tape and you pull them off the surface (that stuff is REALLY sticky!) A bonus is the new contacts are about a 1/4 the thickness of the old contacts therefore are less noticeable/eye sore.

Now if I can just get any ideas on the dimmer switches not responding to commands while the DS7000 is on the same house code. Perhaps I should repost that as a seperate question?

Thanks for everyones help on this! No more false alarms in the middle of the night to scare the wife to death ;-)

jpeckiii,
Glad to hear that corrected your problems.

Yes all reed switches are hermetically sealed and this refers to the seal between the reed leads and the glass. The reed switches I worked with I soldered into printed circuit boards. We had to use heat sinks on the leads to prevent the heat from the soldering damaging the switch (seal). The biggest problem with those switches is the metal in the leads and the glass expand and contract differently with temperature. Our application was a lot more critical than in this application. We actually had a special oven with reed switch clips on the boards that held 100 reed switches each that slid into the brackets in the oven. The switches were heated to 200 degrees and the contacts resistance was measured while hot. Then allowed to slowly cool to room temperature and the contact resistance was remeasured. If the resistance was off by more than 3% the switches were deemed unusable and thrown away. Needless to say we had a lot of bad ones. Oh by the way did I mention that these reed switches had gold plated leads and contacts?  You stated that the contacts  had a yellowish appearance, possibly oxidation from the air. Could have been gold plated contacts.

From your earlier message I would rather believe that the seal was broke and since your contacts are normally closed cold temperatures caused the contacts to contract just enough to show an open and trigger the alarm.

One question about your dimmer switches. Are you using a security remote with the remote arm/disarm units 1-4? Does those switches respond to that remote for ON/Off and Dimming?

Till Later,
Bob
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