Panasonic NN-GD576M User manual

© 2006 Panasonic Home Appliances Microwave
Oven (Shanghai) Co., Ltd. All rights reserved.
Unauthorized copying and distribution is a violation
of law.
NN-GD576M
NN-GD576W
NN-GT546W
NN-ST556M
NN-ST556W
HPE(Hong Kong)
YPQ(Singapore)
MPQ(Malaysia)
TPE(Thailand, Indonesia)
YTE(Others)
KTE(UAE)
PTE(Iran)
KPQ(Kuwait, Doha, Qatar, Oman, Bahrain, Pakistan)
STM(Saudi Arabia)
Microwave Oven
Please file and use this manual together with the service manual for Model NN-S553/K593/K573/K543
(ORDER NO. SIMMC0306022C3).
ORDER NO.PHAMOS0607033A3

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1 SCHEMATIC DIAGRAM (STM) 5
2 SCHEMATIC DIAGRAM (Except STM) 6
3 CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING
7
3.1. Check the grounding 7
3.2. Inverter warnings 7
3.3. Part replacement. 8
3.4. When the 10A fuse is blown due to the operation of the
short switch: 8
3.5. Avoid inserting nails, wire etc. through any holes in the
unit during operation. 8
3.6. Confirm after repair 8
3.7. Sharp edges 8
4 MEASUREMENTS AND ADJUSTMENTS 9
4.1. Adjustment of primary latch switch, secondary latch switch
and short switch. 9
4.2. Measurement of microwave output 9
5 EXPLODED VIEW AND PARTS LIST 10
5.1. EXPLODED VIEW 10
5.2. PARTS LIST 11
5.3. DOOR ASSEMBLY 12
5.4. WIRING MATERIALS 12
5.5. PACKING AND ACCESSORIES 13
5.6. ESCUTCHEON BASE ASSEMBLY 14
6 DIGITAL PROGRAMMER CIRCUIT 16
6.1. NN-GD576M/GD576W 16
6.2. NN-GT546W 18
6.3. NN-ST556M/ST556W 20
6.4. PARTS LIST 22
CONTENTS
Page Page
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1 SCHEMATIC DIAGRAM (STM)
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2 SCHEMATIC DIAGRAM (Except STM)
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Unlike many other appliances, the microwave oven is a high
voltage, high current device. It is free from danger in ordinary
use, though extreme care should be taken during repair.
Caution
Servicemen should remove their watches whenever
working close to or replacing the magnetron.
3.1. Check the grounding
Do not operate on a two wire extension cord. The microwave
oven is designed to be grounded when used. It is imperative,
therefore, to ensure the appliance is properly grounded before
beginning repair work.
3.2. Inverter warnings
DANGER, HIGH VOLTAGE AND HIGH TEMPERATURE
(HOT/LINE) OF THE INVERTER POWER SUPPLY (U)
The high voltage inverter power supply handles very high
voltage and current for the magnetron tube. Though it is
free from danger in ordinary use, extreme care should be
taken during repair.
The aluminum heat sink is also energized with high voltage
(HOT), do not touch when the AC input terminals are
energized. The power device Collector is directly connected
to the aluminum heat sink.
The aluminum heat 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
grounding bracket must be connected to the chassis. If the
inverter board is not grounded it will expose the user to very
high voltages and cause extreme DANGER! Be sure that
the inverter circuit is properly grounded via the inverter
earth bracket.
Grounding of the inverter circuit board
WARNING! DISCHARGE THE HIGH VOLATGE
CAPACITORS
For about 30 seconds after the oven is turned off, an
electric charge remains in the high voltage capacitors in the
inverter power supply circuit board.
When replacing or checking parts, remove the power plug
from the outlet and short the inverter output terminal of the
magnetron filament terminals to the chassis ground with an
insulated handle screwdriver to discharge. Please be sure
to touch the chassis ground side first and then short to the
output terminals.
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.
3 CAUTIONS TO BE OBSERVED WHEN
TROUBLESHOOTING
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3.3. Part replacement.
When any part or component is to be replaced, always ensure
that the power cord is removed from the wall outlet.
3.4. When the 10A fuse is blown
due to the operation of the
short switch:
WARNING
When the 10A 250V fuse is blown due to the operation of
the interlock monitor switch, replace all of the components
(primary latch switch, secondary latch switch, short switch
and power relay B (RY1)).
1. This is mandatory. Refer to “adjustments and
measurements” for the location of these switches.
2. When replacing the fuse, confirm that it has the
appropriate rating for these models.
3. When replacing faulty switches, be sure the mounting
tabs are not bent, broken or deficient in their ability to
hold the switches.
3.5. 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.
3.6. Confirm after repair
1. After repair or replacement of parts, make sure that the
screws of the oven, etc. are neither loose nor missing.
Microwaves 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. (Refer to procedure
for measuring microwave energy leakage).
CAUTION MICROWAVE RADIATION
USE CAUTION NOT TO BECOME EXPOSED TO
RADIATION FROM THE MICROWAVE MAGNETRON OR
OTHER PARTS CONDUCTING MICROWAVE ENERGY
IMPORTANT NOTICE
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.
When the appliance is operated with the door hinges or
magnetron installed incorrectly, the microwave leakage can
exceed more than 5mW/cm2. After repair or exchange, it is
very important to check if the magnetron and the door
hinges are correctly installed.
3.7. Sharp edges
Caution
Please use caution when unpacking, installing or moving
the unit, as some exposed edges may be sharp to the touch
and cause injury if not handled with care.
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4.1. Adjustment of primary latch
switch, secondary latch switch
and short switch.
1. Mount the Primary latch switch, the secondary latch switch
and the short switch to the door hook assembly as shown in
ILL.
NOTE:
No specific individual adjustments during
installation of the Primary latch switch, Secondary
latch switch or Short switch to the door hook are
required.
2. When mounting the door hook assembly to the oven
assembly, adjust the door hook assembly by moving it in
the direction of the arrows in the illustration, so that the
oven door will not have any play in it. Check for play in the
door by pulling the door assembly. Make sure that the latch
keys move smoothly after adjustment is completed.
Completely tighten the screws holding the door hook
assembly to the oven assembly.
3. Reconnect the short switch and check the continuity of the
monitor circuit and all latch switches again by following the
component test procedures.
4.2. 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 using the simple method outlined below.
Necessary Equipment:
*1 liter beaker *Glass thermometer
*Wrist watch or stopwatch
NOTE:
Check the line voltage under load.Low voltage will
lower the magnetron output. Take the temperature
readings and heating time as accurately as possible.
1. Fill the beaker with exactly one liter of tap water.Stir the
water using the thermometer and record the water’s
temperature. (recorded as T1).
2. Place the beaker on the center of glass tray.
Set the oven for High power and heat it for exactly one
minute.
3. Stir the water again and read the temperature of the water.
(recorded as T2).
4. The normal temperature rise at High power level for each
model, is as shown in table.
TABLE (1L-1min.test)
RATED OUTPUT TEMPERATURE RISE
1000W Min. 8.6°C
1100W Min. 9.4°C
4 MEASUREMENTS AND ADJUSTMENTS
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5 EXPLODED VIEW AND PARTS LIST
5.1. EXPLODED VIEW
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