J: Blown Fuse (F2) F8A (Noise Filter); K: Noise Filter Test; L: Grill Heating Elements (Top) And Engine Heating Element Test; M: Control Unit Test - Sharp AX-1100 Service Manual

Microwave oven with steam and grill

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Table Of Contents

Table of Contents

AX1100(R)

[10] J: BLOWN FUSE (F2) F8A (NOISE FILTER)

CARRY OUT 3D CHECKS.

1. If the fuse F2 F8A is blown when the door is opened, check the monitored interlock switch and monitor switch.

2. If the fuse F2 F8A is blown by incorrect door switching replace the defective switch(es) and the fuse F2 F8A.

3. If the fuse F2 F8A is blown, there could be shorts in the asymmetric rectifier or there is a ground in wire harness. A short in the asymmetric rectifier

may be occurred due to short or ground in H.V. rectifier, magnetron, high voltage transformer or H.V. wire. Check them and replace the defective

parts or repair the wire harness.

CARRY OUT 4R CHECKS.

[11] K: NOISE FILTER TEST

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of the noise filter. Using an ohmmeter, check

between the terminals as described in the following table.

MEASURING POINT

Between N and L

Between terminal N and WHITE

Between terminal L and RED

If incorrect readings are obtained, replace the noise filter unit.

CARRY OUT 4R CHECKS.

[12] L: GRILL HEATING ELEMENTS (TOP) AND ENGINE HEATING ELEMENT TEST

CARRY OUT 3D CHECKS.

Before carrying out the following tests make sure the heating element is cool completely.

1. Resistance of heater.

Disconnect the wire leads to the heating element to be tested. Using ohmmeter with low resistance range. Check the resistance across the termi-

nals of the heating element as described in the following table.

Table: Resistance of heater

Parts name

Grill heating element

Engine heating element

2. Insulation resistance.

Disconnect the wire leads to the heating element to be tested. Check the insulation resistance between the element terminal and cavity using a

500V - 100M insulation tester. The insulation resistance should be more than 10M in the cold start.

If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably faulty and should be replaced.

CARRY OUT 4R CHECKS.

[13] M: CONTROL UNIT TEST

The control unit consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper mainte-

nance can not be performed with only a voltmeter and ohmmeter.

In this service manual, the control panel assembly is divided into two units, Control Unit and Key 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.

1) When touching the pads, a certain pad produces no signal at all.

2) When touching a number pad, two figures or more are displayed.

3) When touching the pads, sometimes a pad produces no signal.

2. Control Unit

The following symptoms indicate a defective control unit. Before replacing the control unit perform the key unit test (Procedure N) to determine if con-

trol unit is faulty.

2.1. In connection with pads

1) When touching the pads, a certain group of pads do not produce a signal.

2) When touching the pads, no pads produce a signal.

INDICATION OF OHMMETER

Approx. 680 k

Short circuit

Resistance

Approximately 46.5 ~ 51.1

Approximately 58.0 ~ 62.9

20A

F2: F8A