TV does not switch on despite being plugged in to the mains

SOURCE: Turns off by itself 10 minutes after use, and goes on and off

sounds like a main board problem

SOURCE: After watching HDTV the tv will not switch back on when left for a few hours.

i'm afraid i have no solution for you, but i thought it might help to know that i have the same problem, mine will sometimes take up to half an hour to turn on, while i have to sit and listen to the clicking sound, and watch the power led flash on and off! YOU ARE NOT ALONE!! sorry i couldn't help though.

SOURCE: Same problem: LA40R71B

Does it make the the samsung jingle when it trys to turn on? if it does you need a power supply if not then most likely it is the main board. I would contact you r local service center for help and if the standby lights in the front blink in a certain pattern write that down it is a error code that the technicain can use to solve the problem.

SOURCE: Samsung LCD 40 inch LNT4061

Howdy,
It sounds like you have a Power Supply Board problem. The PSB is the center Board (towards left) after you remove the back off the TV. Remove Board from TV with the 6-7 screws. Replace capacitors CM852 & CM853; 2200ufd 25volts.

Thanks for using FIXYA, big IRISH.

Bud Martin

• 11361 Answers
• Posted on Mar 06, 2011

SOURCE: TV WONT SWITCH ON LE26A456C2D standby light blinks

Please read my giude then you may understand more as to what it takes to make the TV functions.
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: 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.
Please post back what you find.
Please leave rating if it helps.