LG SXS GR-P257/L257 - Manual (Page 40)

1-13. Communication circuit and connection L/Wire between main PCB and display PCB
The following communication circuit is used for exchanging information between the main MICOM of the Main PCB and the
dedicated MICOM of the LED (LCD) Display PCB.
A bi-directional lead wire assembly between the two boards is required for the display to function properly.
Poor communication occurs if a continuous information exchange fail to continue for more than 2 minutes between main
MICOM of main PCB and LCD (LED) dedicated MICOM for LCD (LED) control of display PCB.
(1) GR-P227/L227/P257/L257
EXPLATION FOR MICOM CIRCUIT
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Main MICOM LCD(LED) dedicated MICOM
DC 12V
GND
Transmission (error status)
Reception (notch status)
Main PCB L/Wire FD/H(4-wires) Display PCB