Touch Control Panel Assembly Test - KitchenAid KOMS155MBL Technical Education

TOUCH CONTROL PANEL ASSEMBLY TEST

The touch control panel consists of semicon-
ductor circuits. Unlike conventional microwave
ovens, proper maintenance cannot be per-
formed with only a voltmeter and ohmmeter.
The touch control panel assembly is divided
into the "Control Unit" and the "Key Unit."
BEFORE TESTING
1. Disconnect the power supply cord.
2. Remove the cabinet (see page 4-2).
3. Open the door and block it open.
4. To discharge the high voltage capacitor,
wait for 60 seconds.
5. Disconnect the leads to the primary of the
high voltage transformer. Ensure that these
leads remain isolated from other compo-
nents and oven chassis by taping them
using insulation tape.
Key Unit
1. Check key unit ribbon connection before
replacement.
2. Reinstall the cabinet.
3. Reconnect the power supply cord after the
cabinet is installed.
4. Run the oven and check all functions.
The following symptoms indicate a defec-
tive key unit.
a) When touching the pads, a certain pad
produces no signal at all.
b) When touching a number pad, two fig-
ures or more are displayed.
c) When touching the pads, sometimes a
pad produces no signal. If the key unit
is defective, replace the key unit.
Control Unit
The following symptoms indicate a defective
control unit. Before replacing the control unit,
perform the "Key Unit" test to determine if the
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 pro-
duce a signal.
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 dig-
its do not light up; or they continue to
light up.
e) A wrong figure appears.
f) A certain group of indicators do not light
up.
9) The figure of all digits flicker.
3. Other possible problems caused by defec-
tive 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.
2. Open the door and block it open.
3. To discharge the high voltage capacitor,
wait for 60 seconds.
4. Reconnect all leads removed from compo-
nents during testing.
5. Reinstall the cabinet.
6. Reconnect the power supply cord after the
cabinet is installed.
7. Run the oven and check all functions.
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