Hi Jason, unhook the connector going from the p/s to main board, plug the set in and see if you get backlights, if you do replace the main board, if you don't get backlights test the 13 volt supply, if it's good replace the main if it's missing, low or fluctuating replace the power supply, this is a very easy set to diagnose.
Lets start by eliminating the parts that won't cause your issue, the main board could not cause it, it turns the lamps off, that's correct it turns them off, the inverter will turn the lamps on with the main board not connected. The power board could cause it but it's not probable, only way this could happen would be some shorted windings in the transformer that powers the backlights and in the thousands of?? set's we've repaired in our shop I've only seen excessive backlight voltage a couple times. Considering this set is edge-lite, the lamps get quite warm, if a few are shorted the strip will get hot enough to melt the plexiglass. Where are you getting the replacement lamps from? Is it possible they're not meant for the model set you have? Are you getting a good contact with the tape on the back of the strips? They need to be tight against the frame, is there tape that's bunched up causing a gap between the strips and frame? Without pulling up service lit on the TV (not at shop now) I can't tell you what the correct B+ voltage should be coming out of the inverter but usually it's about 80% of the DC rating of the caps. Other than what I've suggested I can' think of anything else to advise on, I can get the exact voltage of the inverter next week when I get into work.
If one string of LEDs fails to light, the power supply will detect the fault and shut down. That's pretty much standard operation.
Unfortunately, LED backlights have turned out to be more delicate than we were told they would be. They are very susceptible to static electricity damage - they might not show it right away, but eventually a damaged LED develops a short circuit, then burns out. This disables the entire string. So, if you go to all of the work of disassembling the display, use ESD (Electrostatic Discharge) precautions and protection when handling any LED strips or cables connected to them. If you decide to replace the failed LED, it's probably a good idea to change all of them on the string because chances are the other LEDs were also zapped and will fail later on. The LEDs are typically surface mounted with both glue and solder, so replacement is not trivial. You may be able to buy complete LED strip assemblies.
One of these days, some lawyer will figure out that high LED failure rates in certain models were due to careless handling in the factory, and there will be a flurry of class-action lawsuits. The lawyer will get a few million dollars, and all of the people with bad TV sets will get $7.53 each (at least that's how defective product litigation typically plays out).
Samsunghttps://www.samsung.com > ... > TV & AV
Apr 13, 2023 - Troubleshooting. 1 Check whether the lines on the screen are moving or permanent. 2 If the lines sway, check the input source (HDMI 1, Video, ...
Have you tested the backlights by removing the connector going to the main from power board, this will tell if the hot side of the power board is working and you will get backlights if they work?
You will need to unplug your TV from the power outlet and any power source for about 1 minute,then plug it back in. Check to see if the HDMI cable is properly connected.Or change it to a different socket. Do a factory reset.
This sound like an issue with the x-main board, if you unhook the power cable going from the power supply to the y-main board and you get VA and VS voltages there is about a 95% chance of the power board working ok, both the x and y main boards in this model set gave issues, one problem is going to be finding a board at a decent price, you can troubleshoot the board yourself, it's generally the mos-fet's that short, the ones that are attached to the heat sink. If you find some bad, replacement parts can be obtained from Mouser for a few bucks, they're easy to change with a soldering iron and some solder wick or sucker
This set is what's called edge lit, it has 2 led strips on the bottom of the panel, then a defusing screen spreads the light, you have some shorted LED diodes making the darker spots, new lamps should fix the TV as long as the diffuser screen is ok.
It would appear that your Samsung LN-T4665F television is experiencing a problem with discoloration. You can try a few things to get the problem fixed:
Check the connections of the cable: Check to see that the cables that connect the TV to other devices, like a Blu-ray player or cable box, are properly connected and not damaged.
Examine the power supply: Check to see that the TV is plugged in correctly and that the outlet is working properly. Check to see that the switch that controls the outlet is turned on.
Examine the settings: Check to see that the TV is not set to Sports or Game mode, which may cause the screen to appear dimmer.
Reset your TV: Wait a few minutes before reconnecting the TV to the power source. This can sometimes solve problems for a short time.
Examine the T-Con Board: The T-Con Board might be to blame if the problem persists. Discoloration issues can arise from this board, which is in charge of controlling the signal that travels between the television and the main board.
