This document provides a comprehensive service manual for the Panasonic NN-SF564S and NN-SF564M Microwave Ovens, outlining their functions, technical specifications, usage, and maintenance procedures.
Function Description
The Panasonic NN-SF564S and NN-SF564M are microwave ovens designed for cooking and reheating food. They utilize an Inverter Power Supply (U) to control output power, which is regulated by a Digital Programmer Circuit (DPC) using Pulse Width Modulation (PWM) signals. This inverter technology allows for precise power control, enabling features like variable power cooking, turbo defrost, and auto cook. The oven is equipped with a magnetron tube that generates microwaves for heating. Safety features include interlock switches, a thermal cutout, and a thermistor to monitor magnetron temperature, preventing overheating.
Important Technical Specifications
General Specifications:
- Power Source: 120V AC Single Phase, 60Hz
- Power Consumption: 1040W (NN-SF564S), 1040W (NN-SF564M)
- Output: 1000W (NN-SF564S), 1000W (NN-SF564M)
- Microwave Frequency: 2450MHz
- Timer: 30 Min. / Stage (HIGH Power Level) - 3 Stage Maximum; 99 Min. 59 Sec. / Stage (Other Power Level) - 3 Stage Maximum
- Outside Dimensions: 525mm(W) x 320mm(H) x 414mm(D)
- Oven Cavity Dimensions: 354mm(W) x 250mm(H) x 330mm(D)
- Net Weight: 12.7 kg
- PbF: This product with PbF (Lead-free)
Variable Power Cooking:
The oven offers various power settings with corresponding output power percentages and duty cycles:
- HIGH: 100% output, 22 sec ON, 0 sec OFF
- MEDIUM-HIGH: 70% output, 22 sec ON, 0 sec OFF
- MEDIUM: 60% output, 22 sec ON, 0 sec OFF
- MEDIUM-LOW: 45% output, 22 sec ON, 0 sec OFF
- DEFROST: 35% output, 22 sec ON, 0 sec OFF
- LOW: 25% output, 13 sec ON, 9 sec OFF
Magnetron Thermistor:
- Normal Resistance: 35KΩ to 110KΩ at ambient temperatures of 10-30°C.
- Normal Thermistor Level Reading (display): 16-230
Usage Features
Control Panel and Display:
The oven features a display window, micro power pad, grill pad, combination pad, turbo defrost pad, auto cook menu pads, stop/reset pad, and start pad.
Beep Sound:
A beep sound confirms pad presses. If a pad is pressed and no beep is heard, the unit may not have accepted the instruction. The oven will beep twice between programmed stages and five times upon completion.
Note on Operation:
If an operation is set and the Start Pad is not pressed after 6 minutes, the oven will automatically cancel the operation. The display will revert to clock or colon mode.
Cooking Modes:
- Variable Power Cooking: Allows users to select different power levels for precise cooking.
- Turbo Defrost: Automatically determines power level and cooking time based on weight (e.g., 1.0kg takes 15min 50sec).
- Auto Cook (Reheat Meal): Automatically determines power level and cooking time based on servings (e.g., 1 serv takes 1min 40sec).
Maintenance Features
Safety Precautions for Servicing:
- High Voltage and Current: The microwave oven is a high voltage, high current device. Extreme care must be taken during repair.
- Grounding: Always ensure the appliance is properly grounded. Do not operate on a two-wire extension cord.
- Discharging Capacitors: For about 30 seconds after the oven is turned off, an electric charge remains in the high voltage capacitors of the Inverter Power Supply circuit board. Always remove the power plug and short the inverter output terminal of the magnetron filament terminals to the chassis ground with an insulated handle screwdriver to discharge.
- Heat Sink: The aluminum heat sink can be hot and energized with high voltage; avoid touching it when AC input terminals are energized.
- Watches and Rings: Servicemen should remove watches and rings when working near or replacing the magnetron.
- Interlock Switches: The 20A fuse can blow due to malfunction of the primary interlock switch, secondary interlock switch, or interlock monitor switch. All these switches must be replaced at the same time if defective.
- Avoiding Nails/Wires: Do not insert a wire, nail, or any other metal object through the ventilation holes or gaps, as this can cause microwave leakage.
- Microwave Radiation Leakage: Do not operate the oven if the magnetron, high voltage transformer, high voltage capacitors, or interlock switches are defective, as this can lead to microwave radiation leakage.
Troubleshooting Guide:
The manual provides a detailed troubleshooting guide for various issues, including:
- No display/No operation: Checks for open lead wire harness, thermal cutout/thermistor, low voltage transformer, or defective DPC.
- Oven not accepting key input: Checks for incorrect key input sequence, loose connections, or defective DPC.
- Timer starts but no microwave oscillation: Checks for off-alignment of primary interlock switch, open/loose high voltage circuit, defective high voltage components (Inverter Power Supply (U), magnetron), or defective DPC/power relay.
- Oven stops operation during cooking: Checks for open/loose wiring of primary/secondary interlock switch or operation of thermal cutout.
- Failure Codes (H95, H97, H98, H99): These codes indicate magnetron and inverter circuit problems. The manual outlines steps to diagnose these issues using an AC ampere meter, checking magnetron filament continuity, inverter input AC voltages, and inverter control signals.
Component Test Procedure:
- Primary, Secondary Interlock Switch & Power Relay RL1: Continuity checks at door opened and closed positions.
- Interlock Monitor Switch: Continuity checks at door opened and closed positions.
- Magnetron: Continuity checks for filament and between filament terminal and magnetron case.
- Inverter Power Supply (U): Instructions to test for failure codes H95, H97, H98 by programming the DPC and observing input current and oven operation. Replacement of the entire H.V. Inverter(U) Unit is recommended if defective.
- Temperature Thermistor: Resistance checks to determine if the thermistor is defective.
Disassembly and Parts Replacement:
Detailed instructions are provided for disassembling and replacing key components such as:
- Inverter Power Supply: Steps include discharging high voltage, disconnecting wires, removing screws, and releasing locking tabs.
- Magnetron: Steps include removing screws holding the thermistor and air guide.
- Digital Programmer Circuit & Membrane Switch: Steps include removing screws, disconnecting connectors, and separating the DPC board from the escutcheon base. Instructions for replacing the membrane key board are also included, emphasizing the use of hot air for removal and ensuring a clean surface for installation.
- Low Voltage Transformer and/or Power Relays (RL1): Steps include disconnecting connectors, removing screws, and carefully desoldering terminals.
- Fan Motor: Steps include disconnecting lead wires, removing screws, and removing the fan blade.
- Stirrer Motor: Steps include removing the motor cover and disconnecting lead wires.
- Door Assembly: Steps include removing the door key, hinge, and separating door components.
Parts List:
Comprehensive lists of all parts, including part numbers, descriptions, and quantities, are provided for the main unit, escutcheon base assembly, door assembly, wiring materials, and packing/accessories. Components critical for safety are marked with a special symbol.
Schematic Diagram:
A schematic diagram of the Digital Programmer Circuit is included for detailed electrical troubleshooting.
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