Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Gain access to PCB (use Insulation Mat as required)
Remove 4 wire connector from fan and make safe
Remove 4 wire connector from fan and make safe
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the DC volts between the Brown wire on the PCB connector X23 and a suitable earth connection.
Expected voltage approximately 28 vdc.
Is the voltage measured as expected?
Expected voltage approximately 28 vdc.
Is the voltage measured as expected?
Isolate as per TOPs P4
and refit as necessary