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Panasonic NN-S251BL, Service Manual, Page: 17 / 44

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Panasonic NN-S251BL Service Manual Download Page 17

B.  REMOVING THE OUTER CASE(Figure 8)

(1)  Remove the vent grille by removing two screws

securing it to the outer case.

(2)  Remove two screws securing it to the front

bracket.

(3)  Remove two screws securing it to the air duct.
(4)  Remove the wall mounting plate by removing the

two screws securing it to the outer case.

(5)  Remove the base plate by removing six screws

securing it to the outer case. Remove the Mount
from the out case by removing two screws
securing it to the outer case and one screw
securing it to the ventilation motor ASS'Y and
cavity.

(6)  Remove the power cord cover from outer case by

removing a screw.

Vent Grille

Control Panel

Mounting
Plate

Door

Outer Case

Base Plate

Mount

Power cord

Figure 8

7-6

Summary of Contents for NN-S251BL

Page 1: ...mer Outside Dimensions Oven Cavity Dimensions Weight 120 V AC 60 Hz 13 5 Amps 1 550 W 1000 W Full Power IEC 60705 2 450 MHz 99 min 99 sec 197 8 W X 815 16 H X 143 16 D 505mm W X 227mm H X 360mm D 2915 16 W X 167 16 H X 153 8 D 760mm W X 418mm H X 385mm D Approx 52 lbs 23 5 kg Specifications subject to change without notice APH NN S251WL NN S251BL Microwave Oven ORDER NO MOD 0106244C1 E2 Service Ma...

Page 2: ...n the microwave oven which are important for safety These parts are marked with a w on the replacement parts list It is essential that these critical parts should be replaced only with the manufacture s specified parts to prevent microwave leakage shock fire or other hazards Do not modify the orginal design PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESS...

Page 3: ...GRAM 5 1 MATRIX CIRCUIT FOR TOUCH KEY BOARD 5 2 GENERAL INFORMATION FOR SERVICE 6 1 GENERAL PRECAUTIONS IN USE 6 1 TRIAL OPERATION 6 1 FEATURES AND SPECIFICATIONS FEATURES 6 1 SERVICE INFORMATION 7 1 PRECAUTIONS AND REPAIR SERVICE TIPS 7 1 PROCEDURE FOR MEASURING MICROWAVE ENERGY LEAKAGE 7 2 POWER OUTPUT MEASUREMENT 7 3 DISASSEMBLY INSTRUCTIONS 7 4 INTERLOCK SYSTEM 7 12 INTERLOCK CONTINUITY TEST 7...

Page 4: ...ary Interlock Switch Secondary Interlock Switch Interlock Monitor Magnetron 2M214 39F High Voltage Capacitor Capacitor 1 0µF 2 1 KV AC High Voltage Diode Diode 350mA 9 0 KV Cook top Lamp 125 V 30 W Cavity Lamp 125 V 30 W Timer Digital up to 99 mim 99 sec in each cooking stage Tray Tempered Safety Glass Overall Dimensions 2915 16 W x167 16 H x153 8 D Oven Cavity Size 197 8 W x815 16 H x143 16 D Eff...

Page 5: ...equires that the magnetron be assembled to the waveguide and cavity Never operate the magnetron unless it is properly installed Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron Unlike other appliances the microwave oven is high voltage and high current equipment Though it is free from danger in ordinary use extreme care should be...

Page 6: ...d at all times In the event of an electrical short circuit grounding reduces the risk of electrical shock The plug must be plugged into an outlet that is properly installed and grounded BEFORE YOU BEGIN READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY WARNING Improper use of the grounding plug can result in a risk of electric shock Do not under any circumstances cut or remove the third gro...

Page 7: ...4 1 FEATURE DIAGRAM See through Oven Window Door Handle Identification Plate Menu Label Cover do not remove Oven Air Vent Control Panel Cooktop Light Grease Filter Door Safety Lock System Glass Tray ...

Page 8: ...o enter cooking time power level quantities or weights 8 Timer Pad Touch this pad to set the kitchen timer 9 Clock Pad Touch this pad to enter the time of day 10 Timer Off Pad Touch this pad to stop timer function 11 Function Pad Touch this pad to change the oven s default settings for sound clock display speed defrost weight and demo mode operations 12 Quick Min Pad Touch this pad to set and star...

Page 9: ...5 1 SCHEMATIC DIAGRAM OVERALL CIRCUIT DIAGRAM ...

Page 10: ...MATRIX CIRCUIT FOR TOUCH KEY BOARD 5 2 ...

Page 11: ...y light comes on The unit will begin cooking and the display window will show the time counting down by seconds D After about 5 minutes make sure the primary interlock switch the secondary interlock switch and the interlock monitor switch operate properly by opening and closing the door several times Touch the START key each time the door is closed E Continue operating the unit Four long beep soun...

Page 12: ...All service adjustments should be made for minimum microwave energy leakage readings 3 Do not operate the unit until it is completely repaired if any of the following conditions exist The unit must not be operated a The door does not close firmly b The hinge is broken c The door seal is damaged d The door is bent or warped or there is any other visible damage on the unit that may cause microwave e...

Page 13: ...gnetron measure for radiation leakage before the outer panel is installed and after all necessary components are replaced or adjusted Special care should be taken in measuring around the magnetron 2 Measurements with a fully assembled oven After all components including outer panel are fully assembled measure for radiation leakage around the door periphery the door viewing window the exhaust openi...

Page 14: ...in good condition functioning properly and genuine replacement parts which are listed in this manual have been used 3 At least once a year have the electromagnetic energy leakage monitor checked for calibration by its manufacturer 1 Microwave power output measurement is made with the microwave oven supplied at its rated voltage and operated at its maximum microwave power setting with a load of 100...

Page 15: ... ESPECIALLY SWITCHES AND HIGH VOLTAGE CIRCUIT BEFORE A GRILLE HAVE TO REMOVE FIRST A REMOVING POWER AND CONTROL CIRCUIT BOARD Figures 1 2 and 3 1 Remove a screw securing the control panel assembly to the oven cavity 2 Remove the control panel with pushing it upward 3 Remove the connector CN1 and wire leads Relay7 from the circuit board 4 Remove 3 screws securing the circuit board 5 Remove the FPC ...

Page 16: ... F P C connector into the terminal socket securely with the fingers 2 Hold the plastic fastener with thumb and forefinger of the other hand and push it slowly into the terminal socket Figure 6 NOTE When reconnecting the F P C connector make sure that the holes on the F P C connector are properly engaged with the hooks on the plastic fastener 3 Lock the level of the plastic fastener into the hook o...

Page 17: ... removing the two screws securing it to the outer case 5 Remove the base plate by removing six screws securing it to the outer case Remove the Mount from the out case by removing two screws securing it to the outer case and one screw securing it to the ventilation motor ASS Y and cavity 6 Remove the power cord cover from outer case by removing a screw Vent Grille Control Panel Mounting Plate Door ...

Page 18: ... page 7 12 Door Hook Secondary Interlock Switch Interlock Monitor Switch Primary Interlock Switch Figure 10 WIRE COLOR SYMBOL COLOR WH YL RD N P WHITE YELLOW RED GN GREEN Not Provided Door Hook WH from H V Transformer WH from Monitor S W WH from Oven Thermostat WH from Cooktop lamp Secondary Interlock Switch Monitor Interlock Switch Primary Interlock Switch GN from P C B YL from P C B WH from Seco...

Page 19: ... may be damaged When replacing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition After replacing the magnetron check for microwave energy leakage with a survey meter Microwave energy leakage must be below the limit of 5 mW cm2 All service adjustments should be made for minimum microwave energy leakage readings 7 8 Figure ...

Page 20: ...monitor switch is in good operating normally After replacing the door check for microwave energy leakage with a survey meter Microwave energy leakage must be below the limit of 5mW cm2 With a 275 ml water load F DISASSEMBLING DOOR Figure 15 1 Remove the dielectric choke by using knife blade or small screw driver etc 2 Remove two screws securing it to the door handle CAUTION Be careful not to damag...

Page 21: ...waves may leak from the clearance between the door and the oven H REMOVING THE VENTILATION FAN ASS Y 1 Remove the mounting plate by removing two screws securing it to the back plate See Figure 16 2 Remove the two screws securing the MOUNT and one screw securing the ventilation fan ASS Y See Figure 17 3 Carefully pull the ventilation motor ASS Y out of the microwave oven See Figure 18 7 10 Figure 1...

Page 22: ...ecuring it to the oven cavity Figure 20 4 Disconnect the leadwire from the turntable motor terminals 5 Remove the 2 screws securing the turntable motor to the oven cavity ASS Y Figure 21 NOTES Remove the leadwire from the turntable motor VERY CAREFULLY Be sure to grasp the connector not the wires when removing Terminals Turntable Motor Figure 21 Figure 19 Figure 20 Base Plate 7 11 ...

Page 23: ...nt of the latch board may not be necessary Go to Steps 5 and 6 to check the sequence of the switches NOTE To correct sequence of the Primary Interlock Switch Secondary Interlock Switch and the Interlock Monitor Switch is very important If any gap is larger than 1 64 0 5 mm you will need to adjust the latch board Go to step 3 and follow all steps in order ADJUST THE LATCH AND SWITCH CLOSING 3 Loose...

Page 24: ...ro to the body of the switches in the following sequence Interlock Monitor Switch Primary Interlock Switch Secondary Interlock Switch NOTE The Interlock Monitor Switch is an added safety check on the Primary and Secondary Interlock Switches If the Primary and Secondary Interlock Switches allow the oven to operate with the door open the Monitor Switch will blow the fuse 7 When you achieve the prope...

Page 25: ...cate an closed circuit When the secondary switch operation is abnormal make the necessary adjustment or replace the switch only with the same type of switch C MONITOR SWITCH TEST Disconnect the wire lead from the monitor switch Connect the ohmmeter leads to the common COM and normally closed NC terminals of the switch The meter should indicate closed circuit in the door open condition When the doo...

Page 26: ... each filament terminal of the magnetron and the chassis ground with an ohm mater on high test scale 1 Measure the resistance With an ohm meter on Rx1 scale a Primary winding b Filament winding c Secondary winding 2 Measure the resistance With an ohm meter on highest scale a Primary winding to ground b Filament winding to ground Normal reading Less than 1 ohm Normal reading Infinite ohms NOTE Repl...

Page 27: ...mal reading Momentarily indicates several ohms and then gradually returns to infinite ohms Abnormal reading Indicates continuity or infinite ohms from the beginning Normal readings Infinite Abnormal reading Indicates continuity Normal readings continuity Abnormal reading Infinite Note Meter reading depend on the battery in the Meter Normal readings Infinite Abnormal reading continuity Figure 24 a ...

Page 28: ...holes on the FPC connector are properly engaged with hooks on the plastic fastener MATRIX CIRCUIT FOR TOUCH KEY BOARD CONNECTOR KEY CON For detail matrix circuit of each model refer to page 5 2 7 17 COMPONENTS TEST PROCEDURES RESULTS TOUCH KEY BOARD Resistance value When When not touched touched Less than More than 400 ohms 1 mega ohm FPC CONNECTOR Top ...

Page 29: ...r the interlock monitor switch Malfunction of the high voltage transformer the high voltage capacitor including the diode the magnetron the blower motor or the circuit board PROBLEMS CAUSES POWER LEVEL 1 2 3 4 5 6 7 8 9 10 4 sec 6 sec 8 sec 10 sec 12 sec 14 sec 16 sec 18 sec 20 sec 22 sec 18 sec 16 sec 14 sec 12 sec 10 sec 8 sec 6 sec 4 sec 2 sec 0 NOTES If the fuse is blown by an improper switch ...

Page 30: ...Does the unit still operate GOOD Replace the circuit board Replace RELAY7 PROBLEM B Vent fan motor and oven lamp turn on When the door is closed and START key is touched Measure the voltage at pin NO 4 5 6 of U01 Voltage reading 0 Vdc Replace the circuit board Defective RELAY7 or poor connection of RELAY7 Defective RELAY7 Replace RELAY7 or correct the connection NO NO YES YES NO NO YES YES GOOD ...

Page 31: ...the interlock switches the door sensing and the relay check good 2 The unit with a normal relay continuously operates 3 Proper temperature measurement is not obtained 4 The buzzer does not sound or continues to sound 5 Some segments of one or more digits do not light up or they continue to light up or segments light when they should not 6 Wrong figures appear 7 The figures of all digits 8 Some of ...

Page 32: ...PERATION on page 6 1 DISPLAY Problems A thru C HELP UP Problems D thru E BUZZER Problems F Measure voltage between pin 1 and pin 3 of connector CN1 Measure resistance of touch key board after removing connector S1 See page 7 4 and 7 17 0 120 120V Replace circuit board Normal circuit board Normal resistance Voltage incorrect Normal resistance Resistance incorrect Replace touch key board Normal touc...

Page 33: ... H V C Abnormal Replace H V D Normal Magnetron Replace Magnetron Normal Normal H V D Check the continuity of H V D see page 7 16 Replace H V C Normal resistance Replace H V T Normal resistance NO continuity Replace circuit board Normal circuit board Poor contact Replace circuit board Normal circuit board Contact OK Normal contact Correct seating Check contact of connector S1 Check the contact of r...

Page 34: ...7 23 PROBLEM F No buzzing when touching the key between stages or at end of cooking 1 Normal circuit board Check normal operation circuit board Replace circuit board Runs ...

Page 35: ...ontact OK NO contact Replace oven thermostat Poor contact Replace circuit board Normal circuit board Contact OK Normal contact Correct seating Check contact of connector S1 see page 7 4 Replace ventilation motor ASS Y NO runs Normal ventilation motor ASS Y Check the contact of oven thermostat Runs Runs Runs Runs ...

Page 36: ...8 1 SCHEMATIC DIAGRAM OF P C B ...

Page 37: ...8 2 PRINTED CIRCUIT BOARD ...

Page 38: ...3 2 1 EXPLODED VIEW DOOR PARTS MODEL NN S251 4 1 9 7 65 6 5 8 ...

Page 39: ... 2 ESCUTCHEON BASE ASSEMBLY 12 10 13 14 11 67 60 66 ...

Page 40: ... 3 OVEN CAVITY PARTS 26 64 63 65 66 18 16 21 23 24 25 66 66 19 17 15 20 64 22 22 27 ...

Page 41: ... 4 DOOR HOOK PARTS 31 28 32 69 30 29 61 ...

Page 42: ... 5 INTERIOR PARTS I 65 42 33 35 36 37 62 63 34 39 41 38 60 43 63 60 40 63 44 60 60 60 ...

Page 43: ... 6 INTERIOR PARTS II 45 53 46 48 49 51 65 65 60 55 50 47 54 52 ...

Page 44: ... 7 INSTALLATION PARTS VINYL BAG 57 56 59 58 ...

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