Wolf MD24 User manual

MD24 and MD30
Component Access
4-2
#824820 - Revision A - November, 2013
COMPONENT ACCESS AND REMOVAL
This section explains how to adjust, access and remove components in a Microwave Drawer Oven. An attempt has
been made to arrange these procedures in such a way as to simulate which components would need to be removed
first in order to gain access to other components. When following a component removal procedure, it may be neces-
sary to reference another component removal procedures listed earlier in this section.
NOTE: Before continuing, please take note of the WARNINGS and CAUTION below.
HIGH VOLTAGE: MICROWAVE OVENS CONTAIN CIRCUITRY CAPABLE OF PRODUCING VERY HIGH VOLT-
AGE AND CURRENT. CONTACT WITH THE FOLLOWING COMPONENTS MAY RESULT IN SERIOUS PER-
SONAL INJURY OR DEATH:
• TRANSFORMER
• CAPACITOR
• RECTIFIER
• MAGNETRON
• HIGH VOLTAGE HARNESS
• BEFORE SERVICING MICROWAVE OVEN, THE CAPACITOR MUST BE DISCHARGED BY SHORTING THE
CONNECTING LEAD OF THE RECTIFIER AGAINST THE CHASSIS WITH AN INSULATED SCREWDRIVER.
FAILURE TO FOLLOW THIS STEP COULD RESULT IN SERIOUS PERSONAL INJURY OR DEATH.
• TO AVOID ELECTRIC SHOCK, POWER TO UNIT MUST BE DISCONNECTED WHENEVER ACCESSING
AND/OR REMOVING COMPONENTS POWERED BY ELECTRICITY OR COMPONENTS NEAR OTHER
ELECTRICAL COMPONENTS.
• BEFORE WIRING:
1. DISCONNECT POWER SUPPLY CORD, OPEN DRAWER, WAIT 60 SECONDS, THEN DISCHARGE THE
HIGH VOLTAGE CAPACITOR.
2. DON’T LET THE WIRE LEADS TOUCH TO THE FOLLOWING PARTS:
• HIGH VOLTAGE PARTS: MAGNETRON, HIGH VOLTAGE TRANSFORMER, HIGH VOLTAGE CAPACI-
TOR AND HIGH VOLTAGE RECTIFIER ASSEMBLY.
• HOT PARTS: OVEN LAMP, MAGNETRON, HIGH VOLTAGE TRANSFORMER AND OVEN CAVITY.
• TO AVOID EXPOSURE TO MICROWAVES, NEVER OPERATE OR ALLOW DRAWER MICROWAVE TO BE
OPERATED WITH THE DRAWER OPEN. DO NOT OPERATE THE OVEN IF ANY OF THE FOLLOWING CON-
DITIONS EXIST:
1. DRAWER DOES NOT CLOSE FIRMLY.
2. DRAWER LATCH HOOK IS DAMAGED.
3. DRAWER GASKET OR SEAL IS DAMAGED
4. DRAWER IS BENT OR WARPED.
5. THERE ARE DEFECTIVE PARTS IN THE DRAWER INTERLOCK SYSTEM.
6. THERE ARE DEFECTIVE PARTS IN THE MICROWAVE GENERATING AND TRANSMISSION ASSEMBLY.
7. THERE IS VISIBLE DAMAGE TO THE OVEN.
• AFTER PERFORMING ANY REPAIR TO DOOR, DRAWER LATCH MECHANISM, OR DRAWER CLOSING
FACE, YOU MUST TEST INTEGRITY OF THE DRAWER SEAL WITH A MICROWAVE LEAK DETECTOR TO
VERIFY THERE ARE NO MICROWAVE LEAKS. (SEE PROCEDURES ON PAGE 4-3)
• IF NECESSARY TO REMOVE MICROWAVE OVEN FROM ITS INSTALLATION, REMEMBER THAT THE UNIT IS
HEAVY AND COULD TIP AND/OR FALL, RESULTING IN SERIOUS INJURY.
Be careful when handling sheet metal parts - Edges may be sharp.
NOTE: When all service work is completed and the oven is fully assembled, the microwave power output
should be checked and a microwave leakage test should be preformed and drawer interlock operation
checked.

Component Access
MD24 and MD30
4-3 #824820 - Revision A - November, 2013
MICROWAVE MEASUREMENT PROCEDURE
1. Requirements:
A. Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a
microwave oven should not exceed 1mW/cm2 at any point 5cm or more from the external surface of the oven,
measured prior to acquisition by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm2 at
any point 5cm or more from the external surface of the oven.
B. Safety interlock switches: Primary interlock relay switch shall prevent microwave radiation emission in
excess of the requirement as above mentioned. Secondary interlock relay and door sensing switch shall pre-
vent microwave radiation emission in excess of 5 mW/cm2 at any point 5cm or more from the external surface
of the oven.
2. Preparation for testing: Before beginning the actual measurement of leakage, proceed as follows:
A. Make sure that the actual instrument is operating normally as specified in its instruction booklet.
NOTES:
•Survey instruments that comply with the requirement for instrumentation as prescribed by the perform-
ance standard for microwave ovens, 21 CFR 1030.0(c)(3)(i), must be used for testing.
•Survey instruments that comply with the requirement for instrumentation as prescribed by CSA and NHW
performance standard for microwave ovens must be used for testing recommended instruments are,
NARDA 8100 and NARDA 8200.
B. Place a load of 275±15 ml (9.8 oz) of tap water initially at 20± 5C (68F) in the center of the oven cavity. The
water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm (3-1/2
in.) and made of an electrically non-conductive material such as glass or plastic. Placing of this standard load
in oven is important not only to protect oven, but also to insure that any leakage is measured accurately.
C. Set the cooking control on Full Power Cooking Mode.
D. Close drawer and select a cook cycle of several minutes. If water begins to boil before survey is completed,
replace it with 275 ml of cool water.
3. Leakage test: Closed-drawer leakage test (microwave measurement):
A. Grasp probe of survey instrument and hold it perpendicular to gap between drawer and the body of oven.
B. Move probe slowly, not faster than 1in./sec. (2.5 cm/sec.) along gap, watching for maximum indication on the
meter.
C. Check for leakage at drawer screen, sheet metal seams and other accessible positions where continuity of
metal has been breached (eg., around switches, indicator, and vents). While testing for leakage around draw-
er, pull drawer away from the front of oven as far as is permitted by the closed latch assembly.
D. Measure carefully at point of highest leakage and make sure that highest leakage is no greater than
4mW/cm2, and that primary interlock switch/secondary interlock relay does turn oven OFF before any drawer
movement.
BEFORE OPERATING OVEN AFTER SERVICE
1. Disconnect power supply cord.
2. Make sure that a definite ”click” can be heard when microwave oven drawer is unlatched. (Hold drawer in a
closed position with one hand, then pull drawer open, this causes latch leads to rise, it is then possible to hear a
“click’ as the drawer switches operate.)
3. Visually check drawer and cavity face plate for damage (dents, cracks, signs of arcing etc.).
Do not operate oven if any of the following conditions exist:
• Drawer does not close firmly.
• Drawer latch hook is damaged.
• Drawer gasket or seal is damaged.
• Drawer is bent or warped.
• There are defective parts in drawer interlock system.
• There are defective parts in microwave generating and transmission assembly.
• There is visible damage to oven.
Do not operate oven without the RF gasket (Magnetron); if wave guide or oven cavity are not intact; if drawer is
not closed.

MD24 and MD30
Component Access
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#824820 - Revision A - November, 2013
Emergency Opening of Drawer:
If unit is flush mounted and drawer is not opening use
one of following procedures.
1.Use an angled screw driver or allen key wrench and
insert it under bottom middle of drawer to grab the vent
opening at bottom of drawer and carefully pull drawer
open.
2.Use a strong suction cup placed on center of drawer.
Un-installing the Microwave Drawer:
1.Open Microwave Drawer and extract four mounting
screws holding unit on to wall or cabinet opening.
(See Figure 4-1).
Mounting Screws Mounting Screws
Figure 4-1. Mounting Screw Locations
2.Close Microwave Drawer and carefully pull unit out
from opening.
3.Unplug power supply cord.
4.Place Microwave Drawer on secured working surface.
Removing Cord and Outer Case:
1.Extract two screws holding AC Cord Mounting Angle.
Lift mounting angle with AC Cord attached and unplug
AC Cord from molex. (See Figure 4-2).
2.Extract eighteen (18) screws holding the Outer
Case/Side Angles, and latch cover plates.
3.Remove Outer Case. (See Figure 4-2).
AC Cord
Mount Angle
AC Cord
Cord Bushing
Side Angle
Outer Case
Schematic Diagram
Side Angle
Latch Cover Plates
Knockout for Oven Lamp Replacement
Figure 4-2. AC Cord/Outer Case Removal
Accessing Rear Components:
1.Extract ten screws holding Back Cover. (See Figure 4-
3).
Cavity
Back cover
Door Panel
Door
Frame
Assy
Figure 4-3. Back Cover Screws
Metal Key Unit Frame Assembly
1.Remove two side angles.
2.Carefully unsnap Frame Assembly by lifting up and tilt-
ing forward.
3.Be sure and unplug Power Supply Board cable before
lifting off. (See Figure 4-4)
NOTE: when lifting off Metal Key Unit Frame - ground
spring will be loose.
4.Removing Control panel frame will allow access to
Control Board.
NOTE: Metal Key Unit Assembly is held by right & left
side angles. There are also three clips at top and bottom
that snap into cavity faceplate.
Figure 4-4. Metal Key Unit Frame
CPU Board
CPU screws
GND Spring

Component Access
MD24 and MD30
4-5 #824820 - Revision A - November, 2013
Noise Filter Board Replacement
1.Disconnect Black and White wire from Noise Filter
Board. (See Figure 4-5).
2.Extract screw from Noise Filter Board.
3.Remove Noise Filter Board.
Red WireRed Wire
ScrewScrew
DoubleDouble
WhiteWhite
Noise Filter BoardNoise Filter Board
Black WireBlack Wire
White WireWhite Wire
Figure 4-5. Noise Filter Board
Latch Hook and Microswitch Removal
1.Follow Microwave Drawer disassembly as previously
stated.
2.Open drawer and keep it open.
3.To discharge high voltage capacitor, wait for 60 sec-
onds.
4.Disconnect wire leads from each switch.
5.Extract screw holding latch hook to oven flange.
6.Remove latch hook from oven flange.
7.Remove each switch from latch hook by pushing the
one stopper tab holding each switch.
NOTEote: Assure continuity of the Monitor circuit when
reinstalling monitor switch or right side Latch Hook
Assembly.
Adjusting Monitor, Stop, and Secondary Interlock Switches
1.Follow Microwave Drawer disassembly as previously
stated.
2.Open drawer and keep it open.
3.To discharge high voltage capacitor, wait for 60 sec-
onds.
4.If door sensing, third door, secondary interlock and
monitor switch do not operate properly due to a misad-
justment, the following adjustment should be made.
5.Loosen screw holding latch hook to oven cavity flange.
6. With drawer closed, adjust latch hook by moving it
back and forth, and up and down. In and out play of
drawer allowed by upper and lower position of latch
hook should be less than 0.5mm. Vertical position of
latch hook should be adjusted so that secondary inter-
lock switch is activated with drawer closed.
7. Horizontal position of latch hook should be adjusted
so that monitor switch and drawer sensing switch are
activated with drawer closed.
8. Secure screws with washers firmly.
9. Check all switch operation.
(See Figure 4-6 and Figure 4-7).
Third Door Switch
Door Sensing Swtich
Figure 4-6. Left side Latch Hook
Monitor SwtichMonitor Swtich
Secondary Interlock SwtichSecondary Interlock Swtich
Figure 4-7. Right side Latch Hook

MD24 and MD30
Component Access
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#824820 - Revision A - November, 2013
After Adusting Latch Hook - Check the following.
1.In and out play of drawer remains less than 0.5mm
when in latched position. First check upper position of
latch hook, pushing and pulling upper portion of drawer
toward oven face. Then check lower portion of latch
hook, pushing and pulling lower portion of drawer
toward oven face. Both results (play in the drawer)
should be less than 0.5mm.
2.Secondary interlock switch interrupts circuit before
drawer can be opened.
3.Monitor switch contacts close when drawer is opened.
4.Drawer sensing switch contacts open when drawer is
opened.
5.Reassemble unit and check for microwave leakage
around drawer with an approved microwave survey
meter. (Microwave Measurement Procedure Page 4-3)
Drawer Assembly and Choke Removal
1.Follow Microwave Drawer disassembly as previously
stated.
2.Open drawer and keep it open.
3.To discharge high voltage capacitor, wait for 60 sec-
onds.
4.Remove two Drawer Support Covers from Choke
Cover (See Figure 4-8).
5.Extract six screws from all three drawer Support
Angles. (See Figure 4-9).
6.Unhook Drawer Support Angles from drawer, then
remove.
7.Door assembly is free and Choke Cover can be
removed by Inserting a putty knife (thickness of about
0.5mm) into gap between choke cover and door frame.
Carefully slide choke cover away from drawer as far
as possible.
Figure 4-8. Drawer Support Covers
Drawer Support Angle Removal
1.Remove Drawer Assembly and Choke Cover as stated
in prior section.
2.Extract two screws from right or left Drawer Support
Angles, then remove Angle assembly (See Figure 4-
9).
3.Separate Slide Rails by moving inside lever of Slide
Rails. Slide Rail will now separate by pulling straight
forward and out. (See Figure 4-10).
4.Drawer Support Angles or Slide Rails are now replace-
able.
Figure 4-9. Drawer Support Angles
Figure 4-10. Slide Rails

Component Access
MD24 and MD30
4-7 #824820 - Revision A - November, 2013
Door Latch Removal
1.Follow "DRAWER ASSEMBLY AND CHOKE
REMOVAL"
2.Lay door panel and door frame assembly front down
on a protective surface.
3.Extract six screws holding door panel to door frame.
4.With door frame removed, unhook latch spring, then
extract screw.
(See Figure 4-11).
Door Panel Door Panel screws
to door frame
Door Panel screw
to door frame
Door frame
Latch head R
Latch spring
Latch head screw
Latch head L
Latch head screw
Latch spring
Figure 4-11. Door Latch Removal
Auto Drawer Gear Removal
NOTE: This procedure can be performed without remov-
ing outer case.
1.If you are just replacing the Auto drawer Gear, it will
not be necessary to follow "Microwave Drawer
Disassembly"
2.Turn Drawer up on its back and knockout Auto Drawer
Gear hole cover. (See Figure 4-12).
3.Unhook wiring connector to Auto Drawer Gear motor.
5.Extract four screws holding auto drawer gear to bottom
cavity angle. (See Figure 4-13).
6.Disengage (pull) Auto Drawer Gear motor from rack
gear.
7.Auto Drawer Gear motor is now free.
Figure 4-12. Knockout for Auto Gear Assembly
Figure 4-13. Auto Gear Assembly
Auto Drawer Gear Installation
1.Engage Auto Drawer Gear motor into rack gear.
NOTE: Assure gear teeth are set into cavity angle cor-
rectly before tightening screws.
2.Install four screws holding Auto Drawer Gear to bottom
cavity motor.
3.Reconnect wiring to Auto Drawer Gear Motor.
4.After Auto Drawer Gear is reinstalled, insert knockout
hole cover and secure with a 816890 screw.

MD24 and MD30
Component Access
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#824820 - Revision A - November, 2013
Rack Gear/Oil Damper Removal
1.Follow Microwave Drawer disassembly as previously
stated.
2.Open drawer and keep it open.
3.To discharge high voltage capacitor, wait for 60 sec-
onds.
4.Remove Microwave Drawer by following steps under
"DRAWER SUPPORT ANGLE REMOVAL" page 4-6.
5.Extract three screws holding Rack Gear to bottom
slide rail. (See Figure 4-14).
6.With bottom slide rail off, locate tab holding Oil
Damper and remove. Replace with new Oil Damper.
(See Figure 4-15).
NOTE: Purpose of Oil Damper is to prevent drawer from
closing too hard.
Figure 4-14. Rack Gear
Tab
Oil Damper
Figure 4-15. Oil Damper
After Reassembly
1.Make sure that drawer sensing switch, third door
switch, secondary interlock switch and monitor
switch are operating properly.
2.An approved microwave survey meter should be used
to assure compliance with proper microwave radiation
emission limitation standards.
3.Drawer latch heads smoothly catch latch hook through
latch holes and latch head goes through center of latch
hole.
4.Deviation of door alignment from horizontal line of cav-
ity face plate is to be less than 1.0 mm.
5.Drawer is positioned with its face pressed toward cavi-
ty face plate.
NOTE: The drawer on a microwave oven is designed to
act as an electronic seal preventing the leakage of
microwave energy from oven cavity during cook cycle.
This function does not require that door be air-tight,
moisture (condensation)-tight or light-tight. Therefore,
occasional appearance of moisture, light or sensing of
gentle warm air movement around oven drawer is not
abnormal and do not of themselves indicate a leakage of
microwave energy from oven cavity.

Component Access
MD24 and MD30
4-9 #824820 - Revision A - November, 2013