Sharp R-930AK-F Service Manual page 21

PROCEDURE
LETTER
P NOISE FILTER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the lead wires from the terminal the noise filter. Using an
ohmmeter, check between the terminals as described in the following
table. If incorrect reading are obtained, replace the noise filter.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is
installed.
8. Run the oven and check all functions.
MEASURING POINT
Between N and L
Between terminal N and WHITE
Between terminal L and RED
Q TOUCH CONTROL PANEL ASSEMBLY TEST
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 the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that these leads remain isolated from other components and oven chassis by using insulation
tape.
1. Key Unit.
NOTE ;
1) Check Key unit ribbon connection before replacement.
2) Reconnect all leads removed from components during testing.
3) Re-install the outer case (cabinet).
4) Reconnect the power supply cord after the outer case is installed.
5) 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.
4) Replace the Key unit.
5) Reconnect all leads removed from components during testing.
6) Re-install the outer case (cabinet).
7) Reconnect the power supply cord after the outer case is installed.
8) Run the oven and check all functions.
2. Control Unit
The following symptoms indicate a defective control unit. Before replacing the control unit, perform the
Key unit test (Procedure R) to determine if control unit is faulty. Reconnect the power supply cord. And
check for followings.
2-1 In connection with pads.
TEST PROCEDURES
COMPONENT TEST
INDICATION OF OHMMETER
Open circuit.
Short circuit.
Short circuit.
19
NOISE FILTER
N
FUSE 20A
LINE CROSS CAPACITOR
0.22µF / AC 250V
NOISE SUPPRESSION COIL
LINE BYPASS LINE BYPASS
CAPACITOR CAPACITOR
0.0033µF / AC 125V 0.0033µF / AC 125V
WHITE
R-930AK-F
R-930AW-F
L
RED