Procedures For Principal Component Tests - Garland Mealstream Service Manual

PROCEDURES FOR PRINCIPAL COMPONENTS TEST (2)
2. High Voltage Capacitor Test
You will need:
A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.
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.
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
Between Terminals
Between Terminals and Case
5 Using a Megger, test the insulation resistance between the terminals and the case.
Between Terminals and Case
3. 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 following
Open Circuit both ways
Conducts one way only
Short Circuit both ways
Conducts one way, leaks the other
See Safety Code ( Page 4 )
See Safety Code ( Page 4 )
Mealstream Ovens Pt. No. 32Z3403 Issue 15
Page 26
Pass if approximately 10 MΩ
Pass if open circuit
Pass if over 100 MΩ
FAIL
PASS
FAIL
FAIL