Sharp R-1880LS Service Manual page 28

R-1880LS/LST
PROCEDURE
LETTER
Q TOUCH CONTROL PANEL ASSEMBLY TEST
. Control Unit.
The following symptoms indicate a defective control unit. Before replacing the control unit, perform the Key
unit test (Procedure R) to determine if control unit is faulty.
-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.
- 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.
-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.
When testing is completed,
1) Disconnect the power supply cord, and then remove outer case.
) 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.
R KEY UNIT TEST
1. Disconnect the power supply cord, and then remove outer case.
. Open the door and block it open.
3. Discharge high voltage capacitor.
4. If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon is making
good contact, verify that the door sensing switch (stop switch) operates properly; that is the contacts are
closed when the door is closed and open when the door is open. If the door sensing (stop switch) is good,
disconnect the flat ribbon that connects the key unit to the control unit and make sure the door sensing 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.
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.
TEST PROCEDURES
COMPONENT TEST
G 1
Custom
Sensor
G 8
Help Reheat
G 9 Convect Preheat
Slow
G10
Broil
Cook
Kitchen
G11
Clock
Timer
Turntable Power
G12
On / Off Level
8
G 2 G 3 G 4 G 5
Sensor
Minute
Defrost
Popcorn
Plus
Low Mix High Mix
Bake Roast
1 2 3
100 F 150 F 275 F
6 7 8
350 F 375 F 400
F
Start
Keep Stop
Warm Touch on
Clear
G 6 G 7
Sensor
Broil
Cook
Roast Bake
4 5
F
300 325 F
9 0
425 F 450 F
Light
Fan
Hi/Lo
Hi/Lo