Sharp R308jsf Service Manual

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TROUBLESHOOTING GUIDE
Never touch any part in the circuit with your hand or an uninsulated too\
l while the power supply is connected.
When troubleshooting the microwave oven, it is helpful to follow the Seq\
uence of Operation in performing the checks. Many
of the possible causes of trouble will require that a specific test be p\
erformed. These tests are given a procedure letter whic h
will be found in the Test Procedure section.
IMPORTANT: If the oven becomes inoperative because of a blown C/T fuse, check the m\
onitor switch, primary interlock
relay (RY2), door sensing switch and secondary interlock switch before\
 replacing the C/T fuse. If  C/T fuse is
replaced, the monitor switch must also be replaced. Use part FFS-BA034WR\
KZ as an assembly.
IMPORTANT: Whenever troubleshooting is performed with the power supply cord disconn\
ected. It may in, some cases, be
necessary to connect the power supply cord after the outer case has been\
 removed, in this event, 1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power transformer.
5. Ensure that the leads remain isolated from other components and oven cha\
ssis by using insulation tape.
6. After that procedure, reconnect the power supply cord.
When the testing is completed,
1.  Disconnect the power supply cord.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Reconnect the leads to the primary of the power transformer.
5. Reinstall the outer case (cabinet).
6. Reconnect the power supply cord after the outer case is installed.
7. Run the oven and check all functions. 
						

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AMAGNETRON ASSEMBLY TEST
Home fuse or circuit breaker blows
when power cord is plugged into wall
receptacle
C/T fuse blows when power cord is
plugged into wall receptacle.
All letters and indicators do not ap-
pear in display when power cord is
first plugged into wall outlet.
Display does not operate properly
when STOP/CLEAR key is touched.
(Buzzer should sound and : or time
of day should appear in display.)
Oven lamp does not light when door
is opened.
Oven lamp does not go out when
door is closed.
Oven lamp lights but fan motor and
turntable motor do not operate.
Oven does not go into cook cycle
when START pad is touched
Oven seems to be operating but little
or no heat is produced in oven load.
(Food incompletely cooked or not
cooked at all at end of cook cycle.)
Oven goes into a cook cycle but
extremely uneven heating is pro-
duced in oven load (food).
Oven does not cook properly when
programmed for Cooking Power P-
50 mode. (Operates properly on
Cooking Power P-HI (HIGH) mode.)
Oven goes into DEFROST but food
is not defrosted well.
OFF
CONDITION
PROBLEMCONDITIONSHORT IN POWER CORD
SHORT OR OPENED  WIRING
MAGNETRON
POWER TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE CAPACITOR
TEMPERATURE FUSE OR THERMAL
CUT-OUT(OVEN)
PRIMARY INTERLOCK SYSTEM
SECONDARY INTERLOCK SWITCH
MONITOR SWITCH
C/T FUSE
OVEN LAMP
COOLING FAN MOTOR
TURNTABLE MOTOR
TOUCH CONTROL PANEL
WRONG OPERATION
LOW VOLTAGE
DIRTY OVEN CAVITY
KEY UNIT (MEMBRANE SWITCH)
RELAY (RY1)
DEFROST
FOIL PATTERN ON PWB.
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURERE REAB CD E F FG HRE RECKICK CK CKJKLM
COOKING
CONDITION
CK = Check / RE = Replace
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across
the magnetron filament leads should indicate less than 1 ohm.
5. To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads and
chassis ground. This test should indicate an infinite resistance. If there is little or no resistance the magnetron
is grounded and must be replaced.
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST 
						

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TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
BPOWER TRANSFORMER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the primary input terminals and measure the resistance of the transformer with an ohmmeter.
Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of the primary coil should
be less than 1 ohm and the resistance of the high voltage coil should be approximately 122 ohms for RTRN-
A715WRZZ or approximately 102 ohms for RTRN-A705WRZZ; the resistance of the filament coil should be
less than 1 ohm.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
(HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
MICROWAVE OUTPUT POWER
The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer
case fitted).
HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION SHOULD BE
OBSERVED.
Power output of the magnetron can be measured by performing a water temperature rise test. This test should
only be used if above tests do not indicate a faulty magnetron and there is no defect in the following components
or wiring: silicon rectifier, high voltage capacitor and power transformer. This test will require a 16 ounce (453cc)
measuring cup and an accurate mercury thermometer or thermocouple type temperature tester. For accurate
results, the following procedure must be followed carefully:
1. Fill the measuring cup with 16 oz. (453cc) of tap water and measure the temperature of the water with a
thermometer or thermocouple temperature tester. Stir the thermometer or thermocouple through the water
until the temperature stabilizes. Record the temperature of the water.
2. Place the cup of water in the oven. Operate oven at POWER P-HI(HIGH) selecting more than 60 seconds
cook time. Allow the water to heat for 60 seconds, measuring with a stop watch, second hand of a watch or
the digital read-out countdown.
3.Remove the cup from the oven and again measure the temperature, making sure to stir the thermometer or
thermocouple through the water until the maximum temperature is recorded.
4. Subtract the cold water temperature from the hot water temperature. The normal result should be 32.1 to
59.7˚F(17.9 to 33.2˚C) rise in temperature. If the water temperatures are accurately measured and tested for
the required time period the test results will indicate if the magnetron tube has low power output (low rise in water
temperature) which would extend cooking time or high power output (high rise in water temperature) which would
reduce cooking time. Because cooking time can be adjusted to compensate for power output, the magnetron
tube assembly should be replaced only if the water temperature rise test indicates a power output well beyond
the normal limits. The test is only accurate if the power supply line voltage is 120 volts and the oven cavity is clean.
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance across the
terminals and observe, reverse the leads to the rectifier terminals and observe meter reading. If a short is
CHIGH VOLTAGE RECTIFIER TEST 
						

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TEST PROCEDURES
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LETTERCOMPONENT TEST
indicated in both directions, or if an infinite resistance is read in both directions, the rectifier is probably
defective and should be replaced.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
NOTE: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts.
DHIGH VOLTAGE CAPACITOR TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and check
for short or open between the terminals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate continuity for
a short time and should indicate an open circuit once the capacitor is charged. If the above is not the case,
check the capacitor with an ohmmeter to see if it is shorted between either of the terminals and case. If it is
shorted, replace the capacitor.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
FSECONDARY INTERLOCK SWITCH TEST
ETEMPERATURE FUSE (OVEN) TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.A continuity check across the temperature fuse terminals should indicate a closed circuit unless the
temperature of the temperature fuse reaches approximately 302˚F(150˚C).
An open temperature fuse indicates overheating of the oven, exchange the temperature fuse and check
inside of oven cavity and for improper setting of cooking time or operation of control unit. Check for restricted
air flow through the vent holes of the oven cavity, especially the cooling fan and air guide.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
THERMAL CUT-OUT (OVEN ) TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the
temperature of the thermal cut-out reaches approximately 293˚F(145˚C).
An open thermal cut-out indicates overheating of the oven, exchange the oven thermal cut-out and check
inside of oven cavity and for improper setting of cooking time or operation of control unit. Check for restricted
air flow through the vent holes of the oven cavity, especially the cooling fan and air guide.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the 
						

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TEST PROCEDURES
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LETTERCOMPONENT TEST
switch. The meter should indicate an open circuit with the door open and a closed circuit with the door closed.
If improper operation is indicated, replace the secondary interlock switch.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
PRIMARY INTERLOCK SYSTEM TEST
DOOR SENSING SWITCH
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the
switch. The meter should indicate an open circuit with the door open and a closed circuit with the door closed.
If improper operation is indicated, replace the door sensing switch.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
NOTE: If the door sensing switch contacts fail in the open position and the door is closed, the cooling
fan, turntable and oven light will be activated by RY1.
PRIMARY INTERLOCK RELAY (RY2)
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect two (2) wire leads from the male tab terminals of the Primary Interlock Relay. Check the state
of the relay contacts using a ohmmeter. The relay contacts should be open. If the relay contacts are closed,
replace the circuit board entirely or the relay itself.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
GMONITOR SWITCH TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.Before performing this test, make sure that the secondary interlock switch and the primary interlock relay are
operating properly, according to the above Switch Test Procedure. Disconnect the wire lead from the monitor
switch (COM) terminal. Check the monitor switch operation by using the ohmmeter as follows. When the door
is open, the meter should indicate a closed circuit. When the monitor switch actuator is pushed by a screw
driver through the lower latch hole on the front plate of the oven cavity with the door opened (in this condition
the plunger of the monitor switch is pushed in), the meter should indicate an open circuit. If improper operation
is indicated, the switch may be defective. After testing the monitor switch, reconnect the wire lead to the
monitor switch (COM) terminal and
check the continuity of the monitor circuit.
5.Reconnect all leads removed from
components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after
the outer case is installed.
8. Run the oven and check all functions.
Monitor 
Switch
Secondary 
Interlock Switch
Screw Driver
OhmmeterBLKGRY
WHT
HBLOWN C/T FUSE TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open. 
						

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TEST PROCEDURES
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LETTER COMPONENT TEST
3. Discharge high voltage capacitor.
4.
If the C/T fuse is blown when the door is opened, check the primary inte\
rlock relay, secondary interlock switch and
monitor switch according to the TEST PROCEDURE for those switches befo\
re replacing the blown C/T fuse.
CAUTION: BEFORE REPLACING A BLOWN C/T FUSE, TEST THE PRIMARY INTERLOCK RELAY,
SECONDARY INTERLOCK SWITCH, DOOR SENSING SWITCH AND MONITOR SWITCH
FOR PROPER OPERATION.
If the C/T fuse  is blown by improper switch operation, the C/T fuse and\
 monitor switch must be replaced with
C/T fuse and monitor switch assembly part number FFS-BA034WRKZ, even i\
f the monitor switch operates
normally. The C/T fuse and monitor switch assembly is comprised of a 20 \
ampere fuse and switch.
A continuity check across the C/T fuse terminals should indicate a close\
d circuit unless the temperature of the
C/T fuse reaches approximately 302˚F(150˚C).
An open C/T fuse indicates overheating of the magnetron. Check for restr\
icted air flow to the magnetron,
especially the cooling fan air guide.
CAUTION: IF  THE C/T FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE, REPLACE THE
C/T FUSE.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
The touch control panel consists of circuits including semiconductors su\
ch as LSI, ICs, etc. Therefore, unlike
conventional microwave ovens, proper maintenance cannot be performed wit\
h 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 unit replacement
is described according to the symptoms indicated.
Before testing,
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5)Ensure that these leads remain isolated from other components and oven c\
hassis by using insulation tape.
1. Key Unit.
NOTE ;
1) Re-install the outer case (cabinet).
2) Reconnect the power supply cord after the outer case is installed.
3) Run the oven and check all functions.
The following symptoms indicate a defective 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
The following symptoms indicate a defective control unit.
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 contin\
ue 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.
ITOUCH CONTROL PANEL ASSEMBLY TEST 
						

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3. If the Key unit  or control unit is defective.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Replace the control unit assembly.
5) Reconnect all leads removed from components during testing.
6) Re-install the outer case (cabinet).
7) Reconnect the power supply cord after the outer case is installed.
8) Run the oven and check all functions.
4. When testing is completed,
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Reconnect all leads removed from components during testing.
5) Re-install the outer case (cabinet).
6) Reconnect the power supply cord after the outer case is installed.
7) Run the oven and check all functions.
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4.Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check the circuit
between the pins of the key unit that correspond to the STOP/CLEAR pad. When the pad is pressed, the
ohmmeter should indicate short circuit. When the pad is released, the ohmmeter should indicate open circuit.
If incorrect readings are obtained, the key unit is faulty and must be replaced. About the other pads, the above
method may be used.
5. Reconnect all leads removed from components during testing.
6. Re-install the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
JKEY UNIT TEST
G 2G 1
MINUTE
PLUS
DEFROST SOFTEN POWER
LEVELREHEAT WARM
COOK
MELT
POPCORNTIMER
CLOCK
9
3
65 2
8
0
G 3G 4G 5G 6G 7G 8
G 9
G10
G11
G12
1
4
7
START
STOP
CLEAR
Pin
NO. G12Pin
NO. G1
Key unit ribbon cable
Key unit (Membrane Switch) front view
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power transformer.
5. Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.
6. After that procedure, re-connect the power supply cord.
7.Remove the outer case and check voltage between the normal open terminal of the relay RY1 and the normal
open 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.
KRELAY TEST 
						

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DC. voltage indicated ................... Defective relay.
DC. voltage not indicated .............Check diode which is connected to the relay coil. If diode is good,
control unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 Approx. -12.0V D.C. Oven lamp / Turntable motor / Cooling fan motor
RY2 Approx. -11.0V D.C. Power transformer
  8. Disconnect the power supply cord, and then remove outer case.
  9. Open the door and block it open.
10. Discharge high voltage capacitor.
11. Reconnect all leads removed from components during testing.
12. Re-install the outer case (cabinet).
13. Reconnect the power supply cord after the outer case is installed.
14. Run the oven and check all functions.
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
d
ab
c
WARNING : The oven should be fully assembled before following procedure.
(1) Place one cup of water in the center of the turntable tray in the oven cavity.
(2) Close the door, touch the “ DEFROST ” pad once. And then touch the number pad 2.
(3) Touch the number pad 5 and then touch the start pad.
(4) The oven is in Defrost cooking condition.
(5) The oven will operate as follows.
MENU 1ST STAGE 2ND STAGE 3RD STAGE
Steaks/Chops LEVEL TIME LEVEL TIME LEVEL TIME
0.5lb 70% 17sec. 60% 27sec. 30% 40sec.
(6) If improper operation is indicated, the control unit is probably defective and should be checked.
LDEFROST TEST
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.
1. Foil pattern check and repairs.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Follow the troubleshooting guide given below for repair.
STEPS OCCURRENCE CAUSE OR CORRECTION
1Only pattern at “a” is broken. *Insert jumper wire J1 and solder.
2Pattern at “a” and “b” are broken. *Insert the coil RCILF2003YAZZ between “c” and “d”.
5) Make a visual inspection of the varistor. Check for burned
damage and examine the transformer with a tester for the
presence of layer short-circuit (check the primary coil
resistance which is approximately 563Ω ± 10%). If any
abnormal condition is detected, replace the control unit
assembly.
6)Reconnect all leads removed from components during
testing.
7) Re-install the outer case (cabinet).
8)Reconnect the power supply cord after the outer case is
installed.
9) Run the oven and check all functions.
2.Follow the troubleshooting guide given below, if indicator
does not light up after above check and repairs are finished.
1)Disconnect the power supply cord, and then remove
outer case.
MFOIL PATTERN ON THE PRINTED WIRING BOARD TEST 
						

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TEST PROCEDURES
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LETTERCOMPONENT TEST
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5)Ensure that these leads remain isolated from other components and oven chassis by using insulation
tape.
6) After that procedure, re-connect the power supply cord.
7) Follow the troubleshooting guide given below for repair.
STEPS OCCURRENCE CAUSE OR CORRECTION
The rated AC voltage is not present between
1the normal open terminal of the relay RY1 and Check supply voltage and oven power cord.
the normal open terminal of the relay RY2.
2The rated AC voltage is present at primary Low voltage transformer or secondary circuit defective.
side of low voltage transformer. Check and replace control unit assembly.
8) Disconnect the power supply cord, and then remove outer case.
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
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 commu-
nicated among them are explained below.
Key Unit
The key unit is composed of a matrix, signals generated in the
LSI are sent to the key unit through P22, P23, P24, P25, P26,
P31, P32 and P33.
When a key pad is touched, a signal is completed through the
key unit and passed back to the LSI through P50, P51, P52 and
P53 to perform the function that was requested.
Control Unit
Control unit consists of LSI, reset circuit, indicator circuit, power
source circuit, relay circuit, buzzer circuit, synchronizing signal
circuit and back light circuit.
1) Reset Circuit
This circuit generates a signal which resets the LSI to the
initial state when power is supplied.
2) Indicator Circuit
This circuit consists of 14 segments and 3 common
electrodes using a Liquid Crystal Display.3) Power Source Circuit
This circuit generates voltages necessary in the control unit
from the AC line voltage.
In addition, the synchronizing signal is available in order to
compose a basic standard time in the clock circuit.Symbol Voltage Application
VSS -5V LSI(IC1)
4) Relay Circuit
A circuit to drive the magnetron, fan motor, turntable motor
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
The power source synchronizing signal is available in order
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-
LD3). 
						

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DESCRIPTION OF LSI
LSI
The I/O signal of the LSI is detailed in the following table.
Pin No. Signal I/O Description
1P50 INSignal coming from touch key.
When either G9 line on key matrix is touched, a corresponding signal out of P22 - P26 and P31
- P33 will be input into P50. When no key is touched, the signal is held at “H” level.
2P51 IN
Signal similar to P50.
When either G10 line on key matrix is touched, a corresponding signal will be input into P51.
3P52 IN
Signal similar to P50.
When either G11 line on key matrix is touched, a corresponding signal will be input into P52.
4P53 IN
Signal similar to P50.
When either G12 line on key matrix is touched, a corresponding signal will be input into P53.
5ICINConnected to VSS.
6XT1 IN Connected to VSS.
7XT2_
Terminal not used.
8VDD IN
Power source voltage input terminal.
The power souce voltage to drive the LSI. Connected to GND.
9VSS IN
Power source voltage input terminal.
The power souce voltage to drive the LSI.
10 X1 IN
Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the resistor-capacitor oscillation circuit with
respect to X2 terminal.
11 X2 OUT
Internal clock oscillation frequency control output.
Output to control oscillation input of X1.
12 RESET IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied.
13-15 P00-P02 OUT Terminal not used.
16 P03 OUT Back light circuit (Light emitting diodes) driving signal.
17 CAPH_
Terminal not used.
18 CAPL_
Terminal not used.
19-21
VLC0-VLC2INPower source voltage input terminal.
Standard voltage for LCD.
22 COM0 OUT
Common data signal.
Connected to LCD signal COM1.
23 COM1 OUT
Common data signal.
Connected to LCD signal COM2.
24 COM2 OUT
Common data signal.
Connected to LCD signal COM3.
25 COM3 OUT Terminal not used.
26-39
SEG0-SEG13OUTSegment data signal.
Connected to LCD.
The relation between signals are as follows:
LSI signal (Pin No.) LCD (segment) LSI signal (Pin No.) LCD (segment)
SEG 0 (26)...................................
SEG 1 SEG   7 (33)................................
SEG 8
SEG 1 (27)...................................
SEG 2 SEG   8 (34)................................
SEG 9
SEG 2 (28)...................................
SEG 3 SEG   9 (35)..............................
SEG 10
SEG 3 (29)...................................
SEG 4 SEG 10 (36)..............................
SEG 11
SEG 4 (30)...................................
SEG 5 SEG 11 (37)..............................
SEG 12
SEG 5 (31)...................................
SEG 6 SEG 12 (38)..............................
SEG 13
SEG 6 (32)...................................
SEG 7 SEG 13 (39)..............................
SEG 14
40 SEG14 OUT Terminal not used.