LCD is Dim

[screwball]

Hello,
I have a 16x2 Midas LCD which is VATN, the problem I have is that the display is very dim (camera actually pics the display up better than my eyes). The LCD is new and I have had it working perfectly on a different LCD (not VATN).

The part is MC21605G12W-VNMLW

The VO pin is fed by a 10k pot from vdd and vss with wiper going to VO. The potentiometer is at its max (the best constrast I could get).
The kathode of backlight is connected to ground, anode is not connected as I think it is connected internally on the lcd board, I have measured 3.5v between the anode and cathode which is about right for white led. If I do connect the wire for anode to vdd, the display will show blank boxes across the screen (I guess its sequence fault display or something)

Any idea what could be wrong?

 

[pgib8]

Check the voltage on VO as you turn the pot. It should be adjustable just about from Vdd to Vee. Make sure Vee is in fact a negative voltage compared to GND/Vss. Take out the pot. and connect VO directly to Vdd, then disconnect from Vdd and connect to Vee, and see how that interacts.
The LEDs look bright, I definitely think it's a contrast issue, so that's where I would focus. If all fails get another LCD to try in case there is a defect.

 

[screwball]

Check the voltage on VO as you turn the pot. It should be adjustable just about from Vdd to Vee. Make sure Vee is in fact a negative voltage compared to GND/Vss. Take out the pot. and connect VO directly to Vdd, then disconnect from Vdd and connect to Vee, and see how that interacts.
The LEDs look bright, I definitely think it's a contrast issue, so that's where I would focus. If all fails get another LCD to try in case there is a defect.

One gold star for you, I totally missed the fact the pot must receive a negative for VO when reading the datasheet, I'm so used to people referring to vss as vee I thought nothing of it.

Works fine now, black background isn't as good as I think the manufacturers make out but OLED wouldn't have been suitable so good enough.

*Note for others using same LCD,
Pin 15 of LCD is supposed to connect to pot, along with vdd and VO to the wiper.