LCD screen on Roland keyboard lights up everything

[dgsmith]

Hi, I am currently in the process of fixing our damaged Roland E-09 keyboards (we had to wait a few months for the parts to arrive from Japan, but finally they came). One issue in particular is that the central LCD screen lights up all elements (i.e. a signal is received on each and every pixel) which therefore means no actual data can be determined from it.

 

I have checked all the connections and they seem fine, and even when I test with a replacement screen we bought from Roland Japan, the same thing happens so I know the issue isn't with the screen. It would be easier if it didn't work at all as then I would assume it is faulty, but the actual LCD displays correctly for a fraction of a second after turning on before going in to this "activate all the screen" mode. Without wanting to dig too deep in looking at individual electronics on the board, is there a simple explanation for this (even considering on a general level for LCD screens)?