DOWNLOAD Sharp R-8000GK Service Manual ↓ Size: 1.16 MB | Pages: 44 in PDF or view online for FREE

8

RE: Replace / CK: Check

Home fuse blows when power cord is plugged into wall receptacle.

Fuse 20A

 blows when power cord is plugged into wall receptacle.

  

  

  

  

  

 does not appear in display when power cord is first plugged into wall 

receptacle.

Fuse F10A

 blows when the door is Opened.

Oven lamp does not light with door opened. 

High voltage transformer

, heating elements, turntable motor and oven lamp 

do not operate.

Oven lamp lights, but turntable motor does not operate.

T

urntable motor operates normally but cooling fan motor does not operate.

Oven does not go into a cook cycle, when ST

AR

T

 key is touched.

Low or no power is produced during microwave cooking (The food is heat-

ed incompletely or not heated at all)

Extremely uneven heating is produced in oven load (food).

Function of variable cooking does not operate properly except 100% power

.

Heating elements do not heat.

T

emperature in the oven cavity is lower or higher than preset.

Jet motor does not operate at all or properly

.

Oven operates for 10 minutes then shuts down, and "EE-6" appears. 

(THERMIST

OR F

AILURE)

"EE-10" appears. (MEMOR

Y

 F

AILURE)

"EE-9" appears. (MAXIMUM 

TIME EXCEEDED)

"CK-1" appears. (T

otal operation time (hours) of magnetron exceeds 1250 

hours.)

"CK-2" appears. (T

otal operation time (hours) of top heating element ex-

ceeds 4000 hours.)

"CK-3" appears. (T

otal operation time (hours) of side heating element ex-

ceeds 4000 hours.)

MAGNETRON

HIGH VOLT

AGE TRANSFORMER

H.V. RECTIFIER 

ASSEMBLY

HIGH VOLT

AGE CAPACIT

OR

SECONDARY

 INTERLOCK SWITCH

3RD. LATCH SWITCH

DOOR SENSING SWITCH

MONITOR SWITCH

HIGH VOLT

AGE FUSE

FUSE 20A

MAGNETRON TEMPERATURE 

FUSE

THERMAL CUT

-OUT (T

OP) 

TOP 

HEATING ELEMENT

THERMISTOR

NOISE FILTER

TOUCH CONTROL

 PANEL

TACT

 SWITCH

RELAY

 RY

-1

RELAY

 RY

-2

RELAY

 RY

-3

RELAY

 RY

-5

RELAY

 RY

-6

FUSE1 ON PWB.

SOLID-STA

TE RELAY

 (TOP)

SOLID-STA

TE RELAY

 (SIDE)

OVEN LAMP

FAN MOT

OR (MAGNETRON)

TURNTABLE MOT

OR

JET MOT

OR

LOOSE WIRING

SHORTED IN POWER CORD  

NO POWER A

T OUTLET

 

LOW VOLT

AGE

THERMAL CUT

 OUT (SIDE)

SIDE HEATING ELEMENT

FAN MOT

OR (H.V. TRANSFORMER)

T/C TRANSFORMER

FUSE F10A

JET MOT

OR CAPACIT

OR

WRONG OPERATION

MISADUSTMENT SWITCH

HEATER TEMPERATURE 

FUSE

TEST

 PROCEDURE

PROBLEM

POSSIBLE CASE 

AND DEFECTIVE P

A

R

T

S

CONDITION

OFF CONDITION

COOKING CONDITION

MICROW

A

VE COOKING

ERROR MODE

EXCEPT

 FOR MICROW

A

V

E

COOKING

AB

C

D

EE

E

F

H

J

K

M

O

G

U

V

W

W

W

W

W

E

YX

X

RE

T

T

RE

P

RE

CK

CK

CK

CK

CK

RL

N

Y

I

Q

9

NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL WHILE
THE OVEN IS IN OPERATION.

1.

CARRY OUT 3D CHECKS.

2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across

the magnetron filament leads should indicate less than 1 ohm.

4. To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads and

chassis ground. This test should indicate an infinite resistance. If there is little or no resistance the magnetron
is grounded and must be replaced.

5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet) and the back plate.
7. Reconnect the power supply cord after the outer case and back plate are installed.
8. Run the oven and check all functions.

MICROWAVE OUTPUT POWER
The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer
case fitted).
The power output of this oven is rated using the method specified by  IEC 60705. Full details of how to curry out
this procedure can be found in the Sharp Technical Training notes which is available from Sharp Parts Centre
(part number SERV-LITMW01).

The IEC60705 procedure must be carried out using laboratory-type procedures and equipment.
These requirements make the procedure unsuitable for routine performance checks.

Alternative simplified method:
1. Place 2  litres of cold water (between 12

°C and 20°C) in a suitable container.

2. Stir the water and measure the temperature in 

°C. Note temperature as T1.

3. Place the container in the microwave and heat the water for 1 minute and 33 seconds on full power.

4. When the 1 minute and 33 seconds is completed, remove the  container and stir the water. Note the water

temperature as T2.

5. Calculate the output power using the following formula:

R.F. Power Output = (T2 - T1) x 90.

±

MICROWAVE LEAKAGE TEST

This oven should be tested for microwave leakage on completion of any repair or adjustment, following the
procedure described in the Sharp Technical Training notes (part number SERV-LITMW01). The maximum
leakage permitted in BS EN 60335-2-25 is 50W/m

2 

(equivalent to 5W/m

2

), however it is not normal to detect any

significant leakage, therefore, any leakage which is detected should be investigated.

It is essential that only leakage detectors with current calibration traceable to National Physical Laboratories are
used.

Suitable leakage detectors:

CELTEC A100
APOLLO X1

1.

CARRY OUT 3D CHECKS.

2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.

10

3. Disconnect the leads to the primary winding of the high voltage transformer. Disconnect the filament and

secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low range,  it
is possible to check the continuity of all three winding. The following readings should be obtained:-

a. Primary winding .................................... 1.3 ohms approximately
b. Secondary winding ................................. 95 ohms approximately
c. Filament winding ...............................................  less than 1 ohm

If the readings obtained are not stated as above, then the high voltage transformer is probably faulty and
should be replaced.

4. Also, the high voltage transformer has the thermostat in the primary coil. Measure the resistance of the

primary coil. The resistance of the primary coil should be above resistance unless the temperature of the
thermostat in the primary coil reaches approximately 160˚C. The thermostat resets automatically at 105˚C.
If an ohmmeter indicates an open circuit under normal condition, replace the high voltage transformer
because the primary coil (thermostat) has opened. An open primary coil (thermostat) indicates overheating
of the high voltage transformer. Check for restricted air flow to the high voltage transformer, especially the
fan motor (high voltage transformer side).

5. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier  can be tested using

an ohmmeter set to its highest range. Connect the ohmmeter across the terminal of the high voltage rectifier
and note the reading obtained. Reverse the meter leads and note this second reading. The normal resistance
is infinite in one direction and more than 100 k

Ω in the other direction.

4. CARRY OUT 4R CHECKS.

NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF THE

MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE OTHERWISE
AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Isolate the high voltage capacitor from the circuit.
4. Continuity check must be carried out with measuring instrument which is set to the highest resistance range.
5. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10M

Ω after it has

been charged.

6. A short-circuited capacitor shows continuity all the time.
7. An open capacitor constantly shows a resistance about 10 M

Ω because of its internal 10MΩ resistance.

8. When the internal wire is opened in the high voltage capacitor, the capacitor shows an infinite resistance.
9. The resistance across all the terminals and the chassis must be infinite when the capacitor is  normal. If

incorrect reading are obtained, the high voltage capacitor must be replaced.

10. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the

following table.

If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.

3. CARRY OUT 4R CHECKS.

Table: Terminal Connection of Switch

Plunger Operation

COM to NO

COM to NC

Released

Open circuit

Short circuit

Depressed

Short circuit

Open circuit

COM; Common terminal,
NO;

Normally open terminal

NC;

Normally close terminal

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.

11

3. If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.

Check them and replace the defective parts and the high voltage fuse.

4. CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE REPLACEMENT.

1. CARRY OUT 3D CHECKS.
2. Disconnect the leads from the terminals of noise filter.

Using an ohmmeter, check between the terminals as described in the
following table.

Between N and L

Approx. 680 k

Ω

Between terminal N and WHITE

Short circuit

Between terminal L and RED

Short circuit

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

CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. If the fuse 20A is blown, there is a shorts or grounds in electrical parts or wire harness Check then and replace

the defective parts or repaire the wire harness.

3. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. If the fuse F10A is blown when the door is opened, check the secondary interlock switch, relay RY1, relay

RY2 and monitor switch.

3. If the fuse F10A is blown by incorrect door switching, replace the defective switch(es) and the fuse F10A.
4. If the fuse F10A is blown, there is a shorts or grounds in electrical parts or wire harness.

Check them and replace the defective parts or repair the wire harness.

5. CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE FUSE F10A WITH CORRECT VALUE REPLACEMENT.

FUSE

20A

N

L

LINE CROSS CAPACITOR   1.0

µ/AC275V 

NOISE SUPPRESSION COIL 

LINE BYPASS 
CAPACITOR
0.0047

µ/AC250V

LINE BYPASS
CAPACITOR
0.0047

µ/AC250V

RESISTOR   
10M    1/2W

RESISTOR   680K    1/2W

WHT

RED

NOISE FILTER

1. CARRY OUT 3D CHECKS.
2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the

temperature of the magnetron reaches approximately 150˚C. An open temperature fuse indicates overheating
of the magnetron. Check for restricted air flow to the magnetron, especially the cooling duct and cooling fan.

3. CARRY OUT 4R CHECKS.

CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,

REPLACE TEMPERATURE FUSE.

1. CARRY OUT 3D CHECKS.
2. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the

temperature of the thermal cut-out reaches approximately 170˚C. The thermal cut-out resets automatically
at approximately 155˚C. If thermal cut-out has opened under normal condition, replace the same item as in
the parts list.
An open thermal cut-out indicates overheating of the top heating element unit. Check for restricted air flow
to the top heat element  unit through the vent holes of the oven cavity, especially the heater duct upper and
convection fan.

3. CARRY OUT 4R CHECKS.

CAUTION: IF THE THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,

REPLACE THERMAL CUT-OUT.