AKAI PT4298HD no pic and no sound

Most likely, this is a problem with the convergence board. The convergence amps (STK392-040 x 2)are internally shorted. These can be replaced of the whole convergence board can be replaced. It's cheaper to replace the amps, but more convienent to replace the board (especially for the less electronically inclined!! :) Also, this could be from a leaking CRT. In CRT projection televisions, the red, green, and blue tube are filled with coolent (glycol). These 42" models are very bad about the tubes leaking (Akai and Samsung models)and are infamous for destroying the CRT driver board connected to the bottom of each tube. When this happens, the protection circuit kicks in and will not let the television start up. *PLEASE, FOR YOUR OWN SAKE, DO NOT FOLLOW THESE NEXT STEPS IF YOU HAVE NO UNDERSTANDING OF ELECTRONIC EQUIPMENT!!!! There are four screws and three snap clips that hold the bottom on. UNPLUG THE TELEVISION, remove the screws and pull bottom outward to remove. The bottoms of the three tubes should be visible. DON'T TOUCH THEM!! Now look under each tube. If one is leaking, there will be a wet spot (or sometimes a puddle!) underneath the tube. This will have to be serviced by a TV tech. Hope this helps...