I have a Scantronic series 9100 (c1986) alarm and one of the original Racal-Guardall PIRs (Scorpio model) appears to have developed a fault and intermittently triggers the alarm. It seems that I may need to replace the affected PIR unit. I assume that this can be easily done with a similar
12v model (e.g. from Wickes) but how do I do this without disabling the system when I replace the unit which has an anti-tamper device? I have the installation manual but this is remarkably unhelpful because it assumes familiarity with the intricacies of alarm systems! Any advice would be much appreciated.

Rob, June 2007

Any 12v PIR sensor will do the trick, if you don't know the engineers code which is 0 enter and then a four or six digit number you can just change the PIR anyway and when the alarm goes into tamper put your code in to shut it up, when you have fitted the new sensor put in your code to reset the system and all is back to normal.

Jez, August 2007