Service manual

26
R-1855A
2. 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.
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.
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
LETTER
COMPONENT TEST
Q TOUCH CONTROL PANEL ASSEMBLY TEST
R KEY UNIT 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 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.
G12
CUSTOM
HELP
KITCHEN
TIMER
POWER
LEVEL
KEEP
WARM
TURNTABLE
ON / OFF
CONVEC
BROIL
FAN LIGHT
PREHEAT
CLOCK
SENSOR
REHEAT
SLOW
COOK
LOW MIX
BAKE
1
100°F
2
150°F
3
275°F
4
300°F
5
325°F
6
350°F
7
375°F
8
400°F
9
425°F
0
450°F
HIGH MIX
ROAST
STOP
CLEAR
START
TOUCH ON
SENSOR
COOK
MINUTE
PLUS
COMPU
DEFROST
COMPU
ROAST
COMPU
BAKE
COMPU
BROIL
POPCORN
G11
G10
G 9
G 8
G 1 G 2 G 3 G 4 G 5 G 6 G 7