Page 9 MD Series Ovens 32Z3329 Issue 6
Procedure D - High Voltage Capacitor Test
You will need: A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.
5. Using a Megger, test the insulation resistance between the
terminals and the case.
1. Isolate the oven from the mains supply.
2. Ensure that the High Voltage Capacitor is discharged before
commencing work.
3. Remove all connections from the High Voltage Capacitor.
4. Using a D.M.M., check for continuity between the terminals &
compare results with table.
WARNING: High voltages and large currents are present at the High Voltage Capacitor. It is very
dangerous to work near this part when the oven is on. NEVER make any voltage
measurements at the High Voltage circuits, including the magnetron filament .
WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages
present because of the Soft Start circuit. Isolate the oven before testing.
Between Terminals
Pass if approximately 10 MΩ
Between Terminals and Case Pass if open circuit
Between Terminals and Case
Pass if over 100 MΩ
Procedure E - High Voltage Rectifier Test
You will need:
A Megger or similar resistance meter using 500V d.c.
WARNING: High voltages and large currents are present at the High Voltage Rectifier. It is very
dangerous to work near this part when the oven is on. NEVER make any voltage
measurements at the High Voltage circuits, including the magnetron filament .
WARNING: Even when the oven is not cooking, the High Voltage Rectifier has High Voltages
present because of the Soft Start circuit. Isolate the oven before testing.
1. Isolate the oven from the mains supply.
2. Ensure that the High Voltage Capacitor is
discharged before commencing work.
3. Remove all connections from the High Voltage
Rectifier.
4. Using the Megger, test for continuity in both
directions. Compare results with the table.
Open Circuit both ways
FAIL
Conducts one way only
PASS
Short Circuit both ways
FAIL
Conducts one way, leaks the other
FAIL
Procedure F - Magnetron Test
You will need:
A Megger or similar resistance meter using 500V d.c.
A Magnetron can be tested for an open filament or a short circuit
by carrying out a continuity check.
1. Isolate the oven from the mains supply.
2. Ensure that the High Voltage Capacitor is discharged before
commencing work.
3. Remove all connections from the Magnetron.
4. A continuity check across the Filament terminals should be 1ohm or less
5. A continuity check between each filament terminal and the
metal outer should read open.
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