Frigidaire CFMV152KW Servicing Manual page 27

Procedure
Letter
TOUCH CONTROL PANEL ASSEMBLY TEST
L
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc.
Therefore, unlike conventional microwave ovens, proper maintenance cannot 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 troubleshooting by unit replacement is described
according to the symptoms indicated.
Before testing,
1. Disconnect power supply cord, and remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
4. Remove two (2) screws holding the hood intake duct R to the oven cavity top plate and the
base plate R. Remove the hood intake duct R.
5. Disconnect the leads to the primary of the power transformer.
6. Ensure that these leads remain isolated from other components and oven chassis by using
insulation tape.
KEY UNIT
1. Check Key unit ribbon connection before replacement.
2. Reconnect all leads removed from components during testing.
3. Re-install the hood intake duct R with two (2) screws.
4. Re-install the outer case (cabinet).
5. Reconnect the power supply cord after the outer case is installed.
6. 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 high voltage capacitor. (See Warnings and Instructions on page 3-1)
4. Replace the key unit.
5. Reconnect all leads removed from components during testing.
6. Re-install the covers (outer case cabinet and control unit cover).
7. Reconnect the power supply cord after the covers (outer case cabinet and control unit cover)
are installed.
8. Run the oven and check all functions.
Section 3 Troubleshooting and Testing
Component Test
3-9