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Discharging the high voltage capacitors

WARNING

There is high voltage present with high current capabilities
in the circuits of the primary and secondary windings, choke
coil and heat sink of the inverter. It is extremely dangerous
to work on or near these circuits with the oven energized.
DO NOT measure the voltage in the high voltage circuit
including the filament voltage of the magnetron.

WARNING

Never touch any circuit wiring with your hand or with an
insulated tool during operation.

5.3. Part replacement

When troubleshooting any part or component is to be replaced,
always ensure that the power cord is unplugged from the wall
outlet.

5.4. When the 15A fuse is blown

due to the malfunction of the
short switch

WARNING

When the 15A 250V fuse is blown due to the malfunction of
the short switch, replace all of the components (primary
latch switch, monitor interlock switch and power relay RY1).
 1. This is mandatory. Refer to “measurements and

adjustments” for the location of these switches.

 2. When replacing the fuse, confirm that it has the

appropriate rating.

 3. When replacing faulty switches, be sure the mounting

tabs are not bent, broken or deficient in their ability to
hold the switches.

5.5. Avoid inserting nails, wire etc.

through any holes in the unit
during operation

Never insert a wire, nail or any other metal object through the
lamp holes on the cavity or any holes or gaps, because such
objects may work as an antenna and cause microwave
leakage.

5.6. Verification after repair

 1. After repair or replacement of parts, make sure that the

screws of the oven, etc. are neither loose or missing.
Microwave energy might leak if screws are not properly
tightened.

 2. Make sure that all electrical connections are tight before

inserting the plug into the wall outlet.

 3. Check for microwave energy leakage.

CAUTION OF MICROWAVE RADIATION LEAKAGE

USE CAUTION NOT TO BECOME EXPOSED TO
RADIATION FROM THE MICROWAVE MAGNETRON OR
OTHER PARTS CONDUCTING MICROWAVE ENERGY.

IMPORTANT NOTICE

 1. The following components have potentials above 2000V

while the appliance is operated.

  • 

Magnetron

  • 

High voltage transformer (Located on inverter (U))

  • 

High voltage diodes (Located on inverter (U))

  • 

High voltage capacitors (Located on inverter (U))

Pay special attention to these areas.

 2. When the appliance is operated with the door hinges or

magnetron installed incorrectly, the microwave leakage
can exceed more than 5mW/cm

2

. After repair or

exchange, it is very important to check if the magnetron
and the door hinges are correctly installed.

 3. After repair or replacement of parts, make sure that all

the water pipes and tubes are properly connected,
otherwise the water might invade the electric parts and
will cause short circuit even result in electric shock.

5.7. Sharp edges

CAUTION

Please use caution when disassembling or reassembling
internal parts. Some exposed edges may be sharp to the
touch and can cause injury if not handled with care.

9

NN-GF668M

Содержание NN-GF668M EPG

Страница 1: ...pliances Microwave Oven Shanghai Co Ltd All rights reserved Unauthorized copying and distribution is a violation of law NN GF668M EPG Continental Europe SPG Norway Finland Sweden Denmark Microwave Oven ORDER NO PHAMO0806026C2 ...

Страница 2: ...2 NN GF668M ...

Страница 3: ...3 NN GF668M ...

Страница 4: ... Stirrer motor 15 7 COMPONENT TEST PROCEDURE 16 7 1 Primary Secondary Latch Switch interlocks Power Relay RY1 16 7 2 Short Switch 16 7 3 Magnetron 16 7 4 Inverter power supply U 17 7 5 Temperature thermistor 17 8 MEASUREMENTS AND ADJUSTMENTS 18 8 1 Adjustment of Primary latch switch Secondary latch switch and Short switch 18 8 2 Measurement of microwave output 18 9 TROUBLESHOOTING GUIDE 19 9 1 Tro...

Страница 5: ...1 FEATURE CHART 2 CONTROL PANEL 5 NN GF668M ...

Страница 6: ...ating conditions and output necessary to control PWM signal to the Inverter Power Supply for control of the output power 4 3 Auto Weight cooking When the Auto Weight feature is selected and the Start button is pressed 1 The digital programer circuit determines the power level and cooking time to complete cooking and indicates the operating state in the display window Table shows the corresponding ...

Страница 7: ... sink may be HOT due to heat energy therefore extreme care should be taken during servicing H V Inverter warning WARNING FOR INVERTER POWER SUPPLY U GROUNDING Check the High Voltage Inverter Power Supply circuit grounding The high voltage inverter power supply circuit board must have a proper chassis ground The inverter reinforcement and grounding bracket must be connected to the chassis If the in...

Страница 8: ...ty or any holes or gaps because such objects may work as an antenna and cause microwave leakage 5 6 Verification after repair 1 After repair or replacement of parts make sure that the screws of the oven etc are neither loose or missing Microwave energy might leak if screws are not properly tightened 2 Make sure that all electrical connections are tight before inserting the plug into the wall outle...

Страница 9: ... wire harness from locking tabs on inverter bracket A 6 Disconnect 2 high voltage lead wires from magnetron filament terminals 7 Remove 1 screw holding thermistor on magnetron 8 Remove 2 screws holding air guide A on magnetron then remove air guide A 9 Remove 4 screws holding air guide B on magnetron wave guider on base plate respectively then remove air guide B 10 Disconnect 2 lead wires from fan...

Страница 10: ...akage CAUTION When replacing the magnetron be sure the antenna gasket is in place 6 2 Digital programmer circuit D P C AU D P C DU membrane sheet low voltage transfarmer and power relay CAUTION Be sure to ground any static electric charge built up in your body before handling the DPC 1 Disconnect all wiring connectors from D P C board DU relay board 2 Remove 1 screw holding escutcheon base on cavi...

Страница 11: ...heon base with double faced adhesive tape Therefore applying hot air such as using a hair dryer is recommended for smoother removal 2 When installing the new membrane sheet make sure that the surface of escutcheon base is clean 6 3 H V Inverter 1 Discharge high voltage remaining in high voltage capacitor 2 Remove 2 screws holding the inverter reinforcement grounding bracket A on oven cavity 3 Remo...

Страница 12: ...an motor 1 Disconnect 2 lead wires from fan motor terminals 2 Remove 4 screws holding air guide B on magnetron on base plate respectively then remove air guide B 3 Remove 2 screws holding fan motor and detach fan motor from oven assy 4 Remove fan blade from fan motor shaft by pulling it straight out 13 NN GF668M ...

Страница 13: ...en be sure to adjust the door parallel to the cavity front plate by moving hinges back or forward 3 Adjust so that the upper portion of the door will touch firmly to the oven cavity front plate without pushing the door If the door assembly is not mounted properly microwave power may leak from the clearance between the door and oven 4 Be sure the gap between left or right portion of door assembly a...

Страница 14: ... to outside 2 Disconnect 2 lead wires from stirrer motor terminals 3 Remove 2 screws holding stirrer motor NOTE After reinstalling the new stirrer motor and reconnecting the 2 lead wires reinstall the motor cover by rotating it around 180 tucking the 2 tabs under the base in the 2 provided slots then screw the single tab to the base using a screw NOTE Do not remove the two screws holding the left ...

Страница 15: ...r Closed Door Opened Primary Latch Switch 0Ω Close Ω Open Secondary Latch Switch 0Ω Close Ω Open Power Relay RY1 Ω Open Ω Open 7 2 Short Switch 1 Unplug lead wires from Inverter Power Supply U primary terminals 2 Connect test probes of ohm meter to the disconnected leads that were connected to Inverter Power Supply U 3 Test the continuity of short switch with door opened and closed positions using...

Страница 16: ... 23 seconds after started Test 2 Continued from Test 1 1 Unplug the oven s AC power supply cord from outlet 2 Unplug 3 pin connector CN701 CN703 remains unplugged 3 Plug in the oven s AC power supply cord into outlet 4 Program DPC a Press Clock button once b Press Delay Stand button once c Press Start button once d Press Microwave Power button once 5 Program oven at High power for 1 minute and pre...

Страница 17: ...on of door A and cavity front plate is 2 4mm if the door gap is greater than 4mm the Primary latch switch must be OFF If alignment is poor oven may not operate after grill use 8 2 Measurement of microwave output The output power of the magnetron can be determined by performing IEC standard test procedures However due to the complexity of IEC test procedures it is recommended to test the magnetron ...

Страница 18: ...g operate the microwave oven following the correct operating procedures in the instruction manual in order to find the exact cause of any trouble since operator error may be mistaken for the oven s malfunction Self diagnostic display Oven has self diagnostic function but it will not be activated in normal operation mode To show self diagnostic result please take the following steps 1 Firstly you m...

Страница 19: ...or CN701 CN702 4 H V Inverter U Oven stops in 23 seconds after pressing Start button H V Inverter U operates by the control signals from DPC but magnetron is not oscillating 1 Magnetron 2 Loose lead wire connector CN703 3 H V Inverter U 2 No display and no operation at all Fuse is blown Most probably loose connection of connectors or door latch mechanism is not adjusted properly 1 Align door Door ...

Страница 20: ...ge circuit especially magnetron filament circuit NOTE Large contact resistance will cause lower magnetron filament voltage and cause magnetron to have lower output and or be intermittent 3 Defective high voltage component H V Inverter Power Supply U Magnetron Check high voltage component according to component test procedure and replace if it is defective 4 Open or loose wiring of power relay RY1 ...

Страница 21: ...you must program the DPC into TEST MODE press Clock button once Press Delay Stand button once Press Start button once press Microwave Power button once Program unit for operation H95 H97 H98 H99 appears in display window a short time after start button is pressed and there is no microwave oscillation Alternate way to troubleshoot oven with AC Ampere meter used H95 H97 H98 H99 appears in display wi...

Страница 22: ... Abnormal Display H95 H97 H98 appears in window and oven stops operation Program High power for 1 minute and conduct following test quickly unless H95 H97 H98 appears and oven stops 1 Unplug CN702 2 pin connector and measure voltage between terminals Abnormal 0V 1 Latch Switch 2 D P C Power Relay Normal 230V Step2 2 Unplug CN701 3 pin connector and measure pin3 voltage of CN11 Abnormal 0V D P C Ap...

Страница 23: ...s Set Remarks Q701 A691E4V10GP TRANSISTOR SI 1 Q702 TRANSISTOR SI 1 DB701 AESTRS2006M DIODE SI 1 20A 600V D701 D702 A62024V00GP DIODE SI 2 0 3A C704 C705 ECWH30822JUA CAPACITOR 2 8200PF 3000VDC T701 F609A4V00XN H V TRANSFORMER 1 F607D4V00XN D P CIRCUIT KU 1 L701 F50204V00XN CHOKE COIL 1 CT701 F66904V00XN CURRENT TRANSFORMER 1 24 NN GF668M ...

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