accenta optima g3 entry no longer works - any ideas?

[chizsarnie]

Hi - Ive got an accenta optima g3 system which I'm tying to fix:

One day the door sensor stopped working (cant be used to set the alarm, and no longer worked when tested in 'chime' mode). I've tried a few things but cant work out how to fix it. Does anyone have any ideas?

Although the old door sensor seemed to be doing stuff (the voltage drops from 4.2v to 0v when the door was closed), I replaced it anyway as I wasn't too sure what the voltage was supposed to do, but it didn't change anything

The new sensor behaves in the same way as the old. I checked the voltage at the alarm box end and the voltages are the same there, so it doesn't seem to be a cable problem.

The rest of the system works fine.... Should I reset the whole thing (I dont have the engineer code) and try and reprogram it in case the program is corrupted?

Any ideas?
Many thanks..

 

[scott1980]

Cable resistance? Shorting to tamper circuit? Shorting to earth? Panel connections? Is the zone showing open or closed?

 

[saxondale]

what voltage ?

 

[chizsarnie]

what voltage ?

It's the voltage across the sensor, measured either at the sensor itself or at the alarm main cuircuit. Is 4.1-4.2v normal or is that perhaps indication of earth short?
Doesn't look like the tamper circuits are connected (only 2 wires go to the door), but I'll check that again. The zone seems to think the door is closed, which means 0v
Thanks

 

[saxondale]

what voltage ?

It's the voltage across the sensor, measured either at the sensor itself or at the alarm main cuircuit. Is 4.1-4.2v normal or is that perhaps indication of earth short?
Doesn't look like the tamper circuits are connected (only 2 wires go to the door), but I'll check that again. The zone seems to think the door is closed, which means 0v
Thanks

forget the voltage readings - there not real voltages, use your meter on resistance with the cable disconnected from the control unit , 0 ohms ( except it never is really 0 ) is closed