Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Gain access to PCB (use Insulation Mat as required)
Place PCB in test position, click HERE for guidance
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Measure for mains voltage across pin 9 of connector X3 and a suitable earth connection.
Expect mains voltage.