Menta, 4.95V is good. Whats the current rating on the transformer? I can see maybe over an amp of current straight off without studying the schematic for longer than a few minutes. Perhaps there is just not enough current to power the LCD? Failing that, what is the current rating for your 7805? Depending on the package they're good for between 250mA and about 500mA. Try putting 2 in parallel (If the tranny has an output of greater than 1500mA)