DOWNLOAD Sharp R-658SLM Service Manual ↓ Size: 2.92 MB | Pages: 36 in PDF or view online for FREE

R65

8WM

9 – 2

This unit uses CMOS LSI in the integral part of the circuits. When han-
dling these parts, the following precautions should be strictly followed.
CMOS LSI have extremely high impedance at its input and output ter-
minals. For this reason, it is easily influenced by the surrounding high
voltage power source, static electricity charge in clothes, etc., and
sometimes it is not fully protected by the built-in protection circuit.

In order to protect CMOS LSI.

1) When storing and transporting, thoroughly wrap them in aluminium

foil. Also wrap PW boards containing them in aluminium foil.

2) When soldering, ground the technician as shown in the figure and

use grounded soldering iron and work table.

We describe the procedures to permit servicing of the touch control
panel of the microwave oven and the precautions you must take when
doing so. To perform the servicing, power to the touch control panel is
available either from the power line of the oven itself or from an exter-
nal power source.

1. Servicing the touch control panel with power supply of the

CAUTION: THE HIGH VOLTAGE TRANSFORMER OF THE MICRO-

WAVE OVEN IS STILL LIVE DURING SERVICING AND
PRESENTS A HAZARD.

Therefore, before checking the performance of the touch control
panel,

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.

6) After that procedure, re-connect the power supply cord.

After checking the performance of the touch control panel,

1) Disconnect the power supply cord.

2) Open the door and block it open.

3) Re-connect the leads to the primary of the power transformer.

4) Re-install the outer case (cabinet).

5) Re-connect the power supply cord after the outer case is installed.

6) Run the oven and check all functions.

a) On some models, the power supply cord between the touch

control panel and the oven itself is so short that the two can't be
separated. For those models, check and repair all the controls
(sensor-related ones included) of the touch control panel while
keeping it connected to the oven. 

b) On some models, the power supply cord between the touch

control panel and the oven proper is long enough that they may
be separated from each other. For those models, therefore, it is
possible to check and repair the controls of the touch control
panel while keeping it apart from the oven proper; in this case
you must short both ends of the door sensing switch (on PWB)
of the touch control panel with a jumper, which brings about an
operational state that is equivalent to the oven door being
closed.

2. Servicing the touch control panel with power supply from an

Disconnect the touch control panel completely from the oven, and
short both ends of the door sensing switch (on PWB) of the touch
control panel, which activates an operational state that is equiva-
lent to the oven door being closed. Connect an external power
source to the power input terminal of the touch control panel, then it
is possible to check and repair the controls of the touch control
panel.

Tools required to service the touch control panel assembly.

1) Soldering iron: 60W

(It is recommended to use a soldering iron with a grounding termi-
nal.)

2) Oscilloscope: Single beam, frequency range: DC - 10MHz type or

more advanced model.

3) Others: Hand tools

1) Before turning on the power source of the control unit, remove the

aluminium foil applied for preventing static electricity.

2) Connect the connector of the key unit to the control unit being sure

that the lead wires are not twisted.

3) After aluminium foil is removed, be careful that abnormal voltage

due to static electricity etc. is not applied to the input or output ter-
minals.

4) Attach connectors, electrolytic capacitors, etc. to PWB, making

sure that all connections are tight.

5) Be sure to use specified components where high precision is

required.

approx. 1M ohm

R65

8WM

10 – 1

R657(W)

Service Manual

 

The “Main PWB” of this model employs lead-free solder. This is indicated by the “LF” symbol printed on the PWB and in the service manual. The suffix
letter indicates the alloy type of the solder.

When repairing a PWB with the “LF” symbol, only lead-free solder should be used. (Using normal tin/lead alloy solder may result in cold soldered
joints and damage to printed patterns.)

As the melting point of lead-free solder is approximately 40

°C higher than tin/lead alloy solder, it is recommend that a dedicated bit is used, and that

the iron temperature is adjusted accordingly.

As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wettability, (flow), to prevent damage to the land of the PWB, extreme
care should be taken not to leave the bit in contact with the PWB for an extended period of time. Remove the bit as soon as a good flow is achieved.
The high content of tin in lead free solder will cause premature corrosion of the bit. To reduce wear on the bit, reduce the temperature or turn off the
iron when it is not required. 

Leaving different types of solder on the bit will cause contamination of the different alloys, which will alter their characteristics, making good soldering
more difficult. It will be necessary to clean and replace bits more often when using lead-free solder. To reduce bit wear, care should be taken to clean
the bit thoroughly after each use.

Indicates lead-free solder of tin, silver and copper

R65

8WM

11 – 1

R657(W)

Service Manual

 

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts may result in severe, possibly fatal,
electric shock.

(Example)

High Voltage Capacitor, High Voltage Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage fuse, High Voltage Harness etc..

WARNING:

1) Disconnect the power supply cord.

2) Visually check the door and cavity face plate for damage (dents,

cracks, signs of arcing etc.).

Carry out any remedial work that is necessary before operating the
oven.

Do not operate the oven if any of the following conditions exist;

1) Door does not close firmly.

2) Door hinge, support or latch hook is damaged.

3) The door gasket or seal is damaged.

4) The door is bent or warped.

5) There are defective parts in the door interlock system.

6) There are defective parts in the microwave generating and trans-

mission assembly.

7) There is visible damage to the oven.

Do not operate the oven:

1) Without the RF gasket (Magnetron).

2) If the wave guide or oven cavity are not intact.

3) If the door is not closed.

4) If the outer case cabinet is not fitted.

1. Before wiring, 

1) Disconnect the power supply cord.

2) Open the door and block it open.

3) Discharge the high voltage capacitor and wait for 60 seconds.

2. Don't let the wire leads touch to the following parts;

1) High voltage parts:

Magnetron, High voltage transformer, High voltage capacitor
and High voltage rectifier assembly.

2) Hot parts:

Grill heating element, Oven lamp, Magnetron, High voltage
transformer and Oven cavity.

3) Sharp edge:

Bottom plate, Oven cavity, Waveguide flange, Chassis support
and other metallic plate.

4) Movable parts (to prevent a fault)

Fan blade, Fan motor, Switch, Turntable motor and cooling fan.

3. Do not catch the wire leads in the outer case cabinet.

4. Insert the positive lock connector certainly until its pin is locked.

And make sure that the wire leads should not come off even if the
wire leads is pulled.

5. To prevent an error function, connect the wire leads correctly, refer-

ring to the Pictorial Diagram. 

Please refer to ‘OVEN PARTS, CABINET PARTS, CONTROL PANEL PARTS, DOOR PARTS’, when carrying out any of the following removal proce-
dures:

To remove the outer case cabinet, procedure as follows.

1. Disconnect the oven from power supply.

2. Open the oven door and wedge it open.

3. Remove the two screws from the exhaust duct (rear).

4. Slide the exhaust duct (rear) up and pull it away from the oven cav-

ity.

5. Remove the screws from the rear(4).

6. Slide the entire case back about 3 cm to free it from retaining clips

on the cavity face plate.

7. Lift the entire case from the oven.

8. Discharge the H.V. capacitor before carrying out any further work.

9. Do not operate the oven with the outer case cabinet removed.

CAUTION: DISCHARGE HIGH VOLTAGE CAPACITOR BEFORE

TOUCHING ANY OVEN COMPONENT OR WIRING.

To remove the components, proceed as follows.

1. CARRY OUT 3D CHECKS.

2. Disconnect all the leads and terminals of high voltage rectifier from

high voltage capacitor.

3. Remove one (1) screw holding capacitor holder from the base

plate.

4. Remove one (1) screw holding earth side terminal of the high volt-

age rectifier assembly

 

R6

58WM

11 – 2

5. Remove the capacitor from the capacitor holder.

6. Now the high voltage rectifier and capacitor should be free.

CAUTION: WHEN REPLACING HIGH VOLTAGE RECTIFIER

ASSEMBLY, ENSURE THAT THE CATHODE (EARTH)
CONNECTION IS SECURELY FIXED TO THE BASE
PLATE THROUGH THE CAPACITOR HOLDER WITH AN
EARTHING SCREW.

To remove the components, proceed as follows.

1. CARRY OUT 3D CHECKS.

2. Disconnect the primary connections from high voltage transformer.

3. Disconnect the filament leads of the high voltage transformer from

high voltage capacitor and the magnetron.

4. Disconnect the H.V. secondary wire (white) from the high voltage

capacitor.

5. Remove the two (2) screws holding the transformer to base plate.

6. Remove the transformer from the base plate by sliding it away from

the oven cavity and lifting it.

7. Disconnect the high voltage wire from the filament lead of the high

voltage transformer.

8. Now, the high voltage transformer is free.

1. CARRY OUT 3D CHECKS.

2. Disconnect the H.V. wire and filament lead of the transformer from

the magnetron.

3. Remove the one (1) screw holding the air intake duct to the latch

hook.

4. Remove the one (1) screw holding the chassis support to the mag-

netron.

5. Move the air intake duct to left.

6. Carefully remove four (4) screws holding magnetron to the

waveguide.

7. Remove the magnetron from the waveguide with care so the mag-

netron antenna is not hit by any metal object around the antenna.

CAUTION: WHEN REPLACING THE MAGNETRON, BE SURE THE

R.F. GASKET IS IN PLACE AND THE MAGNETRON
MOUNTING SCREWS ARE TIGHTENED SECURELY.

1. CARRY OUT 3D CHECKS.

2. Disconnect the wire leads from the fan motor.

3. Remove the two (2) screws holding the fan motor to the oven cavity

back plate. The fan motor is now free.

4. Remove the fan blade from the fan motor shaft according to the fol-

lowing procedure.

i)

Hold the edge of the rotor of the fan motor by using a pair of
groove joint pliers.

CAUTION: • Make sure that any pieces do not enter the gap

between the rotor and the starter of the fan motor.
Because the rotor is easy to be shaven by pliers and
metal pieces may be produced. 

• Do not let the pliers touch the coil of the fan motor

because the coil may be cut or damaged.

• Do not distort the bracket by touching with the pliers.

ii) Remove the fan blade from the shaft of the fan motor by pulling

and rotating the fan blade with your hand.

CAUTION: • Do not use this removed fan blade again. Because the

hole (for shaft) of it may become bigger than a standard
one.

iii) Now, the fan blade will be free.

1. Install the fan blade to the fan motor shaft according to the following

procedure.

i)

Hold the centre of the bracket which supports the shaft of the
fan motor on a flat table.

ii) Install the fan blade to the shaft of fan motor by pushing the fan

blade with a small, light weight, ball peen hammer or rubber
mallet.

CAUTION: • Do not hit the fan blade when installing because the

bracket may be deformed.

• Make sure that the fan blade rotates smoothly after

installation.

• Make sure that the axis of the shaft is not slanted.

2. Install the fan motor to the oven cavity back plate with the two (2)

screws.

3. Re-connect the wire leads to the fan motor, referring to the pictorial

diagram.

Gap

Rotor

Bracket

Stator

Groove joint pliers

Coil

Shaft

Axis

Stator

Rotor

These are the positions
that should be pinched
with pliers.

Shaft

Table

Center of
bracket