Handheld Game LCD runs on AC voltage?

A $1,000,000 life insurance policy made out to "Luhan Monat"

200 lines? Are you talking about the signal lines. If so then they do need to be AC. Not really sine-wave AC, square waves will do. The signals need to change polarity constantly when the pixel is "on", turning them on-off is not good enough, you really need + and - voltages.

That is just how LCDs work. This is to prevent the liquid crystal from "breaking down" and being forever turned "on". If you "pull" the crystals in just one direction then sooner or later they will permanently "stick" to that direction. Oh, sure they will sort-of work on pure DC, for all of 5 minutes (approximately, the only one I've tested lasted 2 minutes). After which they will be either forever black or forever white and nothing you do will make them display anything else.

There is a very solid reason for that AC feed,if you try to feed DC to those LCDs, they will desintegrate(silently). The ac is to keep chemical reactions to zero. When the two AC signals are at phase 0, there is no exitation voltage at the cell, and with 180 degrees, full exitation.

I'm actually removing the LCD and running the signals to a completely different circuit. I want to switch those signals to DC. So should the diodes work? Is there general frequency for the AC signal, or does it vary per display?

and by the way, i have no oscilloscope or good instruments where i am at the moment unfortunately... that's way i'm so needy for info on this. thanks.