Read Sharp R-657SL (serv.man7) Service Manual online
R657(W)
8 – 4
2. Insulation resistance.
Disconnect the wire leads to the heating element to be tested. Check the insulation resistance between the element terminal and cavity using a
500V - 100M
500V - 100M
Ω insulation tester. The insulation resistance should be more than 10 MΩ in the cold start.
If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably faulty and should be replaced.
CARRY OUT 4R CHECKS.
[12] L: TOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper
maintenance can not be performed with only a voltmeter and ohmmeter.
maintenance can not be performed with only a voltmeter and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key Unit. Troubleshooting by unit replacement is
described according to the symptoms indicated.
described according to the symptoms indicated.
1. Key Unit Note: Check key unit ribbon connection before replacement.
The following symptoms indicate a defective key unit. Replace the key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
2. Control Unit
The following symptoms indicate a defective control unit. Before replacing the control unit, perform the key unit test (Procedure M) to determine if con-
trol unit is faulty.
trol unit is faulty.
2.1. In connection with pads
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
2.2. In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light up.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2.3. Other possible troubles caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
[13] M: KEY UNIT (MEMBRANE SWITCH) TEST
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable is making good contact, verify that the stop switch
operates properly; that is the contacts are closed when the door is closed and open when the door is open. If the stop switch is good, disconnect the
flat ribbon cable that connects the key unit to the control unit and make sure the stop switch is closed (either close the door or short the stop switch
connector). Use the key unit matrix indicated on the control panel schematic and place a jumper wire between the pins that correspond to the STOP/
CLEAR pad making momentary contact.If the control unit responds by clearing with a beep the key unit is faulty and must be replaced. If the control
unit does not respond, it is faulty and must be replaced. If a specific pad does not respond, the above method may be used (after clearing the control
unit) to determine if the control unit or keypad is at fault.
operates properly; that is the contacts are closed when the door is closed and open when the door is open. If the stop switch is good, disconnect the
flat ribbon cable that connects the key unit to the control unit and make sure the stop switch is closed (either close the door or short the stop switch
connector). Use the key unit matrix indicated on the control panel schematic and place a jumper wire between the pins that correspond to the STOP/
CLEAR pad making momentary contact.If the control unit responds by clearing with a beep the key unit is faulty and must be replaced. If the control
unit does not respond, it is faulty and must be replaced. If a specific pad does not respond, the above method may be used (after clearing the control
unit) to determine if the control unit or keypad is at fault.
G8
G9
G10
G1
1
G12
G7
G6
G5
G4
G3
G2
G1
GRILL
ROAST
POULTRY
ROAST
PORK
WHOLE
POULTRY
CHICKEN
QUARTERS
(WEIGHT)
(TIME)
(WEIGHT)
(TIME)
ROAST
BEEF/LAMB
DUAL
GRILL
KITCHEN
TIMER
MEAT
JOINT
MICRO
POWER
CLOCK
SET
AUTO
COOK
START
AUTO MINUTE
STOP
CLEAR
10 sec.
10 min.
1 min.
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