Samsung UN50F6300AF No Picture

Model UN50F6300 UN50F6300AF UN50F6300AFXZA UN50F6300AFXZC

This TV turned on with backlight but no video. Normally in this scenario, the tcon board is suspect. I disconnected the ribbon cables from the tcon to the panel one side at a time and got a good picture on the right side. This test indicates there is a panel fault on the left side. I checked the panel board on the left side for shorts on the chip capacitors but didn’t find any. I next used the the tape cutoff method to block pins on the ribbon of the left side connector on the leftmost side (outer edge). The initial attempt blocking 2-3 pins didn’t work so I used a wider strip. With 5-6 pins blocked, the TV turned on.

Turn Down Your Backlight Level in Roku TVs

LED backlight failure is common in all LED TVs. With Sharp and RCA Roku TVs, turning down the backlight level isn’t very intuitive.

  1. Under Settings-> TV Picture Settings Set the TV Brightness to Normal. It defaults to Brightest I’m not sure if this is controlling image brightness or backlight level but safer to set it to Normal.
  2. With your current input selected (eg HDMI 1), hit * on the remote. Go to Advanced Picture Settings. Set Picture Mode to Low Power, Dynamic Contrast to Off and the Backlight to 60-70. The lower you can tolerate the better. The default for low power is 78 which still seems high. Most picture modes set the backlight at max which will burn out the LEDs.
  3. Repeat step 2 for all inputs you are using and also check all apps (eg. Netflix, Roku media player you are running.

Samsung UN40EH and UN40H LED Backlight Strips

I was doing a led replacement for a UN40H6203AF and ordered replacement strips, but the middle strip didn’t match. These series of Samsung LED TV’s use 3 strips with 2 angled strips and a middle straight strip. Part number is LM41-00001V for the angled ones and LM41-00001W for the straight one. When I installed the straight strip, the holes didn’t match. I noticed there were 12 leds on the strip and I needed 13. Though the angled strips were the same part number, the straight strip was different.

For the 13 led straight strip, the part number is D3GE-400-SMB-R3

LG 32LC7D Slow to Turn On

I don’t see a lot of LCD TVs anymore since they are getting old and obsolete. This one had almost all the 2200uF/10V capacitors bulged. I proactively replaced the 470uF ones as well.

C221, C206, C217, C202, C215 – 2200uF/10V
C222, C226 – 470uF/25V
C203 – 2200uF/25V
C210 – 1500uF/35V

LG 49UJ6500-UB Blue Purple Tint

This 2 year old TV had a blue and purple tint and the backlights were suspected of turning blue. Removing the panel confirmed this colour change happened. Shopjimmy only shows one set of backlights for this model but they didn’t match what was in my tv. Shopjimmy part is 3 rows of left and right strips with 9 LEDs per row and labelled 49UJ65 for panel HC490DGG-ABSR2. My TV has a LC490DGG panel and strips are marked V17 ART3 and there are two rows of 12 LEDs per row.

Update: Seen same issue on 43UJ6300-UA with 3 rows of long strips. They have the same large flat lens.

Update: I popped off the lens to investigate and it appears these LEDs are naturally blue but are covered in a yellow filter. The yellow filter has cracked and crumbled away.

Blue LED Closeup

UN65MU6290 No Backlight

UN65MU6290VXZA UN65MU6290VXZC

I researched this model thinking I could repair it since I had salvaged parts from a cracked screen TV. Apparently, there are two different versions. UN65MU6290F and UN65MU6290V. The V version is edge lit and is very prone to backlight failure. Shopjimmy recommends replacing two resistors to limit the backlight current after LED replacement. This ebay post from a backlight seller indicates bad LEDs can damage the power supply and bad power supplies can damage the LEDs.

“On this model most of time one led strip and power board fail at the same time, to fix this issue you must replace that failed led strip plus power board. If you install this LED strip with failed power board and turn the TV on, LED strip will fail on the spot, also if you install a good power board with bad LED strips the same thing would happen to that power board. “

This ebay listing indicates the LED driver IC IC9101 SEM4082A can fail as well as Q101c and Q201c.

On top of all these potential issues, the back cover is screwless and needs to be pried apart. There are holes at the bottom to insert a tool to start prying apart.

LG 32LK450-UB No Backlight

This LCD tv turned on but without a backlight. Googling found a repair kit for transistors on the inverter board.

Testing the transistors on the inverter board, I found Q103 (Nikos P4004ED PCH, 40V, 21A) shorted and F101 (240V, 7A) blown. Replacing both parts restored the backlight. If Q105 or Q107 are shorted, the part is P2904BD (NCH, 40V, 25A).

Samsung UN55F7050 Won’t Turn On

Model UN55F7050 UN55F7050 AF UN55F7050AFXZC

This model appears to be a Costco Canada version of UN55F7100 UN55F7100AF. When the power button is pressed, the front LED blinks but the tv doesn’t turn on and there is no backlight. Disconnecting the cable between the main board and power supply, the backlights came on indicating the power supply and backlights were good but the main board was suspect. I sent the board to a repair service on ebay and they indicated the board was good. When I got the board back, I tried powering up the tv with one of the ribbon cables between the tcon and panel disconnected and the tv powered up with one side disconnected. This result indicates there is probably a short on the panel. I did measure low resistance between capacitors on the panel board on the bad side but it would have been extremely difficult to trace a shorted capacitor. I also tried blocking some ribbon connector pins with tape and also removed the side tabs but the tv was a lost cause.

Update: It was likely there were shorted caps on the panel board. I should have had the patience to remove and test every one that appeared shorted.

LG 60LN5600 LED Backlight Replacement

LG’s LN series comes in a variety of sizes and variations but they all seem to suffer from LED backlight failure. I did a LED replacement of a 60LN5600 which used the thick style lens but replacement was difficult due to the reflector sheet being glued down to the chassis. It was difficult to remove without stretching or ripping it and I had to tape it back down after I replaced the strips. Some of the new replacement lenses were loose and I had to reglue them back on after they were knocked off.

RCA RTRU5528 No Backlight

RTRU5528 is the Canadian model and RTRU5527 is the US model.

This tv was reported as having no backlights. Opening up the panel, the backlights tested good with an LED tester. There was a standby light and the tv turned on but without backlight. I then noticed a blown up MOSFET on the power supply board. Some components on the back side were also damaged. Checking other components, D401 was shorted as well. I would recommend checking D401 – D404 and checking the main fuse F101. Power supply part number is HSL55D-2S9.

Here is a list of parts replaced
Q506 & Q507 TF5N50 (NCH 500V 5A) Digikey FDPF8N50NZ-ND (8A substitute)
Q504 & Q505 (2T marking) MMBT4403 (PNP 40V 0.6A) Digikey MMBT4403LT1GOSCT-ND
D509 (T4 marking) 1N418 100V 0.3A Digikey 1N4148W-FDICT-ND
R506 240 ohm 1206 Digikey 311-240FRCT-ND
R533 & R528 30 ohm 1206 Digikey 311-30.0FRCT-ND
D401 SF26 400V 2A Digikey 1655-1581-1-ND
F101 4A 250V fuse Digikey 507-1721-1-ND