Panasonic TC-42LD24 occasionally has a blue screen when powered on. After 5 to 10 minutes it operates normally. What component is the most likely culprit?

Sounds like The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts. http://electro-medical.blogspot.com/ It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.

Need leds replacement

First try resetting the unit by unplugging for 30 seconds to 1 minute. plug back in to see what happens. I red light still blinking may be power supply or Main PCB. check voltages from power supply to verify its OK. of all those voltages OK, check the Main PCB.

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Try another source device to verify if the issue occurs with all source devices or just one.

Try to unplug the TV for about 20 minutes and then press and hold power button on the TV for about 10 seconds to reset your television and plug TV back in and see if that resolves the issue.If they problem still is showing up then the screen is broken and the back light is not working anymore and needs to be replaced.

I think some sort of moisture entered in, just open the body with care dry the machine with a hair dryer.

Hello;
I have lost the user manual to a Panasonic TX-32LXD700 32" TV. Does any one know of a link to download a copy?
Many thanks to any one who can help?

Try calling up a Menu for Picture on the screen with your remote.  Also check that it operates the TV and not the VCR or DVD player.
Good luck.