Communication Pcb - LG MULTI V 5 Manual Book

16.2 Failure Cause
1. High voltage (T-N more than 484V, N phase wiring fault) → CH50
2. Rainwater inflow by Control box / Front Panel / Service port open, Control box screw loosening
3. Part short by foreign substance
4. Defective Fan motor / PCB / Diode / Resistance / Capacitor / Regulator
16.3 Precautions of Replacement
1. Be sure to use the main PCB suitable for the model (Check P/No)
2. Be sure to turn off the power and wear insulated gloves before touching the PCB.
3. Use box or bag only for PCB.
4. Be sure to apply thermal grease.
5. When IGBT screw is fastened, it should be fastened two times.
6. If on-boarding is required after replacement, check the program and
EEPROM C/Sum (especially when using an alternate Main PCB)
16.4 Check Point after Replacement
1. Check whether there is any abnormality when the cycle is stabilized at cooling or heating mode.
2. Check current Hz control according to target Hz
3. Over current error check (CH29)
4. Check that fan 1 and 2 are properly connected.
5. Check that the target high / low pressure is reached.
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17. Communication PCB

17.1 Failure Judge Method
1. Error code check
Error Code
- · Checking restart after power reset
· Even after checking 220V connection condition for main SMPS
CH05, CH53
power supply
· Indoor/Outdoor communication PCB connection harness(24pin), Main
CH76, CH107
- External PCB communication harness(10pin) connection condition
CH05, CH53, CH104, · Even after checking the connection condition of indoor and outdoor
CH237, CH238 communication lines (shield wire, unshield wire)
2. Communication PCB check
Connector
(CN-Write)
Connector
(485 Comm. PCB <-> Main PCB)
MICOM
LED
LED
17.2 Failure Causes
1. Part short (by foreign substance, moisture)
2. Resistance / Capacitor / Micom / Comm. IC defect
3. Connector & Housing Pin wrong connection
4. PCB Fault
Error diagnosis
Y-Cap
BEAD
통신 IC
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