Samsung AM080 XV Series Service Manual page 139

Essential Requirements before PCB Changes in Case of Communication Error Occurrence
1. Find the communication IC near the communication terminal.
Indoor Unit
- Coil side or PTC (SMD) side : Communication IC between indoor and outdoor units.
Outdoor Unit
- When there is module communication as in PLUS II and PLUS III –
Above Red Connector of Main Unit : Communication IC between indoor and outdoor units.
- When there is no module communication as in PLUS II and PLUS III –
Above Yellow Connector of Each Unit : Communication IC between outdoor units.
- Other Outdoor Unit- Above Communication Connector : Communication IC between indoor and outdoor unit.
2. Measure the resistance of the communication IC.
Measurement Method : Measure the No.5 - No.6 Pin resistance
3. Defectiveness decision of the communication IC which uses a measurement resistance value.
Judging as Normal
- Each resistance value should be measured in tens of kΩ~to hundreds of kΩ.
- Difference between the two resistance values should be of some number of kΩ.
Judging as defective
- One or both are low with tens of Ω
- One or both of them is open
Samsung Electronics
Indoor Unit
Measure the No.5 - No.7 Pin resistance
Indoor Unit communication
Transmitter communication
Outdoor unit
communication between
Outdoor Unit
Troubleshooting
No.5
No.7
No.6
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