Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove ST5 connector from the PCB
Measurement:
Test 1:
Measure for resistance across pins 6 & 7 (blue)
and 8 & 9 (purple) of ST5 connector.
Expected resistances should be as table below.
Test 2:
Measure the resistance between pin 6 and then pin 9 on ST5 to a suitable earth.
Expect a resistance of 1 Mohm or greater.
Are the resistances as expected?
Measure for resistance across pins 6 & 7 (blue)
and 8 & 9 (purple) of ST5 connector.
Expected resistances should be as table below.
| ST9 Pins | Resistance Ohms (approx) | 5 & 6 (blue) | 164 ohms |
| 7 & 8 (purple) | 164 ohms |
Test 2:
Measure the resistance between pin 6 and then pin 9 on ST5 to a suitable earth.
Expect a resistance of 1 Mohm or greater.
Are the resistances as expected?
Isolate as per TOPs P4
and refit as necessary