The electrical supply to the Sony unit was interrupted --i.e. by clicking off the circuit breaker at the mains --for about an hour while the 2 gang outlet was swapped for a Screwfix Converta 3 outlet unit. When the electrical supply was put back on --nb I'm afraid I omitted to either press the power switch to "off" on the Sony unit, or to pull out the plug from the wall socket-- the unit is completely "dead" 'though the new Converta sockets work perfectly with a table light/fan heater etc. Has an electrical surge affected a component, OR as this Sony system has been left plugged in for many years undisturbed, is it likely that what Sony describe in the manual as the backup battery for the clock,timer ,preset stations etc at long last failed?