R-98STMA (serv.man8). Test Procedures - Sharp Home Appliance Service Manual (repair manual). Page 5

R98STMAA

8 – 5

If the display fails to clear when the STOP/
CLEAR pad is depressed, first verify the flat
ribbon cable is marking 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 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 connecter). 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
marking 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 deter-
mine if the control unit or key pad is at fault.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 4 pin connector (E) on the control unit with an A.C. voltmeter. The meter
should indicate 230 - 240 volts, if not check oven circuit.

Relay Test

Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation, grill operation, convection operation or dual operation.

        DC. voltage indicated ................................... Defective relay.

        DC. voltage not indicated ............................. Check diode which is connected to the relay coil. If diode is good, control unit is defective.

CARRY OUT 4R CHECKS.

Problem: POWER ON, indicator does not light up.

CARRY OUT 3D CHECKS.

NOTE: *At the time of these repairs, make a visual inspection of the varistor

for burning damage and examine the transformer with tester for the
presence of layer short circuit (check primary coil resistance).

If any abnormal condition is detected, replace the control unit.

CARRY OUT 4R CHECKS.

RELAY SYMBOL

OPERATIONAL VOLTAGE

CONNECTED COMPONENTS

RY1

APPROX. 24.0V D.C.

Oven lamp / Turntable motor

RY2

APPROX. 18.0V D.C.

High voltage transformer

RY3

APPROX. 24.0V D.C.

Grill (Top) heating element

RY4

APPROX. 24.0V D.C.

Convection heating element

RY5

APPROX. 24.0V D.C.

Fan motor

RY6

APPROX. 24.0V D.C.

Touch control transformer

RY7

APPROX. 24.0V D.C.

Convection motor

RY8

APPROX. 24.0V D.C.

Damper motor

STEPS

OCCURRENCE

CAUSE OR CORRECTION

1

The rated AC voltage is not present between Pin No. 1 and 3 of 
the 4-pin connector (E).

Check supply voltage and oven power cord.

2

The rated AC voltage is present at primary side of low voltage 
transformer.

Low voltage transformer or secondary circuit defective.
Check and replace control unit.

3

Only pattern at “a” is broken.

*Insert jumper wire J1 and solder.

4

Pattern at “a” and “b” are broken.

Replace control unit. (CARRY OUT 3D CHECKS BEFORE REPAIR)

G8

G7

G6

G5

G1

G2

G3

G4

G9

G10

G12

G

11

MINCED

MEAT

10min.

1min.

10sec.

CHICKEN

PORTIONS

COMBI.

ROAST

PORK

AUTO

COOK

(TIME)

START

AUTO

MINUTE

(WEIGHT)

GRILL

KITCHEN

TIMER

STOP

CLEAR

䂦

ROAST

POULTRY

(TIME)

䂦

MICRO.

POWER

CONV.

(ºC)

(WEIGHT)

ROAST

BEEF/

LAMB

STEAK/

CHOPS

(J1)

(J2)

9

1

7

C

N-E

CN
-A

VRS1

a

c

d

b