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Troubleshooting Guide of Touch Control Circuit
Follow the procedures below to check if the touch control circuit is defective.
1. Check grounding before checking for trouble.
2. Be careful of the high voltage circuit.
3. Discharge the high voltage capacitor(see page 6).
4.
When checking the continuity of the switches or transformer, disconnect one lead wire from these parts and then
check continuity without turning the power source on. To do otherwise may result in a false reading or a damage
to your meter.
5. Do not touch any part of the circuit or the touch control circuit board, since static electric discharge may damage
this control panel. Always touch ground while working on this panel to discharge any static charge built up in your
body.
First of all operate the microwave oven by observing the correct operating procedures by time cooking in order to
find the exact cause of any trouble.
{TROUBLE 1] The following visual conditions indicate a probable defective touch control circuit.
1. Complete segments
(A) Incomplete segments
(B) Partial segments missing
(C) Digit flickering
(Other than normal fluorescent light flickering.)
(D) Colon does not turn on.
2. .A distinct change in the brightness of one or more
numbers in the display.
3. One or more digits in the display does not light when
they should.
4. No indicator lights for the selected cooking function.
5. Display indicates a number different from one touched.
6. Specific pads (for example, 2 or 3) will not display when
the panel is touched.
7. Display does not count down or clock does not operate.
8. Display obviously skips in time while counting down.
9. Display counts down noticeably too fast while cooking.
10. Display can not shift from first stage cooking to the
second stage cooking while 2 phase cooking.
SEB
WAS
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ee eee
er et CI Chet 0 Ton &
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(Fig. 37)
11. Display continues counting down during time cooking
when door-open button is pressed. Check if door sens-
ing switch shorts when door open button is pressed.
If the door sensing switch is normal, replace touch.
control circuit.
12. The time of day in the display does not reappear when
the CANCEL pad is touched twice.
13. The oven lamp and fan motor do not stop although
cooking is finished, Replace the touch control circuit.
[TROUBLE 2] Digital Readout Display does not show programming, even ifthe membrane key board is programmed
by touching proper pads.
CONDITION
CHECK
Display does not
Check continuity of
show programming at
each pad of the
all, even if keyboard
membrane keyboard
is touched
as the following key-
bord check procedure
Check the voitage of
low voltage trans
secondary windings
Abnormal
—enarnal}
CAUSE
:
REMEDY
Malfunction of
Replace the control
touch control
box assembly
circuit of control
assembly
Malfunction: of the
jmembrane keyboard
Malfunction of
touch control circuit
of control box
assembly
Malfunction of the
LV. transformer
Replace the
membrane keyboard
Replace the control
box assembly
Replace the
LV. transfromer
NOTE 1: Before following the particular step above for the membrane key board's failure, please check of the continuity
for each wire harness between the membrane keyboard and touch control circuit.
34
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