Haier HR-6751M User manual

Electronic without Grill
Microwave Oven
Service Manual
HR-6751M
HR-7751M
Features
Safe to use
Shining appearance
Healthy and germicidal
Easy to operate
Haier Group
Manual code:MSMWOE-01 Edition:2003-1-8

Contents
Contents
1. Contents……………..…………………………………………………………………1
2. Product Code illumination and Series Introuduction……………………...…...2
3. Features….……………………………………………………..…………………….3
4. Specifications……..…………………………………………...………………….4
5. Safety Precaution…………………………………………..………………………5
6. Warning and Cautions……………………………………………………………..6
7. Installation and Accessory Parts…………………………………………………9
8. Parts and Functions………………………………………………………………..11
9. Maintenance Service and Trouble Shooting…………………………………...12
10.Circuit Diagram and Circuit Explanation………………………………………..25
11.Exploded View………………………………………………………………………27
12.List of Parts………………………………………………………………………….29
- 1 -

Product Code illurmination and Series Introduction
2.Product Code illurmination and Series Introduction
Model Identification
HR-
A B C D E F
A: Abbreviation of Haier.
B: Code name of Nominal cavity capacity.
5—means the cavity capacity is 22 or 21 liter,
6—means the cavity capacity is 17 liter,
7--- means the cavity capacity is 24 liter,
C:One tenth of the microwave output power consumption.
D: Code name of operation pattern:1,3 means the operation pattern is electronic,
2,5 means the operation pattern is mechnical.
E:Function code:G---with grill
F:Appearance feature
Examples:
HR-6751M
-It represents electronic microwave oven without grill , the cavity capacity is 17 liter , the
microwave output power consumption is 750 Watts.
HR-7751M
-It represents electronic microwave oven without grill , the cavity capacity is 24 liter , the
microwave output power consumption is 750 Watts.
HR-7752D
-It represents mechnical microwave oven without grill , the cavity capacity is 24 liter , the
microwave output power consumption is 750 Watts.
- 2 -

Features
3.Features
3.1 Safe to use
The door adopts unique anti-choke structure and integrated punch forming, and thus
effectively prevents the microwave from leaking.
It is controlled by two-step interlock switch.The power will be switched off automatically
when the door is open,therefore it is much safer to use.
3.2 Shining apppearance
The door shell and operation panel frame shell adopt inported high-quality stainless
steel material, and will never get rust and change color.It has modern applearance and
superior quality,and thus becomes the best chocie for the householed microwave oven.
3.3 Healthy and germicidal
It is produced with antiseptic materials,and can suppress the reproduction of the
bacteria effectively.The special function of the microwave oven can eliminate the germ in
the food quickly and completely.
- 3 -

Specifications
4.Specifications
Item Description
Model HR-6751M HR-7751M
Power source 230V/50Hz 230V/50Hz
Input Power consumption 1250W 1250W
output Power consumption 750W 750W
Power consumption
For grill --------
Oscillating frequency 2450MHz
Timing range 99’99”
Power level 5 5
Unit Dimension
(W DH)mm 458 337 295 510 360 306
Cavity Dimension
(W DH)mm 302 288 183 353 338 202
Carton Dimension
(W DH)mm 514 374 348 570 420 360
Volume/
effective volume 17/11L 24/17L
Weight(unit/carton) 13/15Kg 15.5/17.5Kg
Accessories Instruction manual ,glass tray, trun
plate-btacket groupwaregl, turn axis
- 4 -

Safety Precaution
5.Safety Precaution
Only professional technicians can do the maintenance. Please refer to the proper
maintenance procedures in the service manual for safe operations, so as to avoid
unexpected injury.
Points of attention during maintenance:
1. Do not operate the microwave oven while the door of the oven is open.
2. Please check following before operation: (1) the door lock is flexible; (2) the door
works well in opening and closing; (3) the door is sealed well (without deforming and
bending); (4) identify any damage and loosening of the components and accessories;
(5) identify damages owing to abnormal usage or dropping.
3. Please confirm that the magnetron, microwave conductor pipe and wire are installed
and connected well before switch on the power to do maintenance or check the
functional components.
4. In case that the door lock, seal gasket, microwave radiating and transmission system
are damaged, or something wrong in debugging, please make repair, replacement or
adjustment according to the requirement of this manual before usage.
Components detachable that may
touch voltage higher than 250V
Components that may cause excessive
microwave leakage
1. Magnetron
2. High-voltage transformer
3. High-voltage capacitor
4. High-voltage diode
5. AK rectifier
1. The magnetron is not properly installed on the
wave guide;
2. The door hook, door body and the up/down
hinge are not properly adjusted;
3. The door body or the shell is damaged;
The above reasons may cause excessive
microwave leakage.
During maintenance, the technicians shall pay attention that:
Attention
Microwave radiation
Do not expose to the radiation emitted by the microwave generator or other parts
transmitting the microwave.
- 5 -

Warning and Cautions
6.Warning and Cautions
Danger Warning
Danger
Attention
Do not use the microwave oven for purposes
other than for cooking food.
Do not cook eggs in their shell as they may
burst.
warning
Do not apply excessive force to the door.
It may cause distortion of the door and
result in microwave leakage.
warning
warning
Electric
shock
hazard
Do not use a metal rod to enter the interlock
switch hole on the front side of the cavity.
interlock switch hole
No
dismantle
Danger
This appliance must be earthed.
Remember to clear awa
y
excess
g
rease
form the inside the cavit
y
. Otherwise it ma
y
cause smoke or fire during heating.
Do not use sealed containers. For those
foods with skin, please prick holes on the
skin.
warning
warning
warning
safe and
reliable
- 6 -

Warning and Cautions
1. If the door seal or the door body is damaged, please do not use the
appliance until it is repaired by an authorised service agent.
2. Before use, please check if the cooking containers are suitable for
the microwave oven.
3. If you find smoke in the oven, leave the door in the closed position, and
switch off the power supply of the microwave (remove the plugtop from
the supply socket).
4. We do not recommend the use of plastic, paper or other combustible
containers for cooking, Please be sure to observe the operating
instruction for the microwave oven, in order to avoid accidents.
5. When you heat liquid in the oven, please take care of delayed bubbling
because of boiling liquid.
6. Do not use the microwave oven if there is no food inside.
7.
Waring
warning warning
When roasting, the face of the door and
the top of the cabinet may become hot to
touch.
Do not use the microwave with the cavity
empty. It will damage the microwave oven.
Do not use product for any industrial and commercial purpose.
Do not use metallic dishware to cook as it
will cause internal arcing.
Allow the cavity to cool after long cooking
processes (i.e. Roasting) before starting
another cook cycle.
warning warning
- 7 -

Warning and Caution
POINTS OF ATTENTION
Not like the other household appliances, the microwave oven is a kind of
high-voltage appliance. Although common operations will not risk the user in
hazard, please operate it carefully.
1. Do not use duplex receptacle in usage and maintenance.
2. Do not touch any components and circuit when the microwave is running.
3. Be sure to switch off the power before you touch the inside structure of the oven.
4. The high-voltage capacitor may still maintain electricity even 30 seconds after the
microwave oven stops working. To make replacement or checking at this time, be sure
to use insulated screwdriver to short out the two ends of the capacitor and discharge
the stored electricity.
5. Prevent the wristwatch from touching the microwave oven.
6. Do not operate the microwave oven when there is no food or water inside.
7. Protect the seal gasket and front board of the oven door from damage.
8. Do not put metal tools on the magnetron.
9. Do not put any items into the hole of the door lock or the door lock switch.
10. Confirm that the magnetron is installed properly and firmly.
Only professional technicians can do the maintenance of this
microwave oven.
- 8 -

Installation and Accessory Parts
7.Installation and Accessory Parts
7.1 Installation
attention
Do notinstall the microwave oven in
an environment that is humid or with
high temperature.
Attention
1.7.2 KEY POINT IN INSTALLATION ADJUSTMENT
Please read following before installation.
5.1 Install the microwave oven
1. Clear all of the items inside the oven, then wipe the cavity with wet soft cloth. Check if
the door is even, and if there’s damage on the inner/outer side of the door.
2. The microwave oven, the food and the cooking tools shall be placed on firm and stable
table, desk or shelf. During delivery please note that the side with control panel is much
heavier.
3. Do not block the ventilation hole and air inlet. Otherwise it may damage the oven or
cause poor cooking. Confirm that the oven shelf is placed properly to guarantee the
ventilation.
4. Avoid high temperature and vapor. Protect the appliance and the mechanical part from
damages.
5. The ambient temperature shall be lower than 40 .
6. The plane bearing the oven shall be even and firm.
7. Keep the microwave oven away from the TV, radio, computer, etc. to avoid
interference.
5.2 Installation of the earth wire
The microwave oven must be earthed before use. Please pay special attention on that.
Warning: This microwave oven must be earthed.
- 9 -

Installation and Accessory Parts
Hint:
Connect the wires as indicated below:
The yellow/green wire is earth wire; the blue wire is null wire; the brown wire
is live wire.
If the colors of the wires are not in accordance with the power source
terminals, please operate as per below:
Connect the yellow/green wire to the wire marked with “E” or the green wire;
connect the blue wire to the wire marked with “N” or the black wire; connect
the brown wire to the wire marked with “L” or the red wire.
7.3 Accessory parts
Open the
carton
Install
Put the microwave oven at the position
you choose. Keep good ventilation.
The gaps should all be above 15cm.
accessory box
+ TIME/WEIGHT ADJUST -
AUTO COOKI NG MENU
1. Beverage
2. Fish
3. Auto
Reheat
4. Instant Noodle
5. Barbecue
6. Vegetable 7. Chicken
8. Auto
Defrost
START
+ 30 SEC
AUTO MENU
PAUSE/CANCEL
GRILL/COMBI
MICRO POWER
Glass rotary tray
rotary tray support
Select an independent socket, with
a current of at least 10A. Be sure to
ground it.
Warrant
y
Certificate
- 10 -

Parts and Functions
8.Parts and Functions
g
lass rotar
y
tray
shell
operation
board
diagrammtic sketch for
baking
mesh
cavity
door hook
door seal
door
hb d
- 11 -

Circuit Diagram and Circuit Explanation
10.Circuit Diagram and Circuit Explanation
Circuit description:
1. The Plug 1 is used to supply power for the control panel, at the same time offers the
access for the lamp, the tray motor and the fan motor.
2. After the door is opened, the monitoring switch will close. The first and second lockout
switches will open to guarantee that the microwave oven will not during the door is
open.
MT
MF
Lamp Mn Mt
Monitor
switch
The first lockout switch
L
N
HVD
HVC
AK
Rectifier
Magnetron
E
LIN
FUSE
filter
N
IN
N
OUT
L
OUT
PC control system
RELAY PLUG1 PLUG2
The second lockout switch
HVT
3. When the door is closed, the monitoring switch will open. The first and second lockout
switches will close. Then the microwave oven will start to run. The LED will display the
time remained.
4. After starting, the fan motor, rotary tray motor, the lamp and the magnetron start
working. When the load is not full, the relay will control the transformer power sources
to make the magnetron work intermittently. The fan motor is to cool the magnetron and
transformer. The tray motor is to improve the thermal evenness.
5. The magnetron thermostat is a protective device used to prevent the fan from locking,
and protect the magnetron from too high temperature. The cavity thermostat is to avoid
fire in the cavity.
- 25 -

Circuit Diagram and Circuit Explanation
2. After the oven start working, a 230V AC voltage is added between the two ends of the
high-voltage transformer.
3. The 230V voltage will make 2000V induction voltage between the two ends of the
high-voltage coil, and 3.5V low-voltage between the two ends of the heater winding.
4. The 2000V voltage will be doubled by the high-voltage capacitor, then be rectified by
the high-voltage diode, finally become a 4000V negative high-voltage to ground at the
FA end of the magnetron.
5. One end of the heater coil is connected to the negative high-voltage, the other end to
the F end of the magnetron. Therefore the working condition of the magnetron is made
up: low-voltage and high electric potential.
Magnetron
AK
Rectifier
HVT
HVD
HVC
230 50Hz
- 26 -

Sincere Forever
Haier Group
Tel :[phone]
Web site : http://www.haier.com