Sharp Carousel II R-3A54 Service Manual - Page 14

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R-3A54

R-3E54

TEST PROCEDURES

(CONT'D)

PROCEDURE

LETTER

COMPONENT

TEST

LIVE TEST FOR MOTOR

WINDINGS

CAUTION:

The following

procedure

requires

the oven to be connected

to the supply

and should

only be used if the relevant

"cold"

checks

for the motor

un-

der test are inconclusive.

1. CARRY OUT3JCHECKS

2. Disconnect

the leads from the primary

of the power transformer.

Make sure that the leads

remain isolated from other oven components

and chassis. (Use insulation

tape if necessary,)

3. Connect

a voltmeter,

set to 250V AC, across the motor terminals.

(Refer to the relevant motor

test procedure

or pictorial

diagram for the correct terminal

numbers.)

4. Arrange the meter in a position

where it can be read during the test. (Do not touch the meter,

meter leads or oven circuitry

while the oven is active.)

5. Close the oven door.

6. Set the relevant timer for about three (3) minutes,

set the power level to HIGH and push the

START button.

7. Note the reading on the meter and carefully

observe the motor under test to see if it is turning.

8. CARRY OUT 3D CHECKS

9. Remove test meter leads.

1 O.Reconnect

the leads to the primary of the power transformer.

If a reading of 240 volts AC was obtained

(step 7) but the motor was not turning

then it is faulty

and should

be replaced.

If the meter indicated

that no supply was present then the wiring

to the

motor should

be checked for continuity.

BLOWN

FUSE

F M8A

CARRY OUT 3D CHECKS

1. If the fuse M8A is blown,

there could be a shorts or ground

in electrical

parts or wire harness.

Check them and replace the defective

parts or repair the wire harness.

2. If the fuse M8A

is blown

when

the door is opened,

check the 1st latch switch,

2nd latch

switch,

monitor

switch

and monitor

resistor.

If the fuse M8A is blown

by incorrect

door switching

replace the defective

switch(s)

and the

fuse M8A.

3. If the fuse M8A is blown,

there could

be a short in the asymmetric

rectier or there could

a ground

in wire harness.

A short in the asymmetric

rectifier

may have occured

due to short

or ground

in H.V. rectifier,

magnetron,

power transformer

or H.V. wire.

Check them and re-

place the defective

parts or repair the wire harness.

CARRY OUT 4J CHECKS

CAUTION:

Only

replace

fuse with

the correct

value

replacement.

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 di-

vided into two units, Control

Unit 'and Key Unit, and troubleshooting

by unit replacement

is de-

scribed according

to the symptoms

indicated.

1. Key Unit.

The following

symptoms

indicate

a defective

key unit. Replace the key un t.

When touching

the pads, a certain pad produces

no signal at all.

b) When touching

a number pad, two figures or more are displayed.

When touching

the pads, sometimes

a pad produces

no signal.

2. Control

Unit

The following

symptoms

indicate

a defective

control

unit, Replace the COI

2-l

In connection

with

pads.

trol unit.

When touching

the pads, a certain group of pads do not produce

a signal.