The problem i was having was that the TV has energy saving settings that, when set to a specific mode, cause the TV to go into 'deep sleep' and RS232 cant wake it up.
Do you have the manual for the TV? If not try downloading it with this link [Link: tradenet.sharp.co.uk]
It appears, from the manual, that your menu may be slightly different. Hopefully you can navigate the confusion and find a menu with power settings that will allow you to solve the deep sleep problem.
Check page 14 for Power Management information. According to the manual it looks like the factory default may be to have the power saving settings OFF. And its quite possible that the manual is talking about something completely different and more confusing :). Poke around and see what you can come up with. Good Luck.
Adding... I didnt have to go into a secret service menu but anything is possible and your model may require you to do it. Im not aware of the steps to get into Sharps secret service menu (if it exists) though.