Thanks to all of you who kindly offered suggestions to my 'tr' problem, it got me fluxed for a while too as it didnt seem to have any logical explanation, the panel battery was only renewed 2 yrs ago and i had checked the charging volts across that which was fine , also the volts going down the 12 v line to the bell unit was infact 12 v so that was fine too, but the random triggering of the alarm continued at all hours of the day and night.

I had a lucky break 3 days ago when the problem happened again but this time it wouldnt clear down so i grabbed the opportunity to check out the fault and it turned out that the 12 v supply going to the bell was only showing about 5v when measured at the bell, the bell pcb wasnt faulty as even when the 12v supply core was isolated it still only had 5v on it, so the cable was obviously going high resistance at random times causing the volt drop in the line.The cable from panel to bell hasnt been disturbed in any way and each time the tr fault was cleared down at the panel i was measuring the volts at the bell but it always showed 12 v again so it was very intermittent, but i'm glad to report that i've swapped over this supply core with a spare core and that has cleared the fault completely.

There doesnt seem to be any apparent damage to the cable so i guess that particular core in the cable has gone high resistance simply due to ageing, all the other cores seem to measure fine at the moment.I had measured the resistance on this core before but it hadnt shown any reason to suspect it.!!!

Hope this helps someone out in the same predicament.Looks like i had the same problem as Nikko. thanks for all the tips guys.

Thanks to all of you who kindly offered suggestions to my 'tr' problem, it got me fluxed for a while too as it didnt seem to have any logical explanation, the panel battery was only renewed 2 yrs ago and i had checked the charging volts across that which was fine , also the volts going down the 12 v line to the bell unit was infact 12 v so that was fine too, but the random triggering of the alarm continued at all hours of the day and night.

your charging volts being 12VDC is not ok at all. should be higher.

I had a lucky break 3 days ago when the problem happened again but this time it wouldnt clear down so i grabbed the opportunity to check out the fault and it turned out that the 12 v supply going to the bell was only showing about 5v when measured at the bell, the bell pcb wasnt faulty as even when the 12v supply core was isolated it still only had 5v on it, so the cable was obviously going high resistance at random times causing the volt drop in the line.The cable from panel to bell hasnt been disturbed in any way and each time the tr fault was cleared down at the panel i was measuring the volts at the bell but it always showed 12 v again so it was very intermittent, but i'm glad to report that i've swapped over this supply core with a spare core and that has cleared the fault completely.

There doesnt seem to be any apparent damage to the cable so i guess that particular core in the cable has gone high resistance simply due to ageing, all the other cores seem to measure fine at the moment.I had measured the resistance on this core before but it hadnt shown any reason to suspect it.!!!

Hope this helps someone out in the same predicament.Looks like i had the same problem as Nikko. thanks for all the tips guys.

one core being high res can ofcourse be due to almost anything and necessarily doesn't effect other cores but you never know..

dont be kidded by your 5v reading the fault could be on either of the supply cores and if one core is down they will all be down soon enough

best to rewire the sounder now than later however having said that undamaged faulty cable is very rare ( never seen it in twenty years) and if you are 100% sure the cable isnt damaged i still think the fault is more likely to be the sounder if this was a customer install i would be changing all three parts of the sounder system - bell,cable and battery