Sharp R-8320E, Service Manual

Page: 49 / 140

RELAY UNIT
The relay unit is composed of transformer, buzzer, relays,
printed wiring board, etc.
This unit generates voltage necessary in the control unit
from the A.C. line voltage.
The cook, heater relays and shut-off relays of the printed
Operational circuit is as follows:
1. When the
volts A.C. is supplied, the signal of
D5 terminal (LSI: l-l) goes to “H” level (usually at “L”
level).
The terminal (D-6) on the relay unit become F-3 (OUT)
voltage through the driver IC (IR-2403) and shut-off
relay (RY4) is energized.
The damper motor is energized through the shut-off
relay (RY4) contacts.
Note; If the damper is at the open position (damper
switch is ON), the signal of terminal D5 goes
“L” level and the damper motor is de-energized.
2. During microwave cooking, the signal of terminal
D2 and on LSI (l-l) goes to “H” level and shut-off
relays (RY2 and RY3) are energized.
The components which are connected to the relay
contacts are energized. Also, the cook relay is energized.
During convection cooking, the signal of terminal DO,
D2, D3 and D4 on LSI (l-l) goes to
level and shut-
off relays RY2 and RY3) are energized. The
components which are connected to the relay contacts
are energized.
Also, the heater relay is energized.
Relationship between pin Nos. and Connections
CONNECTOR” CONNECTOR
Pin No.
Pin No.
C-l
IN
Input the A.C. Line voltage:
c-2
IN 1. These terminals are connected to the transformer.
2. The transformer coverts A.C. to 17.4 volts A.C. output
on the secondary winding.
3. The secondary A.C. voltage is rectifier to a smoothing circuit.
4. Control panel is operated on the D.C. voltage that is supplied.
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D-2
D-4
OUT This voltage supply to the DC-DC converter circuit into the control unit.
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OUT
Signal with commercial power source frequency
Signal of commercial frequency is supplied to the circuit in the control
unit.
D-5
This signal will be changed in the circuit to the square wave that is the
basic timing for all of time processing.
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IN
Signal to sound buzzer
Signal coming from D2 terminal of LSI (l-2).
Key touch sound:
Approx. 0.1 sec.
Approx. 2.5 approx. 0.1 sec.
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- 1 5 v
Completion Sound:
(Cook or time)
Approx. 2.5 approx. 2 sec.
Approx. 2sec.
Completion Sound:
(Reached the preheating temp.)
Approx. 2.5 approx. 1 sec.
ON, 1 sec. OFF four times.
Approx. lsec. Approx. 1 sec.
GND
- l s v
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