Sharp R-450H, Service Manual

R-450H

13

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

STEPS

OCCURRENCE

CAUSE OR CORRECTION

1

The rated AC voltage is not present between

Check supply voltage and oven power cord.

Pin No. 1 of the 2-pin connector (A) and the
common terminal of the relay RY1.

2

The rated AC voltage is present to primary

Low voltage transformer or secondary circuit defective.

side of low voltage transformer.

Check and repair.

3

Only pattern at "a" is broken.

*Insert jumper wire J1 and solder.

4

Pattern at "a" and "b" are broken.

*Insert the coil RCILF2003YAZZ between "c" and "d".

NOTE: *At the time of making these repairs,

make a visual inspection of the varistor.
Check for burned  damage and exam-
ine the transformer with a tester for the
presence of layer short-circuit (check
the primary coil resistance). If any ab-
normal condition is detected, replace
the defective parts.

CARRY OUT 4R CHECKS.

T1

AC

VRS1

QKITPB026MRE0

OMIF

DU

CN - A  

(J1) 

a

b

c

d

12

XA

VH

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units.

(1) Key Unit
(2) Control Unit (The Control Unit consists of Power

Unit and LSI Unit).

The principal functions of these units and the signals
communicated among them are explained below.

Key Unit

The key unit is composed of a matrix, signals generated
in the LSI are sent to the key unit through P00-P07.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P14-P17,
AIN6 and AIN7 to perform the function that was re-
quested.

Control Unit

Control unit consists of LSI, reset circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchro-
nizing signal circuit and back light circuit.

1) Reset Circuit

This circuit generates a signal which resets the LSI to
the initial state when power is supplied.

2) Indicator Circuit

This circuit consists of 40 segments and 16 common
electrodes using a Liquid Crystal Display.

3) Power Source Circuit

This circuit generates voltages necessary in the con-

trol unit from the AC line voltage.
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.

Symbol

Voltage

Application

VC

-5V

LSI(IC1)

4) Relay Circuit

A circuit to drive the magnetron, fan motor, turntable
motor and  light the oven lamp.

5) Buzzer Circuit

The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).

6) Synchronizing Signal Circuit

The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
It accompanies a very small error because it works on
commercial frequency.

7)  2nd. Interlock Relay Control Switch

A switch to “tell” the LSI if the door is open or closed.

8) Back Light Circuit

A circuit to drive the back light (Light emitting diodes
LD10-LD15).