I have a lg 42 in flat screen. the sound works but no picture any ideas

Hello, if the model number is correct it's not a projection tv, but an LCD tv. If that's correct, it sounds like a bad main board issue part # is AGF31218501...thanks

NEW YSUS AND BUFFER BOARDS ARE NOW NEEDED THE YSUS IS THE BIG BOARD IN THERE VERY LEFT HAND SIDE ONCE BACK IS OFF BIG BOARD WITH 1 BIG HEATSINK,, THAT AND THE BUFFER BOARD PUSHES INTO THAT WITH TWO BLACK CONNECTION TO THE YSUS REMOVE BOTH BUFFER IS FIDDLEY,,NEED TO REMOVE 4 RIBBON CABLES ATTACHED TO THE SCREEN B4 HAND,,

6871QYH053B IS YSUS MODEL BUFFER U WILL ALSO FIND ON EBAY.

Thats the PIP (picture in picture), which lets you watch two pictures at once.  Push the PIP remote or go into the settings to turn the box off.

It could be the mainboard or the powerboard.

You need to check those boards in order to figure it out wich one need to be replaced

have a du42py10x and i have no pic or sound take the back of and only 2 littel ligh on bottom com on

Most likely what happened is one of the capacitors went bad. When a capacitors goes bad it produces a popping sound. This could be an easy and cheap fix if you find the bad capacitor or capacitors. The bad capacitor will have a bulging top most likely on the power board but could be anywhere.

no picture

You need the Y sustain and y drive boards. No idea where to purchase in australia, but you may be able to order them from LG.

ysus pcb that supplies voltage to the panel is faulty

sounds like it may be a software upgrade