Pin 18 is for providing power,if there is one bigger electrical wire, it should connect to this Position
Take HDMI AM-AM as example 1-12 is for data and time channels,2/5/8/11 four pins is for earth wire 14/19/17 is for independent ethernet channel,17pin is for earth wire Normally, the earth wire use PE insulation If one group of signal wire has problems, we can connect them to the 14/17/19 Pin, in order to guarantee the image data. but if more than one group signal wire has problems, there would be nothing we can do about it.
Some mistake operation would cause high impedance,which would affect the wire signals also the iterference signal of EM: