Merrychef 402s - Manual (Page 24)

402s Ovens Pt. No. 32Z3522 Issue 6
24
PROCEDURES FOR PRINCIPAL COMPONENTS TEST (2)
3. High Voltage Rectifier Test
You will need:
A Megger or similar resistance meter using 500V d.c.
5. Using a Megger, test the insulation resistance between the
terminals and the case.
Between Terminals Pass if approximately 10 M Ω
Between Terminals and Case Pass if open circuit
Between Terminals and Case Pass if over 100 M Ω
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
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.
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.
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.
See Safety Code ( Page 4 )
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.
See Safety Code ( Page 4 )
( High Voltage Capacitor Test continued, ensure steps 1-4 on previous page have been completed)