Hello, I have a hitachi tv mod#LE55A6R9A has sound no picture, I replaced the t con board same problem. What do I replace next?

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.

The led driver may be on the main board or on it's own board. Led strips don't fail all at once so if you had a dark area of the picture then I'd suspect a led strip. TV Parts Universal TV Stands DLP Chips ShopJimmy This is the place to get parts.

First, test fuse if there is one. Second check high voltage near 390 to 400 DC volts at the capacitor. Hopefully, there is only one capacitor.. The high voltage circuit is near where the AC 120 volts plug enters the TV. So, without high voltage, TVs are shutdown. Today's TVs are like computers, sensors on the circuit boards, feed back to a "CPU".

Can you tell if the backlights are on with the back off? If they are on then the T-con board is bad. Hitachi LE55A6R9 LE55A6R9A Complete LED TV Repair Parts Kit SEE NOTE

Two things need to be checked. The ballast board and the T-con board. Shine a flashlight on the screen with the TV on...If you see a faint picture moving, then the T-Con board is OK. The ballast board for the white backlight is bad. If you don't see a faint picture, then the T-con board is bad. You can get parts here: www.shopjimmy.com TV Parts Universal TV Stands DLP Chips ShopJimmy

See the notes on this page Hitachi LE55A6R9 LE55A6R9A Complete LED TV Repair Parts Kit SEE NOTE

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.

Main digital board fault. Check and replace it. If you wish to get more details visit the site linked here. http://electronicshelponline.blogspot.com/

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.

Main board. T con board is only involved with video issues. Main board goes both ways and since you already replaced the T con board that is your only alternative. U got backlite so inverter board is good.