Sharp R-2398G Service Manual ▷ View online
11
R-2398
Room temperature ................................................................................................. T0 = 21
°
C
Initial temperature .................................................................................................. T1 = 11
°
C
Temperature after (28 + 3) = 31 sec ...................................................................... T2 = 21
°
C
Temperature difference Cold-Warm .....................................................................
∆
T1 = 10˚C
Measured output power
The equation is “P = 150 x
The equation is “P = 150 x
∆
T” ................................................ P = 150 x 10
°
C = 1500 Watts
JUDGMENT: The measured output power should be within the range of
±
15 % of the rated output
power.
CAUTION: 1
°
C CORRESPONDS TO 150 WATTS. REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
1000g
1000g
1000g
T1˚C
T2˚C
Heat up for 31 sec.
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.
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.
CARRY OUT 3D CHECKS.
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 windings. The following readings should be
obtained:
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 windings. The following readings should be
obtained:
a. Primary winding ............. approximately 1.8
Ω
b. Secondary winding ......... approximately 75
Ω
c. Filament winding ...................... less than 1
Ω
If the readings obtained are not stated as above, then the high voltage transformer is probably faulty
and should be replaced.
CARRY OUT 4R CHECKS.
and should be replaced.
CARRY OUT 4R CHECKS.
CARRY OUT 3D CHECKS.
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 B+C 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
using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal B+C 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.
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.
OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.
C
HIGH VOLTAGE RECTIFIER ASSEMBLY TEST
B
C
HIGH VOLTAGE RECTIFIER
12
R-2398
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
CARRY OUT 3D CHECKS.
A. Isolate the high voltage capacitor from the circuit.
B. Continuity check must be carried out with measuring instrument which is set to the highest
B. Continuity check must be carried out with measuring instrument which is set to the highest
resistance range.
C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10M
Ω
after it has been charged.
D. A short-circuited capacitor shows continuity all the time.
E. An open capacitor constantly shows a resistance about 10 M
E. An open capacitor constantly shows a resistance about 10 M
Ω
because of its internal 10M
Ω
resistance.
F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
G. The resistance across all the terminals and the chassis must be infinite when the capacitor is
G. 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.
CARRY OUT 4R CHECKS.
D
HIGH VOLTAGE CAPACITOR TEST
E
SWITCH TEST
CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in
the following table.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in
the following table.
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
If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.
CARRY OUT 4R CHECKS.
CARRY OUT 3D CHECKS.
If the fuses M8A are blown, there could be shorts in the high voltage transformers (1) and/or (2) or there
is a ground in wire harness. Check and/ or replace the high voltage transformers(1) and/or (2) or repair
the wire harness.
is a ground in wire harness. Check and/ or replace the high voltage transformers(1) and/or (2) or repair
the wire harness.
CARRY OUT 4R CHECKS.
CAUTION: Only replace
fuses M8A
with the correct value replacement.
F
FUSES M8A TEST
G
FUSE F13A TEST
CARRY OUT 3D CHECKS.
If the fuse F13A is blown, there could be a shorts or grounds in electrical parts or wire harness.
Check them and replace the defective parts or repair the wire harness.
Check them and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION: Only replace fuse F13A with the correct value replacement.
H
FUSE F6.3A TEST
CARRY OUT 3D CHECKS.
If the fuse F6.3A is blown when the door is opened, check the 1st. latch switch, monitor switch and
monitor resistor.
If the fuse F6.3A is blown by incorrect door switching replace the defective switch(s) and the fuse
F6.3A.
monitor resistor.
If the fuse F6.3A is blown by incorrect door switching replace the defective switch(s) and the fuse
F6.3A.
CARRY OUT 4R CHECKS.
CAUTION: Only replace fuse F6.3A with the correct value replacement.
13
R-2398
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
1. CARRY OUT 3D CHECKS.
2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the
2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the
temperature of the temperature fuse reaches specfied temperature as shown below.
I
TEMPERATURE FUSE TEST
3. CARRY OUT 4R CHECKS.
CAUTION: IF THE temperature fuse INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,
REPLACE temperature fuse.
Open
Close
Display or
temperature
temperature
Condition
Check point
Magnetron (1) tem-
perature fuse
perature fuse
Magnetron (2) tem-
perature fuse
perature fuse
Blower motor tem-
perature fuse
perature fuse
Oven temperature
fuse
fuse
150˚C
120˚C
120˚C
Non resetable
type
type
Non resetable
type
type
Non resetable
type
type
EE1
EE3
EE2
Oven shut
off
off
Oven shut
off
off
Magnetron (1) Failure:
Test magnetron (1) and Blower fan motor.
Test magnetron (1) and Blower fan motor.
Magnetron (1) & (2) Failure: Test magnetron (1) & (2).
Check blower fan motor and ventilation opening.
Check blower fan motor and ventilation opening.
Magnetron (2) Failure:
Test magnetron (2) and Blower fan motor.
Test magnetron (2) and Blower fan motor.
Check blower fan motor and ventilation opening or
rocked rotating of blower fan motor.
rocked rotating of blower fan motor.
Food has been burned in oven.
Temperature of oven inside is very high.
Temperature of oven inside is very high.
J
MONITOR RESISTOR TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the monitor resistor. Using an ohmmeter and set on a low range. Check
between the terminals of the monitor resistor.
between the terminals of the monitor resistor.
The resistance of monitor resistor should be read approx. 4.3
Ω
.
If incorrect readings are obtained, replace the monitor resistor.
CARRY OUT 4R CHECKS.
1. CARRY OUT 3D CHECKS.
2. Follow the procedures below for each thermistor.
2. Follow the procedures below for each thermistor.
2-1. MAGNETRON THERMISTOR TEST
Disconnect the connector of the magnetron thermistor from the switch harness. Measure the
resistance of the magnetron thermistor with an ohmmeter. Connect the ohmmeter leads to the leads
of the thermistor.
Disconnect the connector of the magnetron thermistor from the switch harness. Measure the
resistance of the magnetron thermistor with an ohmmeter. Connect the ohmmeter leads to the leads
of the thermistor.
Room Temp.
59˚F (15˚C)
68˚F (20˚C)
77˚F (25˚C)
Resistance
Approx. 373 k
Ω
Approx. 292 k
Ω
Approx. 231 k
Ω
If the meter does not indicate above resistance, replace the thermistor.
2-2. OVEN THERMISTOR (1) TEST
Disconnect the connector of the oven thermistor (1) from the switch harness. Measure the resistance
of the oven thermistor (1) with an ohmmeter. Connect the ohmmeter leads to the leads of the thermistor.
of the oven thermistor (1) with an ohmmeter. Connect the ohmmeter leads to the leads of the thermistor.
Room Temp.
59˚F (15˚C)
68˚F (20˚C)
77˚F (25˚C)
Resistance
Approx. 373 k
Ω
Approx. 292 k
Ω
Approx. 231 k
Ω
If the meter does not indicate above resistance, replace the thermistor.
2-3. OVEN THERMISTOR (2) TEST
Disconnect the two connectors of the magnetron thermistor and oven thermistor (2) from the switch
harness. Measure the resistance of the oven thermistor (2) with an ohmmeter. Connect the ohmmeter
leads to the leads of the thermistor.
harness. Measure the resistance of the oven thermistor (2) with an ohmmeter. Connect the ohmmeter
leads to the leads of the thermistor.
K
THERMISTOR TEST
14
R-2398
O
TOUCH CONTROL PANEL ASSEMBLY TEST
MEASURING POINT
INDICATION OF OHMMETER
Between N and L
Approx. 680 k
Ω
Between terminal N and WHIT
Short circuit
Between terminal L and BLK
Short circuit
If incorrect readings are absorbed, replace the noise filter.
CARRY OUT 4R CHECKS.
N
HIGH VOLTAGE FUSE TEST
CARRY OUT 3D CHECKS.
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.
Check them and replace the defective parts and the high voltage fuse.
CARRY OUT 4R CHECKS.
CAUTION:
Only replace high voltage fuse with the correct value replacement.
F1 : FUSE F13A
NOISE FILTER
NOISE SUPPRESSION COIL
DISCHARGE RESISTOR 680 k
Ω
1/2W
DISCHARGE RESISTOR 10 M
Ω
1/2W
LINE CROSS CAPACITOR 0.22
µ
F/ AC250V
LINE CROSS CAPACITOR
10000 pF/ AC250V
LINE CROSS CAPACITOR
10000 pF/ AC250V
L
BLK
WHT
N
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
L
MOTOR WINDING TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two
terminals.
Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two
terminals.
Resistance of Blower motor should be approximately 52
Ω
.
Resistance of Stirrer motor should be approximately 8.8 k
Ω
.
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS.
M
NOISE FILTER TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of noise filter. Using an ohmmeter, check between the
terminals as described in the following table.
terminals as described in the following table.
Room Temp.
59˚F (15˚C)
68˚F (20˚C)
77˚F (25˚C)
Resistance
Approx. 16 k
Ω
Approx. 13 k
Ω
Approx. 11 k
Ω
If the meter does not indicate above resistance, replace the thermistor.
3. CARRY OUT 4R CHECKS.
3. CARRY OUT 4R CHECKS.
The touch control panel consists of circuits including semiconductors such as LSI, IC, 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 divided into two units,
Control Unit and Key Unit, troubleshooting by unit replacement is described according to the symptoms
indicated.
1. Key Unit Note : Check key unit ribbon connection before replacement.
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 divided into two units,
Control Unit and Key Unit, troubleshooting by unit 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.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching the pads, sometimes a pad produces no signal.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching the pads, sometimes a pad produces no signal.
2. Control Unit
The following symptoms may indicate a defective control unit. Replacing the control unit. Before
replacing the control unit, perform the key unit test (Procedure P) to determine if control unit is faulty.
replacing the control unit, perform the key unit test (Procedure P) to determine if control unit is faulty.
2-1 Programming problems.
a) When touching the pads, a certain group of pads do not produce a signal.
2-2 Display problems.
a) For a certain digit, all or some segments do not light up.
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