Electrolux EI27MO45GSA, Technical & Service Manual

Page: 27 / 52

Troubleshooting and Testing
3-9
Procedure
Letter
J
Component Test
2. Control Unit
The following symptoms indicate a defective control unit. Before replacing the control unit, perform
the Key unit test (Procedure J) to determine if control unit is faulty.
2-1 In connection with pads.
1. When touching the pads, a certain group of pads do not produce a signal.
2. When touching the pads, no pads produce a signal.
2-2 In connection with indicators.
1. At a certain digit, all or some segments do not light up.
2. At a certain digit, brightness is low.
3. Only one indicator does not light.
4. The corresponding segments of all digits do not light up; or they continue to light up.
5. Wrong figure appears.
6. A certain group of indicators do not light up.
7. The figure of all digits flicker.
8. The following symptoms indicate a defective LSI unit.
• When touching the keys on the touch screen, a certain key produces no signal at all.
• When touching a number key on the touch screen, two figures or more are displayed.
• When touching the keys on the touch screen, sometimes a key produces no signal.
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.
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. Isolate the key unit with the control panel frame to be tested.
5. Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit,
check the circuit between the pins of the key unit that correspond to the STOP/CLEAR pad.
When the pad is pressed, the ohmmeter should indicate short circuit. When the pad is released,
the ohmmeter should indicate open circuit. If incorrect readings are obtained, the key unit is
faulty and must be replaced. About the other pads, the above method may be used.
6. Reconnect all leads removed from components during testing.
7. Re-install the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
(See illustration on next page)