Samsung LE37R888D LCD TV. No sound from the main speakers or Line out.

Be sure internal speakers are turned on, then most likely MAIN PCB you will need your complete Model/Serial #s to get the correct pt#

Could be the cable box is bad,u should check all other tvs in the house are find,if it have sound? Yes,tries unplug the tv and the cable box about an hour.Replug both back in.Let the cable box upgrade it software.The tv it now resetting back to it factory setting.Go into the tv Menu,go to AUDIO setting,go down to reset the AUDIO setting back to factory setting.The tv should have sound now.Not,than the Tuner board is dead,that the board take in the tv broscasting cable signal plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a refurbish Tuner board for the replacement.

It sounds like the main board has gone out. The only audio components are the main board, wiring and speakers. Since audio is missing from external speakers as well, that tells you that the main board is at fault. The cost of the board could be from $150.00 to almost $300.00 depending on the version # of your unit and dealer mark up. You can call 1-800-samsung for nearest service center.

It is TV monitor (without TV tuner), you need to feed audio signal from cable box to the audio line input of the minitor.
http://reviews.cnet.com/lcd-monitors/samsung-syncmaster-403-t/1707-3174_7-31491518.html

We need to verify if the problem is in the preamp or poweramp sections. Hook up the powered PC speakers to the AUDIO Line out RCA jacks and verify that sound is OK there, if it is OK, The problem will be in the power amp sections that drive the speakers. If it sounds bad at the RCA jacks, the problem will be in the sound processor board which mean the main board will have to be replaced, same if the power amp is bad.

It depends on where you lose the sound, no sound from speakers? no audio line out?
The amplifier circuits are on the main board. You should try hooking up a powered PC speakers to the audio line out to see if you get the sound, if you do, then the power amplifiers are bad (it is a single IC Class D dual amplifiers, IC U54 on the main board)

Have you try to play with a DVD or other source beside cable? Did you check the TV speaker is on or in mute mode? Try to get TV back to factory reset.
If does not help, check the TV speakers by plug in an AV source.
Lastly, replace the main board.

First try hooking up a different source such as a DVD player or Cable box and see if you have audio. If you do then check the audio output from the computer. If you do not have audio then make sure the tv audio is up half way and turn off the set. When you do this you should hear the down chime provided you have the chime turned "on". If you do not hear the down or up chime then the sudio circuits on the Main bd are bad and the Main bd will have to be replaced. A quick way to check to see if the audio circuits are working is to listen for the up or down chime when turning on of off the set coming from the tv speakers speakers.

First try viewing regular programming and see if you have audio on both channels. If you do not then go to the user menu and make sure that the chim function is turned "on". Then turn off the tv and listen for the down chime coming from both speakers. If you only hear the chime from one speaker then the Aidio circuits are bad on the Main bd and needs to be replaced.

Not that I'm aware of, but it is not that had to tear down the tv and replace them. Just 6 or 7 screw and and carefull pry the rear panel off. Then it is as simple as unplugging the speakers from the main pcb and replacing them.