Matt, Pins 11 and 12 should show closer to 5 volts. You might check those pins all the way back to pins 2 and 3 respectively of the microcontroller IC2. Especially check the soldering of the pins on the male half of the 2X5 connector that connects the display to the main board. Also, on mine when I set the pot to 50% there is no displayed data. For reference, you may need to adjust the pot counterclockwise almost to the stop to get normal display and contrast ... Ron
While building my QCX mini, I damaged my R47 variable resistor while trying to remove it, because I forgot to cut off the feet before soldering it in. I finished the rest of the build a few days ago, and discovered when I powered it on that the display contrast was set well enough that I could use it before the potentiometer came in.
However, while I was unplugging a paddle, the screen suddenly went blank and hasn't displayed anything since, even after installing the replacement potentiometer today. I suppose it's possible I shorted something with my finger? I have an enclosure on the way to prevent further incidents, if so. After reading through the manual, I decided to take a reading on the pins of the display module, and they don't match very well with the expected values. With R47 turned 50%, the voltages I read on pins 1-16, respectively, were: 0, 4.7, 1.5, 0.1, 0, 0, 4.7, 4.7, 4.7, 4.7, 2.6, 1.8, 4.7, 4.7, 4.4, 0. I'm not sure if that's useful information or enough to help you debug it, but I'm happy to provide further detail or information you might need to help me get this fully working.
While the screen was working, I was able to get it set up and tuned, and listened in on a few frequencies and it seemed to be working fine.
TU es 73 de W5JIA
Ronald Taylor