While watching tv sound cutts in and out constantly.

SOURCE: input problem

If you have the original remote, hit video, source, or input button, if it dont have them, then try to change the tv to channel 00 (zero or zerozero), if not then the channels might have to scroll to it, from channel 02 down to make it loop, if it goes to the next highest channel, then you need a remote. It may be set in the menu options to have the video source not saved to your list of saved channels. when you scan the channels, the tv might not look for the A/V source (audio / video), maybe just the RF source. The 3 DVD RCA wires are 1 video and 2 stereo, one stereo for left and one stereo for right. The TV has only 2 , 1 for video and 1 for mono 1 channel sound. This wouldnt have anything to do with why you cant use the DVD player. but try that with the original remote (or a universal remote that is set to your tv set that has either video, input, source or something similar. It is what tells the tv to change from the cable source (RF) and the AV source (the Red White and Yellow plugs, in your TV's case, 2 plugs, one yellow and the other either red or white or something). Dont really know how to explain it much more but hope it helps.

SOURCE: Single Blue vertical line appeared on the sanyo 42'' LCD screen

vertical ic fult or vertical section supplys missing

SOURCE: missing power cord 12v

go to radio shack get a 12 volt 1500ma power supply with I belive it is a N% plug end but any how 800 ma to 1500 ma should run this and the plug end is standard plug with plus 12 volts on the inner side and negitive on the outer case side look at the back of the TV or the old power supply it sould have info on voltags and amprage, and the plug as to inner voltage and outer voltage on the plug any old time radio shack or electronics shop should be able to help you bring in the flat screen if need be as if you know its 12 volts then It wont mater weather you use a 1000ma 1500ma 12 volt ubnaversale power pack as the tv will only use the current needed so more MA is good the only concrn you have is the right mini barrle plug and the right side of +/- voltage on that mini plug being most use + voltage in the inner most circle and - 12 volts on thje outer

SOURCE: We can't figure out how to remove the base on our

look at the rear of the tv there are four phillips head screws holding the base on unscrew them and lift the base off

SOURCE: my sanyo plasma flat screen tv will not come on....

For what it's worth, you can download the official Sanyo repair manual for this TV (DP42746) at http://www.eserviceinfo.com/downloadsm/43343/sanyo_dp42746.html. I uploaded it here when I had some issues with this TV last year. The solution almost always seems to be to replace the Power Board and the Upper and Lower Y Buffers. The parts and costs (from Sanyo in July 2009) are listed below (NOTE: Sanyo will not ship these parts to anyone but a repair shop):
1. V4 Y-Main (Y-Sustain) Circuit Board (Part # LJ92-01200A, Alt Part # LJ41-02759A) - USD $139.00
2. Upper Y-Buffer Circuit Board (Part # LJ92-01202A, Alt Part # LJ41-02760) - USD $64.00
3. Lower Y-Buffer Circuit Board (Part # LJ92-01203A, Alt Part # LJ41-02761A) - USD $64.00
Sanyo charges USD $10.50 for shipping, which brings the total cost for parts to USD $277.50. From my research, a shop would probably charge between USD $500 and $700 to do this repair. FYI - there is a class action lawsuit pending against Sanyo for this issue. The V4 Y-Main (Y-Sustain) Circuit Boards fail VERY frequently in this TV due to overheating. Hope this helps.