Sharp R-8000GK Service Manual ▷ View online
R-8000GK
7
It is intended to heat air driven by the convection fan. The heated
air is kept in the oven and force-circulated and reheated by the
top heating element.
air is kept in the oven and force-circulated and reheated by the
top heating element.
SIDE HEATING ELEMENT
The side heating element is located at the left side of the oven
cavity. It is intended to heat air driven by the convection fan. The
heated air is kept in the oven and force-circulated and reheated
by the top heating element.
cavity. It is intended to heat air driven by the convection fan. The
heated air is kept in the oven and force-circulated and reheated
by the top heating element.
TURNTABLE MOTOR
The turntable motor rotates the turntable located in the bottom of
the oven cavity, so that the food on the turntable is cooked evenly
during cooking. The turntable may turn in either direction.
the oven cavity, so that the food on the turntable is cooked evenly
during cooking. The turntable may turn in either direction.
FAN MOTOR (MAGNETRON SIDE)
The fan motor drives a blade which draws external cool air. This
cool air is directed through the air vents surrounding the magn-
etron and cools the magnetron. This air is channelled through the
oven cavity to remove steam and vapours given off from the
heating foods. It is then exhausted through the exhausting air
vents at the oven cavity.
cool air is directed through the air vents surrounding the magn-
etron and cools the magnetron. This air is channelled through the
oven cavity to remove steam and vapours given off from the
heating foods. It is then exhausted through the exhausting air
vents at the oven cavity.
FAN MOTOR (HIGH VOLTAGE TRANSFORMER
SIDE)
SIDE)
The fan motor drives a blade which draws external cool air. This
cool air is directed through the air vents surrounding the power
transformer and cools the power transformer. This air is chan-
nelled through the oven cavity to remove steam and vapours
given off from the heating foods. It is then exhausted through the
exhausting air vents at the oven cavity.
cool air is directed through the air vents surrounding the power
transformer and cools the power transformer. This air is chan-
nelled through the oven cavity to remove steam and vapours
given off from the heating foods. It is then exhausted through the
exhausting air vents at the oven cavity.
CONVECTION COOKING SYSTEM
This oven is designed with a hot air heating system where food is
not directly heated by the heating element, but is heated by forced
circulation of the hot air produced by the heating elements. The air
heated by the heating elements is circulated through the convec-
tion passage provided on the outer casing of the oven cavity by
means of the convection fan which is driven by the jet motor. It then
enters the inside of the oven through the vent holes provided on the
top and left sides of the oven. Next, the hot air heats the food on the
turntable and leaves the oven cavity through the vent in the centre
of the oven cavity back side wall. Without leaving the oven, this hot
air is reheated by the heating elements, passes through the
convection passage and enters the inside of the oven cavity again,
in a continuing cycle. In this way, the hot air circulates inside the
oven cavity to raise its temperature and, at the same time, comes
into contact with the food being cooked. When the temperature
inside the oven cavity reaches the selected temperature, the
heating elements are de-energized. When the temperature inside
the oven cavity drops below the selected temperature, the heating
elements are energized again. In this way, the inside of the oven
cavity is maintained at approximately the selected temperature.
When the convection time reaches 0, the heating elements are de-
energized and the convection fan stops operating and the oven
shuts off.
not directly heated by the heating element, but is heated by forced
circulation of the hot air produced by the heating elements. The air
heated by the heating elements is circulated through the convec-
tion passage provided on the outer casing of the oven cavity by
means of the convection fan which is driven by the jet motor. It then
enters the inside of the oven through the vent holes provided on the
top and left sides of the oven. Next, the hot air heats the food on the
turntable and leaves the oven cavity through the vent in the centre
of the oven cavity back side wall. Without leaving the oven, this hot
air is reheated by the heating elements, passes through the
convection passage and enters the inside of the oven cavity again,
in a continuing cycle. In this way, the hot air circulates inside the
oven cavity to raise its temperature and, at the same time, comes
into contact with the food being cooked. When the temperature
inside the oven cavity reaches the selected temperature, the
heating elements are de-energized. When the temperature inside
the oven cavity drops below the selected temperature, the heating
elements are energized again. In this way, the inside of the oven
cavity is maintained at approximately the selected temperature.
When the convection time reaches 0, the heating elements are de-
energized and the convection fan stops operating and the oven
shuts off.
Flow of hot air:
The rotation direction of the jet motor is controlled by relay RY6.
When the convection fan rotates clockwise, the hot air from the
oven cavity left side wall blows stronger than one from the oven
cavity top wall. ( This mode is called “Convection mode”.) When
the convection fan rotates counterclockwise, the hot air from the
oven cavity top wall blows stronger than one from the oven cavity
left side wall. (This mode is called “JET mode”.)
When the convection fan rotates clockwise, the hot air from the
oven cavity left side wall blows stronger than one from the oven
cavity top wall. ( This mode is called “Convection mode”.) When
the convection fan rotates counterclockwise, the hot air from the
oven cavity top wall blows stronger than one from the oven cavity
left side wall. (This mode is called “JET mode”.)
Figure D-2. Rotation direction of convection fan
Figure D-3. Flow of hot air
Side heating
element unit
element unit
Top heating
element unit
element unit
Convection
fan
fan
Convection mode
JET
mode
mode
FRONT VIEW
Hot air
Hot air
Hot air
Convection
fan
fan
Hot air
Oven cavity left side
Oven cavity
top wall
top wall
Side heating
element unit
element unit
Side heating
element unit
element unit
Top heating element unit Top heating element unit
Turntable
Convection Mode
JET Mode
TROUBLESHOOTING GUIDE
When troubleshooting the microwave oven, it is helpful to
follow the Sequence of Operation in performing the checks.
Many of the possible causes of trouble will require that a
specific test be performed. These tests are given a proce-
dure letter which will be found in the "Test Procedure
"section.
follow the Sequence of Operation in performing the checks.
Many of the possible causes of trouble will require that a
specific test be performed. These tests are given a proce-
dure letter which will be found in the "Test Procedure
"section.
IMPORTANT:
If the oven becomes inoperative because of a
blown fuse F10A in the secondary interlock
swith - monitor switch - primary interlock relay
RY2 circuit, check the monitor switch, relay
(RY1), primary interlock relay (RY2) and sec-
ondary interlock switch before replacing the
fuse F10A.
blown fuse F10A in the secondary interlock
swith - monitor switch - primary interlock relay
RY2 circuit, check the monitor switch, relay
(RY1), primary interlock relay (RY2) and sec-
ondary interlock switch before replacing the
fuse F10A.
R-8000GK
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
R-8000GK
9
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL WHILE
THE OVEN IS IN OPERATION.
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
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.
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.
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 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.
These requirements make the procedure unsuitable for routine performance checks.
NOTE: The following test method gives an indication of the output power only, it cannot be used to
establish the actual/rated output power. If the true output power is required, then the IEC60705
test method must be used.
test method must be used.
Alternative simplified method:
1. Place 2 litres of cold water (between 12
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.
NOTE: The operation time of microwave oven includes "3" sec. (3 sec. is magnetron filament heat-up
time.)
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.
NOTE: The result from this test should be within the allowance of 2000cc alternative method.
(
±
10%).
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
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.
used.
Suitable leakage detectors:
CELTEC A100
APOLLO X1
APOLLO X1
A
MAGNETRON ASSEMBLY TEST
B
HIGH VOLTAGE TRANSFORMER TEST
WARNING:
High voltage and large currents are present at the secondary winding and filament
winding of the high voltage transformer. It is very dangerous to work near this part
when the oven is on. NEVER make any voltage measurements of the high-voltage
circuits, including the magnetron filament.
winding of the high voltage transformer. It is very dangerous to work near this part
when the oven is on. NEVER make any voltage measurements of the high-voltage
circuits, including the magnetron filament.
1.
CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
R-8000GK
10
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
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:-
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
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.
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).
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
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
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.
AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.
C
HIGH VOLTAGE RECTIFIER TEST
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
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
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
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.
D
HIGH VOLTAGE CAPACITOR TEST
E
SWITCH TEST
1. CARRY OUT 3D CHECKS.
2. Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the
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;
NO;
Normally open terminal
NC;
Normally close terminal
F
HIGH VOLTAGE FUSE TEST
1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
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