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I'm even more puzzled now.

If there are two PCBs, what is on each board, show us the construction or at least add a dividing line on the schematic.

To my mind, the voltage divider looks wrong, as shown and with no load connected, the output voltage will adjust between 0V and 8.182V. Any load current will drop the output voltage. If a 100K potentiometer is wired in the ground pin of the 7809, and that isn't what is shown, the output will vary between 9V and something higher but most of the adjustment will be at the end of the potentiometer rotation. Even then the output will drop under load because of R1.

What exactly are you trying to achieve?

Brian.