LG LSC27990ST, Training Manual

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Circuit Descriptions
CirCUiT DesCripTions
Stepping motor operation circuit
The motor is driven by magnetism formed in the areas of the coils and the stator.
Rotation begins when a HIGH signal is applied to MICOM Pin 33 of IC10 (TA7774F).
This causes an output of HIGH and LOW signals on MICOM pins 34 and 35.
Explanation:
The stepping motor is driven by sending signals of 3.33 mSEC via MICOM pins 33, 34, and 35, as shown
in the chart below. These signals are output via termin als 10, 11, 14, and 15 via input terminals 3, 6, and
8 of IC10 (TA7774F), the motor drive chip. The output signals allow the coils wound on each phase of the
stator to form a magnetic field, which causes rotation. Input to the terminals INA and INB of IC10 as
shown in the chart below drives the motor.
Fan motor drive circuit
1. The circuit cuts all power to the fan drive IC, resulting in a standby mode.
2. This circuit changes the speed of the fan motor by varying the DC voltage between 7.5 Vdc and 16 Vdc.
3. This circuit stops the fan motor by cutting off power to the fan when it senses a lock-up condition.
1-10. Stepping motor operation circuit
(1) GR-G277STSA(LSC27990TT)
The motor is driven by magnetism formed in the areas of the coils and the stator. Rotation begins when a HIGH signal is
applied to MICOM Pin 33 of IC10 (TA7774F). This causes an output of HIGH and LOW signals on MICOM pins 34 and 35.
Explanation) The stepping motor is driven by sending signals of 3.33 mSEC via MICOM pins 33, 34, and 35, as shown in
the chart below. These signals are output via terminals 10, 11, 14, and 15 via input terminals 3, 6, and 8 of
IC10 (TA7774F), the motor drive chip. The output signals allow the coils wound on each phase of the stator to
form a magnetic field, which causes rotation. Input to the terminals INA and INB of IC10 as shown in the chart
below drives the motor.
EXPLANATION FOR MICOM CIRCUIT
- 29 -
INA
INB
A
B
A
B
CCW (Reverse rotation) (Positive rotation) CW
Stepping motor operation circuit
The motor is driven by magnetism formed in the areas of the coils and the stator.
Rotation begins when a HIGH signal is applied to MICOM Pin 33 of IC10 (TA7774F).
This causes an output of HIGH and LOW signals on MICOM pins 34 and 35.
Explanation:
The stepping motor is driven by sending signals of 3.33 mSEC via MICOM pins 33, 34, and 35, as shown
in the chart below. These signals are output via termin als 10, 11, 14, and 15 via input terminals 3, 6, and
8 of IC10 (TA7774F), the motor drive chip. The output signals allow the coils wound on each phase of the
stator to form a magnetic field, which causes rotation. Input to the terminals INA and INB of IC10 as
shown in the chart below drives the motor.
Fan motor drive circuit
1. The circuit cuts all power to the fan drive IC, resulting in a standby mode.
2. This circuit changes the speed of the fan motor by varying the DC voltage between 7.5 Vdc and 16 Vdc.
3. This circuit stops the fan motor by cutting off power to the fan when it senses a lock-up condition.
1-11. Fan motor driving circuit (freezer, mechanical area)
1. The circuit cuts all power to the fan drive IC, resulting in a standby mode.
2. This circuit changes the speed of the fan motor by varying the DC voltage between 7.5 Vdc and 16 Vdc.
3. This circuit stops the fan motor by cutting off power to the fan when it senses a lock-up condition.
(1) GR-G277STSA(LSC27990TT)
EXPLANATION FOR MICOM CIRCUIT
- 30 -
a , d part b part e part
Motor OFF 5V 2V or less 2V or less
Motor ON 2 ~ 3V 12 ~ 14V 8 ~ 16V
b
a
d
e
1-11. Fan motor driving circuit (freezer, mechanical area)
1. The circuit cuts all power to the fan drive IC, resulting in a standby mode.
2. This circuit changes the speed of the fan motor by varying the DC voltage between 7.5 Vdc and 16 Vdc.
3. This circuit stops the fan motor by cutting off power to the fan when it senses a lock-up condition.
(1) GR-G277STSA(LSC27990TT)
EXPLANATION FOR MICOM CIRCUIT
- 30 -
a , d part b part e part
Motor OFF 5V 2V or less 2V or less
Motor ON 2 ~ 3V 12 ~ 14V 8 ~ 16V
b
a
d
e