Set my lg tv and cable box to turn on at 6:15 they both turn on but there is no signal.

SOURCE: no signal when hooked up with a digital cable box

I had the same problem and had the cable guy out and everything thinking it was my box. I figured it out by myself here is what i did to fix it. I have the vizio 32 inch hooked to an hdmi cable and through the cable box i had the aspect ratio on 1080i and i should have had it on 720p once I switched it I havent had the problem since.

SOURCE: Basic Cable (no box); signal "in" to DVD Recorder (from TV)

Problem solved via tech support for Toshiba- thanks!

SOURCE: my LG tv shows no signal with hdmi cable to hp

First you need to state Mac G5 model and MacOS 10.?,? and whether the connection is VGA or mini-DVI. (I'm at 10.5.8.) I would not be helped by LG model other than to know if it is HD 1080 or 720. I'm going to assume you have MacOS 10.4 or later but most should apply. Apple>>About This Mac>>More info...>>Hardware>>Graphics/Display and read more about the display. Digital connection will give you more info. Close the Info but even with VGA you should be able to go to Apple>>System Preferences...>>Displays and have 2 windows--1 for the built-in and 1 for the external. If the latter is off screen, press Gather Windows. On the external display Turn on Show Displays in Menu Bar. This will let you control Mirroring and Resolution. You will need to pick a resolution your TV can do 1920x1080 1280x720 or possibly less to get started. My MacBook has all of those. I usually do not use mirroring and 1920x1080 gives a good pixel match to my DLP. On the external, turn on overscan if you need to put the menu bar on the screen or off if showing maximum of photos. You need to sync first, then play with other things. -Ken

SOURCE: "No signal" sign on TV screen using HDMI selector

it sounds like a refresh issue, double check you selector and make sure it fits the refresh of the tv. i had this once with a sharp where the tv was 120hz and the selector was 60 and it created a no signal and when it did come in it was jumpy. if you have a 120 tv then selector should be the same.

SOURCE: My LG Plasma 42PC3D turns on and off repeatedly. I

Your plasma TV has a power supply 6709900019A. These power supplies failed due to defective capacitors. See the picture below and check the capacitors mark with the red lines. There are 10 capacitors that should be replaced even if they do not show signs of bulging/swelling on top.
The value of the capacitors is 3300uF/10V but you can use 25 volts as long as they fit in the space provided by design.