no picture but good sound and channel changing

jacapozzimd sounds like a backlight issue. If your screen is dark but still displays the menu your can try a reset first . Service Level Initialization

Is designed for Servicers, and resets all options and A/V settings to factory defaults. This initialization is activated through the TV’s Option Menu, showing Figure 3-2.

Service Level Initialization Procedure:

1) Use the Remote control an press “MENU-2-4-7-0” activates the Option Menu shown in diagram

2) Use the Up & Down buttons to highlight INITIAL.

3) Press ENTER (resets setting to factory defaults).

If you cannot see your menu then use the LED diagnostics:

The two front panel LEDs, POWER and STATUS are usefulness determining the cause of a malfunction.

Whether the TV is On or Off, the STATUS LED is normally Off. Table 3-1 shows the normal LED indications if no problem exists.

Attached images describes the abnormal LED indications when a problem exist. If the STATUS LED is steady Red it indicates a circuit problem. Possible causes are:

• Short circuit

• PWB problem

• LCD Panel

• Disconnected or loose cable.

Use the following Error Code feature to further help isolate the problem.

Error Codes

To use the Error Code operational check the TV must be in “Shut Down” and not have been switched off. If the TV has been switched Off the code automatically resets to “12” No Error.

Error Code Activation

While the TV is in “Shut Down”:

• Press and hold for 5 seconds, the top panel “INPUT” and ‘MENU” buttons at the same time.

• The “POWER LED” will start flashing.

• It flashes the value of the MSD (tens digit) of a two digit Error Code.

• There is a 1/2 second pause then the value of the LSD (ones digit) is flashed.

• The value of the Error Code is repeated five times.

Example:

If the LED flashes 3 time, pauses, then flashes 5 time, the error code is 35.

The Error Codes for the new LCD models are listed in Table 3-3.

Error Code Cause Most Likely Failure

12 Normal off No Problem detected

27 Inverter short detected PWB-POWER - No 24 V at PC-Pins 1~5

28 FPGA download failure PWB-MAIN

29 FRC communication error PWB-MAIN

41 3.3VS or 5VS STANDBY-SHORT PWB-MAIN

44 LVDS Cable connection detection Loose LVDS Cable at PWB-MAIN (VR) or Panel Assembly

48 3.3V PON-SHORT PWB-MAIN

59 Panel 12V Short PWB-POWER - No 12 V at PB-Pins 9 & 10

So if that does not yield any results, than you will have to take your TV apart. Unplug it of course, remove the back and take a lot of pictures and post those with your original question. For that use this guide. Again right now you seem to have issues with either your power board or your inverter.