Read Sharp R-895M (serv.man6) Service Manual online
R-895M - 17
M
TOUCH CONTROL PANEL ASSEMBLY TEST
The control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike
conventional microwave ovens, proper maintenance can not be performed with only a voltmeter and
ohmmeter.
In this service manual, the 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.
conventional microwave ovens, proper maintenance can not be performed with only a voltmeter and
ohmmeter.
In this service manual, the 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.
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 Panel
The following symptoms indicate a defective control unit. Before replacing the control unit perform
the key unit test (Procedure N) to determine if control unit is faulty.
the key unit test (Procedure N) 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.
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 up.
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.
b) At a certain digit, brightness is low.
c) Only one indicator does not light up.
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 troubles 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.
d) Proper temperature measurement is not obtained.
b) Clock does not operate properly.
c) Cooking is not possible.
d) Proper temperature measurement is not obtained.
PROCEDURE
LETTER
COMPONENT TEST
N
KEY UNIT TEST
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the ribbon cable is
making good contact, verify that the stop switch operates properly; that is the contacts are closed when
the door is closed and open when the door is open. If the stop switch is good, disconnect the flat ribbon
cable that connects the key unit to the control unit and make sure the stop switch is closed (either close
the door or short the stop switch connecter). Use the Key unit matrix indicated on the control panel
schematic and place a jumper wire between the pins that correspond to the STOP/CLEAR pad making
momentary contact. If the control unit responds by clearing with a beep the key unit is faulty and must
be replaced. If the control unit does not respond, it is a faulty and must be replaced. If a specific pad
does not respond, the above method may be used (after clearing the control unit) to determine if the
control unit or key pad is at fault.
CARRY OUT 4R CHECKS.
making good contact, verify that the stop switch operates properly; that is the contacts are closed when
the door is closed and open when the door is open. If the stop switch is good, disconnect the flat ribbon
cable that connects the key unit to the control unit and make sure the stop switch is closed (either close
the door or short the stop switch connecter). Use the Key unit matrix indicated on the control panel
schematic and place a jumper wire between the pins that correspond to the STOP/CLEAR pad making
momentary contact. If the control unit responds by clearing with a beep the key unit is faulty and must
be replaced. If the control unit does not respond, it is a faulty and must be replaced. If a specific pad
does not respond, the above method may be used (after clearing the control unit) to determine if the
control unit or key pad is at fault.
CARRY OUT 4R CHECKS.
G 9
G10
G11
G12
Pie/
Quiche
Ready
Meals
Rice/
Pasta
Italian
Dish
Indian
Dish
Roast
Pork
Chinese
Dish
Crispy
Potatoes
Roast
Beef/
Lamp
Crispy
Crumb
Foods
DUAL
CONV. /
GRILL
Roast
Poultry
POWER
LEVEL
STOP
CLEAR
PIZZA
Desserts
10sec.
1min.
10min.
GRILL BREAKFAST
MORE
Chicken
Quarters
Whole
Poultry
CONV
(˚C)
Meat
Joint
G 8
G 7
G 6
G 5
G 4
G 3
G 2
G 1
UP
LESS
DOWN
info
START
AUTO MINUTE
KITCHEN TIMER
CLOCK SET
TEST PROCEDURES
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