Set Appliance State:
Mains Power Off
Set Multimeter to AC Volts 
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage across Brown lead (live)
and the Blue lead (neutral) on connector
marked X24 on the control PCB.
Fine probes should be used.
Expected voltage 24 Volts AC.
and the Blue lead (neutral) on connector
marked X24 on the control PCB.
Fine probes should be used.
Expected voltage 24 Volts AC.
Isolate as per TOPs P4
and refit as necessary