On this one the top right pin is the GND, it goes to the VSS pin on the LCD module, right?
On that mjkdz module in the photo,
pin 1 (vss) of the hd44780 interface is the upper left and pin 16 (kathode) is on the upper right.
If you look closely you can see the trace from the pot wiper running over to pin 3 (Vo, contrast in)
over twards the upper left in your photo and you can see the trace from the 2TY transistor going
over to pin 15 (Anode) in the upper right.
This orientation means that when you solder the board to most hd44780 modules the side facing up
in your photo will be down. i.e. the pot will be up against the lcd module.
(See attached photo)
While that orientation is nice to have access to the address jumpers (A B C )
(which are on the back side of the board in the photo)
since they will be facing out, once soldered you will not be able to adjust the
I have a couple of these.
My recommendation if soldering these directly to the lcd,
is to either change out the pot for one with a thumb wheel,
or a side screw access or unsolder the pot and move it to the other
side of the board. That way when the board is soldered directly to the lcd,
you will still have the ability to adjust the pot.
Depending on your lcd, you may
also want/need to re-solder the i2c header to the other side of the pcb as well since in
its current location it can end up touching the lcd module making it difficult
to connect to the i2c connector/wires.
Alternatively, you could desolder the 16 pin header and flip it around. Then
the pcf8574, pot, and i2c header will be on top. The down side to that is that
you will not be able to get to the address solder jumpers to change the i2c address.