Hi I have a Philips 40PFL3705D/F7 LCD TV. The picture shuts down after a while. Could be 3 weeks, 3 days or 3 hours of watching TV. Still have sound.

Sounds like white balance adjustment mistuned. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
Faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.

Philips 42pfl3704d/f7 power reset when HDMI, USB, or cable ...

www.badcaps.net > ... > Troubleshooting TVs and Video Sources

Oct 9, 2012 - 5 posts - ‎2 authors
Philips 42pfl3704d/f7 power reset when HDMI, USB, or cable attached ... or Cable TV to unit the power resets, philips screen comes on and keeps on resetting. ... I tried a cable to the tv without the box and I do get picture.

Philips 42PFL3704D/F7 42-Inch 1080p LCD HDTV

www.amazon.com/Philips-42PFL3704D-F7.../B001LP...

Amazon.com, Inc.
Rating: 3.3 - ‎50 reviews
Amazon.com: Philips 42PFL3704D/F7 42-Inch 1080p LCD HDTV: Electronics. ... Will do all I can to prevent others from getting ripped off by Philips. ... came up every few weeks and would take an hour or so of reset before working properly.

Visit the support page for your Philips LCD TV 42PFL3704D ...

www.philips.ca > philips > Televisions > 3000 series

PhilipsFind support for your LCD TV 42PFL3704D/F7. ... How do I output sound from myPhilips TV to external audio devices such as Home Theaters, Soundbars, AV ...

42" Philips 42PFL3704D/F7 LCD TV WON'T COME ON - A

Sounds like T'Con board fault. Contact the authorized service center for Philips. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy. Pull up older posts. Surf the site with patience. Do a search by type in the brand name of your device at its search box.
http://electronicshelponline.blogspot.com/

You might need to get this checked with the manfucaturer, looks like a malfunctioning remote control. Or you can just replace the remot and see if that helps.

looking online as i have same problem, sound without picture points to T CON board. approx $50-100 part + labor

http://www.p4c.philips.com/cgi-bin/dcbint/cpindex.pl?scy=US&slg=AEN&mid=Link_FAQs&new_tmpl=1&session=20100701083748_66.249.65.50&ctn=40PFL5705D%2FF7&dct=FAQ

Look for loose contacts in power outlet, RC Jacks, sockets, cables. Change input device to some other like a DVD that you are sure works. Swith off TV, switch off power, remove plug and retry after 48 hours.

If problem persists, call in a qualified service technician.

Paste the following link in your browser & download the manual.

http://download.p4c.philips.com/files/4/40pfl3705d_f7/40pfl3705d_f7_dfu_aen.pdf

sonsunny

the flash drive connection is usually for viewing pictures, but in most cases its used to upgrade the tv

Sound like the logic board or panel. Don't do any repairs if the set is under warranty contact Philips and have get a tech to your house and do the repairs.