tech-sheet-8205889
Tech Sheet Do not discard

WARNING

Electrical Shock Hazard Disconnect power before servicing. Replace all parts and panels before operating. Failure to do so can result in death or electrical shock.

PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE

MICROWAVE ENERGY

a. Do not operate or allow the oven to be operated with d. Any defective or misadjusted components in the the door open. interlock, monitor, door seal, and microwave generation and transmission systems shall be b. Make the following safety checks on all ovens to be repaired, replaced, or adjusted by procedures serviced before activating the magnetron or other described in service manual before the oven is microwave source, and make repairs as necessary: released to the owner.

1. Interlock Operation e. A microwave leakage check to verify compliance with the Federal Performance Standard should be 2. Proper Door Closing performed on each oven prior to release to the owner.

3. Seal and Sealing Surfaces (Arcing, Wear and Other f. Do not attempt to operate the oven if the door glass is Damage) broken.

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.

8205889 / 4619-651-98961 FOR SERVICE TECHNICIAN’S USE ONLY

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Monitor Primary Interlock Switch Fuse Interlock

20 Amp Switch 4OR

33 BK 2BK 6 BK 7 BR

3BR 5W

8BU Electronic Control L.V. 1BK Transformer AC120V/125V 60Hz AC Line Filter MW-Relay Cavity HL 4903 Thermostat 2 Relay HLRelay 4911 4912 2 1

L1 3 CL HF Triac Red Tube Relay 7104 Black Tube BK 4901 L 33K WIRING DIAGRAM

Pri. Sec. Schematic Diagram

Cy 1 R 31R(HV) R Cx 2 G 32Y/G White GND HF Relay Diode 68K C 4902 6101 Tube TTM 33K GND Relay Cy 4906 H.V.Capacitor 4 TTM CL L HF2 Door HF1 HL N1 NFS H.V.Diode 1 P2 2L P3 1 P4 P11 30Y/G

N W R W 16GY 25BK 14G BK

9BU 17R 15Y 5P5 20R HL 21W 4P5 HF NTC F FA 18 R Humidity Magnetron Cavity 1P5 (Golden 1P6 (Golden (White Sensor Thermostat 1 tab) BK tab) tab) H.V. 26W Magnetron Transformer CL 10BU W HF Thermostat BU TTM (White 27Y Y 13BU

tab) Motor

11W Capacitor 28R R 19 W 2P5 22W 5P6

23BU

12W 24BU 29W

Secondary DWG NO. MU-076 Interlock Condition: Door Open Switch P1/P2/P3/P4/P5/P6: Connectors Symbol Notes Hood Exhaust P4 BK Fan Motor R: Red W: White BR: Brown HF NTC HL Hood (Cooktop) Lamp W HF Y: Yellow G: Green BU: Blue CL Cavity Lamp BU TTM Turntable Motor OR: Orange GY: Gray BK: Black

Y 1BK

R Wire Color-Black

Wire NO.-1

Parts Layout

(not to scale)

A

X BC D E

F

U P5 G W 3551 H I V M U J TS N K R L Q P. Electronic control P O Q. Touch panel R. Secondary interlock switch A. Hood fan motor assembly H. Cavity thermostat 2—opens at 257ºF S. Monitor interlock switch B. Humidity sensor (125ºC), closes at -31ºF (-35ºC) T. Primary interlock switch C. H.V. capacitor U. Lamp holders D. AC line filter I. H.V. transformer V. Hood (cooktop) lamp E. Magnetron J. H.V. diode W. Turntable motor F. Magnetron thermostat—opens at 257ºF K. NTC thermistor X. Cavity lamp L. Motor capacitor (125ºC), closes at 185ºF (85ºC) M. Line fuse G. Cavity thermostat 1—opens at 257ºF N. Fuse holder O. Power display (125ºC), closes at -31ºF (-35ºC)

Primary, Secondary, and Monitor Interlock Switch Checkout Procedures

Switch Check By Door Open Door Closed

1. Unplug microwave oven or disconnect power. – + 2. Disconnect the wires at the Primary Interlock Switch. Primary 3. Check from the common terminal (black/brown wires) to the Interlock normally open terminal (black/white wires). + – 1. Unplug microwave oven or disconnect power. 2. Disconnect the wires at the Primary Interlock Switch. 3. Check from the common terminal (black/brown wires) to the

normally closed terminal (orange wire).

Secondary 1. Unplug microwave oven or disconnect power. – + Interlock 2. Disconnect the wires at the Secondary Interlock Switch. 3. Check from the common terminal (blue/white wires) to the

normally open terminal (blue wires).

Monitor 1. Unplug microwave oven or disconnect power. + – Interlock 2. Disconnect the wires at the Monitor Interlock Switch.

3. Check from the common terminal (white wire) to the normally closed terminal (blue/white wires).

(+) Continuity (-) No Continuity

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NOTE: These diagrams are not intended to show a complete circuit; they represent the position of switches during “DOOR OPEN” or “DOOR CLOSED” (continuity checks only).

Door Closed Door Open

L (NC) (NO) (NC) N L (NC) (NO) (NC) N (NO) (NC) (NO) (NO) (NC) (NO)

Primary Monitor Secondary Primary Monitor Secondary Interlock Interlock Interlock Interlock Interlock Interlock Switch Switch Switch Switch Switch Switch

TROUBLESHOOTING

Do not continue with the diagnostics of appliance if the 3. Disconnect white wire from power transformer and household fuse is blown, a circuit breaker is tripped or if there discharge high-voltage capacitor. is less than 120-volt power supply at the wall outlet. 4. All testing must be done with an ohmmeter having a Complete the following steps before checking microwave sensitivity of 20,000 ohms per volt DC or greater, and oven circuitry: powered by at least a 9-volt battery.

1. Unplug microwave oven or disconnect power. 5. All operational checks using microwave energy must be done with the microwave oven loaded with a minimum of 2. Check for loose wiring or incorrect wiring within 8 oz (250 mL) of water in a microwave safe container. microwave oven.

Microwave Cooking

BR 5P2 Electronic Control 1P3 G 4P5 BU OR L.V. Magnetron 3P2 Transformer Fuse BK 2 Thermostat Cavity MW Relay Thermostat 1 L Filter 20AMP BK 4903 H.V. Secondary R Interlock BK W TTM Relay Transformer BK 4906 1 BR W Switch BK BK W BU CL Relay Cavity Primary 4901 BU Thermostat 2 Interlock Switch Turntable P1 Motor 1 7P2 R R W BU Humidity TT Sensor 1P5 2P5 W BU Filter

Cavity N Lamp W 6P2 GY CL

HF Triac 2P2 1P6 7104 BK BK 4P2 HF Relay WW

4902 BU BU HF

Y Y

RR

5P6 Motor Capacitor

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Hood Exhaust Fan On High Automatically

Cavity Electronic Control Cavity Thermostat 1 L Thermostat 2 L.V. Transformer BK BK BK BK BR 5P2 G 4P5 BU W BU 1P3

Filter Fuse 20 Amp W BU

HF Triac BK 1P6 BK 7104 2P2

HF Relay BU BU HF Filter N 4902 W Y Y

RR

P4 5P6 Motor Capacitor

HF NTC

Hood Exhaust Fan On Low Speed

Cavity Electronic Control Cavity Thermostat 1 L Thermostat 2 L.V. Transformer BK BK BK BK BR 5P2 G 4P5 BU W BU 1P3

Filter Fuse W BU 20 Amp HF Triac 7104 W 2P6 W HF Filter

4P2 BU BU N HF Relay W Y Y 4902

RR

5P6 Motor Capacitor

Hood Exhaust Fan On High / Medium

Cavity Electronic Control Cavity Thermostat 1 L Thermostat 2 L.V. Transformer BK BK BK BK BR 5P2 G 4P5 BU W BU 1P3 W

Filter Fuse BU 20 Amp HF Triac BK1P6 BK 7104 2P2

HF Relay BU BU HF Filter N 4902 W Y Y

RR

5P6 Motor Capacitor

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Microwave Oven Plugged In—Time of Day Displayed

L Fuse Electronic Control

Filter 20 Amp L.V. 4P5 BU Filter N Transformer BK BK BK BK BR 5P2 G W BU W 1P3 Cavity Cavity Thermostat 1 Thermostat 2

Door Open—Oven Cavity Light is On

Electronic Control Cavity

L.V. 1P3 G 4P5 BU Thermostat 1 N Transformer BR 5P2 W BU W

Fuse OR Filter 3P2 L Filter 20 Amp CL Relay 4901 BK BK BK BK

Cavity 6P2 GY W BU Thermostat 2 CL Primary Cavity Interlock Lamp Switch

Cooktop Light on High

Electronic Control

L Cavity Cavity

Thermostat 2 L.V. Thermostat 1 N

BK BK BK BK BR 5P2 Transformer G 4P5 BU W BU W 1P3

Filter Fuse Filter 20 Amp

HL Relay W 4911 1P2 Y 5P5 R HL Hood Lamp

Cooktop Light on Low (Night Light)

Electronic Control

L Cavity Cavity

Thermostat 2 L.V. Thermostat 1 N

BK BK BK BK BR 5P2 Transformer G 4P5 BU W BU W 1P3

Filter Fuse Filter 20 Amp

W

HL Relay Diode 4912 6101 1P2 Y 5P5 R

HL

Hood (Cooktop) Lamp

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Touch Panel

Touch Panel and Electronic Control Test

The microwave hood combination is provided with a self-diagnostic routine that can be accessed through the touch keypad.

To initiate this routine: 2. Release the OFF/CANCEL button and close the door. All 1. Press and hold the OFF/CANCEL button while opening VFD segments will be lit to indicate the test mode has been entered. the door. While still holding the OFF/CANCEL button, unplug the microwave oven for 2 seconds, then plug it NOTE: If the OFF/CANCEL button is pressed during this back in. diagnostic routine, you will exit the test mode.

Key Tables for Test Mode

Key Name Function Display Buzzer Key Name Function Display Buzzer Start – Key 1 1 beep 0 1 beep Light Hi/Lo/Off – Key 3 1 beep 1 – Key 32 1 beep Hood Exhaust Fan 1 beep (HF) Hi/Med/Lo/ – 2 Cavity Light Key 33 1 beep Off On—Relay 1 beep Turntable On/Off – 3 4901 1 beep Clock – 1 beep Timer Set/Off – Key 4 1 beep 4 1 beep Add 30 Sec – 5 1 beep Cook Time – 6 Cooktop Light Key 34 1 beep Cook Power – On (High)— Warm Hold – Key 5 1 beep 7 Relay 4911 1 beep Cook – Key 6 1 beep 8 Reheat – Key 7 1 beep Microwave Key 35 Defrost – Key 9 1 beep 9 Oven On for Frozen Entrée – Key 10 1 beep 10 Seconds— Beverage – Key 11 1 beep Off/Cancel (to Relay 4903 Popcorn – Key 12 1 beep lock hold, hold Baked Potato – Key 13 1 beep for 3 seconds) – Key 36 Frozen Vegetable – Key 14 1 beep Fresh Vegetable – Key 15 1 beep – Key 37 Key 16 1 beep Key 17 1 beep Cavity Light & Key 38 Key 18 1 beep Turntable On— Key 19 1 beep Relay 4901 Key 21 1 beep &4906 Key 22 1 beep – Key 39

Cooktop Light Key 40 On (Night)— Relay 4912

HF On (High Key 41 Speed)— Relay 4902 & Triac 7104

Exit Test Mode –

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Microwave Oven Power Output Test

1. Place 8 oz (250 mL) of lukewarm water in the center of the NOTE: If the water takes longer than 2 minutes to heat, microwave oven. this may indicate either the operating voltage is lower than 110 volts or there is a problem with the microwave 2. Operate on HIGH power level for 2 minutes. Water oven. should be hot.

Failure Codes Indications

Display Likely Failure Condition Recommended Repair Procedure Flashing Power failure colon “:” Touch panel failure After a power failure, the colon “:” will be flashing. Press any key to end this F2 indication. The colon will then be steady when in standby. Humidity sensor failure F3H 1. Unplug microwave oven or disconnect power. Microwave relay failure 2. Replace touch panel. F6 3. Plug in microwave oven or disconnect power. 4. If problem persists, unplug microwave oven or disconnect power. 5. Replace electronic control. 6. Plug in microwave oven or reconnect power.

1. Unplug microwave oven or disconnect power. 2. Connect a new sensor to the electronic control (at P1). 3. Plug in microwave oven or reconnect power. 4. If problem persists, unplug microwave oven or disconnect power. 5. Replace electronic control. 6. Plug in microwave oven or reconnect power.

1. Unplug microwave oven or disconnect power. 2. Check wiring to Relay 4903 for short circuits. 3. If wiring is OK, replace electronic control. 4. Plug in microwave oven or reconnect power.

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Component Tests

IMPORTANT:

s Unplug microwave oven or disconnect power. s Conduct a microwave energy test after performing any tests or repairs to the microwave oven. s Remove the lead wires from the related component before conducting any of the following tests. s Check that all wire leads are in the correct positions before operating the microwave oven. s Discharge the high-voltage capacitor and remove the lead wires from the primary winding of the high-voltage s Grasp wire connectors when removing the wire leads transformer before conducting any of the following from microwave oven parts. tests. s All testing must be done with an ohmmeter having a s All operational checks using microwave energy must be sensitivity of 20,000 ohms per volt DC or greater, and done with the microwave oven loaded with a minimum powered by at least a 9-volt battery. of 8 oz (250 mL) of water in a microwave safe container.

Components Test/Results

H.V. Transformer 1. Unplug microwave oven or disconnect power. Filament (orange/red wires) 2. Remove wire leads. Primary 3. Measure resistance (ohmmeter scale: Rx1): Secondary s Primary winding: Less than 0.5 ohm (approximate) (white wire – s Secondary winding: 80 ohms (approximate) ground to transformer case) s Filament winding: 0 ohms

4. Measure resistance (ohmmeter scale: Rx1k): s Primary winding to grounding: Normal: Infinite s Filament winding to grounding: Normal: Infinite

Magnetron 1. Unplug microwave oven or disconnect power. 2. Remove wire leads. Check that the seal is in good condition.

3. Measure resistance (ohmmeter scale: Rx1): s Filament terminal: Normal: Less than 1 ohm

4. Measure resistance (ohmmeter scale: Rx1k): s Filament to chassis: Normal: Infinite

H.V. Capacitor 1. Unplug microwave oven or disconnect power.

2. Remove wire leads.

3. Measure resistance (ohmmeter scale: Rx10k): s Terminal to terminal: Normal: Momentarily indicates several ohms, and then gradually returns to infinite. s Terminal to case: Normal: Infinite

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Components Test/Results H.V. Diode NOTE: Some inexpensive meters may indicate infinite resistance in both directions. Turntable Motor 1. Unplug microwave oven or disconnect power. 2. Measure resistance (ohmmeter scale: Rx1k): Humidity Sensor W s Forward: Normal: Continuity; Abnormal: Infinite R s Reverse: Normal: Infinite; Abnormal: Continuity BK 1. Unplug microwave oven or disconnect power. Resistor 2. Remove wire leads. 3. Measure resistance (ohmmeter scale: Rx1k): Hood Exhaust Fan Motor s Turntable Motor—Normal: 2.7k-3.8k ohms (approximate); Abnormal: Infinite AC Line Filter 1. Unplug microwave oven or disconnect power. 1 2 2. Remove the 3-pin connector from the electronic control (P1).

3 1U 2 NOTE: Do not remove the attached resistor, which is used for internal resistance calibration. L N 4 3. Measure resistance across pins 1 & 3, and across pins 2 & 3 (ohmmeter scale: Rx1k): 3 4 s Normal: 2.8k ohms (approximate) at 77ºF (28ºC) +/- 18ºF (-10ºC) s Abnormal: Infinite

1. Unplug microwave oven or disconnect power. 2. Remove wire leads. 3. Measure resistance (ohmmeter scale: Rx1):

s High Speed—Normal: Red (R) and Blue (BU) wires: 100-200 ohms (approximate); Blue (BU) and Black (BK) wires: 40-100 ohms (approximate) ; Abnormal: Infinite

s Low Speed—Normal: Red (R) and Blue (BU) wires: 100-200 ohms (approximate); Blue (BU) and White (W) wires: 80-150 ohms (approximate); Abnormal: Infinite

1. Unplug microwave oven or disconnect power. 2. Remove wire leads. 3. Measure resistance (ohmmeter scale: Rx1):

s Normal: 1-3 (coil): Less than 1 ohm; 2-4 (coil): Less than 1 ohm; 3-4 (resistor): 550k-800k ohms

s Abnormal: Infinite

Thermostats NOTE: Refer to “Parts Layout” for opening and closing temperatures. 1. Unplug microwave oven or disconnect power. Cavity Thermostats 2. Remove wire leads. Magnetron Thermostat 3. Measure continuity (ohmmeter scale: Rx1):

s Cavity and Magnetron Thermostats—Normal: Continuity; Abnormal: Infinite

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Notes

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8205889 / 4619-651-98961 2/06 FOR SERVICE TECHNICIAN’S USE ONLY