Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
Gain access to PCB (use Insulation Mat as required)
Attach a crocodile clip to the rectification lead
Temperature control to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset appliance as necessary.
Allow boiler to complete its self check.
Once boiler begins its ignition sequence,
measure the voltage between the green wire
on X7 marked 11.1 and the crocodile clip.
Approx. 40V AC should be measured.