Read Sharp R-84ST (serv.man3) Service Manual online
R-84STM - 8
PROCEDURE
LETTER
COMPONENT TEST
A
TOUCH CONTROL PANEL ASSEMBLY TEST
TEST PROCEDURES
B
KEY UNIT TEST
The touch 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 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.
unlike conventional microwave ovens, proper maintenance can not 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.
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 P) to determine if control unit is faulty.
key unit test (Procedure P) 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.
G 8
G 7
G 6
G 5
G 4
G 3
G 2
G 1
G12
G11
G10
G 9
ROAST BEEF / LAMB
WHOLE POULTRY
CHICKEN QUARTERS
CHICKEN QUARTERS (INSTANT COOK)
ROAST PORK
PASTA DISH
RISOTTO
GRATIN
MEAT JOINT
OVEN CHIPS
ROAST POULTRY
GRILL
MICRO.
POWER
DUAL CONV. /
GRILL
CONV.
( ˚C )
DOWN
LESS
MORE
UP
CLEAR
AUTO MINUTE
STOP
START
KITCHEN TIMER
CLOCK SET
KG / LB
CONVERSION
BREAKFAST
BAKED POTATOES
PIZZA
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat 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 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.
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 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.
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