PC Engine GT / Turbo Express Question

[MasterOfBiscuits]

Hi everyone, I'm new here.

Looking for help with my PC Engine GT. I'm in the process of modding it and have so far added a 3.5" screen, lithium battery, RGB output and a controller output. One issue I can't find any info for is the power saving function that turns the screen off when no inputs are detected. When using an external controller it bypasses this detection and the screen contrast (internal and external) is affected. You have to wake the machine up by touching the in-built controls to restore it.

Does anyone have info on how this feature works or how it ican be disabled? I was thinking of maybe running a single wire from one of the external controller lines to the internal control board so it always sees a signal?