Set Appliance State:
Set Multimeter to AC Volts 
Isolate Mains Power to appliance as per TOPs P4
Ensure the boiler is cool so that there is demand for preheat
Remove rear cover of control panel to expose main PCB
Ensure the boiler is cool so that there is demand for preheat
Remove rear cover of control panel to expose main PCB
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Mains reset switch ON.
Measure voltage across the blue and brown connections on connector marked H3 on the main PCB.
Mains voltage expected.
Measure voltage across the blue and brown connections on connector marked H3 on the main PCB.
Mains voltage expected.
Isolate as per TOPs P4
and refit as necessary