Panasonic NE-2156 User manual

©2001 Matsushita Electric Industrial Co., Ltd. All
rights reserved. Unauthorized copying and
distribution is a violation of law.
NE-2156
NE-2146
NE-1656
Microwave Oven
ORDER NO. MOD0108246C2

1 OUTLINE DIAGRAM 3
2 OPERATION PROCEDURE (NE-2156/NE-1656) 5
3 OPERATION PROCEDURE (NE-2146) 10
4 SCHEMATIC DIAGRAM NE-2146 11
5 SCHEMATIC DIAGRAM NE-2156/NE-1656 12
6 WIRING DIAGRAM 13
7 DESCRIPTION OF OPERATING SEQUENCE 14
8 CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING
14
9 DISASSEMBLY AND PARTS REPLACEMENT PROCEDURE 15
10 COMPONENT TEST PROCEDURE 19
11 MEASUREMENTS AND ADJUSTMENTS 21
12 TROUBLESHOOTING GUIDE 22
13 EXPLODED VIEW AND PARTS LIST 23
14 PARTS LIST 24
15 DOOR ASSEMBLY 27
16 ESCUTCHEON BASE ASSEMBLY 28
17 PACKING AND ACCESSORIES 30
18 WIRING MATERIAL 31
19 DIGITAL PROGRAMMER CIRCUIT 32
20 DIGITAL PROGRAMMER CIRCUIT 34
CONTENTS
Page Page
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1 OUTLINE DIAGRAM
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4
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2 OPERATION PROCEDURE (NE-2156/NE-1656)
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6
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7
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3 OPERATION PROCEDURE (NE-2146)
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4 SCHEMATIC DIAGRAM NE-2146
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5 SCHEMATIC DIAGRAM NE-2156/NE-1656
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6 WIRING DIAGRAM
NOTE: When replacing, check the lead wire colour as shown.
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Variable power cooking control
The coil of power relay A and B are energized intermittently by
the digital programmer circuit, when the oven is set to MEDIUM
or DEFROST power position. The digital programmer circuit
controls the ON-OFF time of the power relay A and B contacts
Unlike many other appliances, the microwave oven is high
voltage, high current equipment. Though it is free from danger
in ordinary use, extreme care should be taken during repair.
CAUTION
Servicemen should remove their watches whenever working close to
or replacing the magnetron.
8.1. Check the earthing
Do not operate on a 2 wire extension cord. The microwave
oven is designed to be used in a completely earthed condition.
It is imperative, therefore, to make sure it is properly earthed
before beginning repair work.
in order to vary the output power of the microwave oven. One
complete ON and OFF cycle of the power relay is 44 seconds.
The relation between indications on the control panel and the
output power of the microwave oven is as shown in Figure.
8.2. If the door lock, the door
switch, the door seal or the
door develops a malfunction,
be sure not to operate the
oven until complete repairs
are made.
If the oven is operated with any of these parts in imperfect
condition, hazardous microwave leakage might occur.
WARNING
Never operate the oven until the following are confirmed:
1. The door is tightly closed.
2. There is no broken hinge or door arm.
3. The door seal is not damaged.
4. The door is not bent or warped.
5. There is no other visible damage.
7 DESCRIPTION OF OPERATING SEQUENCE
8 CAUTIONS TO BE OBSERVED WHEN
TROUBLESHOOTING
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8.3. Warning about the electric
charge in the high voltage
capacitor.
For about 30 seconds after the oven is turned off, an electric
charge remains in the high voltage capacitor. When replacing
or checking parts, remove the power plug from the outlet, wait
30 seconds and short the terminal of the high voltage capacitor
(terminal of lead wire from diode) to chassis ground with an
insulated jumper lead wire or an insulated handle screwdriver
to discharge.
Important Note
1. High voltage above 250 volts are existing on following parts during
operation.
· Magnetron
· High Voltage Transformer
· High Voltage Diode
· High Voltage Capacitor
Unusual attention should be paid during repair or
troubleshooting of product.
2. If the microwave oven is operated with incorrect installed door
hinge or magnetron, it can cause microwave leakage of over
5mW/sequar centimeter. Hence it is absolutely necessary to
check if magnetron and door hinge are correctly and safely
installed after repairs or replacement.
CAUTION
Servicemen should remove their watches whenever working close to
or replacing the magnetron.
9.1. Replacement of magnetrons
(Upper and Lower)
Upper magnetron
WARNING
Never touch any circuit wiring with your hand nor with an insulated tool
during operation.
8.4. When parts must be replaced,
always remove the power plug
from the outlet, and discharge
the high voltage capacitor.
8.5. Confirm after repair
1. After repair or replacement of parts, make sure that the
screws of the oven, etc. are neither loose nor missing.
Microwave 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.
8.6. Avoid inserting nails, wire, etc.
through holes in unit during
operation.
Never insert a wire, nail or any other metal object through the
lamp holes on the cavity or any other holes or gaps, because
such objects may work as an antenna and cause microwave
leakage.
8.7.
CAUTION MICROWAVE RADIATION
Personnel should not be exposed to the microwave energy which may
radiate from the magnetron or other microwave generating device if it
is improperly used or connected all input and output microwave
connections waveguides, flanges, and gasket must be secure. Never
operate the device without a microwave energy absorbing load
attached. Never look into an open waveguide or antenna while the
device is energized.
8.8.
CAUTION
High voltage parts may become uncovered when outer cabinet is
removed.
1. Discharge electric charge remaining on the high voltage
capacitors.
2. Remove the entire rear panel by removing screws as
shown.
3. Disconnect all lead wires from magnetron and thermal
cutout.
4. Remove the 4 screws holding magnetron.
9 DISASSEMBLY AND PARTS REPLACEMENT
PROCEDURE
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5. Remove 2 screws holding thermal cutout.
6. Remove the mounting bracket from magnetron and install it
on the new magnetron.
Lower magnetron
1. Discharge electric charge remaining on the high voltage
capacitors.
2. Remove the entire rear panel by removing screws as
shown.
3. Carefully place the unit on its left side (H.V.Capacitor side).
4. Remove the cover by removing 2 screws.
5. Remove the 4 screws holding magnetron by inserting
screwdriver through the 4 openings on bottom plate.
6. Remove 2 screws holding thermal cutout.
7. Remove the mounting bracket from magnetron and install it
on the new magnetron.
NOTE:
To prevent microwave leakage, tighten mounting
screws properly making sure there is no gap between
the waveguide and the magnetron.
CAUTION
When connecting 2 filament lead wires to the magnetron terminals, be
sure to connect the lead wires in the correct position. The lead wire
with blue connector should be connected to “FA terminal” and white or
pink one should be connected to “F terminal”.
Removal of Positive Lock connector
The positive lock connector is a specially designed loose free
connector and you will find this connector in many lead wire
connections. To remove this connector, pull the lead wire by
pressing an extruded lever in the center of receptacle terminal
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as shown.
9.2. Replacement of power supply
circuit board
NOTE:
Be sure to ground any static electric charge built up on
your body, before handling the power supply P.C.B.
and D.P.C..
1. Disconnect all lead wires from power supply circuit board.
2. Remove the power supply P.C.B. together with its mounting
bracket by first removing the 2 bracket holding screws.
3. The power supply P.C.B. can be separated from mounting
bracket by removing the 2 L.V.T. holding screws and
unfastening the plastic clips.
9.3. Replacement of digital
programmer circuit board
1. Remove grounding screw for membrane switch and D.P.C.
ground.
2. Remove 3 screws holding control panel assembly to detach
it from main unit then remove connectors.
3. Remove 2 screws holding the D.P.C. board and while
pushing back on 2 plastic holding clips, remove the board.
NOTE:
Please use care in handling the power supply P.C.B.
and D.P.C. board to avoid damage.
9.4. Replacement of upper antenna
CAUTION
The upper and lower rotating antennas are different type and are not
interchangeable each other. Care should be taken not to reverse the
top and bottom antennas.
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1. Remove ceiling plate by gently moving the left and right
tabs inward while pulling the plate down and outward.
2. Using a small flat screwdriver or the like, remove two plastic
clips located on the antenna ring. Next turn the antenna ring
approx. 1/8 turn clockwise to unhook the tabs and pull off.
9.5. Replacement of floor shelf and
lower antenna
1. To remove the floor shelf, insert a screwdriver through the
small opening on the left side of the oven cavity and
carefully lift the floor shelf.
2. For removal of lower antenna, use the same procedure as
upper antenna.
9.6. Replacement of temperature
sensor (Thermal protector)
1. Cut 2 lead wires at the top of sensor terminals.
2. Remove 2 screws holding temp sensor and replace with
new one.
3. Solder the lead wires securely to the sensor terminals.
9.7. Disassembly of door assembly
1. Remove each 2 bolts holding upper and lower hinges.
2. Open the door and while pulling the door outward, work
upper and lower hinges out through the holes of the front
surface of oven.
3. Remove door C (choke cover) from door E by carefully
pulling outward starting from the upper right hand corner.
4. Remove 2 screws holding door handle and separate door A
from door E by carefully freeing catch hooks.
5. Remove door key, door key lever, door key spring and
handle pins from door E.
6. Assemble the door by taking the above steps in a reverse
order.
Replacement
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1. When mounting the door to the oven be sure to adjust the
door parallel to the bottom line of the oven face plate by
moving the upper hinge and lower hinge in the direction
necessary for proper alignment.
2. Adjust so that the door has no play between the inner door
surface and oven front surface. If the door assembly is not
mounted properly, microwave may leak from the clearance
between the door and the oven.
NOTE:
Please refer to MEASURENMENT AND ADJUSTMENT.
CAUTION
1. High voltage is present at the high voltage terminal of the high
voltage transformer during any cook cycle.
2. It is neither necessary nor advisable to attempt measurement of
the high voltage.
3. Before touching any oven components, or wiring, always unplug
the oven from its power source and discharge the high voltage
capacitor.
10.1. High voltage transformer
1. Remove connections from the transformer terminals and
check continuity.
2. Normal (cold) resistance readings should be as follows:
Secondary winding Approx. 80Ω— 120Ω
Filament winding Approx. 0Ω
Primary winding Approx. 0Ω—3Ω
10.2. High voltage capacitor
1. Check continuity of capacitor with meter on highest OHM
scale.
10 COMPONENT TEST PROCEDURE
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2. A normal capacitor will show continuity for a short time, and
then indicate 9MΩonce the capacitor is charged.
3. A shorted capacitor will show continuous continuity.
4. An open capacitor will show constant 9MΩ.
5. Resistance between each terminal and chassis should be
infinite.
10.3. Magnetron
Continuity checks can only indicate an open filament or a
shorted magnetron. To diagnose for an open filament or
shorted magnetron.
1. Isolate magnetron from the circuit by disconnecting the
leads.
2. A continuity check across magnetron filament terminals
should indicate one ohm or less.
3. A continuity check between each filament terminal and
magnetron case should read open.
10.4. Diode
1. Isolate the diode from the circuit by disconnecting the leads.
2. With the ohmmeter set on the highest resistance scale,
measure the resistance across the diode terminals.
Reverse the meter leads and again observe the resistance
reading. Meter with 6V, 9V or higher voltage batteries
should be used to check the front-to-back resistance of the
diode, otherwise an infinite resistance may be read in both
directions. A normal diode’s resistance will be infinite in one
direction and several hundred kΩin the other direction.
10.5. Membrane key board
(Membrane switch assembly)
Check continuity between switch terminals, by tapping an
appropriate pad on the key board. The contacts assignment of
the respective pads on the key board is as shown in digital
programmer circuit.
10.6. Protector diode
1. Isolate the protector diode assembly from the circuit by
disconnecting its leads.
2. With the ohmmeter set on the highest resistance scale,
measure the resistance across the protector diode
terminals. Reverse the meter leads and again observe the
resistance reading. A normal protector diode’s resistance
will be infinite in both directions. It is faulty if it shows
continuity in one or both directions.
10.7. Temp sensor (Thermal
protector)
A temp sensor is mounted on exhaust guide. Its purpose is to
automatically shut off the oven in case the cavity overheats for
any reason.
The thermal protector will operate at 257°F (125°C).
The device is connected to the DPC on touch control models.
When the thermal protector exceeds its temperature it will turn
off the power to oven cavity and display will go to reset mode.
The cooking program can be reset after cool-down.
THERMISTOR RESISTANCE VALUE
30K—120K at 10°C-30°C (50°F — 86°F)
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