Thanks for your replies
I turned off the mains power, opened the alarm casing, disconnected the internal battery,reconnected the internal battery (alarm then started ). I then put my normal code in to cancel it, replaced the cover, and everything seems to work OK
Incidentally, the system has never been wired up to use a PA so maybe it was a fault with the main board
Think I'll get a new internal battery as suggested just in case
beegee
January 2010