Sharp R9h56 Service Manual

R-9H56
9
Microwave Cooking:
Damper is in the open position, because a portion of cooling
air is channelled through the cavity to remove steam and
vapours given off from the heating foods.
It is then exhausted at the top of the oven cavity into a
condensation compartment.
Convection Cooking:
Damper is in the closed position, so that no hot air will be
allowed to leak out the oven cavity.
Damper Operation
1. When power supply cord is plugged in:
1-1. When power supply cord is plugged in, a signal is
sensed...

R-9H56
10
 WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with any part of the
high voltage circuit will result in electrocution. High voltage capacitor, Power transformer, Magnetron, High voltage
rectifier assembly, High voltage harness.
 REMEMBER TO CHECK 
3D
1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.
WARNING:AGAINST THE CHARGE OF THE
HIGH-VOLTAGE CAPACITOR
The high-voltage...

R-9H56
11
MAGNETRONPOWER TRANSFORMERH.V. RECTIFIER ASSEMBLYHIGH VOLTAGE CAPACITORLATCH AND STOP SWITCHESMONITOR SWITCHDAMPER SWITCHMAIN FUSETEMPERATURE FUSE 150ûCTHERMAL CUT-OUTCONVECTION HEATERTHERMISTORFAN MOTORTURNTABLE MOTORCONVECTION MOTORDAMPER MOTORMONITOR RESISTORTOUCH CONTROL PANELKEY UNITRELAY (RY-1)RELAY (RY-2)RELAY (RY-3)RELAY (RY-4)RELAY (RY-5)RELAY (RY-6)FOIL PATERN ON P.W.B.AH. SENSOROVEN LAMP OR SOCKETOPENED OR SHORTED WIRE HARNESSWALL OUTLETLOW POWER SUPPLY VOLTAGE
SHORTED POWER CORD...

R-9H56
12 TEST PROCEDURES
PROCEDURE
LETTER
CARRY OUT 3D CHECK.
Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.
To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron
filament terminals, the meter should show a reading of less than 1 ohm.
To test for short filament to anode condition, connect ohmmeter between one of the filament terminals
and the case of the magnetron (ground). This test should be indicated...

R-9H56
13 TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
6. Measure the final water temperature. (Example: The final temperature T2 = 21°C)
7. Calculate the microwave power output 
P in watts from above formula.
Initial temperature ...........................  T1 = 11°C
Temperature after (49 + 2) = 51 sec. ..............  T2 = 21°C
Temperature difference Cold-Warm ...............  DT1 = 10°C
Measured output power
The equation is ÒP = 85 x DTÓ .............. P = 85 x 10°C = 850 Watts
JUDGMENT: The...

R-9H56
14 TEST PROCEDURES (CONTD)
Example
Initial temperature ....................... T1 = 23ûC   T2 = 24ûC
Temperature after 1 min. 51 sec. ............ T1 = 33ûC   T2 = 34ûC
Temperature difference Cold-Warm ............DT1 = 10ûC  DT2 = 10ûC
Mean temperature rise DT .........DT  = (DT1 ± DT2) / 2 = (10ûC+10ûC) / 2 = 10ûC
Measured output power
The equation is P= 75 x DT .................. P= 75 x 10ûC = 750 Watts
NOTE: The measured output power should be at least 
± 15 % of the rated output power....

R-9H56
15 TEST PROCEDURES (CONTD)
PROCEDURE
LETTERCOMPONENT TEST
ASYMMETRIC RECTIFIER TEST
CARRY OUT 
3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The asymmetric can be tested using an
ohmmeter set to its highest range across the terminals A+B of the asymmetric rectifier and note the
reading obtained. Reverse the meter leads and note this second reading. If an open circuit is indicated
in both direction then the asymmetric rectifier is good. If an asymmetric rectifier is...

R-9H56
16
PROCEDURE
LETTERCOMPONENT TEST TEST PROCEDURES (CONTD)
GTEMPERATURE FUSE AND THERMAL CUT-OUT TEST
 CARRY OUT 
3D CHECKS.
 Disconnect the leads from the terminals of the temp. fuse or thermal cut-out. Then using an ohmmeter,
make a continuity test across the two terminals as described in the table below.
 CARRY OUT 
4R CHECKS.
Table: Temperature Fuse and Thermal cut-out Test
Temperature of ÒONÓ condition Temperature of  ÒOFFÓ condition Indication ofohmmeter
Parts Name (closed circuit) (ûC) (open...

R-9H56
17 TEST PROCEDURES (CONTD)
PROCEDURE
LETTERCOMPONENT TEST
Disconnect the leads from the motor.
Using an ohmmeter, check the resistance between the two terminals as described in the table below.
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 295 W
Turntable motor Approximately 10.5 kW
Convection fan motor Approximately 210 W
Damper motor Approximately 11 kW
If incorrect readings are obtained, replace the motor.
CARRY OUT
 4R CHECKS.
The touch control panel consists of circuits...

R-9H56
18 TEST PROCEDURES (CONTD)
PROCEDURE
LETTERCOMPONENT TEST
MKEY UNIT TEST
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon is making
good contact, verify that the door sensing switch (stop switch) operates properly; that is the contacts are
closed when the door is closed and open when the door is open.
If the door sensing switch (stop switch) is good, disconnect the flat ribbon that connects the key unit to
the control unit and make sure the door...