| Posted: Wednesday Aug 15th, 2012 01:50 pm |
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ComfortGeek
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Hopefully someone can help!
I have 3 PA buttons wired with end of line resistors on one circuit. All works fine. You press the PA's, they go off as expected. You try take the cover off, the tamper alarm goes off as expected.
But then at random, the PA alarm just goes off on it's own!
I don't think it's the wiring as they normally work ok, I don't think it's a problem with the resistors for the same reason, the EOL setting for the zone is correct - so what could it be?
Coudl it simply by the reed switch in one of the PAs is dodgy and is opening the circuit perhaps as temperature changes? Could the 60 metres of wire be reducing the resistance?
Or am I being dumb and have missed something more fundametal?
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| Posted: Wednesday Aug 15th, 2012 02:01 pm |
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slychiu
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There should be 1 set of EOL resistors in the circuit and not for each contact
There may be resistance issues. Measure the voltage when the switches are open and Closed. The voltage will show how close to the threshold the open and close states are
It could also be a fault or intermittent switch
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| Posted: Thursday Aug 16th, 2012 09:21 am |
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ComfortGeek
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Thanks
I can confirm that only one set of EOL resistors (two resistors, 1 x 4.7k, 1 x 2.7k) is being used across the 3 PA contacts, as per the installation manual and as supplied with the comfort PCB.
I have changed the PA button I thought might be faulty, but the random alarm occured again at 3am! So this did not sort it.
Next I'll try measuring the voltage to see if resistance is an issue- can you let me know what I should be looking for? i.e. what is right and what is wrong? Do I measure at the comfort zone terminals or remotely at each PA?
Only other thing I can think of is 20cm of the alarm cable to one of the PAs runs along side a 240v lighting cable - I have no choice. I have used screened 8 core wire, so didn't think this would be a problem for a PA circuit? Could this be it?
Finally, just for info, all three PA's are wired back to the CPU where I have used a terminal block to connect the wires - so it is wired correctly, the wires simply all come back to the CPU rather than being a daisy chain. This makes the wires longer but cannot see how this could effect anything other than circuit resistance?
So, in summary, the issue could be due to either:
- a Fault on comfort PCB for that zonet - if so, how resolve?
- Wire being along side 240v cable - if so, how resolve?
- faulty resistors - I'll change them to rule this out
- circuit cable length too long - if so, not sure what to do as I don't want to use 3 zones for the PA circuits....
If I've missed any, would be good to get your view.
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| Posted: Thursday Aug 16th, 2012 12:40 pm |
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Vangelis
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A couple of thoughts...
Could try wiring the PA buttons into the Comfort 'case tamper' cct (not very eloquent I know) but will rule out a faulty onboard issue (guess you will need to remove the EOLs)
If you have spare Zones then wire the PA's into their individual zone - this will rule out the shielded cable running via the lighting cct and faulty unit and identify a failing units.
You could sacrifice another Zone temporarily to do this - especially if its going off at 3am!!!
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| Posted: Thursday Aug 16th, 2012 01:01 pm |
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ident
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closed 1.12V
open 1.87V
measured at terminal block
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| Posted: Thursday Aug 16th, 2012 01:04 pm |
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ComfortGeek
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Thanks - All good ideas, will give it all a go!
Would still be good to know what I should be looking for in terms of measuring the voltage / resistence in the circuit...
Thanks again - it's driving me (and the household) bonkers!
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| Posted: Friday Aug 17th, 2012 04:12 am |
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cleaner
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Set longer sensitivity of the zone type eg to 1 second so that short pulse do not trigger the alarm
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| Posted: Wednesday Aug 22nd, 2012 05:23 pm |
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ComfortGeek
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Ok - I have measured the circuit at the terminal block
When closed, it is 1.17v
When open, it is 1.9v
So, what does that mean? Comparing it to the numbers you said, sounds like it's right?
So, if it keeps false alarming and the circuit voltage is ok, what could it be?
Can a resistor be ok one minute then faulty the next?
or
could the voltage be effected becuase the alarm cable runs alongside a 240v cable for about 10cm?
or
Can comfort PCB for that zone intermitemtly be faulty?
Please help, it's driving me mad!
I'm thinking the only answer will be to do away with the resistors and just have a normal circuit and wire the tamper contacts in series with the alarm contacts - then the PA will go off if anyone tries to tamper with it
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| Posted: Thursday Aug 23rd, 2012 06:58 am |
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ident
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The voltages are correct which means that the resistors and wire resistance is not the problem
The 240V wires running close to the zone wires may be a problem
Have you increased the zone sensitivity to 1 second as suggested below
What zone sensitivity is being used now?
It is highly unlikely the Comfort Input is fault. To check, connect a short circuit with EOL resistors at the Inputs and see if there are any more false alarms.
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| Posted: Thursday Aug 23rd, 2012 09:48 am |
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ComfortGeek
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Thanks
Really stupid question. Sensitivity is currently 500. The drop down box to change the sensitivity goes up to 850 ms but can't see option for 1second.
So question is, how do I change sensitivity to one second?
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| Posted: Thursday Aug 23rd, 2012 11:07 am |
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ident
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Sorry I waS mistaken
850 ms is the maximum sensitivity. Try that instead of 500 ms
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| Posted: Thursday Aug 23rd, 2012 09:51 pm |
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ComfortGeek
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Ok, I've changed the sensitivity of the PA alarm type - when I change it to 50ms, if I tap the panic alarm button with a piece of plastic (doesn't conduct), it goes off every time I tap it.
When I change it to 850 ms and tap it, it will go off much less frequently - i really have to bang it.
I've changed the PA unit already, so can't see why it would be a fault with the unit / contact / reed switch....could tapping it effect the resistors somehow? ie they are vibrating? I know that sounds daft!
So basically I have identified that tapping a PA button with a non-conducting tool sets it off, less often when sensitivity is lower.
What could it be causing it? It could be the 240v lighting cable near it, it could be another faulty PA unit (but what are the chances)?
I'm going to leave it on tonight and see if it goes off at 3 am again!
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| Posted: Friday Aug 24th, 2012 02:20 am |
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ident
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Perhaps it could be a problem with the brand of PA buttons
Tapping on the button without activating it should not be causing it to activate
Increasing the sensitivity value should reduce the incidence of the false alarm according to what you have found
There is a way to increase the value further
There is an action found in Response Wizard in Inputs > Set Extended Sensitivity Count 1 to 5
This multiplies the sensitivity to a maximum 850 x 5
This response should be in the Zone Response
When you press the PA button you would expect it to be pressed for a few seconds
This should help reduce the false activation
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| Posted: Tuesday Oct 9th, 2012 07:33 pm |
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ComfortGeek
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Hi - I'm still having problem with this PA circuit.
I measured the resistance and it goes up and down randomly, so clearly this is the problem. But what is causing it?
Quick question - in the comfort installation manual, the 4.7k resistor is in parallel but looks like it is housed in the 1st detector - should both EOLs be in the last detector? could the resistor being in the 1st detector be the resistance problem?
As there is a 20m wire from each of the 3 PAs back to the panel where they are wired together using a terminal block (as per the multiple dectector wiring digram in the manual) I was wondering if the length of the totsl circuit and the reistor being in the 1st detector could be the problem?
My next step will be to loop out PA one by one until I find the issue and connect each loop to its own zone to find the issue.
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| Posted: Wednesday Oct 10th, 2012 02:08 am |
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slychiu
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The location of the series resistor should not be an issue, although the correct place is in the last detector.
Possible cause of resistance fluctuation may be induced voltages from a noise source
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