R-22AMM (serv.man7). Test Procedure - Sharp Home Appliance Service Manual (repair manual)

r-22amm (serv.man7) service manual
Model
R-22AMM (serv.man7)
Pages
6
Size
203.48 KB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven / Test Procedure
File
r-22amm-sm7.pdf
Date

Read Sharp R-22AMM (serv.man7) Service Manual online

R22AMM
7 – 1
R22AMM
Service Manual
 
CHAPTER 7. 
TEST PROCEDURE
[1] A: MAGNETRON TEST
CARRY OUT 3D CHECKS.
Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.
To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron filament terminals, the meter should show a
reading of less than 1 ohm.
To test for short circuit filament to anode condition, connect ohmmeter between one of the filament terminals and the case of the magnetron (ground).
This test should be indicated an infinite resistance. If a low or zero resistance reading is obtained then the magnetron should be replaced.
1. MICROWAVE OUTPUT POWER (1 litre water load)
The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer case fitted). Microwave output power
from the magnetron can be measured by IEC test procedure, i.e. it can be measured by using water load how much it can be absorbed by the water
load. To measure the microwave output power in the microwave oven, the relation of calorie and watt is used. When P(W) heating works for t (sec-
ond), approximately P x t/4.187 calorie is generated. On the other hand, if the temperature of the water with V(ml) rises  T (
°C) during this microwave
heating period, the calorie of the water is v x  T.
Measuring condition:
1) Container
The water container must be a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of
approximately 190 mm.
2) Temperature of the oven and vessel
The oven and the empty vessel are at ambient temperature prior to the start of the test.
3) Temperature of the water
The initial temperature of the water is (10
±1)°C
4) Select the initial and final water temperature so that the maximum difference between the final water temperature and the ambient temperature is
5
°C.
5) Select stirring devices and measuring instruments in order to minimize addition or removal of heat.
6) The graduation of the thermometer must be scaled by 0.1
°C at minimum and an accurate thermometer.
7) The water load must be (1000
±5) g.
8) “t” is measured while the microwave generator is operating at full power. Magnetron filament heat-up time is not included.
NOTE: The operation time of the microwave oven is “t + 3" sec. (3 sec. is magnetron filament heat-up time.)
Measuring method:
1) Measure the initial temperature of the water before the water is added to the vessel.
(Example: The initial temperature T1 = 11
°C)
2) Add the 1 litre water to the vessel.
3) Place the load on the centre of the shelf.
4) Operate the microwave oven at HIGH until the temperature of the water rises by a value  T of (10
±2)K.
5) Stir the water to equalize temperature throughout the vessel.
6) Measure the final water temperature. (Example: The final temperature T2 = 21
°C)
7) Calculate the microwave power output P in watts from above formula.
NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL WHILE THE OVEN IS IN OPER-
ATION.
SERVICE INFORMATION
IMPORTANT:
When the magnetron MG1 and/or MG2 is replacing, the relays (RY3 and RY4) on control unit must be replaced at the 
same time. Because if the magnetron's life has been over, the relay's life may also be over.
   The formula is as follows;
           P x t / 4.187 = V x   T+ 0.55 x mc (T2-T0)                                   P (W) = 4.187 x V x  T / t + 0.55 x mc (T2-T0)/t
   Our condition for water load is as follows:
          Room temperature (T0) ......................... around 20°C                         Power supply Voltage ........................... Rated voltage
          Water load ........................................................1000 g                          Initial temperature (T1) .................................... 10±1°C
          Heating time ..................................................... 28 sec.                          Mass of container (mc) ...................................... 330 g
        T2 .................................................... Final Temperature               P = 150 x  T
R22AMM
7 – 2
JUDGEMENT: The measured output power should be at least 
± 15% of the rated output power.
CAUTION: 1
°C CORRESPONDS TO 150 WATTS. REPEAT MEASUREMENT IF THE POWER IS INSUFFICIENT.
2. MICROWAVE OUTPUT POWER (2000 cc alternative method)
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 IEC-60705 procedure must be carried out using laboratory-type procedures and equipment.
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.
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 59 sec. on full power.
4. When the 59 sec. is completed, remove the container and stir the water. Note temperature as T2.
5. Calculate the output power using the following formula:
R.F. Power Output = (T2 - T1) x 150.
NOTE: The result from this test should be within the allowance of 2000cc alternative method. (
±10%).
3. 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 Techni-
cal 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
[2] B: HIGH VOLTAGE TRANSFORMER TEST
1. CARRY OUT 3D CHECKS.
2. 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 -------------------- approximately 1.4 
Ω
                  b.Secondary winding --------------- approximately 63 
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.
3. CARRY OUT 4R CHECKS.
          Room temperature ................................................................. To = 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  T" .................... P = 150 x 10
°C = 1500 Watts
WARNING: High voltages and large currents are present at the secondary winding and filament winding of the power transformer. It is 
very dangerous to work near this part when the oven is on. NEVER make any voltage measurements of the high-voltage cir-
cuits, including the magnetron filament.
1000g
1000g
1000g
T1 C
T2 C
Heat up for 31 sec.
R22AMM
7 – 3
[3] C: HIGH VOLTAGE RECTIFIER TEST
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
Ω in the other direction.
CARRY OUT 4R CHECKS.
NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF THE MEA-
SURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE OTHERWISE AN
INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.
[4] D: HIGH VOLTAGE CAPACITOR TEST
CARRY OUT 3D CHECKS.
1. Isolate the high voltage capacitor from the circuit.
2. Continuity check must be carried out with measuring instrument which is set to the highest resistance range.
3. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10M
Ω after it has been charged.
4. A short-circuited capacitor shows continuity all the time.
5. An open capacitor constantly shows a resistance about 10M
Ω because of its internal 10MΩ resistance.
6. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
7. 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.
[5] 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.
If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.
CARRY OUT 4R CHECKS.
[6] F: WEAK POINT FFS-GA014 TEST
CARRY OUT 3D CHECKS.
If the weak point FFS-GA014 is blown, there could be a shorts or grounds in the oven lamp, control unit, T/C transformer or control unit. Check them
and replace the defective parts.
CARRY OUT 4R CHECKS.
CAUTION: Only replace weak point FFS-GA014 with the correct value replacement.
[7] G: WEAK POINT A017 TEST
CARRY OUT 3D CHECKS.
If the weak point A017 (F3) 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.
CARRY OUT 4R CHECKS.
CAUTION: Only replace weak point A017 (F3) with the correct value replacement.
[8] H: FUSE F10A TEST
CARRY OUT 3D CHECKS.
If the fuse F10A (F1 or F2) is blown when the door is opened, check the interlock switch (SW1 or SW2) and monitor switch (SW3 or SW4).
If the fuse F10A (F1 or F2) is blown by incorrect door switching replace the defective switch(es) and the fuse F10A (F1 or F2 F10A).
CARRY OUT 4R CHECKS.
CAUTION: Only replace fuse F10A (F1 or F2) with the correct value replacement.
Table: Terminal Connection of Switch
Plunger Operation
Common terminal to Normally open terminal
Common terminal to Normally close terminal
Released
Open circuit
Short circuit 
Depressed
Short circuit 
Open circuit.
B
C
HIGH VOLTAGE RECTIFIER
R22AMM
7 – 4
[9] I: TEMPERATURE FUSE TEST
1. CARRY OUT 3D CHECKS.
2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the temperature of the temperature fuse reaches
specified temperature as shown below.
3. CARRY OUT 4R CHECKS.
CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE, REPLACE TEMPERATURE FUSE.
[10] J: THERMISTOR TEST
CARRY OUT 3D CHECKS.
Follow the procedures below for each thermistor.
Disconnect the connector of the 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.
                 Resistance: Approx. 500 k
Ω -- 1 MΩ
If the meter does not indicate above resistance, replace the thermistor.
CARRY OUT 4R CHECKS.
[11] K: MOTOR WINDING TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals.
         Resistance of Blower motor should be approximately 60
Ω.
         Resistance of Antenna motor should be approximately 8.8k
Ω.
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS.
[12] L: NOISE FILTER TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the noise filter. Using an ohmmeter, check between the
terminals as described in the following table. 
If incorrect readings are obtained, replace the noise filter unit.
CARRY OUT 4R CHECKS.
[13] M: HIGH VOLTAGE FUSE TEST
CARRY OUT 3D CHECKS.
If the high voltage fuse (F4 or F5) is blown, there could be a short in the high voltage rectifier or the magnetron (MG1 or MG2). Check them and
replace the defective parts and the high voltage fuse (F4 or F5).
CARRY OUT 4R CHECKS.
CAUTION: Only replace high voltage fuse with the correct value replacement.
Open temperature 
Close temperature 
Display or 
Condition
Check point
Magnetron temperature 
fuse (Upper) TF1
150
°C
Non resetable type
EE1
Magnetron MG1 Failure:
Test magnetron MG1 and Blower motor.
Magnetron temperature 
fuse (2) (Lower) TF2
EE2
Magnetron MG2 Failure: 
Test magnetron MG2 and blower motor.
Magnetron temperature 
fuses TF1, TF2
EE3
Magnetron MG1, MG2 Failure: Test magnetron MG1, 
MG2. Check blower motor and ventilation opening.
Exhaust temperature 
fuse TF3
120
°C
Non resetable type
Oven shut off
Food has been burned in oven.
Temperature of oven inside is very high.
MEASURING POINT 
INDICATION OF OHMMETER
Between N and L 
Approx. 680 k
Ω
Between terminal N and WHITE 
Short circuit
Between terminal L and BLK 
Short circuit
F 3 : W E AK P OINT
NOIS E F ILT E R
NOIS E S UP P R E S S ION C OIL
DIS C HAR G E R E S IS T OR 680 k 1/2W
DIS C HAR G E R E S IS T OR 10 M 1/2W
LINE C R OS S C AP AC IT OR 0.22μF / AC 250V
LINE C R OS S C AP AC IT OR
10000 pF / AC 250V
LINE C R OS S C AP AC IT OR
10000 pF / AC 250V
L
B LK
WHT
N
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