Hello i have a philips tv 20PF4121/05. When plugged, light will flash green for few seconds then turn red.When remote is used, red light will flash but no picture or sound. A dvd player plugged on tv wont give any better results

SOURCE: No Picture and Red Blinking Light

Plasma TV blinks red LED 7 times, no picture, no sound.

I have the same issue with my plasma tv model 42PF7320A/37 and by process of elimination, this are the results: replacing the power supply board did not make a difference.  I've been reading about people that contacted Philips and they have replaced the SSB (Main Logic Board+Output/Inpunt Signal Board)

I'm about to replace it in a couple of days but them I ran into something I'm suspecting of and that is Y-Main board.  I begin my diagnostic by disconnecting power to one board at the time and notice that power use to shutdown at the Y-Main board.  I had a problem with the TV before it completely died and that was the lack of video signal at exactly half bottom of the screen.  Read this also:

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Philips has no such code for telling you what is wrong.  What it does tell you is that somewhere in the set a shorted condition has occurred which was detected by the protection circuit; the protection circuit then shut down the set in order to prevent further damages from occurring.

So, one cannot tell what is wrong without defeating the protection circuit and firing it up at least long enough to tell where the problem is.

Mostly, when a set shuts down it is from one of the high current draining sections of the tv.  Those are the high voltage and horizontal sections.  The vertical deflection amplifier, the audio amp and the main power supplies can be the culprits as well.

The video processor chip does not usually cause the system to shut down."

Good luck!

SOURCE: red light flashes

This is a well known and very common problem with all Philips plasma tvs 42 and 50 inch. The problem is they used under rated capacitors in the power supply. If you have electronics experience or a friend that is, remove the cover and look in the back for malformed or leaking capcitors. Replace them and see if that takes care of the problem. The caps only cost $2 or $3 each, so the cost to try this is pretty reasonable although you might have an added cost of buying beer for your electronics friend. If this does not fix your problem you are down to replacing boards that can be purchased around $300 ea.
I have found my set will come on "finally" after I get the back of the set warmed up and the bad caps finally charge up. Hope this is useful.

SOURCE: green light turns red and red light blinks 4 times

Replace the Main Power Supply inside the TV.

SOURCE: red light blinking, tv doesn't start

Your TV is in Protection Mode right now. A part inside the TV has failed and the TV will not turn ON to prevent other parts from being damaged. The red light blinking is an error code for diagnosing the problem part on the one of the power supply boards. The problem boards that need to be looked at is the Backlight Inverter Board or the Main Power Supply Board.
There is a slim chance you can leave the TV unplugged for an hour so the TV can discharge and reset itself. But other than that, I would use the warranty if possible. The TV repair shop maybe expensive, so get some price quotes to see if it worth the trouble.

SOURCE: why wont my tv turn on? a red light just flashes

Right now, your TV is in " Protection Mode". A damaged part has occurred inside on one of the power supply boards. The red flashing light is a trouble code for a tech to trace the trouble circuit path.

If you have electronic experience with circuit boards, you can find a Service Manual for the TV on the internet for less than $20. This Service manual will have the schematics, red light codes, circuit diagram, and part number list you need to fix the board.