Sharp Carousel R-310AK User manual

SUPPLEMENTAL SERVICE MANUAL
SHARP ELECTRONICS CORPORATION
Service Headquarters: Sharp Plaza, Mahwah, New Jersey 07430-2135
R-310AK
R-330AK
R-330AW
TABLE OF CONTENTS
Page
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICE TO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY ...................INSIDE FRONT COVER
BEFORE SERVICING ......................................................................................................INSIDE FRONT COVER
FOREWORD.....................................................................................................................INSIDE FRONT COVER
TEST PROCEDURE ..............................................................................................................................................1
TOUCH CONTROL PANEL ASSEMBLY ..............................................................................................................3
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..................................................................9
PICTORIAL DIAGRAM ........................................................................................................................................10
POWER UNIT CIRCUIT ......................................................................................................................................11
CPU UNIT CIRCUIT ............................................................................................................................................13
PRINTED WIRING BOARD OF POWER UNIT ...................................................................................................15
PARTS LIST FOR CONTROL PANEL ................................................................................................................16
INFORMATION FOR PARTS CHANGING ..........................................................................................................17
S1702R330APK/
MICROWAVE OVEN
FOR OVENS FROM JANUARY 1997 PRODUCTION
MODELS R-310AK
R-330AK
R-330AW
Intheinterestofuser-safetytheovenshouldberestoredtoitsoriginalconditionand
only parts identical to those specified should be used.
This is a supplemental Service Manual for Models R-310A K, R-330A K and R-330AW.
This supplemental service manual is mainly described the touch control panel parts information for the ovens from
January 1997 production. Use this supplemental manual together with the Base Model Service Manual (Refer No.
is S8605R330APK/) for complete operation, service information, etc..

R-310AK
R-330AK
R-330AW
PRECAUTIONSTO BE OBSERVED BEFORE AND
DURING SERVICINGTO AVOID POSSIBLE
EXPOSURETO EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open.
(b) Make the following safety checks on all ovens to be serviced before activating the magnetron or other
microwave source, and make repairs as necessary: (1) interlock operation, (2) proper door closing, (3) seal
and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and latches, (5)
evidence of dropping or abuse.
(c) Before turning on microwave power for any service test or inspection within the microwave generating
compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment,
integrity, and connections.
(d) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and
transmission systems shall be repaired, replaced, or adjusted by procedures described in this manual before
the oven is released to the owner.
(e) A microwave leakage check to verify compliance with the Federal Performance Standard should be performed
on each oven prior to release to the owner.
BEFORE SERVICING
Beforeservicinganoperativeunit,performamicrowaveemissioncheckaspertheMicrowaveMeasurement
Procedure outlined in this service manual.
If microwave emissions level is in excess of the specified limit, contact SHARP ELECTRONICS CORPO-
RATION immediately @1-800-237-4277.
If the unit operates with the door open, service person should 1) tell the user not to operate the oven and
2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's Center for
Devices and Radiological Health immediately.
Service personnel should inform SHARP ELECTRONICS CORPORATION of any certified unit found with
emissionsinexcessof4mW/cm2.Theowneroftheunitshouldbeinstructednottousetheunituntiltheoven
has been brought into compliance.
SERVICE MANUAL
MICROWAVE OVEN
R-310AK/ R-330AK/ R-330AW
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp. Service Personnel with Operation and Service
Information for the SHARP MICROWAVE OVENS, R-310AK, R-330AK, R-330AW.
Itis recommendedthat servicepersonnel carefullystudythe entiretext ofthis manualsothat theywill bequalified torender
satisfactory customer service.
Check the interlock switches and the door seal carefully. Special attention should be given to avoid electrical shock and
microwave radiation hazard.
This supplemental service manual contains update information only. Please refer to base model service manual
(Refer No. is S8605R330APK/) for complete service information.

1
R-310AK
R-330AK
R-330AW
JTOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter
and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key
Unit, and also the Control Unit is divided into two units, CPU Unit and Power Unit, and troubleshooting
by replacement is described according to the symptoms indicated.
1. Key Unit. Note : Check key unit ribbon connection before replacement.
The following symptoms indicate a defective key unit. Replace the key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
2. Control Unit
Thefollowingsymptoms indicateadefectivecontrolunit. Beforereplacingthecontrolunit,perform
the Key unit test (Procedure K) to determine if control unit is faulty.
2-1 In connection with pads.
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
2-2 In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
Note:Whendefectivecomponents,thePowerUnitorKeyUnitarereplaced,thedefectivepartorparts
mustbe properlypacked forreturn inthe shippingcarton, withits cushionmaterial, inwhich the
new replacement part was shipped to you.
L RELAY TEST
Remove the outer case and check voltage between Pin No. 3 of the 2 pin connector (A) and the common
terminal of the relay RY2 on the control unit with an A.C. voltmeter.
The meter should indicate 120 volts, if not check oven circuit.
RY1 and RY2 Relay Test
These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.
DC. voltage indicated ............. Defective relay.
DC.voltagenot indicated ........Check diodewhichisconnectedto the relaycoil. Ifdiodeisgood,control
unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS
R-330AK/AW R-310AK
RY1 Approx. 24.5V D.C. Approx. 14.0 D.C. Oven lamp / Turntable motor / Cooling fan motor
RY2 Approx. 24.0V D.C. Approx. 12.8 D.C. Power transformer
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST

2
R-310AK
R-330AK
R-330AW
RY2
a
b
cd
HVT
AC
(COM)
VH
XH
3
3
CN - A
(J1)
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the
PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide given
below for repair.
Problem: POWER ON, indicator does not light up.
STEPS OCCURRENCE CAUSE OR CORRECTION
1 The rated AC voltage is not present between Check supply voltage and oven power cord.
Pin No. 3 of the 2-pin connector (A) and the
common terminal of the relay RY2.
2 The rated AC voltage is present at primary Low voltage transformer or secondary circuit defective.
side of low voltage transformer. Check and repair.
3 Only pattern at "a" is broken. *Insert jumper wire J1 and solder.
4 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".
NOTE:*At the time of making these repairs,
makeavisualinspectionofthevaristor.
Check for burned damage and exam-
ine the transformer with a tester for the
presence of layer short-circuit (check
the primary coil resistance which is ap-
proximately212Ω±10%(forR-330AK/
AW), 563Ω±10% (for R-310AK)). If
any abnormal condition is detected,
replace the defective parts.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
N PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN

3
R-310AK
R-330AK
R-330AW
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power Unit and
CPU Unit).
The principal functions of these units and the signals com-
municated among them are explained below.
Key Unit (R-330AK/AW)
The key unit is composed of a matrix, signals generated in
the LSI are sent to the key unit through P20 - P27.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P74 - P77
to perform the function that was requested.
Key Unit (R-310AK)
The key unit is composed of a matrix, signals generated in
the LSI are sent to the key unit through P73, P81, P82, P83,
P90 and P91.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P60 - P63
to perform the function that was requested.
Control Unit
Control unit consists of LSI, ACL circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchroniz-
ing signal circuit, absolute humidity sensor circuit and back
light circuit.
1) ACL
This circuit generates a signal which resets the LSI to the
initial state when power is supplied.
2) Indicator Circuit (R-330AK/AW)
This circuit consists of 25 segments and 4 common elec-
trodes using a Liquid Crystal Display.
2) Indicator Circuit (R-310AK)
This circuit consists of 12 segments and 3 common elec-
trodes using a Liquid Crystal Display.
3) Power Source Circuit
This circuit generates voltages necessary in the control
unit from the AC line voltage.
Inaddition,thesynchronizing signal is availableinorderto
compose a basic standard time in the clock circuit.
Symbol Voltage Application
VC -5.3V LSI(IC1)
4) Relay Circuit
Acircuit todrivethemagnetron, fanmotor,turntablemotor
and light the oven lamp.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion sound).
6) Synchronizing Signal Circuit
Thepowersourcesynchronizingsignalisavailableinorder
to compose a basic standard time in the clock circuit.
It accompanies a very small error because it works on
commercial frequency.
7) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1-
LD5).
9) Absolute Humidity Sensor Circuit (R-330AK/AW)
Thiscircuitdetectsmoistureofthecookingfoodtoallowits
automatic cooking.

4
R-310AK
R-330AK
R-330AW
A
B
0.1 sec.
2 sec.
H : GND
L : -5V
H : GND
L : -5V
16.7 msec.
During cooking
H : GND
L : -5V
P-HI
H : GND
L : -5V
H : GND
L : -5V
P-70
ON
ON
OFF
OFF OFF
24 sec.
8 sec.
16.7 msec.
H : GND
L : -5V
DESCRIPTION OF LSI
LSI(IZA757DR) : R-330AK/AW
The I/O signal of the LSI(IZA757DR) is detailed in the following table.
Pin No. Signal I/O Description
1 C1 IN Terminal not used.
2 VL1 IN Power source voltage input terminal.
Standard voltage for LCD.
3-6 AN7-AN4 IN Terminal to change cooking constant according to the Model.
By using the A/D converter contained in the LSI, DC voltage in accordance with the Model
in operation is applied to set up its cooking constant.
7 AN3 OUT Terminal not used.
8 AN2 IN To input signal which communicates the door open/close information to LSI.
Door closed; “H” level signal (0V).
Door opened; “L” level signal (-5V).
9 AN1 IN AH sensor input.
This input is an analog input terminal from the AH sensor circuit, and connected to the A/D
converter built into the LSI.
10 AN0 IN Used for initial balancing of the bridge circuit (absolute humidity sensor). This input is an
analoginputterminalfromtheAHsensorcircuit,andconnectedtotheA/Dconverterbuiltinto
the LSI.
11-13 P57-P55 OUT Terminal not used.
14 P54 OUT Signal to sound buzzer (2.0KHz).
A: key touch sound.
B: Completion sound.
15-18 P53-P50 OUT Terminal not used.
19-23 P47-P43 OUT Used for initial balancing of the bridge circuit (absolute humidity sensor).
24 INT0 IN Signal synchronized with commercial power source frequency.
This is basic timing for time processing of LSI.
25-26 P41-P40 OUT Terminal not used.
27 P77 IN Signal coming from touch key.
When either G12 line on key matrix is touched, a corresponding signal out of P20 - P27 will
be input into P77. When no key is touched, the signal is held at “H” level.
28 P76 IN Signal similar to P77.
WheneitherG11lineonkey matrix is touched, a correspondingsignalwillbeinput intoP76.
29 P75 IN Signal similar to P77.
WheneitherG10lineonkey matrix is touched, a correspondingsignalwillbeinput intoP75.
30 P74 IN Signal similar to P77.
When either G9 line on key matrix is touched, a corresponding signal will be input into P74.
31 P73 OUT Oven lamp, fan motor and turntable motor driving signal.
To turn on and off shut off relay (RY1). The
square waveform voltage is delivered to the
RY1 driving circuit and RY2 control circuit.
32 P72 OUT Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay (RY2). The
signals holds “L” level during microwave cook-
ing and “H” level while not cooking. In other
cooking modes (variable cooking) the signal
turns to “H” level and “L” level in repetition
according to the power level.

5
R-310AK
R-330AK
R-330AW
Pin No. Signal I/O Description
33 P71 OUT Terminal not used.
34 P70 IN Connected to VC.
35 RESET IN Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied. Temporarily set to
“L”levelthemomentpowerisapplied,atthistimetheLSIisreset.Thereaftersetat“H”level.
36-37 P81-P80 OUT Terminal not used.
38 XIN IN Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with
respect to XIN terminal.
39 XOUT OUT Internal clock oscillation frequency control output.
Output to control oscillation input of XOUT.
40 VSS IN Power source voltage : -5.1V.
VC voltage of power source circuit input.
41 P27 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G8 line keys on key matrix is touched.
42 P26 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G7 line keys on key matrix is touched.
43 P25 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G6 line keys on key matrix is touched.
44 P24 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G5 line keys on key matrix is touched.
45 P23 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G4 line keys on key matrix is touched.
46 P22 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G3 line keys on key matrix is touched.
47 P21 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G2 line keys on key matrix is touched.
48 P20 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal while one
of G1 line keys on key matrix is touched.
49-50 P17-P16 OUT Terminal not used.
51-62 SEG39-SEG28 OUT Terminal not used.
63-66 SEG27-SEG24 OUT Segment data signal. Connected to LCD.
The relation between signals are as follows:
LSI signal (Pin No.) LCD (Pin No.) LSI signal (Pin No.) LCD (Pin No.)
SEG 27 (63) ........................ S0 SEG 12 (78)..........................S5
SEG 26 (64) ........................ S1 SEG 11 (79)..........................S6
SEG 25 (65) ........................ S2 SEG 10 (80)..........................S7
SEG 24 (66) ........................ S3 SEG 9 (81)...........................S8
SEG 22 (68) ........................ S4 SEG 8 (82)...........................S9
SEG 21 (69) ...................... S26 SEG 6 (84).........................S10
SEG 20 (70) ...................... S25 SEG 5 (85).........................S11
SEG 19 (71) ...................... S24 SEG 4 (86).........................S12
SEG 18 (72) ...................... S23 SEG 3 (87).........................S13
SEG 17 (73) ...................... S22 SEG 2 (88).........................S14
SEG 16 (74) ...................... S21 SEG 1 (89).........................S15
SEG 14 (76) ...................... S20 SEG 0 (90).........................S16
SEG 13 (77) ...................... S19

6
R-310AK
R-330AK
R-330AW
Pin No. Signal I/O Description
LSI(IZA758DR) : R-310AK
The I/O signal of the LSI(IZA758DR) is detailed in the following table.
Pin No. Signal I/O Description
67 SEG23 OUT Terminal not used.
68-74 SEG22-SEG16 OUT Segment data signal.
Signal similar to SEG27.
75 SEG15 OUT Terminal not used.
76-82 SEG14-SEG8 OUT Segment data signal.
Signal similar to SEG27.
83 SEG7 OUT Terminal not used.
84-90 SEG6-SEG0 OUT Segment data signal.
Signal similar to SEG27.
91/92 VCC/VREF IN Connected to GND.
93 AVSS IN Connected to VC.
94 COM3 OUT Common data signal: COM3.
Connected to LCD (Pin No. C0).
95 COM2 OUT Common data signal: COM2.
Connected to LCD (Pin No. C1).
96 COM1 OUT Common data signal: COM1.
Connected to LCD (Pin No. C2).
97 COM0 OUT Common data signal: COM0.
Connected to LCD (Pin No. C3).
98-99 VL3-VL2 IN Power source voltage input terminal.
Standard voltage for LCD.
100 C2 IN Terminal not used.
1-12 SEG0-SEG11 OUT Segment data signal.
Connected to LCD.
The relation between signals are as follows:
LSI signal (Pin No.) LCD (Pin No.) LSI signal (Pin No.) LCD (Pin No.)
SEG 0 (1) ...................................S12 SEG 6 (7) ....................................S6
SEG 1 (2) ...................................S11 SEG 7 (8) ....................................S5
SEG 2 (3) ...................................S10 SEG 8 (9) ....................................S4
SEG 3 (4) .....................................S9 SEG 9 (10) ..................................S3
SEG 4 (5) .....................................S8 SEG 10 (11) ................................S2
SEG 5 (6) .....................................S7 SEG 11(12) .................................S1
13 R60 IN Signal coming from touch key.
WheneitherG12 line onkeymatrixistouched,a corresponding signaloutofR73,R81-R83
and R90-R91 will be input into R60. When no key is touched, the signal is held at "H" level.
14 R61 IN Signal similar to R60.
WheneitherG11lineonkeymatrixistouched,acorrespondingsignalwillbeinputintoR61.
15 R62 IN Signal similar to R60.
WheneitherG10lineonkeymatrixistouched,acorrespondingsignalwillbeinputintoR62.
16 R63 IN Signal similar to R60.
Wheneither G9lineon key matrixis touched, acorresponding signal willbeinput intoR63.
17 AIN0 IN To input signal which communicates the door open/close information to LSI.
Door close "H" level signal (0V). Door open "L" level (-5V)
18-20 AIN1-AIN3 IN Terminal to change functions according to the Model.
By using the A/D converter contained in the LSI, DC voltage in accordance with the Model
in operation is applied to set up its function.
21 VSS IN Power source voltage: -5V
VSS voltage of power source circuit input.

7
R-310AK
R-330AK
R-330AW
Pin No. Signal I/O Description
A
B
0.1 sec.
2 sec.
H : GND
L : -5V
H : GND
L : -5V
16.7 msec.
During cooking
H : GND
L : -5V
16.7 msec.
H : GND
L : -5V
P-HI
H : GND
L : -5V
H : GND
L : -5V
P-70
ON
ON
OFF
OFF OFF
24 sec.
8 sec.
22 R70 OUT Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay (RY2). The
signalsholds"L"levelduringmicrowavecooking
and "H" level while not cooking. In other cooking
modes (variable cooking) the signal turns to "H"
level and "L" level in repetition according to the
power level.
(ON and OFF times for other power level.)
23 PULSE OUT Signal to sound buzzer (2.0 kHz).
A: key touch sound.
B: Completion sound.
24 R72 OUT Oven lamp, fan motor and turntable motor driving signal
To turn on and off shut off relay (RY1). The
square waveform voltage is delivered to the
RY1 driving circuit and RY2 control circuit.
25 R73 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to R60 - R63 terminal while one
of G8 line keys on key matrix is touched.
26 INT2 IN Signal synchronized with commercial power source frequency.
This is the basic timing for time processing of LSI.
27 R81 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to R60 - R63 terminal while one
of G7 line keys on key matrix is touched.
28 R82 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to R60 - R63 terminal while one
of G6 line keys on key matrix is touched.
29 R83 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to R60 - R63 terminal while one
of G5 line keys on key matrix is touched.
30 R90 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to R60 - R63 terminal while one
of G4 line keys on key matrix is touched.
31 R91 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to R60 - R63 terminal while one
of G3 line keys on key matrix is touched.
32 R92 OUT Terminal not used.
33 XIN IN Internal clock oscillation frequency setting input.
The internal clock frequency is set by inserting the capacitor and resistor circuit with respect
to XOUT terminal.
34 XOUT OUT Internal clock oscillation frequency control output.
Output to control oscillation input of XIN.
35 RESET IN Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is supplied. Temporarily set "L"
level the moment power is supplied, at this time the LSI is reset. Thereafter set at "H" level.
36 HOLD IN/OUT Connected to GND.
37 VLC IN Signal synchronized with commercial power source frequency.
Signal similar to VSS.
38 COM1 OUT Common data signal: COM1.
Connected to LCD (Pin No. C1)
39 COM2 OUT Common data signal: COM2.
Connected to LCD (Pin No. C2)

8
R-310AK
R-330AK
R-330AW
(1) Structure of Absolute Humidity Sensor
The absolute humidity sensor includes two thermistors as
shown in the illustration. One thermistor is housed in the
closed vessel filled with dry air while another in the open
vessel. Each sensor is provided with the protective cover
made of metal mesh to be protected from the external
airflow.
(2) Operational Principle of Absolute Humidity Sensor
The figure below shows the basic structure of an absolute
humiditysensor.Abridgecircuitisformedbytwothermistors
and two resistors (R1 and R2).
The output of the bridge circuit is to be amplified by the
operational amplifier.
Each thermistor is supplied with a current to keep it heated
at about 150˚C (302˚F), the resultant heat is dissipated in
the air and if the two thermistors are placed in different
humidity conditions they show different degrees of heat
conductivityleadingtoapotentialdifferencebetweenthem
causing an output voltage from the bridge circuit, the
intensity of which is increased as the absolute humidity of
the air increases. Since the output is very minute, it is
amplified by the operational amplifier.
(3) Detector Circuit of Absolute Humidity Sensor Circuit
This detector circuit is used to detect the output voltage of
the absolute humidity circuit to allow the LSI to control
sensorcookingoftheunit. Whentheunitissetinthesensor
cooking mode, 16 seconds clearing cycle occurs than the
detector circuit starts to function and the LSI observes the
initial voltage available at its AN1 terminal.
Withthisvoltagegiven,theswitchesSW1toSW5intheLSI
are turned on in such a way as to change the resistance
valuesinparallelwithR107~R111.Changingtheresistance
values results in that there is the same potential at both F-
3terminaloftheabsolutehumiditysensorandAN0terminal
of the LSI. The voltage of AN1 terminal will indicate about
-2.5V. Thisinitialbalancingissetupabout16secondsafter
the unit is put in the Sensor Cooking mode. As the sensor
cooking proceeds, the food is heated to generate moisture
by which the resistance balance of the bridge circuit is
deviated to increase the voltage available at AN1 terminal
of the LSI.
Then the LSI observes that voltage at AN1 terminal and
compares it with its initial value, and when the comparison
rate reaches the preset value (fixed for each menu to be
cooked), the LSI causes the unit to stop sensor cooking;
thereafter,theunitgoesinthenextoperationautomatically.
When the LSI starts to detect the initial voltage at AN1
terminal 16 seconds after the unit has been put in the
SensorCookingmode,ifitisnotpossibletobalance,ofthe
bridgecircuit due todisconnectionofthe absolute humidity
sensor,ERROR will appearonthe displayandthe cooking
is stopped.
1) Absolute humidity sensor circuit
ABSOLUTE HUMIDITY SENSOR CIRCUIT (R-330AK/AW)
C
S
R3
R1
R2
+
-
Operational
amplifier Output
voltage
S : Thermistor
open vessel
C : Thermistor
closed vessel
2
Absolute humidity (g/m )
Output voltage
Absolute humidity vs,
output voltage characterist

Sensing part
(Open vessel) Sensing part
(Closed vessel)
Thermistors
ventilation opening for sensing
Pin No. Signal I/O Description
40 COM3 OUT Common data signal: COM1.
Connected to LCD (Pin No. C3)
41 COM4 OUT Terminal not used.
42 VDD IN Power source voltage input terminal.
Connected to GND.
SW1
SW2
SW3
SW4
SW5
R47
R46
R45
R44
R43
LSI
(IC1)
AN0
AN1
620k
300k
150k
75k
37.4k
19
10
9
22
23
21
20
47k
47k
IC2 10k
0.01uF
0.015uF
0.01uF
R102
360k
+
-
VA : -15V VA : -15V
R90
C101
C102
C103
C104
S
F-2 1.8k
F-1
F-3C3.57k
3.32k
VC : -5V
0.1
uF
C. Thermistor in 
closed vesssl
S. Thermistor in
open vessel
R107

R108
R112
R105 R101
R103 R104
D101
R109
R110
R111
R106