H: Blown Monitor Fuse Test; I: Noise Filter Test; J: Touch Control Panel Assembly Test - Sharp R-351NW Service Manual

Service manual
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[9] H: BLOWN MONITOR FUSE 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. If the monitor fuse is blown when the door is opened, check the primary interlock relay, secondary interlock switch and monitor
switch according to the "TEST PROCEDURE" for those switches before replacing the blown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE PRIMARY INTERLOCK RELAY, SECONDARY INTER
LOCK SWITCH, DOOR SENSING SWITCH AND MONITOR SWITCH FOR PROPER OPERATION.
If the monitor fuse is blown by improper switch operation, the monitor fuse and monitor switch must be replaced with "monitor fuse
and monitor switch" part number QFS-BA009WRE0 and QSW-MA086WRE0, even if the monitor switch operates normally. The
monitor fuse and monitor switch assembly is comprised of a 20 ampere fuse and switch.
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.

[10] I: 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 fi lter. Using an ohmmeter, check
between the terminals as described in the following table. If incorrect reading are obtained,
replace the noise fi lter.
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

[11] J: 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 also the Control Unit is divided into two units, CPU Unit and Power
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) Re-install the outer case (cabinet).
2) Reconnect the power supply cord after the outer case is installed.
3) 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 fi gures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
INDICATION OF OHMMETER
Open circuit.
Short circuit.
Short circuit.
8 - 4
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-351NW
L
RED

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