Category Archives: TV Repair

UN58H5202AF Flashing Backlight No Video

UN58H5202 UN58H5202AF UN58H5202AFZXC UN58H5202AFZXA

This model suffers from backlight failure that pops a transistor on the power supply leaving the tv dead. See post here. This tv had different symptoms with a flashing backlight and no video.

I opened up the tv and the majority of leds had burned out so I replaced them with used strips I had salvaged. With the main board unplugged, the backlights came on. With the main board plugged back in, but panel still disconnected, the tv went through the normal start up processs when turned on. I reassembled the tv and it still did not display a picture. Suspecting a bad panel, I was able to get a picture with only the right side tcon cable connected indicating a fault on the left side of the panel. I checked the left side panel board for shorted chip caps but didnt find any. Next, I tried blocking some of the left side tcon flex cable with tape (“tape cutoff method”) but that didnt work either. As a last resort, I ripped off all the side tabs on the left side of the panel and was able to get a good picture.

I’ve only done this once before on a Sharp 60 inch tv but it only lasted a month or two before the panel had other issues.

Sony KDL-55EX620 Dead 10 Blinks

I previously repaired this model with 2 blinks by replacing some mosfets here. This one appeared dead with no standby light and it didn’t turn on. A service manual and service/training manual can be found online. Checking for standby voltage, both 12V and 3.3V were present on the main board. I also checked all the fuses and regulators and they all were good.

Searching the main board part number, I ordered one from an online tv parts supplier. When Sony main boards are replaced, the firmware needs to be updated.

Downloading the firmware from Sony’s website, I extracted the file and subfolder onto the root of a FAT32 formatted USB drive. I did have some trouble getting the firmware to update but what worked for me was turning the TV on which flashed green and amber. I then plugged the USB in and after a few minutes if flashed red and amber. Instead of rebooting, it blinked an error code. With the USB unplugged, and the tv turned on again, the tv flashed on for a second before giving me a 10 blink error code. I tried going in to the service menu, but couldn’t because of the error.

The service manual had no listing for a 10 blink code so I was stuck. I suspected that the main board had to be configured for my panel so purchased another main board from a KDL-55EX720 which uses the same panel. This model is 3D and has a higher maximum refresh rate.

When I installed the second board, the tv flashed the same 10 blink code but I didn’t need to update the firmware. Looking at the service manual for the KDL-55EX720, it had an entry for the 10 blink code – Emitter Error. The flowchart indicates to check the HEM2 board. Looking for the HEM2 board on my TV, I didn’t have one. The HEM2 board is for mounting IR LED emitters connected to the tcon used to sync with active 3D glasses. The schematic for the HEM2 board shows an EMI_FAIL pin which I assumed would trigger the 10 blink error. It is either open collector or at ground.

I ordered a HEM2 board with cable from ebay but decided to see if I could get the tv to turn on by grounding EMI_FAIL (pin 7) on the tcon board. I had to ground it before plugging in and kept on grounding it to prevent the 10 blink code from reappearing.

Multiple versions of the Sony model use the same main board and firmware. So it appears if the main board was configured for a 3D one, it will be checking for the EMI_FAIL signal and produce a 10 blink error if the board is not installed.

Most board sellers group all the boards together since they have the same part number so you will encounter this issue if the board is configured for a 3D TV and you are trying to install in an non 3D model.

Toshiba 58L1350U Backlights Flash

Canadian model number is 58L1350UC. Power supply part number is PK101W0220I.

I had previously repaired this model with a shorted power supply transistor here. On this tv, the backlights would flash on power up which is a sign of bad backlights. I ordered a full set of backlights since the owner said it had been previously repaired and it may have been run at maximum backlight level.

With the TV opened up, I found one out of five strings with multiple led failures. I replaced all the strips anyways. With the new strips installed and the tv plugged in but off, the string with the previous failed leds glowed. When turned on, the backlights did not come on.

Checking the LED controller circuit on the power supply board, it appeared each strip was individually powered and controlled. I checked all the transistors in the circuit and they all appeared good. I suspected the bad LEDs damaged the LED controller IC OZ9908BGN. I was able to find a replacement on Aliexpress.

Once the part came in, I did have a lot of issues soldering the IC since the part was probably old and there was poor solderability on the pins. With each pin tested for continuity, I finally got the TV to power up with all the backlights staying on.

Samsung LN40B500P3F Backlights Flash

Model LN40B500 LN40B500P3F LN40B500P3FXZA

When turned on, the backlight would come on for a second, turn off and this would repeat for a couple of times. Power supply part number is BN44-00264A. Schematic is available online. This badcaps thread indicates potentially bad transfomers on the inverter or bad ccfl bulbs in the backlight. I hooked probes to the main filter cap to monitor the PFC voltage and it was steady around 390VDC throughout. The thread indicates to connect a wire to pin 10 of the UI801 to see if the overvoltage protection was being triggered from faulty bulbs. This signal was high when the backlights were on confirming the fault. The thread also mention to bypass CI805 on pin 2 which should keep the backlight from shutting off. This modification worked as well. I put a plain white image on the screen and could verify a few bulbs were dim and triggering a fault.

Since the LCD TVs are becoming old and obsolete, I decided to scrap the TV and was able to use the main board on a LN46B500 TV I had.

Samsung LN46B500P3F Doesn’t Turn On

Model LN46B500 LN46B500P3F LN46B500P3FXZA

This TV had a standby light but didn’t turn on. With the main cable unplugged from the power supply, the backlights turned on. The main suspect in this scenario is the main board. Searching for the part BN94-02746Z on ebay yielded some expensive boards and an eeprom from Shopjimmy. I tried freezing the eeprom but the TV didn’t start but I bought a new eeprom anyway. After installation, it still didn’t work. Shopjimmy indicated BN94-02746L was a substitute part but I couldn’t find either at a reasonable price. Searching without a suffix showed BN94-02746Y from LN40B500 may work since the board picture matched but again there weren’t any reasonably priced boards on ebay.

Putting the TV aside, I was able to get a LN40B500P3F with backlight issues and a BN94-02746Y main board. Plugging it into the 46 inch model worked. A second LN40B500 substitute is BN94-02746K.

I proactively replaced four electrolytic capacitors on the power supply board BN44-00265A.

CM858, CM859 – 1000uF/25V
CM852, CM853 – 1000uF/10V

Haier 55UFC2500 No Picture

This TV turned on with no backlight. Google indicates this model suffers from backlight failures but replacement LED strips are not readily available. This set is configured as two strings of LEDs and one open LED was found. It was repaired with a 3V Samsung compatible LED module.

Backlight level can only be adjusted in the service menu under Panel Settings. With the tv on, menu-1-1-4-7. Vivid mode sets the backlight to 100%, Standard is 85%, and Energy Saving 50%. You should keep the TV in Energy Saving mode or adjust Standard mode to 65% which gets saved as User mode. You will need to make this adjustment for all inputs.

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

Update: I encountered another 32LC7D with one bulged cap but the backlight did not come on. Backlight control comes from the pin labelled I-C and there was no high signal from the main board so I replaced the board. The capacitors on this board were also replaced.

C207 – 1000uF/35V
C212 – 2200uF/25V
C203, C208 – 470uF/35V (one is actually 25V)
C215, C225 – 2200uF/10V
C204, C205 – 3300uF/10V
C221, C222, C223, C232 – 680uF/35V