Procedures For Principal Component Tests - Garland Mealstream CTM3 Service Manual

PROCEDURES FOR PRINCIPAL COMPONENTS TEST (2)
( High Voltage Capacitor Test continued, ensure steps 1-4 on previous page have been completed)
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 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
Rectifier.
4. Using the Megger, test for continuity in both
directions. Compare results with the table.
4. 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.
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 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.
Pass if approximately 10 MΩ
Pass if open circuit
Pass if over 100 MΩ
See Safety Code ( Page 4 )
See Safety Code ( Page 4 )
Mealstream Ovens Pt. No. 32Z3403 Issue 16
Page 26
Open Circuit both ways
Conducts one way only
Short Circuit both ways
Conducts one way, leaks the other
FAIL
PASS
FAIL
FAIL