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Mealstream Ovens Pt. No. 32Z3403 Issue 15
Page 25
1. Power
Transformer
Test
You will need:
A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.
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 Power Transformer.
4 Using a D.M.M., check the resistance of the windings. Results should be as follows:
WARNING:
High voltages and large currents are present at the secondary winding
and filament winding of the Power Transformer. 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 Power Transformer has High
Voltages present because of the Soft Start circuit. Isolate the oven
before testing.
See Safety Code
( Page 4 )
5 Using a Megger, test the insulation resistance between
:
Mains winding (between tags)
Approximately 1.1
Ω
High Voltage winding (between tag and chassis)
Approximately 60
Ω
Filament winding (between terminals)
Less than 1
Ω
Primary winding and chassis
Pass if over 10 M
Ω
Filament winding and chassis
Pass if over 10 M
Ω
One end of the High Voltage winding is connected to the chassis, so this is not tested.
PROCEDURES FOR PRINCIPAL COMPONENTS TEST (1)