do you part set the system at night ?do you have the engineering code?if the answer to these questions is yes,heres what to do,key in the engineering code,all the lights should flash,now key in 35 then press enter,(the tick bottom right button)key in 1 enter,then key in 99 enter,all lights will stop flashing ,then you will be back in day mode,what you have just done is switch off the setting tone on part set,(silent set )
gts, January 2013