Originally Posted by geekmaster
The pins in the bottom connector are (from the bottom):
Power Enable (when shorted to GND, turns on power to top connector for LED book light)
I gimp'd that photo a bit so we could "see through" the masking:
Click for: j14 masked, full image
From this transformed photo, I expect that tomorrow I will find that the outside and inside rows of pads are indeed connect together one-to-one.
TP-77 For testing that control signal
The Rx pin is clearly connected to that chip and what is most likely a pull-up resistor above.
The Tx pin may also be connected to that chip, and is connected to what is most likely a pull-up resistor above.
Had a re-think of the above. If the SoC and this mystery chip are sharing the serial lines, those two resistors are in series with the serial line from the SoC to provide a bit of isolation between the two devices.
Those two little SMD thingies in the top left of the photo would be the pull-up resistors.
(Although SMD caps, diodes, inductors, etc. all look pretty much alike to the eye.)
That control lead on the pad and TP-77 might
also be connected to that chip. It wouldn't need to be routed under the chip to reach a via, it already has a via on its path.
Which poses an interesting question of what the chip is and what it is doing on the console operator's serial port. ? ? ?
Is nothing sacred any longer?
The operator's console is wire-tapped?
As my eyes have aged to almost useless condition, digital photography has more than compensated for that loss. 1,500 pixels per inch make looking at this stuff easy.