TV Picture gone very dark, can hardly see anything. Sound is okay.

Hi Stephen,
This is a case of backlight failure. Some of the LEDs in the backlight array have failed and causing this trouble. To repair it the LCD panel has to be opened and I am sorry You can not do anything about it yourself, because it is a highly delicate job and needs a fair degree of expertise. You will have to handover the job to some good local TV Tech.
Good Luck.

Usually means inverter or power board is bad! Check power board for voltages. Voltages are usually printed on the header port. if Inverter is bad panel would need replacing. If TV is less than or equal to 12 months contact Samsung for warranty repair.

Sounds like the screen voltage has been gone very low than normal. This might happen, if the CRT base socket have any damage. If you wish to get more details, check the site linked here. Surf the site in "MOSAIC" view.
http://electronicshelponline.blogspot.com/

The most likely thing is that your screens backlight or inverter has gone faulty.
When you turn it on, you may be able to see a very very dark image of something (best seen by activating the TV menu). On some screens the picture is still far too dark to be visible though.
With this kind of fault, its down to fitting a new inverter, and if that doesn't cure it, then fitting a new backlight bulb (or bulbs) will sort it out, but these are not jobs that can be done without some expertise at them.
Most TV inverters are large circuit boards inside, and take about 20-30 minutes to change as the whole TV has to be dismantled, but the backlight bulbs are much more complicated (and extremely fragile too).
Unfortunately, there's not much else that can be done except trying changing those 2 parts. Although its possible for the screen cable inside to become disconnected and lose your picture, that results in the screen lighting up brightly (usually pure white if the cable comes off completely).

No Picture and not sound RCA TV Model no.27R410T

have sound but picture is too dark to watch on tv

sound is okay, images can be seen but it's still to dark to see

sitnlisten - yes it does appear your pix tube is getting weak,but we may be able to turn up the flyback alittle to brighten up the picture.If you take the back off you will see the flyback-large black unit with a wire going to the round rubber cap on the back of the pix tube.Look at the flyback there are usually 2 adjusters one marked focus the other screen,just turn up the screen a little bit at a time.If you turn this up too much you will wind up with retrace lines on the screen.You may also want to check the pcboard ass'y for a sub bright adjust,and same thing small adjustments.If this don't help your pix tube may be too far gone.I hope this helps. cooltek Feb.1/08

Solder any / all bad connections , esp. vertical output IC......

zenith have many problems with crt (picture tube) they comes be short or one or more canon fail, there are nothing to do, replace the picture tube, and thats a lot of money for an old tv...good luck ps adjusting the screen and resoldering the picture tube card could help but remember there are many dangerous circuit in a tv...