The screen on my Proscan Model # 40LC45S57 is black. I changed the main board but it's still the same. What else could it be?

Fault to its main board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/ . In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
Some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement.

Hi Lee,
Failed speakers is a common cause for no sound in flat panel TVs. Please check if it helps.

Check whether the control voltage comes to the inverter section cirlcuit at its power board; from the main board. There is a control voltage that controls the light intensity; as well as start, of the inverter section circuit at the main power regulator [SMPS]. It should come from the main board. It this voltage is absent, the main board is faulty. Check whether it is present or not. It will be best to contact any service technician in this case. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/

Oops. When lightening strikes, you have to consider the whole equipment as defect. Even if you manage to get it playing, components that stay behind, can be damaged, but only stop working after hours, weeks or even months. Please also read what ESD does to electronic equipment. I hate to say this, but everything you invest in the TV will be in vane.

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Proscan 40LC45S57 remote control

Back-light inverter board fault. Replace it as card basis. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy. Surf the site with patience. Pull up older posts.
http://electronicshelponline.blogspot.com/

Must return for waranty repair ur main video board backlight is dead,the main video board no good.

This set should have a digital tuner.. If it is more than 3 years old it could still be using an anolog tuner.

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.