LG THERMA V AHBW076A0, Service Manual, Page: 60 / 98

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Check Point
1. Unplug the sensor on PCB(Heater).
2. Estimate the resistance of each sensor.
3. If the resistance of the sensor is 5 KΩ at 25°C, then sensor is normal.
4. If the resistance of the sensor is 0 KΩ or ∞, then sensor is abnormal.
’
Change the sensor.
5. Plug the sensor on PCB(Heater) and Power ON.
6. Estimate the voltage of each sensor.
7. If the voltage of the sensor is 2.5Vdc at 25°C, then sensor is normal.
8. If the resistance of the sensor is 0 or 5Vdc, then sensor is abnormal.
’
Repair or Change the PCB.
5k
Unplugged Plugged
Check the resistance Check the voltage
V
2.5Vdc
Unplug the sensor
on PCB(Heater)
Estimate the Voltage
of each sensor.
Is the voltage of
the sensor 2.5Vdc
at 25˚C
Repair or Change the PCB.
Check the
Connector connection
Is it normal ?
Estimate the resistance
of each sensor.
Plug the sensor
on PCB(Heater)
Is the resistance of
the sensor
5k at 25˚C?
Yes
Yes
No
Correct connection
Yes
No
Correct connection
No
Correct connection
Check Flow Chart
Display
code
Title Cause of error Check point & Normal condition
08
Problem in
Water Tank
sensor
• Connector connection error
• Faulty PCB(Heater)
• Faulty sensor (Open / Short) Normal resistor : 5KΩ/ at 25˚C(Unplugged)
Normal voltage : 2.5Vdc / at 25˚C(Plugged)
Refer to sensor resistance table.
13
Problem in
Solar-thermal
sensor
• Connector connection error
• Faulty PCB(Heater)
• Faulty sensor (Open / Short) Normal resistor : 5KΩ/ at 25˚C(Unplugged)
Normal voltage : 2.5Vdc / at 25˚C(Plugged)
Refer to sensor resistance table.