Panasonic NN-A774SBEPG User manual

MOP0408003S2
Microwave Oven
NN-A774SBEPG
NN-A734MBEPG
NN-A764WBEPG
NN-A764WBWPG
g
g
! 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 expe-
rienced 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

2
EPG
Power source 230 V AC Single Phase 50Hz
Power requirements Microwave 1250W
Grill 1350W
Convection 1470W
Combi 2770W
Output (IEC60705) Microwave 1000W
Grill1300W
Convection 1400W
Microwave frequency 2450Mhz
Timer 99 min 99 second
Oven cavity size 27L
Outside dimensions 510mm(W) x 477mm(D) X 304MM (H)
Inside dimensions 359mm(W) X 352mm(D) x 217mm(H)
Weight 15Kg
Specifications subject to change without notice
WPG
Power source 230 V AC Single Phase 50Hz
Power requirements Microwave 1260W
Grill 1360W
Convection 1470W
Combi 2150W
Output (IEC60705) Microwave 1000W
Grill1300W
Convection 1400W
Microwave frequency 2450Mhz
Timer 99 min 99 second
Oven cavity size 27L
Outside dimensions 510mm(W) x 477mm(D) X 304MM (H)
Inside dimensions 359mm(W) X 352mm(D) x 217mm(H)
Weight 15Kg
Specifications subject to change without notice

3
1 Contents
1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Feature Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Inverter Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Schematic Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7 Description of the Operation Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8 Cautions to be Observed when Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9 Part Replacement Proceedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
10 Component Test Proceedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
11 Measurements and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
12 Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
13 Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
14 Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
15 Door Assy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
16 Escutcheon Base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
17 Packing and Accesories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
18 Trim Kit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
19 Digital Programmer Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4
2FeatureChart
Function EPG Models
Microwave 4
Grill 1
Convection 17
Combi Yes
Weight Reheat 1
Weight Cook 4
Weight Combination 11
Weight Defrost 2
Weight Crisp 1
Delay / Stand Yes
Kg / lb No
Stage Cooking 1
Clock 24 h
Word prompt French, Dutch, English, German,
Italian, Spanish, Polish, no lan-
guage
Function WPG Model
Microwave 4
Grill 1
Convection 17
Combi Yes
Weight Reheat 1
Weight Cook 4
Weight Combination 9
Weight Defrost 2
Weight Crisp 0
Delay / Stand Yes
Kg / lb No
Stage Cooking 1
Clock 24 h
Word prompt French, German, English, Ital-
ian, no language

5
3 Control Panel
(1)
(2)
NN-A774/NN-A734/NN-A764*
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.

6
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 volt-
age charge even when the oven is not operating.
Warning
• Do not touch the high voltage circuit. When replac-
ing 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 volt-
age 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

7
5 Schematic Diagram
SW1
SW2
SW3
SW4
SW5
M
T
T
NOISE FILTER
NOISE FILTER
P240
P0
SECONDARY INTER-
SECONDARY INTER-
LOCK SWITCH
LOCK SWITCH
PRIMARY INTER-
PRIMARY INTER-
LOCK SWITCH
LOCK SWITCH
GROUNDING
GROUNDING
CHASSIS GROUND
CHASSIS GROUND
FUSE
FUSE
FAN MOTOR
FAN MOTOR
POWER RELAY
POWER RELAY
OVEN LAMP
OVEN LAMP
M
F
DIODE
RY1
L
VARISTOR
RY6
Note : Door is closed.
Note : Door is closed.
Unit is not operated
Unit is not operated
Y/G
BL
BR
2.0mH
4700pF
4700pF
4700pF
4700pF
AC230-240V
50Hz
75k
W
75k
W
2.2M
W
2.2M
W
2.0mH
SW3
L
MONITOR DEVICE
MONITOR DEVICE
TURN TABLE MOTOR
TURN TABLE MOTOR
M
TT
THERMAL CUT OUT
THERMAL CUT OUT
THERMAL CUT OUT
(OVEN)
(OVEN)
(MAGNETRON)
SW5
RY1
F
M
1
CN3
3
4
CN4
1
3SW4
CN5
CN6
P.C.B AU
2.2F Fm
2.2F Fm
16A
P.C.B DU
P.C.B DU
2
1
2
CN702
13CN703
F
FA
MAGNETRON
MAGNETRON
2M236-M42
321CN701
E701
INV.
INVERTER P.C.B.
INVERTER P.C.B.
RY4
HEATER
8A 0R 10A
8A 0R 10A
RY5
M
c
RY2
9511
RY3
73
RY6
DIGITAL PROGRAMMER CIRCUIT
DIGITAL PROGRAMMER CIRCUIT
( 8.00MHz )
( 8.00MHz )
CN1
SW1
1
CN7
3
2
Temperature sensor
SW2

8
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)
21
BL
SYMBOL COLOUR
BL BLUE
BK BLACK
BR BROWN
WH WHITE
YE YELLOW
N NATURAL
R RED
R

9
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 program-
mer 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 compo-
nents.
EPG MODEL
Auto weight defrost
Auto Weight Cook
WPG MODEL
Auto weight defrost
Category 1st Touch weight Cooking time
Defrost Small Pieces 300g 5 Min 40 Sec
Defrost Big Piece 600g 7 Min 30 Sec
Frozen Bred 100g 3 Min 55 Sec
Category 1st Touch volume/weight Cooking time
1. Cup 150cc 1 Min 20 Sec
2. Bowl 300cc 2 Min 20 Sec
3. Reheat Meal 500g 3 Min 35 Sec
4. Gratin 400g 12 Min 00 Sec
5. Fresh Vegetables 500g 12 Min 30 Sec
6. Fresh Fish 300g 4 Min 00 Sec
7. Chicken Pieces 500g 13 Min 00 Sec
8. Whole Chicken 1200g 21 Min 55 Sec
9. Pork 1000g 28 Min 20 Sec
10. Beef 800g 23 Min 25 Sec
11. Lamb 1200g 28 Min 00 Sec
12. Chilled Pizza 300g 8 Min 10 Sec
13. Frozen Pizza 200g 10 Min 00 Sec
14. Chilled Quiche 300g 6 Min 54 Sec
15. Frozen Quiche 300g 11 Min 30 Sec
16. Fries 300g 14 Min 00 Sec
Category 1st Touch weight Cooking time
Small Pieces 500g 6 Min 42 Sec
Big Pieces 1000g 21 Min 15 Sec
Frozen Bread and Rolls 50g 6 Min 00 Sec

10
Auto Weight Cook
Category 1st Touch weight Cooking time
1. Reheat 300g 3 Min 00 Sec
2. Frozen Reheat 300g 7 Min 00 Sec
3. Vegetables 500g 10 Min 20 Sec
4. Fish 500g 5 Min 00 Sec
5. Rice 200g 14 Min 45 Sec
6. Rice Pudding 600g 4 Min 00 Sec
7. Roast Pork 1000g 36 Min 20 Sec
8. Roast Beef 700g 16 Min 25 Sec
9. Poultry 500g 16 Min 15 Sec
10. Frozen Chicken Pieces 500g 23 Min 50 Sec
11. Jacket Potatoes 500g 14 Min 00 Sec
12. Fresh Lasagne Gratin 1000g 20 Min 20 Sec
13. Frozen Pizza 300g 12 Min 30 Sec
14. Frozen Potato products 300g 17 Min 00 Sec