N: Key Unit (Membrane Switch) Test - Sharp AX-1100 Service Manual

AX1100(R)
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 ribbon 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, discon-
nect the flat ribbon cable that connects the key unit to the control unit and make sure the door sensing switch is closed (either close the door or short
the door sensing 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 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.
9 – 5