Samsung 48inch tv has backlights, sound but no picture, when I disconnect the cable between the main board and the power supply the back lights come on and the tv screen lights up blue.

SOURCE: no picture

The way to isolate the failure to the power supply would be to measure the voltages going to the backlight inverter board. If all the voltages are normal then is more likely a defective backlight inverter board or LCD controller board.

SOURCE: olevia 437-s11

Most likely the CCFL inverter has been the problem all along....

Bud Martin

• 11361 Answers
• Posted on Oct 04, 2010

SOURCE: I have an insignia NS-LCD37HD that has backlight

Chec to see if you are getting 12vdc at the T-CON board power input pin first.
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:

Please see my basic troubleshooting guide here:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide

Failed TV and Monitors: http://s807.photobucket.com/home/budm/allalbums

http://en.wikipedia.org/wiki/Capacitor_plague

Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.

Testimonial: "So far so good! Almost got it figured out. Thanks!"

Loretta Northcutt

• 736 Answers
• Posted on Feb 05, 2011

SOURCE: I have Samsung UN46B8000XFXZA LED TV. After power

Yes based on your testing it appears that the power supply is at fault solely and you can opt to attempt a repair or replace it altogether. Unfortunately you will not be certain that the main board does not also need to be replaced until you have repaired the power supply.

SOURCE: I have an RCA TV

The fact that the screen illuminates properly and does not stay absolutely pitch black means that the backlights are working properly.

A faulty LCD Controller Board (or TCon board for short) could possibly cause the symptoms you describe. The Tcon board is usually located under its own RF shield and will have a large braided steel multiwire cable coming into the bottom of the board and several flat ribbon cables connected to the top by little plastic flip up connectors. A replacement board can be purchased on Ebay for around $70 plus shipping. See the following link for one example:


http://cgi.ebay.com/LCD-CONTROLLER-V320B1-L01-C-RCA-L32WD12-/360142646595?pt=LH_DefaultDomain_0&hash=item53da2cad43


Just use your mouse to click on the link, which is the underlined and highlighted text just above. This will open a new web browser page automatically for you and allow you to view the item information at the website indicated.

Just don't buy any that say AS IS for their description of condition. That is EBay speak for broken.
Make sure they say TESTED FULLY WORKING in the item description.

The best way to be sure you are getting the right part is to open up your set and check the part number that is printed directly on the circuit board itself. Then look that part number up on the internet or type that number into the EBay search box.

Just typing in the model number of your TV will sometimes give you a few different part numbers so you have to confirm which part is in your particular set.

Make sure any part that you order online has exactly the same part number as the one you are replacing. Sometimes it it just the last few digits that are different and it can make a difference.

Here are some links to some excellent LCD Troubleshooting Guides from another expert (BUDMRTN) that you can read through and get an idea of the LCD repair process:


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

http://s807.photobucket.com/albums/yy352/budm

http://en.wikipedia.org/wiki/Capacitor_plague

Please leave a Thumbs Up rating on his pages if you find his guides helpful.

Please comment back here to this page if you have any details to add, have any questions, have difficulty accessing the links, or just require further general assistance and I will respond as soon as I see it.

Thank you very much and good luck.

Joe.