I had previously encountered this model with failed backlights. This TV had different symptoms and the backlights were working but with no video. The usual suspect when there is backlight and sound but no video is the tcon board. The TV appeared previously repaired since the main board was from the 65″ version of the this TV. I still had the other TV so tested the 65″ main board on it and it was working fine. I couldn’t swap tcon boards since the panels were different even though it was the same model.
Searching the tcon part number BN96-27249A found repair kits indicating it had a common fault. Used boards were actually cheaper than the repair kit and only $12 USD from Electroparts online.
The replacement tcon worked and fixed the TV.
The backlights appeared good. I checked the backlight setting and it was in standard mode with a default level of 12/20 on all inputs. Though not the problem in this tv, It does appear running the backlights at 100% is what causes failure.
This TV responded to the power button and attempted to turn on but there was no backlight. Checking the signals at the power connector, I measured 19V at the 12V pins and 3.6V at the PS-ON pin but BL-ON wasn’t getting a signal so the main board was suspect.
Checking shopjimmy, they sell an eeprom for the main board with the symptom no backlights. They have a video showing the symptom on a similar model P502UI-B1
Ordered the eeprom but the problem was still there. Luckily, new main boards were available for $30 USD from Electroparts online through their ebay store. I have had a good experience from Electroparts since they had free returns and provided USPS labels.
After main board replacement, the TV turned on with backlight. There were also LEDs on the main board that lit up. A post on badcaps for P502UI-B1 indicates BGA failures on the main processor are the suspect and not the eeprom. Usually with eeprom failures, the tv doesn’t respond to the power button.
When plugged in, the TV squealed and wouldn’t turn on. Squealing is a sign of a shorted output on the transformer.
The service manual for this model can be found with a quick google search.
Checking the power supply board, the fuse was not blown and none of the output diodes on the AMP+13V and P-ON+21V lines were shorted. The squealing stopped when the cable from the power supply to the main board was disconnected. Measuring the resistance of the P-ON+21V line, it was 8 ohms indicating a short on the main board.
The schematic shows the P-ON+21V is input to five regulators on the main board that have decoupling capacitors for each one. The 4.7uF 0805 ones could potentially short. You will need to remove C3943, C3645, C3616, C3674 and C3625 to determine which one is shorted. It is advised to replace all of them. Digikey part would be 1276-6722-1-ND (4.7uF 35V X5R 0805)
The LG LN series is probably the most common model I perform LED backlight repair and replacement on. Symptom is typically the backlights flashing momentarily on power up or plug in before an error is detected causing the backlights to shut down.
In most cases, the panels use strips labelled L1 & R1 and L2 & R2 with 3 black dots and thin lenses and the LED themselves can be replaced with 3V 2835 ones.
I recently encountered a 50LN5310 with a slightly different panel and LED strips. Shopjimmy indicates there are 2 different strips that could be used on this model. On disassembly, the screws for the metal bezel holding the panel in place were different and the side tabs on the panel were taped to the plastic bezel holding the diffusers. The LED strips used the thick style lenses and measuring the LEDs themselves indicated they were the standard LG 3V 2835 type. If you try to remove a strip, you will likely pop off the lenses so it is recommended to replace the LED with the strip attached to the chassis.
On the TV I worked on, many of the lenses were loose and ready to fall off. It is recommended to keep the exact same orientation and have the lens perfectly centered on the LED when gluing it back on. I have been using 5 second fix glue recently since you can adjust the lens and check it before curing it with the UV light. The glue is fairly cheap on ebay shipped from China. If the lens is not perfectly centered, it could create bright spots on the screen. If the lens falls off, it will create another bright spot.
This TV would show the power up logo for about 10 seconds before shutting off. Normally, the logo shows for a couple of seconds before turning on. With backlight failures, the logo flashes briefly before the backlight shuts down.
TV’s not booting or stuck on the logo is usually a symptom of bad or corrupt firmware or a bad eeprom. If the firmware can not be reloaded, the only option is to replace the main board.
This model appears to be a Canadian model and used main boards are very scarce and expensive. A tip on badcaps indicated a 55LB6100 main board should work.
My exact model was 55LB5800-UG.ACCWLJR part# EBT63056403 and I bought a main board from 55LB6100-UG.BUSWLJR part# EBT62902106 ($45 USD). It fit and worked perfectly.
Make sure the date/time is correct. Set the date/time under Menu->System->Time->Clock
Make sure DNS is correct. I would try to go to Netflix.com in the web browser to verify it is working. If it doesn’t connect, check the setting under Network->Network Status. Change the DNS to manual and set to 126.96.36.199
Reset the Smart Hub. In the Smart Hub screen, press Tools->Settings->Reset. Pin is 0000.
Reinstall Netflix app. Under the Smart Hub and Netflix selected, press Tools->Reinstall.
What finally worked for me was signing out of Netflix with the instructions in the Netflix help page. On the error screen, press Up, Up, Down, Down, Left, Right, Left, Right, Up, Up, Up, Up A deactivation screen should come up. If it doesn’t, try again. Click on the option to Deactivate. You need to use this combination to sign out of Netflix even when it is working. https://help.netflix.com/en/node/57687
I picked up this Vizio with a dim screen and I was pretty sure it needed new backlights. With a TV that big and still valuable, I decided to do a full replacement with new strips from Shopjimmy. Shopjimmy has a video for this repair but there are some corrections needed in their video.
There are clips holding the back cover in place and you will need a putty knife to push them in to release the back cover
The panel is held in place by brackets and these are on all four sides. I initially missed the ones on the sides.
I removed the diffuser sheets together with the white plastic bezel and tried to keep it all together to simplify disassembly.
The white plastic rivets holding down the reflector sheet and strips can be removed from the top with a putty knife. The standoffs don’t need to be removed.
There are strips of double side tape holding down the reflector sheet. You will need work carefully to not damage the sheet too much.
It appears each strip is individually powered for local dimming. I only found 9 shorted LEDs out of 96 so they could have been repaired. 9 out of 12 strip had one bad LED. It appears the whole strip is shut down if there is a shorted LED on one.
When replacing the panel there is some black tape at the top. Make sure it in on the outside of the plastic bezel or else it might fold itself in to the viewing area.
There also side tabs that are covered by tape. Make sure they are covered again during assembly.
I have recently gotten a hold of several Samsung TVs with bad backlights. Unlike LG TVs which shut down the backlight if failures are detected, Samsungs will continue to run leading to failure of almost every LED. Damage to the power supply could also occur. For most Samsung TVs, disconnecting the cable from the main board to the power supply board should light up the backlights. Here is a list of models and the corresponding LED strip part numbers I have encountered .
UN40EH5300FXZC, UN40H5203AFXZC – both use a 3 strip setup with 2 angled strips and 1 straight strip. Part numbers LM41-00001V/ LM41-00001W or D3GE-400SMA-R2/ D3GE-400SMB-R2
UN46H5203AFXZA, UN46EH5300FXZC – LM41-00001X / LM41-00001Y or D3GE-460SMB-R1 / D3GE-460SMA-R2 or BN96-28769A / BN96-28768A I have encountered damage to power supply BN44-00771A (traced to a bad diode D9801C) on one TV.
UN50EH5300FXZC – D3GE-500SMA-R3 / D3GE-500SMB-R2
UN55FH6030FXZC – BN96-28772A / LM41-00001P
UN60ES8000FXZC – Edge lit 10 pin connector wired in 4 banks of 22 LEDs (88 total per side). Should measure around 67V per bank with LED tester. 2012SVS60 7032NNB 3D LEFT88 RIGHT88
This TV attempted to turn on (the front LED would flash) but there was no backlight. With the main board cable disconnected from the power supply board, the backlights came on confirming the power supply and backlights were good. This test indicated the problem was with the main board. Searching the part number BN94-05113J on ebay found a few expensive used boards and one repair service indicating the board suffers from BGA connection failures on the main processor. Shopjimmy had a long list of substitute boards and I was able to find a more reasonably priced one searching the BN97-06022A part number. This board part number was BN94-05038B and was from the 40″ version of this TV UN40D6000SF.
With the new board installed, the TV turned on and also didn’t need anything changed in the service menu.
This model didn’t have built in wifi (requires dongle or wired ethernet) and youtube is no longer supported.
This TV turned on but the backlights were very dim. Disconnecting the cable from the main board to the power supply board had the backlight light up but at the same dimness. Probing the connector to the LED strips with an LED tester got very low voltage and unusual readings. Searching the power supply part number BN44-00771A on Shopjimmy got a warning that this model was prone to LED backlight failure.
With the TV apart, I could test the strips directly and over 50% of the LEDs had failed. Some were visibly black. I have found new replacement strips on Aliexpress (search 2013SVS46) which have been ordered.
With Samsung TVs, the power supply appears to not shut down the backlight when there is a LED failure unlike with LG TVs. This appears to lead to a higher number of LED failures since people will continue using their TVs. Hopefully, there is no damage to the power supply board with so many shorted LEDs.
I previously had to do a full backlight replacement on model UN50EH5300F with one or two LEDs out on every strip.
Update: The strips came in and TV has been repaired. I checked the screen settings and the TV had been running in Dynamic mode which runs the backlights at maximum brightness. There is an option in the settings to apply the picture settings to all sources when I reduced the backlight level to 12.
The LED strips I purchased from Aliexpress were from seller KCLCD Store and the brand is Rzconne. It was shipped using tracked epacket.