Sanyo EMV5404S Schematic

SERVICE MANUAL
CAUTION
Before servicing the oven, read the “Safety Precautions” section on page 2 of this manual.
Safety Precautions.......................................................................Cover
Installation Instructions........................................................................2
General Information.............................................................................2
Microwave Radiation Test ...................................................................2
Safety Precautions for Disassembly and Repair.................................3
Electrical Operation .............................................................................4
Door & Interlock Adjustments..............................................................4
Component Test Procedures ...............................................................5
Disassembly & Replacement of Parts.................................................6
Wiring Diagram ...................................................................................9
Schematic Diagram ............................................................................10
Exploded View ..................................................................................11-16
Exploded View Parts List...................................................................17-18
SPECIFICATIONS
CONTENTS
NOTICE
This service information is intended for use by a service technician who is familiar with proper and safe procedures to be followed when repairing any electrical or gas appliance and who is equipped with proper tools and testing devices. Repairs covered in this publication and made by uninformed persons can result in hazards developing due to improper assembly or adjustment. While mak­ing such repairs, persons not having the proper background may subject themselves to the risk of injury or electrical shock which can be serious or even fatal. A. If the oven is operative prior to servicing, a microwave emission check should be performed prior to servicing the oven. B. Inform the manufacturer, importer, or assembler of any certified oven unit found to have a microwave emission level in excess
of 5 mW/cm2. Repair any unit found to have excessive emission levels at no cost to the owner (see 21 CFR 1004.2) and attempt to ascertain the cause of the excessive leakage. The owner of the unit should be instructed not to use the unit until the oven has been brought into compliance.
C. If the oven operates with the door open: 1) tell the user not to operate the oven and 2) contact the manufacturer and/or importer
and CDRH immediately.
D. Remember to connect the monitor switch after replacement and to check interlock/monitor continuity.
IMPORTANT NOTE TO THE CONSUMER
The manufacturer will not be responsible for injury or property damage arising from service performed by anyone other than author­ized Service Centers. If you perform service on your own products, you must assume responsibility for personal injury or property damage which may result.
COMMERCIAL MICROWAVE OVEN
EM-S1100 EM-E1100
REFERENCE NO. SM-2400012
02-03
MODEL EM-V5404SW Power Source: 120V AC, 60Hz Max. Output Power: 1100 watts Cavity Size: 1.4 cu-ft Overrall Dimensions: 549(W)x457(D)x296(H)mm Net Weight: 17.5 kgs  Model EM-V5430 Power Source: 120V AC, 60Hz Max. Output Power: 1050 watts Cavity Size: 1.4 cu-ft Overall Dimensions: 520(W) x 412(D)x296(H)mm Net Weight: 17 kgs
EM-V5404 ECO  EM-V5404 EUK  EM-V5430
Product Code No.
EM-V5404SW
14
15
2
(a) Do not operate or allow the oven to be
operated with the door open.
(b) Make the following safety checks on all
ovens to be serviced before activating the magnetron or other microwave source and make repairs as necessary: (1 ) Interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and
latches, (5) evidence of dropping or abuse.
(c) Before turning on microwave power for
any service test or inspection within the microwave generating compartments, check the magnetron, waveguide or transmission line, and cavity for proper alignment, integrity, and connections.
d) Any defective or misadjusted compo-
nents in the interlock, monitor, door seal,
and microwave generation and transmis­sion systems shall be repaired, replaced, or adjusted by procedures described in this manual before the oven is released to the owner.
(e) A microwave leakage check to verify
compliance with the Federal performance standard should be performed on each oven prior to release to the owner.
INSTALLATION INSTRUCTIONS
IMPORTANT: BEFORE THE UNIT IS
INSTALLED, INSPECT THE OVEN AND DETERMINE IF ANY OF THE FOLLOWING DAMAGE CONDITIONS EXIST.
1. The door does not close firmly against the door support because the door is warped or the hinge is damaged.
2. Either the door seals or the trim is dam­aged.
3. If there is any visible damage to the oven.
If any of the above conditions exist, DO NOT OPERATE THE OVEN. Call your local author­ized service representative.
If none of the above conditions exist, proceed with properly installing the oven.
A minimum clearance of 3” on both sides and 1” on top and rear must be observed. This will allow proper internal ventilation of the unit. Also, do not remove the legs because of the possibil­ity of restricting the ventilation.
This appliance is equipped with a three-prong grounding plug for your protection against shock hazard and must be plugged directly into a properly grounded receptacle.
Use a properly polarized and grounded three hole receptacle as is required by NATIONAL ELECTRICAL CODES on all new construction.
NOTE: APPLIANCE MUST BE GROUNDED
For the safety of the user, it is required that all major appliances requiring electricity for opera­tion be electrically grounded in accordance with the National Electrical Code ANSI C1-1981.
Check all code rules and regulations for connect­ing the appliance to be certain the installation con­forms with all local, municipal and state codes as well as local utility regulations.
Where a two-prong wall receptacle is encoun­tered, it is the personal responsibility of the user to contact a qualified electrician and have it replaced with a properly grounded three-prong wall receptacle in accordance with the National Electrical Codes.
DO NOT use a two-prong adapter, since proper grounding is not assured even if the ground wire or metal tab is connected to the outlet box.
The use of an extension cord is not recom­mended. However,if it is necessary to use an extension cord, it must be a type s, with 3 num­ber 14 wires and have a 3 prong grounded plug. The extension cord should not drape over a countertop where it can be pulled on or tripped over accidentally.
Under no circumstances should the rounded ground prong be removed from the plug. Failure to comply with the above could result in a serious shock hazard .
GENERAL INFORMATION
IMPORTANT: BEFORE PROCEEDING,
THE FOLLOWING INFORMATION MUST BE CAREFULLY READ TO AVOID POSSIBLE
EXPOSURE TO MICROWAVE RADIATION.
Before servicing the oven, unplug the oven, remove the cabinet and take a continuity read­ing of the interlock switches to assure they are operating properly.
Refer to the Component Test Section in this service manual.
Also, it is very important to insure that the door seals are not damaged. If a microwave leakage instrument is available, check the oven for any possible microwave leakage.
Do not operate the oven if the following condi­tions exist.
1. The door does not close firmly against the door support because of the door being warped or the hinge is damaged.
2. The door seals or door trim are damaged.
3. If there is any visible damage to the oven.
Do not operate the oven if the front frame of the oven is dirty or if the interlocks are loose. Microwave leakage may be present if these conditions exist.
Do not operate the oven if:
1. any door gaskets or trim surrounding the oven door or control panel are missing.
2. the waveguide and oven cavity are not intact.
3. the door does not close properly.
Avoid operating the oven if known components in the interlock, oven door or microwave generting transmission assembly are defective. They must
be replaced.
After the above precautions have been taken, proceed with normal repair procedures.
Remember that high voltage is present, so use caution to avoid electrical shock.
MICROWAVE RADIATION TEST
NOTE: A MICROWAVE LEAKAGE CHECK
SHOULD BE PERFORMED AFTER ANY REPAIRS OR ADJUSTMENTS HAVE BEEN MADE ON THE DOOR, FRONT FRAME AND/OR INTERLOCK SWITCHES,
IMPORTANT: IF THE READING IS OVER 2 mW/cm2, REFER TO THE DOOR AND INTER­LOCK ADJUSTMENTS SECTION IN THIS MAN­UAL. THE DOOR IS DESIGNED FOR LEAKAGE OF LESS THAN 1 mW/cm2, ADJUSTMENTS SHOULD BE MADE TO BRING ALL READINGS TO BELOW 1 mW/cm2.
The microwave leakage measurement equip­ment manufacturers presently acceptable are NARDA, SIMPSON and HOLADAY. More infor­mation on these units can be obtained from the respective equipment manufacturers.
WARNING
ELECTRICAL GROUNDING INSTRUCTIONS
PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE EX-
POSURE TO EXCESSIVE MICROWAVE ENERGY
POWER SUPPLY CORD WITH 3-PRONG GROUNDING PLUG
3-PRONG GROUNDING PLUG WALL RECEPTACLE
TO PERFORM MICROWAVE LEAKAGE CHECK:
1. Fill 275 milliliters or 9 ounces of tap water in a 2 cup measuring cup.
2. Place the container in the center of the oven cavity on the glass tray.
3. Set power control for microwave “Cook” (high) or 100% operation. Set timer for 3 minutes.
4. Close the door securely and start the oven.
5. Perform the proper adjustment and opera­tions check with the microwave leakage meter (refer to the operation instructions with the meter). Check the oven by moving the probe, starting at the top right-hand side of the door, clockwise no faster than one inch per second, back to the starting position. Also, a check over the entire visu­al screen must be made.
Probe Speed: One inch per second (max.) IMPORTANT: MICROWAVE LEAKAGE
CHECK MUST BE PERFORMED ON THE REAR VENTS AND SIDE VENTS.
NOTE: THE METER PROBE MUST BE HELD APPROXIMATELY TWO INCHES FROM THE POINT OF MEASUREMENT. THIS IS ACCOMPLISHED BY THE USE OF A TWO­INCH (5 cm) PLASTIC SPACER THAT IS SUP­PLIED WITH THE METER. IT IS NORMALLY ATTACHED TO THE PROBE.
6. The maximum allowable microwave leak­age level is 5mW/cm2 by government stan­dard.
IMPORTANT: IF THE READING IS OVER 2 mW/cm2, REFER TO THE DOOR AND INTER­LOCK ADJUSTMENTS SECTION IN THIS MAN­UAL. THE DOOR IS DESIGNED FOR LEAKAGE OF LESS THAN 1 mW/cm2, ADJUSTMENTS SHOULD BE MADE TO BRING ALL READINGS TO BELOW 1 mW/cm2.
MAGNETRON FAILURE MODES
LOSS OF VACUUM
This is a case where the tube has had the vac­uum envelope destroyed and air has entered the tube. This will cause internal arcing. With continued use, the transformer will eventually fail and the circuit fuse will blow.
OPERATION FAULTS OPEN FILAMENTS
A magnetron with an open filament will produce
no heating power. An open filament lead or “dead” filament trans­former will give the same indication as an open filament in the magnetron. This possibility should be eliminated before the magnetron is considered open.
INTERNAL PLATE CATHODE SHORT
A shorted magnetron will give the same indica­tions as the loss of vacuum.
MODING
Moding occurs when the magnetron momentar­ily operates at a different frequency and a high­er voltage than designed. Moding results in low heating power. Moding is usually caused by the cathode losing emission characteristics.
LOW POWER
Low emission will result in low cooking power. Food will require a longer than normal cooking time. It can be detected by a lower than normal water temperature rise.
LOW EMISSION
Caused by “wearout” of the emission charac­teristics of the directly heated cathode. The tube current does not get high enough to cause the tube to oscillate with normal line voltage. Everything will appear normal, but the tube will not heat.
SAFETY PRECAUTIONS FOR DISASSEM­BLY AND REPAIR
-Cautions to be observed when trou­bleshooting.
Unlike many other appliances, the microwave oven is a high-voltage, high-current piece of equipment. It is completely safe during normal operation. However, carelessness in servicing the oven can result in an electric shock or pos­sible danger from a short circuit. You are asked to observe the following precau­tions carefully.
(1) Always remove the power plug from the out­let before servicing. (2) Use an insulated screwdriver and wear rub­ber gloves when servicing the high voltage side. (3) Discharge the high voltage capacitor before touching any oven components or wiring.
1. Check the grounding. Do not operate on a 2-wire extension cord. The microwave oven is designed to be used when grounded. It is imperative, therefore, to make sure it is grounded properly before beginning repair work.
2. Warning about the electric charge in
the high voltage capacitor.
For about 60 seconds after the operation stops, an electric charge remains in the
high voltage capacitor. When replacing or checking parts, create a short between oven chassis and the negative high termi­nal of the high voltage capacitor, by using a properly insulated screwdriver to dis­charge it.
(4) When the 20 Amp. fuse is blown out due
to the operation of the monitor switch, replace primary and secondary interlock switches, monitor switch and relay 2.
(5) After repair or replacement of parts, make
sure that the screws are properly tight­ened, and all electrical connections are tightened.
(6) Do not operate without cabinet.
DESCRIPTION & FUNCTION OF COM­PONENTS
FAN MOTOR
The fan motor drives a blower fan which draws cool air through the back of the oven. This cool air is directed through the air ducts surrounding the magnetron tube to cool the magnetron. Some of the air is then exhausted directly through the bottom vents. However, a portion of this air is channeled through the cavity to remove the steam and vapors given off from heating food.
OVEN LIGHT
The oven light illuminates the interior of the cavity so the food can be visually examined through the door.
POWER TRANSFORMER
The purpose of the power transformer is to pro­vide the filament voltage for heating the mag­netron filaments as well as to produce the high voltage needed for magnetron tube operation. During a cook cycle, the 120 Volts AC applied to the primary winding is converted to approxi­mately 3.22 Volts AC on the filament winding. The same 120 Volts AC primary input is con­verted to approximately 2070 Volts AC on the high voltage secondary winding of the power transformer. CAUTIONS: AFTER REMOVING THE CABI­NET, DISCHARGE THE CAPACITOR BY PLACING AN INSULATED SCREWDRIVER ACROSS THE TERMINALS.
PRIMARY (UPPER) INTERLOCK SWITCH
The primary protective switch (interlock) is acti­vated by the latch when the door is closed. The switch, in the open position when the door is open, interrupts the current to the magnetron. Closing the door will close the interlock switch and normal operations can be continued.
SECONDARY (LOWER) INTERLOCK SWITCH
The secondary protective interlock switch is located behind the front control panel and is acti­vated when the door is closed. When the door is open, this switch will interrupt the circuit.
3
Short
MONITOR (MIDDLE) INTERLOCK SWITCH
This interlock switch disables the control panel if the door is open or the catch is out of adjust­ment or the primary interlock switch fails. If for some reason the primary switch and sec­ondary switch stick in the closed position and the door were to be opened, the circuit would be shorted through the normally closed safety switch. This would blow the fuse.
If there appears to be an interlock switch prob­lem, but the fuse is not blowing, refer to the Component Test Procedure Section in this service manual.
NOTE:IF THE INTERLOCK SWITCHES ARE REPLACED, THE CATCH MUST BE ADJUST­ED. SEE DOOR AND INTERLOCK ADJUST­MENTS SECTION FOR PROPER ADJUST­MENT PROCEDURE. DEFECTIVE SWITCHES SHOULD BE DESTROYED TO PREVENT POSSIBLE FUTURE USE. IMPORTANT: IF AT ANY TIME THE OVEN FUSE BLOWS DUE TO AN OVEN FAULT, OR THE CIRCUIT BREAKER TRIPS AFTER BEING RESET ONE TIME WITH THE HOUSE CIRCUIT UNLOADED EXCEPT FOR THE OVEN, THE INTERLOCK SWITCHES MUST BE REPLACED AS A GROUP. THIS IS BECAUSE THE SHORT CIRCUIT CURRENTS WILL HAVE DAMAGED THESE IMPORTANT SWITCHES.
MAGNETRON THERMAL PROTECTOR
The magnetron thermal protector located on the magnetron is designed to prevent an over­heated condition in the tube due to fan failure, obstructed air ducts, etc. Under normal operating conditions, the thermal protector remains closed. However, If abnor­mally high temperatures within the magnetron approach a critical level, the thermal protector will interrupt the circuit to the magnetron. When the magnetron has cooled to a safe operating temperature, the thermal protector closes and a cook (or defrost) cycle can be resumed.
HALF-WAVE VOLTAGE DOUBLER CIRCUIT
The half-wave rectification circuit consists of a diode package and a single capacitor. The 2070 Volts AC from the high voltage secondary wind­ing is rectified to approximately 3680 Volts DC (peak voltage) needed for magnetron operation.
1. Diode - a diode is a solid state device that allows current flow in one direction, but pre­vents current flow in the opposite direction.
2. Capacitor - a capacitor is able to store elec­tric energy, as well as pass AC and block DC current.
WATER TEMPERATURE RISE CHECK
The following procedure should be followed when low power is suspected in the oven but all other operations, including cooking light opera­tion, appear normal. Power output of the magnetron can be meas­ured by performing a water temperature rise check. This test will require a quart glass cup and an accurate mercury thermometer or ther­mocouple-type temperature tester. For accu­rate results the following procedure must be fol­lowed carefully.
1. Fill a measuring cup with one quart of tap water and measure temperature of the water with a thermometer or thermocouple tester. Stir the temperature probe through the water until the temperature stabilizes. Record the temperature of the water and remove the temperature probe.
2. Place the measuring cup in the oven and put the oven into the cook (high) cycle for exactly two (2) minutes. Allow the water to heat.
3. Remove cup from the oven and again meas­ure temperature making sure to stir the tem­perature probe through the water until max­imum temperature is recorded.
4. Subtract the cold water temperature from the hot water temperature. The result should be 25°F±4°F, or between 21°F to 29°F rise in temperature. If the water temperature is accurately measured and tested for the required time period, the test result will indi­cate if the magnetron tube has low power output (low rise in water temperature) which would extend cooking time, or high power output (high rise in water temperature) which would reduce cooking time.
Because cooking times can be adjusted to compensate for power output, the magnetron tube assembly should be replaced only if the water temperature rise test indicates a power output well beyond the normal limits. This test is only accurate if the power supply line voltage is 120 Volts while the oven is operating.
ALTERNATE TEST-METRIC
Use same procedure as in preceding para­graphs except as noted.
1. Use 1000 ML water.
2. Timer for two minutes.
3. Same
4. Water temperature will be between 8°F to
12°F higher.
ELECTRICAL OPERATION
By closing the door, the primary and secondary interlock switches close and monitor switch opens. The closed switches allow line voltage to flow through the 20 amp fuse to interlock to magnetron thermal switch. At this point, line voltage splits and power is applied to primary side of high voltage transformer, oven cavity light, fan motor, and timer. To complete the circuit, two things must happen to energize the above Components. The timer must be set, which will close timer contacts, and the door must be closed, which activates the interlock switches. At this time, line voltage to neutral is applied across high voltage pri­mary, timer, oven light, and fan. The 120 Volt AC input to the primary winding of the power transformer is converted to approxi­mately 2070 Volts AC output from the high volt­age secondary winding. At the same time, the filament secondary winding of the power trans­former provides 3.32 Volts AC to heat the mag­netron filaments. The 2070 Volts AC output from the power trans­former high voltage secondary winding is sent to a half-wave doubling circuit comprised of a single diode and capacitor where approximate­ly 4140 Volts DC (peak voltage) is provided to the magnetron tube. The negative 4140 Volts DC applied to the cathode of the magnetron tube causes the
magnetron to oscillate and produce the 2450 MHz cooking frequency. The microwave energy produced by the mag­netron tube is channeled through a waveguide into the cavity past the diffuser and finally into a cavity where the load is placed to be heated. When the timer has completed the selected cooking time, the timer switch opens. The cir­cuits are open to the light, timer, fan motor, and power transformer, and the microwave energy is no longer produced. Five beeps signal the end of the cook cycle.
DOOR & INTERLOCK ADJUSTMENTS
DOOR ADJUSTMENTS
The door adjustment on all microwave ovens is very important to prevent any excessive leak­age. The microwave leakage levels should be checked after all door, interlock switches and associated repairs are made. See the Microwave Radiation Test Section in this man­ual for proper testing procedures.
The following door adjustments must be fol­lowed.
LATCH & CATCH ASSEMBLY ADJUST­MENTS
CAUTION: AFTER REMOVING THE CABI-
NET, DISCHARGE THE CAPACITOR BY PLACING AN INSULATED SCREWDRIVER ACROSS THE TERMINALS. To make proper latch and catch assembly adjustment:
1. Disconnect the power to the unit, remove the cabinet and discharge the capacitor by placing an insulated screwdriver across the terminals.
2. Open the door.
3. Loosen the screws that secure the plastic interlock bracket until the assembly can be moved freely back and forth.
4. Hold the door closed securely.
5. Move the plastic catch toward the door until it stops and door is latched. Next, move the catch toward the back panel making sure it is snug against door latch. Check by open­ing and closing the door. Using an ohmme­ter, place the leads of the meter across the terminals of the monitor switch. As the door is opened, your meter should show a short, as the door is closed it should show an open circuit.
4
6. Tighten and secure the plastic bracket with screws.
7. To be totally sure that switches are func­tioning properly, see Primary, Secondary Interlock Switch and Monitor Switch Test Procedures.
DO NOT ATTEMPT TO ADJUST INTERLOCK SWITCHES WITH OVEN ENERGIZED. IF THIS WARNING IS NOT OBSERVED, HIGH LEVELS OF MICROWAVE LEAKAGE MAY BE PRESENT.
NOTE: IF THE INTERLOCKS ARE
REPLACED, THEY MUST BE ADJUSTED. SEE INTERLOCK ADJUSTMENTS SECTION FOR PROPER ADJUSTMENT PROCE­DURE.
PRIMARY (UPPER) INTERLOCK SWITCH TEST
1. Disconnect power to the unit. Remove the cabinet and discharge the capacitor.
2. With the ohmmeter set on the RX1 scale, take continuity readings as noted below.
A) Condition: Door open
Test: Ohmmeter check from LC to MSC indicates open circuit.
B) Condition: Door closed
Test: Ohmmeter check from LC to MSC indicates short circuit.
3. If the switch does not operate as described above, replace all the switches and relay2. Repeat the above tests.
SECONDARY (LOWER) INTERLOCK SWITCH TEST
1. Disconnect power to the unit, remove the cabinet and discharge the capacitor.
2. With the ohmmeter set on the RX1 scale, take continuity readings as noted below.
A) Condition: 1)Door open
Test: Ohmmeter check from SISC to SISNO indicates open circuit.
B) Condition: Door closed
Test: Ohmmeter check from SISC to SISNO indicates short circuit.
3. If the switch does not operate as described above, replace all the switches and relay2. Repeat the above tests.
WARNING:FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMIS­SION REPLACE ONLY WITH PARTS AS DESCRIBED IN THE PARTS LIST
CAUTION: WHEN REPLACING THESE SWITCHES, USE ONLY FACTORY REPLACE­MENT PARTS. REPLACING WITH ANY OTHER PART WILL VOID THE WARRANTY AND MAY CAUSE INJURY TO THE USER.
MONITOR (MIDDLE) INTERLOCK SAFETY SWITCH TEST
1. Disconnect power to the unit. Remove the cabinet and discharge the capacitor.
2. With the ohmmeter set on the RX1 scale, take continuity readings as noted below.
A) Condition: Door open
Test: Ohmmeter check from MSC to MSNC indicates open circuit.
B) Condition: Door closed
Test: Ohmmeter check from MSC to MSNC indicates short circuit.
3. If the switch does not operate as described above, replace all the switches and relay2. Repeat the above tests.
COMPONENT TEST PROCEDURES
HIGH VOLTAGE COMPONENT OPERA­TIONAL TEST
In this section we have tried to lay these tests out in a logical sequence so that you can iso­late any suspected high voltage problem.
1. Unplug oven from its power source.
2. After removing the cabinet discharge the capacitor by shorting the two capacitor ter­minals together with an insulated screw­driver.
3. Visually check the high voltage wiring for proper connections. Refer to wiring dia­gram for proper wiring sequence.
CAUTIONS: HIGH VOLTAGES ARE PRE­SENT DURING THE COOK (HIGH) CYCLE, SO EXTREME CAUTION SHOULD BE OBSERVED. WHEN TESTS ARE COMPLETE, ALWAYS UNPLUG THE OVEN FROM ITS POWER SOURCE AND DISCHARGE THE CAPACITOR. NOTE: DO NOT TOUCH ANY OVEN COM­PONENTS OR WIRING DURING OVEN OPERATION.
POWER TRANSFORMER TESTS TRANSFORMER INPUT VOLTAGE CHECK
An operational test can be made in order to determine whether or not primary power is being applied to the transformer. CAUTION: APPROXIMATELY 1840V AC IS PRESENT AT THE HIGH VOLTAGE TERMI- NAL OF POWER TRANSFORMER DURING COOK CYCLE. OBSERVE CAUTION AT ALL TIMES.
1. With the oven power cord unplugged and
cabinet removed, discharge the capacitor with an insulated screwdriver.
2. With alligator clips, connect a meter capable of measuring at least 120V AC, across the input terminals to the transformer.
3. Plug oven in and set for regular cook opera­tion. If all primary circuits are functioning properly, 120V should be applied and meas­ured across transformer.
FILAMENT VOLTAGE CHECK
An operational test can be made in order to determine the amount of filament voltage pro­duced by the power transformer. CAUTION: APPROXIMATELY 2070 VOLTS AC ARE PRESENT AT THE HIGH VOLTAGE TER­MINAL OF THE POWER TRANSFORMER DURING COOK (HIGH CYCLE). OBSERVE CAUTION AT ALL TIMES.
1. With oven power cord unplugged and cab-
inet removed, discharge the capacitor with an insulated screwdriver.
2. Remove the high voltage lead that con-
nects the capacitor to the high voltage ter­minals.
NOTE: DURING TEST OPERATION, KEEP
METER, HANDS, ETC., WELL AWAY FROM THE HIGH VOLTAGE TERMINALS OF THE POWER TRANSFORMER.
3. With alligator clips, connect a meter capa-
ble of measuring up to 10 Volts AC across the magnetron filament terminals.
4. Apply power to the oven and put the oven
into cook (high) cycle to get a filament volt­age reading. A normal indication should be approximately 2.8 to 3.75 Volts AC. Unplug the oven before disconnecting the meter leads.
5. If a normal 2.8 to 3.75 Volts AC reading
was indicated on the meter, go to step 6.
6. If the input voltage is normal, but no fila-
ment voltage is present, replace the power transformer.
5
120V AC
PRIMARY
2
FILAMENT WINDING (CATHODE)
F
LOW VOLTAGE - 3.35V AC
HIGH CURRENT
FA
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