Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove ST9 connector from the PCB
Measurement:
Test 1:
Measure for resistance across pins 6 & 7 (blue).
Test 2:
Measure the resistance between pins and 8 & 9 (purple).
Expect a resistance of approximately 400 ohms on one test and
180 ohms on the other, It does not matter which way round the
results are as long as approximately 400 ohms is measured on
one test and 180 ohms is measured on the other.
Test 3:
Measure the resistance between pin 6 and then pin 9 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).
Test 2:
Measure the resistance between pins and 8 & 9 (purple).
Expect a resistance of approximately 400 ohms on one test and
180 ohms on the other, It does not matter which way round the
results are as long as approximately 400 ohms is measured on
one test and 180 ohms is measured on the other.
Test 3:
Measure the resistance between pin 6 and then pin 9 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