Magnavox 42MF231D/17, screen just turned black,

These blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit section inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices. http://electronicshelponline.blogspot.com/

Have tech check power board.

You may have a weak power supply. This would indicate one or two capacitors that are weak or bad. This model may be about 4 years now and this is a good indicator as these capacitors need replacing. The other problem may be the infared board in the TV that receives the signal from the remote may be a problem as well. I would certainly investigate my first thought. The latter is kind of rare. Thanks for asking and show a few hands of support.

That may be a bad video board, which will probably out cost replacement.

Replace lower scan converter PCB, which plugged into Y-Sustainer Board, located to the left of the display if you poke back cover open. There are 2 of them, but in some models might be the one, long PCB.don't wait to fix it! otherwise, you will knock out Y-
Sustainer and upper scan converter. That will cause you to spend few hundreds to fix it.
Good luck,
Alex's TV Service,
Philadelphia,
Pa, 215-806-5980.

Hi my name is Roety,
I can help you with your issue ,
Sounds like a bad SSB small signal board
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I’m happy to help further over the phone at https://www.6ya.com/expert/eric_ab7c09ec01841771

Alot of times i have noticed that when i have worked on these, it has been the Backlight Inverter. 32 inch televisions had same problem as the 42 inch

Magnavox suggests unplugging the tv for exactly 10 minutes to reset the tv---try that---or call the service number for assistance

there's no signal comes to you tv that why the screen is blue, the problem of your tv is the tuner, so check the the requirment of the tuner to determen if its good or not.

Check your input cabling and connectors and make sure you have a good input signal. Put another tv on this same input cable and see what happens. Keever