Key Unit Test - Sharp R-409JS Supplemental Service Manual

R - 4 0 9 J S
PROCEDURE
LETTER
J

KEY UNIT TEST

1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check the
circuit between the pins of the key unit that correspond to the STOP/CLEAR pad. When the pad is
pressed, the ohmmeter should indicate short circuit. When the pad is released, the ohmmeter should
indicate open circuit. If incorrect readings are obtained, the key unit is faulty and must be replaced.
About the other pads, the above method may be used.
5. Reconnect all leads removed from components during testing.
6. Re-install the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
TEST PROCEDURES
G8 G7 G6 G5
5
0
MINUTE PLUS
STOP
COOK
CLEAR
DEFROST POPCORN
Pin
NO. G1
COMPONENT TEST
G4 G3 G2
4 3 2
9
8 7
POWER
START
LEVEL
TIMER
CLOCK
REHEAT
Pin
NO. G13
Key unit ribbon cable
Key unit (Membrane Switch) front view
6
G1
1
6