DOWNLOAD Sharp R-2277 Service Manual ↓ Size: 730.87 KB | Pages: 44 in PDF or view online for FREE

27

1. CARRY OUT 3D CHECKS.
2. Remove four (4) screws holding the upper and lower

oven hinge to the oven cavity.

3. Remove door assembly with upper and lower oven

hinges by pulling it forward.

4. On re-installing new door assembly, secure the upper

and lower oven hinges with the four (4) mounting
screws to the oven cavity. Make sure the door is
parallel with bottom line of the oven face plate and the
latch head pass through the latch holes correctly.

5. CARRY OUT 4R CHECKS.

Note:

After any service to the door, the

approved microwave survey meter should be
used to assure in compliance with proper
microwave radiation  standards. (Refer to
Microwave Measurement Procedure.)

When removing and/or loosening hinges such as in door

replacement, the following adjustment criteria are taken.
Door is adjusted to meet the following three conditions by
keeping screws of hinge loose.
1. Adjust door latch heads at a position where they

smoothly catch the latch hook through the latch holes.
Refer to latch switch adjustments.

2. Deviation of the door alignment from horizontal line of

cavity face plate is to be less than 1.0mm.

3. The door is positioned with its face depressed toward

the cavity face plate.

4. Reinstall outer case and check for microwave leakage

around the door with an approved microwave survey
meter. (Refer to Microwave Measurement Proce-
dure.)

UPPER
OVEN 
HINGE

LOWER
OVEN 
HINGE

DOOR 
ASSEMBLY

LATCH HEADS

OUTER CASE
CABINET

1. Insert an iron plate (thickness of about 0.5mm or flat

type screw driver to the gap between the choke cover
and door panel as shown figure to free the engaging
part. The protect sheet may be used not to damage
the door panel.

2. Lift up the choke cover, now cove is free.

DOOR
PANEL

CHOKE
COVER

FLATE TYPE
SCREW DRIVER

PROTECTION 
BY TAPE

LOWER
OVEN HING

UPPER
OVEN HING

Remove the door assembly, referring to from item 1
through item 3 of “DOOR REPLACEMENT”.
1. Place the door assembly on a soft cloth with facing up.

2. Remove the choke cover, referring to “CHOKE COVER

REMOVAL”.

3. Release the oven hinges from the door panel.
4. Now, the  oven hinges are free.

5. Remove the two (2) screws holding the door handle to

door.

6. Remove the door handle from the door panel.

(UPPER AND LOWER LATCH HEADS REMOVAL)
7. Remove the door release lever from the door assem-

bly.

8. Remove the three (3) screws holding the joint plate to

the door panel.

9. Release the latch spring from the tab of the joint lever

and joint plate.

10.Release the latch heads from joint lever and joint plate.
11.Now, the latch heads are free.

12.Set the four (4) tabs of the door frame upright.
13.Remove the door frame from the door panel. Now,

door frame is free.

14.Remove the four (4) screws holding the two (2) outside

window fixing plates to the door panel.

15.Now, the door glass is free.

28

After adjustment of door latch switches, monitor switch
and door are completed individually or collectively, the
following leakage test must be performed with a survey
instrument and it must be confirmed that the result meets the
requirements of the performance standard for microwave
oven.

The safety switch must prevent microwave radiation emis-
sion in excess of 5mW/cm2 at any point 5cm or more from
external surface of the oven.

Before beginning the actual test for leakage, proceed as
follows;
1. Make sure that the test instrument is operating normally

as specified in its instruction booklet.
Important:
Survey instruments that comply with the requirement for
instrumentations as prescribed by the performance
standard for microwave ovens must be used for testing.

Recommended instruments are:
NARDA 8100
NARDA 8200
HOLADAY HI 1500
SIMPSON 380M

2. Place the oven tray into the oven cavity.
3. Place the load of 275 

±

 15ml of water initially at 20 

±

5˚C in the centre of the oven tray. The water container
should be a low form of 600 ml beaker with inside
diameter of approx. 8.5cm and made of an electrically
non-conductive material such as glass or plastic.
The placing of this standard load in the oven is important
not only to protect the oven, but also to insure that any
leakage is measured accurately.

4. Close the door and turn the oven ON with the timer set for

several minutes. If the water begins to boil before the
survey is completed, replace it with 275ml of cool water.

5. Move the probe slowly (not faster that 2.5cm/sec.)

along the gap.

6. The microwave radiation emission should be measured

at any point of 5cm or more from the external surface of
the oven.

29

Parts

Symbol

Value / Data

Weak point

WP1 , WP1

A018 for R-2287

Fuse

WP1, WP2

M6.3A for R-2277

Weak point

F1

A017 for R-2287

Fuse

F1

13A for R-2277

Fuse

F2

F6.3A 250V

Thermal cut-out (Mag)

TC1

145˚C

Thermal cut-out (Mag.)

TC2

145˚C

Thermal cut-out (Blower motor)

TC3

115˚˚C

Thermal cut-out (Oven)

TC4

115˚˚C

Thermistor (Exhaust)

Approx.  77.45k

Ω

 at 15˚C, 61.47K

Ω

 at 20˚C, 49.12K

Ω

 at

25˚C

Thermistor (Intake)

Approx. 15.8k

Ω

 at 15˚C, 13.03K

Ω

 at 20˚C, 10.74K

Ω

 at 25˚C

Thermistor (Magnetron)

Approx. 15.91k

Ω

 at 15˚C, 13.04K

Ω

 at 20˚C, 10.74K

Ω

 at 25˚C

Monitor resistor

R1

4.3

Ω

 20W

Oven lamp

OL

250V 25W

High voltage capacitor  (R-2287)

C1, C2

1.07

µ

F AC 2100V

High voltage capacitor  (R-2287)

C1, C2

0.94

µ

F AC 2100V

High voltage transformer   (R-2287)

T1, T2

Filament winding   < 1

Ω

Secondary winding Approx. 57

Ω

Primary winding Approx. 1

Ω

High voltage transformer   (R-2277)

T1, T2

Filament winding   < 1

Ω

Secondary winding Approx. 83

Ω

Primary winding Approx. 2

Ω

Magnetron

MG1

Filament winding < 1

Ω

Filament winding - chassis 

∞

 

Ω

Magnetron

MG2

Filament winding < 1

Ω

Filament winding - chassis 

∞

 

Ω

Resistance (Disconnect the

In/Out pit terminal

Test Point

Volt

power plug and close the door.)

Input terminal (Power suplly)

A5- A7

230V

Approx. 790

Ω

Output terminal (Stop switch)

B1- B2

0

Output terminal
(Oven lamp +Blower motor

A1- A7

230V

Approx. 225

Ω

 + Stirrer motor)

Output terminal (Earth)

B1- Chassis

0

30

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED

2.

        APPEARS ON DISPLAY

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. COOKING TIME ENTERED.

3. 

/100%  BUTTON TOUCHED.

4. START

BUTTON TOUCHED.

F1 : WEAK POINT A017

NOISE FILTER

SW1: 
1ST LATCH SWITCH
(PRIMARY INTERLOCK SWITCH)

SW4:

MONITOR

SWITCH

R1:

MONITOR

RESISTOR

TC3:

BLOWER MOTOR

THERMAL CUT OUT

115C°

A7

A5

TC4: 

OVEN THERMAL 

CUT OUT 115C°

F2:

FUSE

F6.3A

SW2: 2ND LATCH SWITCH

WP2:WEAK POINT A018

A3

TC2: MAGNETRON
        THERMAL CUT OUT
        145C°(LOWER)

OVEN LAMP

BLOWER MOTOR

A1

CONTROL
UNIT

B1

SW3: 
3RD LATCH SWITCH

EXHAUST 

THERMISTER

SW5: STOP SWITCH

TAB3

D3

TAB2

TAB1

TAB4

T1: HIGH VOLTAGE

      TRANSFORMER

230V~50Hz

ASYMMETRIC
RECTIFIER

 H. V. RECTIFIER

C1: H.V. CAPACITOR

MG1: MAGNETRON (UPPER)

(REAR)

WP1:
WEAK POINT 
A018

OL

SM

STIRRER MOTOR

SM

BM

RY1

RY3

RY4

TC1: 
MAGNETRON
THERMAL 
CUT OUT
145C°(UPPER)

B2

B3

D1

H1

H3

 INTAKE 

THERMISTER

MAGNETRON

THERMISTER

ASYMMETRIC
RECTIFIER

 H. V. RECTIFIER

C2: H.V. CAPACITOR

MG2: MAGNETRON (LOWER)

T2: HIGH VOLTAGE

      TRANSFORMER

(FRONT)

F1 : WEAK POINT A017

NOISE FILTER

SW1: 
1ST LATCH SWITCH
(PRIMARY INTERLOCK SWITCH)

SW4:

MONITOR

SWITCH

R1:

MONITOR

RESISTOR

TC3:

BLOWER MOTOR

THERMAL CUT OUT

115C°

A7

A5

TC4: 

OVEN THERMAL 

CUT OUT 115C°

F2:

FUSE

F6.3A

SW2: 2ND LATCH SWITCH

WP2:WEAK POINT A018

A3

TC2: MAGNETRON
        THERMAL CUT OUT
        145C°(LOWER)

OVEN LAMP

BLOWER MOTOR

A1

CONTROL
UNIT

B1

SW3: 
3RD LATCH SWITCH

EXHAUST 

THERMISTER

SW5: STOP SWITCH

TAB3

D3

TAB2

TAB1

TAB4

T1: HIGH VOLTAGE

      TRANSFORMER

230V~50Hz

ASYMMETRIC
RECTIFIER

 H. V. RECTIFIER

C1: H.V. CAPACITOR

MG1: MAGNETRON (UPPER)

(REAR)

WP1:
WEAK POINT 
A018

OL

SM

STIRRER MOTOR

SM

BM

RY1

RY3

RY4

TC1: 
MAGNETRON
THERMAL 
CUT OUT
145C°(UPPER)

B2

B3

D1

H1

H3

 INTAKE 

THERMISTER

MAGNETRON

THERMISTER

ASYMMETRIC
RECTIFIER

 H. V. RECTIFIER

C2: H.V. CAPACITOR

MG2: MAGNETRON (LOWER)

T2: HIGH VOLTAGE

      TRANSFORMER

(FRONT)

NOTE: " " INDICATES COMPONENTS WITH POTENTIALS ABOVE 250V.