I need a manuel for my lg lcd tv.

https://www.lg.com/us/support-product/lg-50PS80-UA

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

You should try tristatemodule.com it sounds like its your main board thats shorting out give them a call and they can give you a cheap price on a replacement and guide you through the repair over the phone.

Tries websites like Shopjimmy.com,Ebay.com to buy a whole new refurbish tv Tuner signal board for the replacement.

User manual: http://www.retrevo.com/support/LG-47LG70-TVs-manual/id/18841dj795/t/2/
TV uses VESA mounting pattern, each TV are different.
See page 17.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm
Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague
Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.
Or www.digikey.com, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.

http://www.lg.com/common/product/support.jsp?localeCd=US&productId=32LH20&uri=/us/tv-audio-video/televisions/LG-lcd-tv-32LH20.jsp&categoryIdCms=3#

I have had the same problem off and on with my 47LG70 for months. When the "popping" noise happens, the blue light in the corner stays on, so I know the tv is still on (sometimes I still have sound, sometimes I don't). Sometimes the screen goes black, but other times it is blue. If I turn the tv off then on again, it might stay on for seconds, minutes or hours. It's been very frustrating.

This seemed to happen right after I got my new Comcast box, which came with an HDMI 1.3 cable. I read somewhere online that this tv might not be compatible with that cable, so I unplugged it and am using component cables again. I just did this today, so I don't know if it will work, but so far the tv has been on for 30 minutes with no problems.

I'm pretty ignorant about HDMI compared to component cables. I imagine I will not get as good a picture with the component cables, but I am willing to sacrifice quality if I can just get the darn thing to work. Mine is also only 18 months old.

Hope this helps. If it doesn't, maybe someone else out there can help us both.

I'm sure this is the manual your looking for:
http://safemanuals.com/user-guide-instructions-owner-manual/LG/LAFINION%2082W-_E