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FAULT DIAGNOSIS when 12V short occurs
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 Posted: Tuesday Nov 14th, 2006 09:28 pm
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Odd this but over the past cople of weeks we have had had several short circuits in various installations. In all situations we have isolated the short and the system has subsequently been OK. However there have been some odd symptoms ..

We have had one system giving low battery after changing the battery the same fault started to occur a couple of days later.

In all cases the system appears to dial out with security off messages (not related to te other posting). Is there any way of identifying and sensibly reporting a short curciut on the 12V.

If not is there a sequence of events that clearly defines a short (other than the obvious physical testing of the system).



 Posted: Wednesday Nov 15th, 2006 12:06 pm
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A short circuit on the 12V will cause the resettable fuse to open up and protect the Comfort circuitry. You will find the fuse (yellow looks like a capacitor) hot to the touch. When the short is removed, the fuse recovers and everything is back to normal
This allows Comfort to continue functioning even with the short, rather than shutting down the voltage regulator and the whole system



 Posted: Wednesday Nov 15th, 2006 02:15 pm
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Yes but in the process Comfort exhibits ODD behaviour along the lines of dialout with security off or announcing zones that have not been activated etc.

So is there a way of determening when this happens and reporting it?

 



 Posted: Thursday Nov 16th, 2006 09:07 am
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For dial-out with security off, bear in mind that Comfort always announces the most recent "alarm", not necessarily the alarm that started the dial-out
Comfort "Alarms" consist of all the 31 alarm types like System Disarmed, System Armed, New message etc which are not normally considered Alarms

Hence if there was an Intruder Alarm, which caused the dial-out, and by the time you answered the cal, the user disarmed the system, you would first hear the prevailing or current alarm. "Security Alarm" and not the historical alarm which caused the dialout. Once you sign in, Comfort announces the Alarm History which starrts from when Comfort was last armed, and will include all events causing the alarm and subsequent disarm/unset




 Posted: Thursday Nov 23rd, 2006 01:25 pm
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OK thanks

BUT  back to the original question - is it possible to have a report when the 12V gets shorted?

 



 Posted: Thursday Nov 23rd, 2006 01:32 pm
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It is not possible for Comfort to know this with the present design



 Posted: Thursday Nov 23rd, 2006 01:46 pm
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Would it be possible (I know it would but at what cost) to develop a PCB that could do the same - so this would sit in the 12v line and have a VF output to a comfort input!

 

 



 Posted: Saturday Nov 25th, 2006 04:53 am
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It is possible to design such a board which monitors the 12V line and gives a contact to one of the zones which you can program as an alarm
How useful would this be? Is the 12V short a significant enough problem to require this type of solution



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