42" Polaroid tv lost picture
Hello. I have 42" polaroid tlx 04244 b lcd tv. It has two power inverter boards. Master board is on the left and the slave is one on the right side of the back of the tv. At first, when it all started, the tv will make high pitch electric sound coming from the back of the tv when it is powered on. After a warn up the sound would dissipate and everything would return to normal. It lasted about 3 days. Then one morning the tv on the power on showed the usual blue booting screen with the polaroid logo in the middle and went black. Sound was still coming normally but screen was black. The power indicator was on like under normal functioning. I took whole back cover off and powered it in the dark room. No glow after the creen shuts off. I found that one of the two transformers on the master board making that noise I mentioned earlier, but no evidence of damage on inspection. I replaced both inverter boards with the new ones. It did not solved the problem. I tested the voltage on the DC outputs on the main power board and they are acording to the "book"-24v,12v,5v. It ruled out power main power board. Then I disconnected the cable that goes to the T-Con board and powered the tv on and there was just dark screen slightly lit up for the moment of time it usualy takes to boot up the tv and then the screen got shutt off as earlier. Who knows where else to look for the root of the problem please give an advice to me. Thanks to everyone who took a look at this post.