Alarm tamper return

[AlanC]

Hi,

Our alarm system has just started playing up. Typical, just a few days before we are due to go away on holiday.

Its a Scantronic 9800 and it just went off reporting 'tr' which is tamper return. After digging around for about half an hour, I managed to find the instructions. I have the user guide and the installation instructions as I fitted it myself quite a few years ago. There isnt much info on the tamper return, but from what I can remember its just the switch in the bell box housing. When the switch is closed, its returning 0v when its open it returns +v. As a temporary measure, I have disconnected the return wire from the bell box that goes onto the tr terminal and put in a piece of cable that loops from the 0v terminal into the tamper return terminal (all in the control panel). I have done a quick test and it appears to be functioning OK. Is this the correct thing to do ? or will it have some side effect?

Thanks

Alan

[Sparks]

It will stop the alarm going into tamper for this circuit, but the side effect is, if someone opens the bell box cover to disable it, then, your alarm panel won't know about it, so won't activate.

Sparks...

[Sparks]

..I forgot to say, when the switch is closed (Bell cover on), the 0v and the TR terminals are connected together, but when the switch is open (bell cover off) the TR is not connected to anything, it doesn't apply a voltage to the TR terminal (this is so it can detect a cut wire too)

[AlanC]

Oh, OK. I thought I checked the voltage across the 0v and TR connectors and it read something. I could have been wrong.

I'm not too worried about the tamper circuit not working at the moment as the bell box is very high up and we have very nosey neighbours ;-) I just wanted to make sure it wasnt going to cause any other problems especially as we are going to be away. I dont want the system going off all the time while we are away.

Thanks

Alan

[Sparks]

Not wrong, it will :-) current is flowing from TR to 0v when this current flow stops (the switch opening when the cover is removed, or the wires being cut) the alarm panel "sees" this, and takes the appropriate action. so putting you meter between the disconnected terminals 0v and TR will show about 12v.

If the +12v or the 0v from the panel to the external sounder is cut, then the external sounder should sound (powered by it's internal battery) for 20 minutes or less.

So you can loop the 0v and the TR together at the panel, but make sure you leave the 0v connected to the sounder, or it will (should) go off.

If the problem is the tamper switch in the bell box, or the TR wire, then this will be fine, if the 0v wire from the panel to the sounder is faulty, then this will (should) cause the external sounder to activate when it goes open circuit.

If the battery in the external sounder is dead, disconnected or non-existent, then random blasts from the external sounder won't be a problem. However, if the alarm were to activate for other reasons (intruder) then your external sounder may not sound if the 0v wire is faulty.

Sparks...