Info Center
Refrigerator Info Center Training
24
Circuit Descriptions
CirCUiT DesCripTions
Oscillation circuit
Figure 1
The oscillation circuit generates a basic clock signal for synchronization and time calculation related to the
transmission of data and calculations made by the MICOM (IC1). The oscillator (OSC1) must always be
replaced with an exact replacement part. If this specification is changed, the change will affect the time
calculations of the MICOM and it might not work at all.
Fig 1
Fig 2
Reset circuit
Figure 2
The RESET circuit allows various parts of the MICOM, such as RAM, defrosting, etc., to be restarted from
the initial state when power is interrupted or restored. A LOW signal applied to the reset terminal for 10
ms causes the MICOM to reset itself. During normal operation, the voltage at the reset terminal is 5 Vdc.
If the reset fails, the MICOM will not operate.
LOAD DRIVING CIRCUIT
•The fan operates at the regular speed even if the door
of the refrigerator or freezer is opened. When the
doors are closed, the fan reverts to its original speed.
•(A), (B), (C), and (D) of door switch for the freezer or refrigerator are connected to the door open sensing
circuit in parallel toward both ends of switch to determine door open at MICOM.
•In the TEST mode, the fan will stop if any door is ope
ned. It will resume operation when the door is closed.
Oscillation circuit
Figure 1
The oscillation circuit generates a basic clock signal for synchronization and time calculation related to the
transmission of data and calculations made by the MICOM (IC1). The oscillator (OSC1) must always be
replaced with an exact replacement part. If this specification is changed, the change will affect the time
calculations of the MICOM and it might not work at all.
Fig 1
Fig 2
Reset circuit
Figure 2
The RESET circuit allows various parts of the MICOM, such as RAM, defrosting, etc., to be restarted from
the initial state when power is interrupted or restored. A LOW signal applied to the reset terminal for 10
ms causes the MICOM to reset itself. During normal operation, the voltage at the reset terminal is 5 Vdc.
If the reset fails, the MICOM will not operate.
LOAD DRIVING CIRCUIT
•The fan operates at the regular speed even if the door
of the refrigerator or freezer is opened. When the
doors are closed, the fan reverts to its original speed.
•(A), (B), (C), and (D) of door switch for the freezer or refrigerator are connected to the door open sensing
circuit in parallel toward both ends of switch to determine door open at MICOM.
•In the TEST mode, the fan will stop if any door is ope
ned. It will resume operation when the door is closed.
1-2. Oscillation circuit
The oscillation circuit generates a basic clock signal for synchronization and time calculation related to the transmission of
data and calculations made by the MICOM (IC1). The oscillator (OSC1) must always be replaced with an exact replacement
part. If this specification is changed, the change will affect the time calculations of the MICOM and it might not work at all.
(1) GR-G277STSA(LSC27990TT)
1-3. Reset circuit
The RESET circuit allows various parts of the MICOM, such as RAM, defrosting, etc., to be restarted from the initial state
when power is interrupted or restored. A LOW signal applied to the reset terminal for 10 ms causes the MICOM to reset
itself. During normal operation, the voltage at the reset terminal is 5 Vdc. If the reset fails, the MICOM will not operate.
(1) GR-G277STSA(LSC27990TT)
EXPLANATION FOR MICOM CIRCUIT
- 23 -
1-2. Oscillation circuit
The oscillation circuit generates a basic clock signal for synchronization and time calculation related to the transmission of
data and calculations made by the MICOM (IC1). The oscillator (OSC1) must always be replaced with an exact replacement
part. If this specification is changed, the change will affect the time calculations of the MICOM and it might not work at all.
(1) GR-G277STSA(LSC27990TT)
1-3. Reset circuit
The RESET circuit allows various parts of the MICOM, such as RAM, defrosting, etc., to be restarted from the initial state
when power is interrupted or restored. A LOW signal applied to the reset terminal for 10 ms causes the MICOM to reset
itself. During normal operation, the voltage at the reset terminal is 5 Vdc. If the reset fails, the MICOM will not operate.
(1) GR-G277STSA(LSC27990TT)
EXPLANATION FOR MICOM CIRCUIT
- 23 -
1-4. Load/dispenser operation, door opening circuit
1. LOAD DRIVING CIRCUIT
�
The fan operates at the regular speed even if the door of the refrigerator or freezer is opened. When the doors are closed,
the fan reverts to its original speed.
�
(A), (B), (C), and (D) of door switch for the freezer or refrigerator are connected to the door open sensing circuit in parallel
toward both ends of switch to determine door open at MICOM.
�
In the TEST mode, the fan will stop if any door is opened. It will resume operation when the door is closed.
(1) GR-G277STSA(LSC27990TT)
EXPLANATION FOR MICOM CIRCUIT
- 24 -
Measuring part (IC6)
IC6-16
IC6-13
IC6-12
IC6-15
IC6-14
Status
ON
Within 1 V
OFF
12 V
Type of Load
Compressor
Defrost
Heater
AC Converting
Relay
Refrigerator
LAMP
Dispenser
Heater
Summary of Contents for LSC27990ST
Page 1: ...LG TRAINING MANUAL LSC27990ST Refrigerator Info Center Fall 2007 LG TRAINING MANUAL ...
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