Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
On/Off Switch ON
NO demand
Preheat switched OFF (ECO button illuminated)
Gain access to PCB (use insulation mat as necessary)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Step 1: Measure the voltage across pin 1 of ST17 and DC neutral terminal Expected voltage 26V DC.
Step 2: Press and hold the reset button on the control panel for 2 seconds and then release, the voltage should then drop away and return to 26V DC.
Step 3: Repeat Steps 1 and 2 at the following locations.