John Lewis NN-GT578SBJQ OEM 27L JLFSMWG002, OEM 27LJLFSMWG002 Service Manual
HAD0901002C2
Microwave Oven
NN-GT578SBJQ
OEM 27L JLFSMWG002
NN-A764WBEPG
NN-A764WBWPG
! WARNING
This service information is designed for experienced repair technicians only and is not designed for use by the
general public. It does not contain warnings or cautions to advise non-technical individuals of potential dangers
in attempting to service a product. Products powered by electricity must be serviced or repaired only by experienced proffesional technicians. Any attempt to service or repair the product or products dealt with this service
information by anyone else could result in serious injury or death.
There are special components used in this equipment which are important for safety. These parts are marked
by (!) in the schematic diagrams, circuit board diagrams, exploded views and replacement parts lists. It is
essential that these critical parts are replaced with parts specified by the manufacturer, preventing shock, fire
or other hazards. Do not modify the original design without permission from the manufacturer.
IMPORTANT SAFETY NOTICE
© Panasonic Home Appliance Division. 2008
Unauthorized copying and distribution is a
violation of law.
2
1 Contents
1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Feature Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4 Inverter Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5 Schematic Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6 Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7 Description of the Operation Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8 Cautions to be Observed when Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9 Part Replacement Proceedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
10 Component Test Proceedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
11 Measurements and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
12 Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
13 Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
14 Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
15 Door Assy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
16 Escutcheon Base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
17 Packing and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
18 Digital Programmer Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Power source 240V AC Single Phase 50Hz
Power requirements Microwave 1260W
Grill 1360W
Convection 1470W
Convection + Grill 2770W
Micro + Grill Combi 2430W
Micro + Convection Combi 2550W
Micro + Grill + Convection Combi 2550W
Output (IEC60705) Microwave 1000W
Grill 1300W
Convection 1400W
Microwave frequency 2450Mhz
Timer 99 min 99 second
Oven cavity size 27L
Outside dimensions 510mm(W) x 477mm(D) X 304MM (H)
3
2Feature Chart
Function
Microwave 6
Grill 3
Convection 17
Combi Yes
Sensor Reheat Sensor Cook Sensor Combi Weight Defrost 3
Weight Combi 8
Weight Reheat 4
Weight Cook 2
Memory Cook Weight Crisp Stage Cooking 3 stage
Delay / Stand Yes
More / Less No
Kg -> lb/oz Yes
Clock 12h
Word Prompt English
Step by Step No
4
3 Control Panel
(1)
(2)
1min 10s
1h 10min
Combi
1-2-3
Panacrunch
AUTO /
g
g
(3)
(4)
(5)
(6)
(7)
(8)
(11)
(15)
(10)
(12)
(13)
(14)
(9)
(1) Display Window
(2) Time Pads
(3) Microwave Power Pad
(4) Grill Power Pad
(5) Convection Pad
(6) Grill Convection Pad
(7) Combination Pad
(8) Auto Defrost Pad
(9) Weight Select Pads
(10) Clock Pad
(11) Delay/Stand Pad
(12) Auto Weight Program Pads
(13) Panacrunch Program Pads
(14) Start Pad:
Press to start operating the oven.
If during cooking the door is opened or
Stop/Cancel Pad is pressed once, Start
Pad has to be pressed again to continue
cooking.
(15) Stop/Cancel Pad:
Before cooking: one press clears your
instructions.
During cooking: one press temporarily
stops the cooking program. Another press
cancels all your instructions and the time of
day will appear in the display.
*The design of your control panel may vary from
the panel displayed (depending on colour), but the
words on the pads will be the same.
5
4 Inverter Warnings
The inverter circuit board supplies the magnetron tube with a very high voltage (4000 volts).
Danger
• The inverter circuit board operates at high voltages
and high temperatures.
The Inverter PCB
• Operates at a very high voltage and current.
• Has an aluminium heat sink which becomes very
hot.
• Has capacitors in the circuitry that hold a high voltage charge even when the oven is not operating.
Warning
• Do not touch the high voltage circuit. When replacing the board care must be taken to avoid possible
electric shock.
• Do not touch the aluminium heat sink as it is part of
the high voltage circuit and becomes very hot.
• Do not attempt to repair the inverter PCB, this
can be very dangerous. Replace the high voltage inverter circuit as a complete unit.
• Do not adjust or tamper with the pre-set volume on
the inverter board. It is very dangerous to adjust
this pre-set without proper test equipment.
• Do not operate the microwave oven when the
inverter grounding plate and fixing screw is loose.
It is very dangerous to operate the inverter circuit
board without a proper ground connection.
figure 1Assembly of the inverter circuit board
HEAT SINK
RECTIFIER BRIDGE
CHOKE COIL
SAND BAR RESISTOR
CURRENT TRANSFORMER
HIGH VOLTAGE TRANSFORMER
PRESET VOLUME *4
(DO NOT ADJUST)
FILM CAPACITORS
HIGH VOLTAGE
DIODES
HIGH VOLTAGE
CAPACITORS
CN 702
CN 703
CN 701
CONTROL BOARD
WITH CUSTOM IC
PHOTOCOUPLER
DO NOT TOUCH
HOT/HIGH VOLTAGE *2
HIGH VOLTAGE AREA *1
H.V.INVERTER(U)
INVERTER SUPPORT BRACKET
GROUNDING BRACKET
6
5 Schematic Diagram
7
6 Wiring Diagram
R
NOTE WHEN REPLACIN ANY COMPONENT S RECONNECT THE WIRE HARNESS
ACCORDIN T O THE COLOURS BELOW
COL OURS INDICATED INSIDE BRACKETS () INDICATE THE COLOUR O
THE CONNECTOR HOUSIN
MA NETRON
HI H OL TA E IN ER TER
CAUTION
HEAT SINK
(HOTLIE)
ER Y HI H OL TA E
AND TEMPERATURE
BR
BR
BR
OR
1C2
PRIMARY LATCH SWITCH
TOP
(WH)
WH
WH
SECONDARY LATCH SWITCH
OUTSIDEBOTTOM
BR
(N)
(YE)
YE
SHORT SWITCH
INSIDEBOTTOM
YE
BL
POWER RELAY
(RY1)
(N)
2
1
BL
SYMBOL COLOUR
BL BLUE
BK BLACK
BR BROWN
WH WHITE
YE YELLOW
N NATURAL
R RED
R
8
7 Description of the Operating Sequence
7.1 Variable power cooking control
The output power is controlled by the inverter power
supply. The level of output from the inverter circuit is
controlled by a pulse width modulated signal from the
digital programmer circuit (DPC). The digital programmer circuit operates relay RY1 to supply power to the
inverter circuit.
NOTE: If the microwave cooking time is longer than 3
minutes, the cooling fan will operate for 1 minute to
cool the oven and its electronic components.
7.2 Auto weight defrost, Auto weight
Cook
When an auto control feature is selected and the start
pad pressed:
1. The digital programmer circuit determines the
power level and the cooking time and indicates the
operating state in the display. The table shows the
corresponding cooking times and weights for the
selected category.
2. When the cooking time in the display window has
elapsed, the oven turns off automatically via the
control signal from the digital programmer circuit.
Note: After auto cooking if the oven temperature
is over the predetermined temperature the fan
motor rotates to cool the oven and its components.
Auto weight defrost
Auto Weight Cook
Category 1st Touch weight Cooking time
Defrost Small Pieces - Meat 150g 2 Min 23 Sec
Defrost Big Pieces - Meat 400g 7 Min 00 Sec
Frozen Bread 200g 0 Min 50 Sec
Category 1st Touch volume/weight Cooking time
Cup 150cc 1 Min 20 Sec
Bowl 300cc 2 Min 20 Sec
Curry 300g 3 Min 45 Sec
Chinese style 200g 3 Min 08 Sec
Fresh vegetables 100g 2 Min 20 Sec
Fresh fish 100g 1 Min 10 Sec
Jacket potatoes 200g 8 Min 00 Sec
Whole chicken 1000g 19 Min 30 Sec
Chicken portions 200g 8 Min 00 Sec
Frozen potato products 100g 9 Min 38 Sec
Chilled pizza 100g 7 Min 10 Sec
Frozen pizza 100g 5 Min 20 Sec
Chilled crispy top 300g 8 Min 30 Sec
Frozen crispy top 300g 10 Min 00 Sec
Reheat pastry 100g 5 Min 20 Sec
Chilled quiche 100 4 Min 58 Sec
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