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5.7 High voltage components (casing removed).
High voltage transformer test.
Ensure the following requirements have been met before starting the test:
1. The appliance has been disconnected from the power supply and protective measures have been taken to ensure
the power cannot be switched on again.
2. The appliance is cool.
3. The high voltage capacitors are discharged before commencing work.
See section 2.15 ‘How to discharge the conneX
®
HV’.
4. The casing of the appliance has been removed.
DANGER
High voltages and significant currents are present at the high voltage capacitor and HV Circuit.
It is very dangerous to work near this part when the oven is on.
NEVER make any electrical measurements on the high voltage circuits, including the magnetron filament, whilst the oven is
connected to the mains power supply.
1. Remove all connections from the transformer.
2. Using a Digital Multi-Meter (DMM), check the resistance of the windings.
Results should be as follows:
• 200 – 230V Transformer
3. Mains winding between tags,
approx.;
0 to 230; 0.6 Ω
0 to 200; 0.5 Ω
200 to 230; 0.1 Ω
• 208 – 240V Transformer
3. Mains winding between tags,
approx.
0 to 200/208; 0.5 Ω
0 to 220; 0.6 Ω
0 to 240; 0.6 Ω
208/208 to 220; 0.1 Ω
208/208 to 240; 0.1 Ω
220 to 240; 0.1 Ω
4. High Voltage winding, approx.
57 Ω.
4. High Voltage winding, approx.
47 Ω.
5. Filament winding between
terminals, less than 1 Ω.
5. Filament winding between
terminals, less than 1 Ω.
6. Using a megger/insulation tester, test the insulation resistance between:
Primary winding and chassis. Pass if reading is over 10 MΩ
Filament winding and chassis. Pass if reading is over 10 MΩ
NOTE: One end of the high voltage (secondary) winding is connected to the chassis, so this is not tested.
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