Sharp R-23GT-F Service Manual page 20

R-23GT-F
R-24GT-F
PROCEDURE
LETTER
Before testing,
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge two high voltage capacitors.
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.
1. Key Unit.
NOTE ;
1) Check Key unit ribbon connection before replacement.
2) Reconnect all leads removed from components during testing.
3) Re-install the outer case (cabinet).
4) Reconnect the power supply cord after the outer case is installed.
5) 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.
If the Key unit is defective.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge two high voltage capacitors.
4) Replace the Key unit.
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.
2. Control Unit
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.
Re-connect the power supply cord. And check for followings.
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 display
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) 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 two high voltage capacitors.
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
COMPONENT TEST
18