20
R-84ST -
TEST PROCEDURES
M
TOUCH CONTROL PANEL ASSEMBLY TEST
N
KEY UNIT TEST
If the display fails to clear when the STOP pad is depressed, first verify the flat ribbon cable is
marking good contact, verify that the door sensing switch (stop switch) operates properly; that is
the contacts are closed when the door is closed and open when the door is open. If the door
sensing switch (stop switch) is good, disconnect the flat ribbon cable that connects the key unit to
the control unit and make sure the door sensing switch is closed (either close the door or short
the door sensing switch connecter). Use the Key unit matrix indicated on the control panel
schematic and place a jumper wire between the pins that correspond to the STOP pad marking
momentary contact. If the control unit responds by clearing with a beep the key unit is faulty and
must be replaced. If the control unit does not respond, it is faulty and must be replaced. If a
specific pad does not respond, the above method may be used (after clearing the control unit) to
determine if the control unit or key pad is at fault.
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance can not 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 also the Control unit is divided into two units, CPU unit and Power unit, and troubleshooting by
replacement is described according to the symptoms indicated.
1. Key Unit Note : Check key unit ribbon connection before replacement.
The following symptoms indicate a defective key unit. Replace the 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.
2. Control Panel
The following symptoms indicate a defective control unit. Before replacing the control unit perform the
key unit test (Procedure P) to determine if control unit is faulty.
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 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 up.
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 troubles 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.
d) Proper temperature measurement is not obtained.
CARRY OUT 4R CHECKS.
PROCEDURE
LETTER
COMPONENT TEST
G 8
G 7
G 6
G 5
G 4
G 3
G 2
G 1
G12
G11
G10
G 9
