Quite a few years ago I came across a 2X16 LCD where pin1=Vdd & pin2=Vss, when generally they are always pin1=Vss & pin2=Vdd.
It was only one supply of LCD's that was consistantly the same & I avoided using it.
Recently, I came across a recovered LCD which had exactly the right size to be able to fit into a faulty piece of equipment that has a faulty display (Icom IC-R7000).
So I made up the right lead, hooked it up to the MPU on which I have the retrofit code running ....nothing... but a warm Hitachi chip & a hot regulator. I thought I had stuffed up my cable, but alas, checking it with a multimeter it has pin1 & pin2 transposed. Bugger! I will make up another lead with just pin 1 & 2 transposed and hope that it still works!
In retrospect I should have checked! :oops:
A tip to consider when using LCD's without a data sheet.
I was lucky. After transposing wire 1 & 2 only on a 2X7 IDC connector, the LCD sprung into life. :)