Set Appliance State:

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)
Pull connector X3 back slightly to expose test points
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset appliance as necessary.
Measure the voltage between pin 4 (brown) and pin 5 (blue) at X3 on the PCB.
At 15 second intervals mains voltage should be measured
for 3 seconds as power is sent to the spark generator, this
will be repeated 5 times until lockout occurs.
Is the voltage measured as expected?
Notes:
1. Timings quoted are approximate.
2. Reset appliance and repeat test as necessary until outcome is determined.