Philips 20PF5121/58 - problem: very long start. It can stay 5 min or more (to 15-20min), with green indicator blinking, then turns on and then works OK (the picture and sound are not distorted). If i switch it off and then on, it goes on immediately. If it stays off hour or more, starting is a problem.

replace battery

Try changing the input device to something you are sure, works such as a DVD player.

Switch off TV manually, switch off power, remove plug and retry after 48 hours.

If problem persists, please refer it to a qualified service technician.

what kind of tv is it, plasma, projection, lcd??

check all caps in the power supply especially the 10mf 22vols cap.the caps are not filtering the voltage properly when the the current i off the caps drain the voltage and does not keep charging.until when current is applied to the set.good luck.

your tv has bad power supply. Repair it or replace.

I hooked a 12 volt car battery charger to the battery for about two min. Then I put it in it's own charger,the yellow & green lights came on for about 5 sec. then the red light came on . About 30 min. later the green light came on and the battery is fine.

most philips universal remotes have the "code search" option this is done by:
1: Manually turn on ur tv
2:hold setup untill red indicator stays on and release button
3: press and quickly release what you wanna program (i.e tv,vcr,ect.)
4:press channel up repeatedly untill your t.v changes channels(up to 300 times) if you over shoot the channel change press down til it changes again.
5: press and release MUTE to install the code.

check the capacitors in the power supply that is the first thing to do, just check if anyone is swallen or pregnant jajajaja that's how some people call it

may be the sleeping mode is enabled and activated for every 5 min.. so better check the sleepin mode is disabled to fix the problem.

Well since you seem to have tried a bunch of thing why nor go a bit more and replace your video card. Below is a link to your PC:
http://support.packardbell.com/uk/item/index.php?pn=P280110001&g=1400