This document is a service manual for Panasonic microwave ovens, covering models NN-P794, NN-T794SF, NN-T784SF, NN-T774SF, NN-T764SF, NN-T754SF, NN-H764, NN-S754, NN-H744, NN-S744, and NN-H724. It also includes information relevant to models NN-S560BF/WF, NN-S550BF/WF, NN-S40BF/WF, NN-L530BF/WF, NN-L520WF, and NN-S510WF. The manual provides detailed specifications, safety warnings, troubleshooting guides, and parts lists for these microwave ovens.
Function Description
The Panasonic microwave ovens described in this manual are designed for cooking and reheating food using microwave energy. They feature an Inverter Power Supply circuit, which drives the magnetron tube with high voltage and current, allowing for precise power control and consistent cooking results. The ovens incorporate a digital programmer circuit for various cooking functions and settings.
Important Technical Specifications
The technical specifications vary slightly across the models but share common core characteristics.
General Specifications (for APH models):
- Power Source: 120V AC Single Phase, 60Hz
- Power Requirement: 1460W (for NN-P794, NN-T74, NN-H74, NN-S7*4 models)
- For NN-S560BF/WF, NN-S550BF/WF, NN-S540BF/WF, NN-L530BF/WF (APH): 1370W
- Output (IEC705-88):
- 1250W (for NN-P794, NN-T74, NN-H74, NN-S7*4 models, except NN-T774SF, NN-T764SF, NN-S744, NN-H724 which are 1200W)
- For NN-S560BF/WF, NN-S550BF/WF (APH): 1300W
- For NN-S540BF/WF (APH): 1100W
- For NN-L530BF/WF (APH): 1000W
- Microwave Frequency: 2450MHz
- Timer: 30 min. / Stage (HIGH Power) ~ 5 Stage Maximum; 99 min. 99 sec. / Stage (Other Power Levels) ~ 5 Stage Maximum
- For NN-S560BF/WF, NN-S550BF/WF, NN-S540BF/WF, NN-L530BF/WF (APH): 99min.99sec
- Outside Dimensions: 21 7/8" (555mm)(D) x 19 9/16" (497mm)(W) x 11 15/16" (304mm)(H)
- For NN-S560BF/WF, NN-S550BF/WF, NN-S540BF/WF, NN-L530BF/WF (APH): 20 3/8" (518mm)(W) x 16" (407mm)(D) x 11 7/8" (301mm)(H)
- Oven Cavity Dimensions: 16 7/16" (418mm)(D) x 18 1/2" (470mm)(W) x 9" (228mm)(H)
- For NN-S560BF/WF, NN-S550BF/WF, NN-S540BF/WF, NN-L530BF/WF (APH): 14 3/4" (375mm)(W) x 15 3/16" (386mm)(D) x 8 7/8" (225mm)(H)
- Weight: 31 lbs. / 14.3kg
- For NN-S560BF/WF, NN-S550BF/WF, NN-S540BF/WF, NN-L530BF/WF (APH): 26.5 lbs. (12.0kg)
General Specifications (for CPH models):
- Power Source: 120V AC Single Phase, 60Hz
- Power Requirement: 1370W (for NN-S560BF/WF, NN-S540BF/WF, NN-L530WF, NN-L520WF, NN-S510WF)
- Output (IEC705-88):
- 1200W (for NN-S560BF/WF)
- 1100W (for NN-S540BF/WF, NN-L530WF, NN-L520WF)
- 1000W (for NN-S510WF)
- Microwave Frequency: 2450MHz
- Timer: 99min.99sec
- Outside Dimensions: 20 3/8" (518mm)(W) x 16" (407mm)(D) x 11 7/8" (301mm)(H)
- Oven Cavity Dimensions: 14 3/4" (375mm)(W) x 15 3/16" (386mm)(D) x 8 7/8" (225mm)(H)
- Weight: 26.5 lbs. (12.0kg)
Usage Features
The microwave ovens offer a range of cooking modes and controls:
- Three Stage Cooking: Allows for complex cooking sequences with varying power levels and durations.
- Inverter Turbo Defrost: A defrosting feature that uses inverter technology for even and efficient thawing.
- Auto Reheat: Automatically reheats food to an optimal temperature.
- Inverter Auto Cook: Pre-programmed settings for various food types, simplifying the cooking process.
- Sensor Reheat: Uses a steam sensor to detect moisture and automatically adjust reheating time and power.
- Sensor Cook: Similar to Sensor Reheat, this feature uses a steam sensor to optimize cooking for various foods.
- Quick Min: Provides a quick start for cooking in one-minute increments.
- Popcorn: Dedicated setting for popping popcorn.
- Timer: A versatile timer for setting cooking durations or as a kitchen timer.
- Digital Clock: Displays the time of day.
- Power Level Control: Offers 10 power levels (P1 to P10), from 10% (LOW) to 100% (HIGH), with a complete ON and OFF cycle of power relay B being 22 seconds for precise cooking.
- Child Safety Lock: A feature to prevent unintended operation, activated by pressing the "Start" pad three times continuously.
Maintenance Features
The service manual provides comprehensive guidelines for maintenance and repair, emphasizing safety due to the high voltage and current present in microwave ovens.
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Safety Precautions:
- Qualified Personnel Only: Servicing should only be performed by trained and qualified technicians.
- Radiation Leakage Check: Mandatory checks for microwave radiation leakage before and after any servicing, especially after replacing radiation safety devices.
- Special Components: Critical parts marked with a triangle on the replacement parts list must be replaced with manufacturer-specified parts to prevent hazards.
- Grounding: Ensure proper grounding of the unit before beginning any repair work.
- High Voltage Warning: Extreme caution is advised when working with the Inverter Power Supply circuit, which operates at very high voltages and currents. Technicians are warned not to touch circuitry or the aluminum heat sink when the oven is energized, and to discharge high voltage capacitors after unplugging the unit.
- PbF Solder Caution: Lead-free solder (PbF) has a higher melting point (30-40°C higher than standard solder) and requires a high-temperature soldering iron (370 ± 10°C). It may splash if heated too high (around 600°C).
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Measurements and Adjustments:
- Latch Switch Adjustment: Procedures for adjusting the primary, secondary, and short latch switches to ensure proper door closing and interlock operation.
- Microwave Output Measurement: A simplified method using a 1-liter beaker, glass thermometer, and stopwatch to measure magnetron output by observing water temperature rise.
- Radiation Leakage Measurement: Detailed procedure for measuring radiation leakage with and without the outer panel, using a radiation monitor and a 2-inch spacer.
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Component Test Procedures:
- Inverter Power Supply (U) Test: Specific tests for the inverter power supply, including input ampere measurements, to diagnose failure codes (H97, H98, H99). For USA models, repair of the Inverter PCB is not recommended; replacement of the complete unit is advised.
- Magnetron Test: Continuity checks to diagnose open filaments or shorted magnetrons.
- Membrane Key Board Test: Checking continuity between switch terminals.
- Steam Sensor and Digital Programmer Circuit Test: Procedure to verify the functionality of the steam sensor by observing cooking time changes.
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Disassembly and Parts Replacement:
- Magnetron Replacement: Instructions for discharging high voltage capacitors, disconnecting lead wires, and removing screws. Emphasizes tightening screws in an X pattern and ensuring the antenna gasket is in place.
- Digital Programmer Circuit (DPC) and Membrane Key Board Replacement: Guidelines for handling the DPC, disconnecting connectors, and replacing the membrane key board, including tips for adhesive removal and alignment.
- Low Voltage Transformer and Power Relays (RY1, RY2) Replacement: Instructions for desoldering and resoldering these components.
- Fan Motor Replacement: Steps to disconnect wires, remove the fan blade, and separate the motor from the orifice assembly.
- Door Assembly Replacement: Detailed steps for disassembling and reassembling the door, emphasizing proper alignment to prevent microwave leakage.
- Inverter Power Supply (U) Replacement: Cautions for ensuring proper grounding and secure connections when replacing the inverter unit.
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Troubleshooting Guide: A systematic approach to diagnose common issues, linking symptoms to potential causes and recommended corrections. This includes issues like oven not operating, no display, fuse blown, key input not working, no microwave oscillation, low microwave output, and fan motor/turntable issues.
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