SUNTHORNES!! (made in Aldershot I think) Yes, used to service loads of them in the late 80's and 90's.
I remember the BELL TEST button, which was really just a Normally Closed button that removed the power to the external sounder!
No bell timer, had to fit a seperate PCB inside panel to time the bell to 20 minutes.
The cybertone sounder drilled into the front of the panel which gave you three tones. A continuous whine when you tried to set the system with a zone in fault, a wheeee-wheeee-wheeee for setting and unsetting and a lower faster tone for alarm.
You couldn't set any of the zones (with exception of Exit/Entry zone) as "entry route", instead we fitted relays inside the panel which was connected into the E/E sounder to short out the relevant zones during Entry and Exit time.
The zone cards, each of which had a Green LED for "ON" (not isolated), Yellow for "Zone in alarm" and Red as a memory after an alarm activation.
The really old ones,the isolate button on the front panel used to toggle the Green LED off and on, but it was updated so that the Green LED would come back on when the keyswitch was turned back to off.
On the front was a keyswitch and a large piece of darkened plastic where you could see the LEDs of all the zone cards.
There was also an expansion board where you could fit loads of zone boards and have up to about 30 zones. There was one of these fitted in Jabro Cash and Carry in Luton (is it still there? this is about 20 years ago now!!) before it was updated to a 9500!
Wish I had a photo of the panel! (I don't know why, just memories I guess!)
Matt (not from Vidionics anymore like my username says)