Samsung LN-R408D 40 in. no picture

SOURCE: Samsung LN-T4042H 40" LCD

This may not really be a solution to your problem, but here it goes. If you are not sitting a particular distance from your tv you will experience slight pixelation. I have this tv myself and I think it looks great. Now when I am sitting up close on a station that is broadcasting in 720p(which is pretty much every HD station) It looks only pretty good...I sit back and it is fantastic. The good rule of thumb is take the number or inches your TV is in yours and my case 40, divide by 10 and then multiply by 2...and that is the number of feet you should be for optimal viewing distance. So 8 feet, you would be surprised to see how sitting this magic number away makes a difference.

SOURCE: Samsung LN-R408D - No Picture

My Mom's LNR408D also had sound but no picture. I was able to fix it by soldering in a jumper wire across a blown (1.5A ???) SMD picofuse on the "T-Con" board.
Consider attempting this ONLY if you: 0) Know enough to avoid the potentially fatal High Voltage parts of the power supply board!!!
1) Are a fearless hackazoid 2) know what you're doing with a soldering iron and teensie SMD parts 3) are gonna throw the busted thing out anyway so you have nothing to lose and won't be sad if you screw something up.
4) Know enough to avoid the potentially FATAL High Voltage parts of the power supply board!!!!!


This board is at the top center under a close fitting RF shield. The suspect part was labeled "CP" on the board and marked with "P" on the part. It is visible above the right-center of the connector from the main board. An ohmmeter showed it as open, so I bypassed it with a jumper wire from connector VIN to the hot side of C13. One image shows the suspect part and the jumper in place.


The other shows the TCON board placement top-center (under its RF shield). With care, it seems possible to test the fuse and put the jumper in place without removing the shield. (Obviously don't touch anything else with the VOM leads!)

Thanks to ZORBUS and Steve's TV and Electronics for the idea.
http://www.avforums.com/forums/lcd-televisions/892447-no-picture-but-got-sound-my-samsung-lcd.html
http://www.gesda.com/transformer/Fall08_files/Page336.htm
Steve C

SOURCE: LN-R408D Samsung LCD flat screen TV

they must try to repair the smps [puff capacitors]first.then try a master reset thru the service mode.if these steps do mot solve the problem replace the t-con board on lcd panel.

SOURCE: My Samsung LN-R408D 40 in.

It could be the power chord thats gone bad. I have the same television. Mine is broken as well. Would you be willing to part wit it?

Bud Martin

• 11361 Answers
• Posted on Nov 02, 2011

SOURCE: my 40" samsung model no.LN-R409D has sound, no

You have bad T-CON board, check the surface mounted fuse (2A fuse) to see if it is blown, you may want to replace the board, common failure in this model.
http://s807.photobucket.com/albums/yy352/budm/SAMSUNG/SAMSUNG%20LN-R409D/

Read below for more details:
First, look at the screen in darkened room to see if you can see any slight glow from the screen, if it does, then the problem can be the T-CON (not getting the 12vdc) or the main logic board not feeding the signals to the T-CON board.
if not, next place to check will be the power supply module, make sure it has 24vdc which is required by the backlight inverter to work, the reason for not having 24vdc can be from bad DC filter caps (leaking/bulging top, high ESR) or short circuits in the inverter board which will cause the 24vdc supply to go into shutdown mode, so you may have to disconnect the power cable that feed the inverter board to see if the 24vdc will work without the inverter board hookup, you will need to apply about 3~4 amp of load to the 24vdc to make sure it can handle that. There are fuses on the backlight inverter boards also. So there is some troubleshooting you will have to do to find out the causes of the problem you are having.

If you are going to DIY and have proper tools, electronics knowledge, and know safety precaution then please read on:
Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm
Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague
Parts: www.shopjimmy.com
Parts: www.interliquidparts.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.
Or www.digikey.com, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.