Touch Control Panel - Sharp R-209HW Service Manual

PROCEDURE
LETTER
6) After that procedure, re-connect the power supply cord.
7) Follow the troubleshooting guide given below for repair
STEPS
8) Disconnect the power supply cord and then remove outer case.
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
The touch control section consists of the following units as
shown in the touch control panel circuit.
(1) Key Unit
(2) Control Unit
The principal functions of these units and their related signals
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 R00, R01, R02, R03, R20
and R21.
When a key pad is touched, a signal is completed through the
key unit and passed back to the LSI through R23, K00, K01 and
K02 to perform the function that was requested.
Control Unit
Control unit consists of LSI, reset circuit, indicator circuit, power
source circuit, relay circuit, buzzer circuit and synchronizing
signal 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 4-digits, 12-segments and 3-common
electrodes using a Liquid Crystal Display.
TEST PROCEDURES
OCCURRENCE
The rated AC voltage is not present between
1 Pin No. 3 of the 2-pin connector (A) and the
normal open terminal of the relay RY2.
The rated AC voltage is present at primary
2
side of low voltage transformer.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
COMPONENT TEST
.
CAUSE OR CORRECTION
Check supply voltage and oven power cord.
Low voltage transformer or secondary circuit defective.
Check and replace control unit.
3) Power Source Circuit
This circuit generates voltage necessary in the control 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
VSS
4) Relay 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) Door Sensing Switch
A switch to "tell" the LSI if the door is open or closed.
17
Application
-5V LSI(IC1)
R-209HK
R-209HW