O.k then , while waiting for your reply I did pull out the service manual on this tv and as I suspected , there is no info whatsoever on the power board or what kind of voltages should be coming out of it.
This usually means the power board is made by another company and perhaps sharp doesn`t even have the right to publish info on it.
In any case , pretty much all the service manual you get now are mainly block diagrams and board numbers , no info on how to repair them but how to replace them.
So we`ll do like we usually do in a shop and go by the indications written on that board.
There is a connector labeled as PD on the secondary side of the board and it has 24 pins , 12 of them are accessible from the back of the connector and the rest from underneath the board where they are soldered.
You will see the number 1 written at the first visible pin on the left of that connector .
The pins visible would count like this ; 1 , 3 , 5 ,7 and so on .
What I would need you to do is to measure the voltage on pin 15 , that would be the 5th one from the right .
With the power cord plugged in , tell me what you get there .