Set Appliance State:
Set Multimeter to DC Volts 
Isolate Mains Power to appliance as per TOPs P4
Hinge down the electrical control box and remove back of control box to expose PCBs
Selector Switch in DHW position
Hinge down the electrical control box and remove back of control box to expose PCBs
Selector Switch in DHW position
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure voltage between points D6 and D7 on the power board.
Is the voltage between 20-40 Volts DC?
Note:
It is important to measure at points shown (i.e. correct side of resistor) otherwise false readings may be obtained.
Is the voltage between 20-40 Volts DC?
Note:
It is important to measure at points shown (i.e. correct side of resistor) otherwise false readings may be obtained.
Isolate as per TOPs P4
and refit as necessary