I have a Sharp lc-58q7370u that I received in a non working state. The code the red light was flashing pointed me to the power board so I replaced it. Now it still won't power on. The light is flashing once every 2 seconds. I have tried a factory reset but it didn't respond to that. I haven't seen any specific answers to this problem. I wanted to see if it looks like a bad main board or if there is something else I could try? I am also comfortable repairing the board if there is a known part that could be causing the problem. (Rather replace a 50 cent capacitor than the entire board.) Thank you.

I'd start with a replacement main board

It is most commonly the backlight strips themselves that fail. They are over driven to give high brightness.

. 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.

It should turn green.

The code that is flashing usually points to a main board failure. I would recommend getting it diagnosed. If you want to be gutsy and try and replace the main board yourself, MAKE SURE YOU GET A BOARD THAT MATCHES YOUR PART # EXACTLY. Sharp makes several revisions of main boards for various models, and they ARE NOT compatible.

check if their is a signal on voltages around 3.3v at the inverter board if none their is a problem in the board which is in the processor.

This problem very common in sharp tv.The POWER,OPC flashes.First turn on have power LED indicator light stable at all? Tries the power again couple times will have backlight come back on,than it will work.Not at all more than 5-6 times than ur main turner signal board is the problem,must replaced.

This is very common in sharp tvs.U turn it on.U get power on light stable right?U hear a click,one or twice,sometime tv is good right?Sometime POWER light and OPC light flashes?Push the power button on/off couples times will work, picture will come on.If keep trying off/on couples time after POWER and OPC flashes,don't ever stop and never get backlight and picture.Ur Video backlight board is dead must replaced.

If the TV goes in standby, then it is in protection mode.

Ensure also that the fault is not coming from a faulty receiver box sending
bad signal, check if you get same problem on DVD with no receiver box
connected.

Try first leaving the TV power cord unplugged for some times, let say one hour or so.

The flashing light indicates a diagnostic state called protection.
When the TV goes on protection there are only two possible causes.

1The internal circuits are jammed because of electrostatic charges accumulating on capacitors, or because of a wrong voltage read by the main chip on your monitor controller board. this started the protection circuit.

2 The protection circuit detected a wrong voltage or abroken contact, identified an internal fault and kicked in , starting the flashing light.

If you are in situation one, then the TV will reset just unplugging power cord for one or two hours,sometimes even minutes.

If you are in situation 2 , then there is an internal fault.

If under warranty contact the manufacturer ringing the number on the user manual

If you want to repair at your own expenses, just locate any good qualified repairer.

If you want to DIY you find parts here,

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On LCD Pay particular attention at inverter and power board, power board can be inspected looking for bulged or leaking capacitors, then tested with a multimeter. The inverter is more difficult to test , there is need to read voltages, should be done by a tech. Also the LCD controller board can cause same problem

On Plasma, test Sustain (Ysus/Zsus) / Buffer boards , cables to plasma, digital board and power board.

On Rear Projection : check lamp, lamp ballast, power board, and convergence.

On CRT TVs, check ballast , flyback transformer, CRT, Tuner, Convergence.