Sharp R-22AT Service Manual

14
R-22AT
R-23AM
R-24AT
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
The touch control panel consists of circuits including semiconductors such as LSI, IC, 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, troubleshooting by unit 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 the pads, sometimes a pad produces no signal.
2. Control Unit
The following symptoms may indicate a defective control unit. Replacing the control unit. Before
replacing the control unit, perform the key unit test (Procedure P) to determine if control unit is faulty.
2-1 Programming problems.
a) When touching the pads, a certain group of pads do not produce a signal.
2-2 Display problems.
a) For a certain digit, all or some segments do not light up.
b) For a certain digit, brightness is low.
c) Only one indicator does not light.
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 problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Cooking is not possible.
CONTROL PANEL ASSEMBLY TEST FOR R-23AM
The control panel consists of circuits including semiconductors such as LSI 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 three units, Control Unit,
Switch Unit and Encoder Unit troubleshooting by unit replacement is described according to the symptoms
indicated.
1. Switch Unit Note : Check the lead wire harness connections among big and small switch units and
control unit before replacement.
The following symptoms indicate a defective switch unit. Replace the switch unit.
a) When touching the buttons, a certain button produces no signal at all.
b) When touching the buttons, sometimes a button produces no signal.
2. Encoder Note : Check the lead wire connection between encoder and control unit before replacement.
The following symptoms indicate a defective encoder. Replace the encoder.
O TOUCH CONTROL PANEL ASSEMBLY TEST FOR R-24AT / R-22AT
MEASURING POINT INDICATION OF OHMMETER
Between N and L Approx. 680 kΩ
Between terminal N and WHIT Short circuit
Between terminal L and BLK Short circuit
If incorrect readings are absorbed, replace the noise filter.
CARRY OUT 4R CHECKS.
N HIGH VOLTAGE FUSE TEST
CARRY OUT 3D CHECKS.
If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.
Check them and replace the defective parts and the high voltage fuse.
CARRY OUT 4R CHECKS.
CAUTION: Only replace high voltage fuse with the correct value replacement.
F1 : FUSE F13A
NOISE FILTER
NOISE SUPPRESSION COIL
DISCHARGE RESISTOR 680 kΩ 1/2W
DISCHARGE RESISTOR 10 MΩ 1/2W
LINE CROSS CAPACITOR 0.22µF/ AC250V
LINE CROSS CAPACITOR 
10000 pF/ AC250V
LINE CROSS CAPACITOR 
10000 pF/ AC250V
L
BLK
WHT
N

Sharp R-22AT Specifications