Variable Power Cooking Control; Cautions To Be Observed When Troubleshooting; Check The Grounding - Panasonic NN-CT577SEPG Service Manual

7 Description of the Operating Sequence

7.1 Variable power cooking control

The output power is controlled by the inverter power
supply. The level of output from the inverter circuit is
controlled by a pulse width modulated signal from the
digital programmer circuit (DPC). The digital program-
mer circuit operates relay RY1 to supply power to the
inverter circuit.
NOTE: If the microwave cooking time is longer than 3
minutes, the cooling fan will operate for 1 minute to
cool the oven and its electronic components.
7.2 Auto weight defrost, Auto weight
Cook
When an auto control feature is selected and the start
•
Weight Defrost
Cook / Combi
Combi

8 Cautions to be Observed when Troubleshooting

The microwave oven is a high voltage, high current
device. Although it is free from danger in ordinary use,
extreme care should be taken during repair.
Caution: Servicemen should remove their watches
whenever working close to or replacing the magnetron.

8.1 Check the grounding

Do not operate the microwave oven on a two wire
extension cord. The microwave oven is designed to be
used only when grounded. It is imperative that the
appliance is properly grounded before beginning repair
work.
Category
1. Defrost Small Pieces
2. Defrost Big Piece
3. Frozen Bread
Category
1. Fresh Vegetables
2. Baked Potatoes
3. Chicken Pieces
4. Whole Chicken
Category
5. Frozen Pizza
6. Frozen Quiche
7. Frozen Fries
pad pressed:
2. The digital programmer circuit determines the
power level and the cooking time and indicates the
operating state in the display. The table shows the
corresponding cooking times and weights for the
selected category.
3. When the cooking time in the display window has
elapsed, the oven turns off automatically via the
control signal from the digital programmer circuit.
Note: After auto cooking if the oven temperature
is over the predetermined temperature the fan
motor rotates to cool the oven and its compo-
nents.
1st Touch weight
300g 5 Min 21 Sec
600g 11 Min 30 Sec
100g 4 Min 19 Sec
1st Touch weight Cooking time
500g 12 Min 30 Sec
400g 14 Min 00 Sec
500g 10 Min 15 Sec
1200g 21 Min 55 Sec
1st Touch weight Cooking time
300g 5 Min 45 Sec
400g 10 Min 45 Sec
300g 10 Min 50 Sec
8.2 Inverter Warnings
DANGER, HIGH VOLTAGE AND HIGH TEMPERATURES
ON THE INVERTER POWER SUPPLY
This high voltage inverter power supply supplies very
high voltage and current to the magnetron. Though it
is free from danger in ordinary use, extreme care
should be taken during repair. This circuit looks like a
TV flyback transformer, however, the currents and volt-
ages in this circuit are very high, this means this circuit
is extremely dangerous.
The aluminium heat sink is also energized with high
voltage, never touch this heat sink when the micro-
wave oven is plugged into the mains outlet. The collec-
tor of the power device (IGBT) is directly connected to
the aluminium heat sink.
8
Cooking time