DOWNLOAD Sharp R-822STM Service Manual ↓ Size: 1.63 MB | Pages: 23 in PDF or view online for FREE

Model
R-822STM
Pages
23
Size
1.63 MB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven
File
r-822stm.pdf
Date

Sharp R-822STM Service Manual ▷ View online

 
 
 
MOTOR TEST PROCEDURE
 
COMPONENTS TEST 
PROCEDURE 
RESULTS 
Fan Motor 
(Wire leads removed) 
Measure the resistance. 
(Ohm-meter scale:R
×100) 
 
 
 
Normal:Approx. 47Ω 
Abnormal:
∞ 
or Several Ω 
 
 
Turntable Motor 
(Wire leads removed)
 
Measure the resistance. 
(Ohm-meter scale:R
×1000) 
 
 
 
 
Normal:Approx. 3.2kΩ 
Abnormal:
∞ 
or Several Ω 
 
 
NOTE:   
z  A MICROWAVE LEAKGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS 
SERVICED FOR ANY REASON.   
z  MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION. 
z  WHEN REMOVING THE WIRE LEADS FROM THE PARTS,BE SURE TO GRASP THE 
CONNECTOR ,NOT THE WIRES.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5-8
 
 
 
 
COMMON BREAKDOWN AND MEANS OF REPAIRING 
PHENOMENON CAUSE REPAIRING 
MEANS 
 
 
 
1.When starting the 
oven, the lamp is not on, 
the turntable tray can’t 
rotate and the food can’t 
be heated 
1. fuse 
broken 
2.  The primary and secondary winding of the 
transformer are short-circuited. 
3.  The earthing or the polarity of the capacitor is 
punctured. 
4.  The pilot switch can’t cut off. 
5.  The interlock switch hasn’t closed. 
6.  The power plug and the socket are not in good 
connection. 
7.  The door hook broken. 
1.  Change a new fuse. 
2. 
Change a new 
transformer. 
3.  Change a new capacitor.
4. Change a new pilot 
switch. 
5.  Change a new interlock 
switch. 
6.  Adjust the connection or 
replace it by a new one. 
7.  Change a new book. 
2.When starting the 
oven, the lamp is on, the 
turntable rotating, the fan 
cycling but the food can’t 
be heated. 
1. The primary and secondary winding, the 
filament of the transformer are open-circuited. 
2.  The magnetron filament is open-circuited, the 
magnetic steel of the magnetron broken or the 
magnetron is air leaking. 
3.  Time and power distributor broken.. 
4.  The plugs of the magnetron of the capacitor 
loosed. 
1. 
Change a new 
transformer. 
2.  Change the magnetron. 
3.  Change the time power 
distributor or the micro-
switch. 
4. Fix 
them. 
3.The food can be 
heated, but the lamp is 
not on. 
1.  The lamp broken. 
2.  The plug fall off. 
1.  Change a new lamp 
2.  Insert the plug again 
4.The food can be 
heated but the turntable 
tray is not rotating. 
1.  The turntable motor broken 
2.  The plug fall off 
3.  Connecting shaft weave broken 
1. Change the turntable 
motor 
2.  Insert the plug securely 
3.  Change the weave 
5.The oven can heat 
within 2-3 minutes, but 
can not heat from the 
fourth minutes. 
1.  The winding of the fan motor in open-circuited.
2.  The fan falls off 
3.  The plug of the fan motor falls off 
4.  The turntable shaft is griped with the motor 
bearing. 
5.  The cooling vent blocked 
1.  Change the fan motor 
2.  Change the fan 
3.  Insert the plug 
4. Overhauling 
them 
5. Repairing 
it 
6.When starting the 
oven, it can’t heat, and 
with “wenwen” noise 
The high voltage diode was punctured 
Change a new diode 
7.The oven can heat,but 
with sound “shishi” noise 
The iron core of the transformer loosed 
Change a new transformer 
8.Large amount of 
microwave leakage 
1.  The door deformed 
2.  The door metal net cracked 
3.  The gap of the door crack is too large 
4.  The welding point of the oven fall off 
5.  The screws which fix the magnetron loosed 
6.  The wave guide connection oxidized 
7.  The magnetron copper filament washer is too 
thin cause the wave guide opening not in good 
earth. 
1.  Mend the door 
2.  Change the door 
3.  Adjust the gap 
4.  Change the oven 
5.  Tighten the screws 
6.  Scrape the oxidized and 
tighten the screws 
7.  Thick the copper filament 
washer 
9.The door can’t open 
1.  After  long  time using, the wear and the rust-
eaten enlarged the gap of the door shaft and 
the shaft hole, thus cause the door crooked. 
2.  The door hook broken 
1.  Adjust the hinge to rectify 
the position of the door. 
2.  Change the hook 
 
10.The door release 
button fall off 
Wore aged after long time operating 
Overhaul it or renew it 
11.Electricity leaking 
The  earthing  insulation resistances of all the 
motors or the transformer are less than 2 mega 
ohm. 
Test where is the leaking 
place, then repair it or 
change those damaged 
components. 
 
5-9
 
 
 
IMPORTANT THINGS TO DO PRIOR TO CRITICAL PART 
SERVICING 
The following instructions are CRITICAL to the owner’s safety. Be sure to follow all the instructions. Contact the 
manufacturer of distributor if you have any question. 
 
1.1   If the oven is operative prior to servicing a Microwave Leakage Test (Microwave Emission Check) should be    
performed prior to servicing the oven. 
1.2   in the event that any microwave oven found to have microwave emission level in excess of 1 mW/cm
2
.The 
following procedures should be followed: 
a. Inform the distributor, importer, or manufacture the finding. Record it in the      logbooks well. 
b. Repair the unit at no cost to the owner. 
c. Investigate the oven and ascertain the cause of the excessive leakage. 
d. Hold the oven in your facility and instruct the owner not to use the unit until the oven has been brought into 
compliance. 
1.3      In the event that the oven operates with the door open. The following procedures should be followed: 
a. Tell the user not to operate the oven. 
b. Hold the oven in your facility until it is investigated and repaired. 
c. Contact the manufacturer immediately. 
 
2.  Interlock Assembly Replacement and Adjustment 
2.1 
If you suspect defective primary, secondary or monitor interlock switches, use your ohmmeter(digital or analog 
type the check the electrical continuity. 
2.2 
Make sure the power cord is pulled out and the high-voltage capacitor is discharged before the electrical 
continuity check. 
2.3 
Set the ohmmeter to “Low Resistance” range and connect both leads (alligator clips) to the switch terminals. 
2.4 
Open the door and notice the meter reading. The primary or secondary interlock switch should show an “infinite” 
resistance when the door is open. Replace it when it is defective. The monitor interlock should show a “zero or 
near zero” resistance when the door is open. When the door is closed, the readings will be opposite. 
2.5 
If the oven has been received inoperative due to the failure of the monitored safety(primary and/or secondary) 
interlock(s),you should replace all of the monitored safety interlock switched and the monitor switch. 
3.  Door and Hinge Replacement and Adjustment 
3.1 
Pull the power cord from the outlet. Check the door for warped or damaged areas. Check the hinges for broken 
or worn areas. Check other areas such as cracked from glass, broken door latched, worn/cracked viewing 
screen and etc. 
3.2 
After determining the door assembly should be replaced, check the parts list for the correct part number. All oven 
door components must be ordered directly from the manufacturer or its authorized distributor. 
 
4. Magnetron 
Replacement 
4.1 
Check for the presence of the wire mesh gasket before installation. 
 
4.2 
Conduct a Microwave Leakage Test at the magnetron area prior to installing the top cover. 
 
 
 
 
 
 
5-10
 
 
 
SAFETY CHECKS AND TESTS AFTER SERVING 
Constructional Checks 
 
If mechanical or electrical(electronic) parts have been replaced be sure to follow the following steps. 
 
1.1 
Check for correct wiring, adequate mechanical decrements of parts, and firm connectors. 
 
1.2 
Check for adequate grounding. 
 
1.3 
Check the following items before turning the oven ON. 
 
1) 
Proper door closing, seal/choke surfaces, and hinges. 
 
2) 
No outer case damage. 
 
3) 
Proper interlock and monitor operations. 
 
Insulation Resistance Test
 
 
If the low voltage power supply has been repaired, use a 500 V Mega ohmmeter to measure the resistance between the 
primary(Line and Neutral)of the power plug and operator accessible metal parts. The resistance should be no less than 2 Mega 
Ohms. Repair the oven again when necessary. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5-11 
 
 
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