Your UE50TU8005K is probably similar to North America model UN50TU8000
https://www.youtube.com/watch?v=6mm5zQSD_DM
which has T-Con on main board, single flex to left panel board, flex from left panel board to right panel board. This kind of T-Con connection doesn't allow testing of left and right panel board independently so finding which side of the panel is shorted is difficult.. If fault is in left panel baord, there is no way to disconnect it and just test the right panel....
howardc64
Badcaps Veteran
Last Activity: Today, 02:20 AM
Joined: 06-03-2017
Location: Seattle WA
-
Leave a comment:
-
Probably good to clarify what is "blinking" but sounds like you've not seen it. Backlight blinking and LCD panel blinking would be very different problems.
Those 4 diodes you changed looks fairly close to the backlight output connector and after the backlight voltage transformer. I'd guess they are on the output path to the LED power rail. I recently fixed a LED TV PSU with shorted diode in the backlight output path ( barrier rectifiers link ) I ended up replacing the entire board set (main, zoned LED driver, PSU) due to Samsung's firmware update that killed the dimming...Leave a comment:
-
Yes thought about similar. Did this (no change to the lines) and unfortunately seems to have developed another problem. Left 1/2 of the screen now has a white color overlay (with and without TVS) Not sure what caused it. This panel does have some strange behaviors. Have seen it go from no screen error (other than lines) to screen error back to no screen error without changing anything.
Trace the likely white overlay 1/2 screen to the base voltage of couple of transistors after discovering really hot resistor and COF (mp4 file attached) Transistor Q002 is putting out 14V across 100...Last edited by howardc64; 07-26-2025, 08:18 PM.Leave a comment:
-
TCL 55S425 few horizontal lines, potential failure on both side of panel/buffer board
All left and right refers to looking from rear of TV (or looking from front with TV upside down)
- TV came with vertical bars and no image. Found faulty TVS on left buffer board. Also replaced T-Con (may have damaged the original while hot air removing components, board has slight warp) and have full image but few horizontal lines on the screen. Some of the lines appears to be 2 pixel tall while others are 1 pixel tall.
- Disconnecting left and right buffer board potentially reveals problems on both sides with different signals (unless this T-Con require jumper like Samsung FB_TRDY1&3) Fault
Last edited by howardc64; 07-24-2025, 05:53 PM. -
Samsung UN55NU7300F Curved TV. Half side backlight out. Fixed by just removing the rear snap cover
TV was fixed just after removing Samsung's rear snap cover.
This curved TV's construction is rather interesting. When the snapped on back is removed, rest of the TV will relax the curvature. Top of LCD panel is loose as it wants to straighten out against the slightly curved bezel. Snapped back provide most of the curvature shape. So just simple disassembly of rear cover will allow the rest of the TV frame to relax its curvature. Thats probably what fixed it but no idea which connection. 4x LEDs are edge lit.
Maybe PSU->backlight connector didn't have a good contact?... -
Yeah, thanks for the hint. The video you shared also shows masking LC1 LC2. Don't know what are equivalent Samsung signals. Regardless, the T-Con connector signal spec in this TV's service manual is incorrect so need some detective work to find them. Curious if that'd improve the few not so noticeable lines I have remaining....Leave a comment:
-
UPDATE : Fixed enough to be useful. Don't know how long it will last or if faulty side panel color can be improved.
- All 6 pairs of CKV CKVB lines (12 total) masked
- All 6 pairs of CKV CKVB lines jumpers at TVS
- Faulty side has color fade and lines
- Service Manual T-Con connector labeling is likely wrong for 75" (probably also 85?) panel
- Making some guesses on clock line short failures
The Service Manual left panel T-Con connector CN1300 is likely wrong. Able to trace ~9V on all CKV* signals to determine the missing CKV*[5-6] pins (21-24) These...Last edited by howardc64; 07-22-2025, 02:48 PM.Leave a comment:
-
Unfortunately masking 8 CKV* lines and shorting their TVS connection didn't work for me
- masking CKV[1-4] and CKVB[1-4] and shorting all their connections on TVS didn't help. Picture got an extra line when 8 CKV* lines were masked
- TVS connection to CKV5 and CKVB5 has no T-Con connection on CN1300
- CKV6 connects to CN1300 pin 21 STVP1_GOA (but not pin 20 which is also STVP1_GOA)
- CKVB6 connects to CN1300 pin 22 ST_GOA
- Clearly CN1300 signal labling in service manual is wrong for 75" panels.
- Masking CKV4 and CKV4+CKVB4 shows identical line pattern on screen. So masking CKVB4 does nothing.
Leave a comment:
-
Thanks! I actually did find these data sheets but couldn't understand the buffer board circuit. pin 4,5,6 are all connected to ground on every TVS (4x on left and right buffer board) I guess only 3/5 channels are used on each TVS. Thanks again for confirming the TVS spec....Leave a comment:
-
Thanks. Before anyone suggest. Just traced the CKV4_GOA signal to the TVS (Transient Voltage Supressor diode array, marking is E5 4(side ways) in SOT363 package, could'n't locate data sheet) and removed it. Fault is unfortunately in the COF/panel. Studying more on CKV*/CKVB* before trying the mask all CKV* lines and short their ESD diodes. Buffer board shows 12 CKV lines (CKV[1-6] CKVB[1-6]) but service manual T-Con connector (CN1300) list only 8 (CKV[1-4] CKVB[1-4])
...Leave a comment:
-
Thanks. Interesting trick.
I tried also blocking the CKVB4 but no difference so removed it.
Was it necessarily to block VGH VGL?
Finally I wonder if can block and short less CKV* lines to get good image. Will study more....Leave a comment:
-
Samsung QN75Q6FNA backlight no display, red LED blink 2x, fault in panel
- Prior owner tried a replacement main board. No difference.
- Samsung 2x red blinking standby LED = panel fault
- Jumpered FB_TRDY_1 (pin 1 CN1300 left. main tcon->left side buffer boards) and FB_TRDY_3 (pin 95 CN1301 right. main tcon->right side buffer boards) This allows testing individual T-Con (on main board) connection to panel on this Samsung. Found fault on left side (viewing from rear of TV)
- Each side has 2 buffer boards, disconnected left side flex between 2 buffer boards. Fault is on the left most board.
- Tape masking eventually isolated to CN1300 pin 15 (CKV4_GOA) Display
Last edited by howardc64; 07-20-2025, 12:11 AM. -
This review claims 54 dimming zones. Can't find any details on SONY website. Can't seem to find LED strips for these.
https://www.rtings.com/tv/reviews/sony/x90k-x90ck
I've taken apart an XBR-65X900F with 2 dimensional dimming zones. LED strips require much more complex flex attachment to be able to control the 2D dimming zones. Here is shopjimmy's backlight pictures ( link ). You can see a flex connector for each of the 10 row LED bars to be able to control individual LEDs on each row independently. Here is a video of the 65X900F backlight system
https:...Leave a comment:
-
I got some before from aliexpress that seems to work pretty well. No idea if genuine. Search "3M 5952 4mm" Probably good to check the width after cutting the screen open.
On no bezel LCD panels, here are some dis/reassembly notes- 2012+ iMacs also use double sided tape to glue on screen. A plastic pizza cutting wheel tool is used to cut open the iMac screen. This is probably more desirable than a non rolling cutting tool to minimize producing debris on the back (clean) side of the LCD panel that has to be ultra clean.
- I took the time to painstakingly remove the old tape
Last edited by howardc64; 07-18-2025, 02:32 PM.Leave a comment:
-
Generally, not all pads are stuffed with components.
Unfortunately, the section is below bottom heat sink so not many pics show such area
https://www.shopjimmy.com/vizio-756t...masnar-serial/
You can go through posts for searching "M65-C1" on badcaps.
https://www.badcaps.net/search?q=m65...22m65-c1%22%7D
These ~2015 era Vizio main boards with BGA failures all look similar. Here is a video for heat sink removal but probably too low resolution and blurry...Leave a comment:
-
This connection path is harder to diagnose which side is bad because right side (looking from back) buffer boards signal goes through the left side. So no way to disconnect the left side and see if right side imagine is okay. Only if the fault is on the right side, then disconnecting it can potentially it’s the half containing the failure....Leave a comment:
-
I usually put tv on bed /carpet upside down (often the fragile buffer boards / flex is exposed during diagnostics ) then not too hard to hold it vertically or lean against the wall. makes navigating menu a little difficult
...
Leave a comment:
-
Thanks, I pulled dumps from the 8pin Winbond.
The other chip you pointed out that is programmed is interesting. Its a Transceiver FPGA ARTIX 7 XC7A50T by AMD (orignially by Xilinx which is a major FGPA producer acquired by AMD in 2022) Device summary below (pg3) These FPGAs are designed to transmit high speed signals across long distances (a hard problem, higher the speed, more signal delay variation from wire length even board level trace lengths ) They use typical differential signaling etc. XC7A50T has 120 differential signal pairs. I guess LED dimming is probably accomplished...Leave a comment:
-
Thanks for the hint. These are high end Samsung TVs (neo QLED series) and still under 3 year warranty. Most of the failure repairs are just warranteed Samsung service or refund. Samsung support said no older firmware is available and I didn't find anyone posting FW 0000.0 for this TV. Since I got the TV for free after Samsung failed repair attempt and refunded prior owner, Samsung support repair is unavailable for me.
Dumped the Flash ROMs on the original and replacement LED driver board (attached) to compare and has many differences. This board has complex chip including processors...Last edited by howardc64; 07-17-2025, 04:46 PM.Leave a comment:
No activity results to display
Leave a comment: