SANYO EMV5404SW User Manual

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

Description & Function of Components...............................................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

(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.

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.

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.

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.

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.

120V AC

PRIMARY

FILAMENT WINDING (CATHODE)

LOW VOLTAGE - 3.35V AC

HIGH CURRENT

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