That is a real problem as almost all those sets you need the remote to do anything---What is the model number of the set---I ask as I used to repair them when they were under warranty and have 3 brand new remotes for certain models
All warm-up symptoms is an indication of faulty (leaky/dried) electrolytic capacitor and very basic to an experienced technician. Faulty electrolytic capacitor most of the time has a physical indication of fault like bulged/dome at the top and can be easily identified through visual inspection. See sample picture below.
Capacitor act like a huge power reservoir needed by the circuitry to perform well most of the time upon starting, variable and peak performance of the circuitry. If the reservoir(capacitor) is faulty, the circuitry will not function well. In the first stage of fault, warmp-up will make itself stable but the symptoms will get worst and worst as time goes by until the circuitry will be un-operational (capacitor is totally faulty). A lot of stages on the board will be considered to be with faulty electrolytic capacitor with the symptoms you've described. The technician must be look for faulty capacitor on the following stages : 1. Output of the chopper transformer feeding the jungle IC. 2. ABL circuitry of the pin-out of the FBT(flyback) transformer. This is responsible for blanking (black picture with sound) of the picture, enhance the brightness and clarity of the picture. 3. Jungle IC. This IC called jungle because it contains a lot of circuitry in one IC. It is located on the center of the mainboard and controlled the VIDEO, chroma(color), tuning frequencies, vertical and horizontal output, protection circuitry, audio frequency, etc. He must concentrate on the said sections on the board, he will be lucky if the faulty capacitor has a physical indication of fault like what in the picture above because the troubleshooting will be narrow down or if not, he needed a capacitor checker to pinpoint the faulty one. Watch the video below for more info regarding electrolytic capacitor.
Yes this is fixable and the parts is widely available at electronics store and one of the cheapest part on the board. Hope I helped you. Have a nice day! Thanks for using Fixya.
I had a similar problem, and I fixed it with my new Sony flat screen by going into the zoom mode and then menu on the tv remote. You can then access settings such as horizontal and vertical and change them so that your screen can adjust. The only way you can access those settings is in zoom mode.
It seems as if the Picture-in-Picture feature of your television is activated. Please take a look at the remote control and find the PIP button and press it, this should bring the picture into full-screen and allow you to hear the audio.
Look for bulging or leaking capacitors. There's been a lot of capacitor failures in all kinds of devices lately. Since you know what a MOSFET is, I'll assume that's really all the explanation you need to go looking for the damaged compunents. Check most carefully on the power supply and inverter boards.