I have Samsung tv UN32EH4300F about 5 years old and the picture is barely visible but sound works fine. What is wrong one of the boards or the led strips?

SOURCE: Lost picture and sound

If you're handy enough you could check for a blown fuse. Unplug TV of course. You'll usually find the fuse somewhere near to where the mains voltage cable is soldered into the motherboard. A lot of TVs are fitted with a fuse which is JUST enough to handle the job and after 5 years of continuous on and off that fuse heats up and cools down. Repeat that over the years and the fuse can simply fracture. You'll need a simple ohm meter to check as these fuses may look OK but are open circuit. If the glass in the fuse is black then it's not fatigue and time to call a tech. Make sure you replace the fuse with the same value. BMW

SOURCE: no picture

Sounds like one of the CCFL's is failing.. (Backlight bulbs).. Some use multiples and others have singular.

SOURCE: half screen showing

ok
keep tv off.
it will only get wors
if sumon dosent work on it soon
the problem you are having in the vertical section of the tv
hav a repairman resolider all conection on the vertical IC and check the serounding componets for falts.

regards daniel.
PS the repair takes me about 15 min.

SOURCE: No Picture & No sound. Red LED, Green LED, Red LED.

If the power supply outputs are good! Then I would say the back light inverter is bad! If the screen stays black and does not come on.

SOURCE: how hard it is to replace by yourself main board Samsung LN-T4065

You need to do some more diagnosing of the problem. If you get sound and change channels take a bright flashlight and place it again the screen. Look for an image around the edge of the flashlight.
If you see an image that means the LCD controller board (TCON) is probably good.

The problem is probably one of three causes;
1) Inverter board is bad
2) CCFT (cold cathode fluorescent light) are bad.
3) Power to the inverter board is bad. You can also check the connectors.