Sharp R-21JCA-F Manuale Utente

13

WARNING : To prevent an electric shock do not touch the electrical parts and the printed wiring

board. Because the control unit is "TRANSLESS CIRCUIT" and many electrical parts
are used at A.C. line voltage.

The 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 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. 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 INTERLOCK 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 assembly" part number FFS-BA015WRK0, 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.

FUSE

LINE CROSS CAPACITOR  0.22 F AC250V

WHITE

RED

NOISE SUPPRESSION COIL

LINE BYPASS

CAPACITOR

0.003300 F / AC 125V

LINE BYPASS

CAPACITOR

0.003300 F / AC 125V

20A

NOISE FILTER

N

L

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

INDICATION OF OHMMETER

Between N and L

Open circuit

Between terminal N and WHITE

Short circuit

Between terminal L and RED

Short circuit