R-61FBSTM - Sharp Home Appliance Service Manual (repair manual). Page 14

R-61FBSTM/R-62FBSTM - 14

If the display fails to clear when the STOP key is depressed, first verify the lead wire harness is
marking 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
lead wire harness that connects the switch unit to the control unit and make sure the stop switch
is closed (either close the door or short the stop switch connecter). Use the switch unit matrix
indicated on the switch unit circuit 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
switch 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 key does not respond, the above method may be used (after clearing the
control unit) to determine if the control unit or switch unit is at fault.

Remove the outer case and check voltage between Pin No. 1 and Pin No. 3 of the 3 pin connector (A)
on the control unit with an A.C. voltmeter.
The meter should indicate rated voltage, if not check oven circuit.

RY1, RY2, RY3 and RY4 Relay Test
These relays are operated by D.C. voltage.
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation, dual or
grill cooking 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.

RELAY SYMBOL

OPERATIONAL VOLTAGE

CONNECTED COMPONENTS

RY1

Approx. 12.0V D.C.

Oven lamp / Turntable motor

RY2

Approx. 12.0V D.C.

Heating element

RY3

Approx. 12.0V D.C.

High voltage transformer

RY4

Approx. 12.0V D.C.

Fan motor

CARRY OUT 4R CHECKS.

(J1

1)

(J10)

13

12

10

11

SW2

ENCODER

A

B

C

RSW1

6

7

8

+1MIN

SW4

(J13)

(J12)

(J15)

(J14)

(J17)

(J16)

STOP

1.

2.

SW3

9

2

5

4

3

1

Switch unit

14

AUTOMATIC

SW1

4.7KF

24KF

3.

+

CARRY OUT 3D CHECKS.

Before carrying out the following tests make sure the heating element is cooled completely.
1. Resistance of heating element.

Disconnect the wire leads to the heating element to be tested.  Using ohmmeter with low resistance
range. Check the resistance across the terminals of the heating element as described in the
following table.

Table: Resistance of heating element

Parts name

Resistance

Grill heating element (top)

Approximately 76 

Ω

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

Ω

 insulation tester.  The insulation

resistance should be more than 10 M

Ω

 in the cold element.

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.