Read Sharp AX-1100(R)M / AX-1100(SL)M (serv.man8) Service Manual online
AX1100(R)M
9 – 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
insulation tester. The insulation resistance should be more than 10M 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.
[13] M: CONTROL UNIT TEST
The control unit consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper mainte-
nance can not be performed with only a voltmeter and ohmmeter.
nance can not be performed with only a voltmeter and ohmmeter.
In this service manual, the control panel assembly is divided into two units, Control Unit and Key Unit, and troubleshooting by 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.
1) When touching the pads, a certain pad produces no signal at all.
2) When touching a number pad, two figures or more are displayed.
3) 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 N) to determine if con-
trol unit is faulty.
trol unit is faulty.
2.1. In connection with pads
1) When touching the pads, a certain group of pads do not produce a signal.
2) When touching the pads, no pads produce a signal.
2.2. In connection with indicators
1) At a certain digit, all or some segments do not light up.
2) At a certain digit, brightness is low.
3) Only one indicator does not light up.
4) The corresponding segments of all digits do not light up; or they continue to light up.
5) Wrong figure appears.
6) A certain group of indicators do not light up.
7) The figure of all digits flicker.
2.3. Other possible troubles caused by defective control unit.
1) Buzzer does not sound or continues to sound.
2) Clock does not operate properly.
3) Cooking is not possible.
4) Proper temperature measurement is not obtained.
[14] N: KEY UNIT (MEMBRANE SWITCH) TEST
If the display fails to clear when the STOP key is depressed, first verify the rib-
bon cable is making good contact, verify that the door sensing 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 is good, disconnect the flat ribbon
cable that connects the key unit to the control unit and make sure the door sens-
ing switch is closed (either close the door or short the door sensing switch con-
nector). Use the Key unit matrix indicated on the control panel schematic and
place a jumper wire between the pins that correspond to the STOP key 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 a
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 key pad is at fault.
bon cable is making good contact, verify that the door sensing 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 is good, disconnect the flat ribbon
cable that connects the key unit to the control unit and make sure the door sens-
ing switch is closed (either close the door or short the door sensing switch con-
nector). Use the Key unit matrix indicated on the control panel schematic and
place a jumper wire between the pins that correspond to the STOP key 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 a
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 key pad is at fault.
CARRY OUT 4R CHECKS.
