Set Appliance State:

Set Multimeter to AC Voltage Set meter to measure AC Volts
Isolate Mains Power to appliance as per TOPs P4
Gain access to PCB (use insulation mat as necessary)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure approximately 24V AC across connector CN1 on the Main Control PCB connections 6 (Black wire) and 7 (Red wire).