TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

[nomoresonys]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

If none of that works I'm thinking it's a problem with the mainboard, one of the chips is probably bad or has bad connection, maybe a bad mlc capacitor. Open to other suggestions on this mystery, I don't think they are all bad panels or bad driver boards.

[nomoresonys]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

And there's always the simple reset, unplug tv for 5 minutes, press and hold the power button on tv for 30 seconds if it has one, then plug tv back in and try it. Just some simple things to try first.

[nomoresonys]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

If that doesn't help, try, Turn on the tv.

Press the home page button 5 times.

Press the cursor up button 1 time

Press the rewind button 2 times.

Press the fast forward button 2 times.

The tv should start a reset and will likely turn on and off two or three times, might take a while, maybe just give it 15, 20 minutes to make sure or it comes back on whatever it does.

[nomoresonys]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

Hopefully it will start for you at some point, then

disable Fast Tv Start in the power section of the system section in settings if it is enabled.

[cusspide]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

I read the entire post, I have exactly the same problem. I see that there was no solution.

[ngth82]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

Yep. RIP to this TV... onwards to other things. Thank you again!

[budwich]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

:-( and wow... you got some where but it continues to not operate in an expected manner. It is definitely hard to troubleshoot this type of set where there is so much happening between boards / system components... without any service manual.

I am rather surprised that the OS doesn't do anything with the usb port once it is being punched in as even very simple system "acknowledge" a port "intrusion".
This kind of reminds me of problems that people have with the "stupid" one connect box and samsungs.

Anyway RIP.

[CapLeaker]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

thats too bad... but it had to end sooner or later...

[ngth82]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

:-(... I don't think the set like you... :-) I don't believe the main card has fully started up IF the usb port does not cause any light to happen on the a plugged in stick. Check for 5v at the usb plug.

I'm pretty sure i don't like the TV set right now either!

There is 5V on the USB port. Regarding Post #81 about the light blinking on the USB stick - i was using a USB stick that didn't have a light. I swapped to one that does - nothing happens - there is no "access" blinking on the USB stick when you plug it in. It just stays illuminated (e.g. "idle"). It's a SanDisk USB stick.

Anyway, I placed the guts back inside the TV and closed up the cover yesterday afternoon. I turned it on for the last time before i kick it to the curb. -- The screen worked (for that time anyway). I grabbed the USB stick, plugged it in to observe the behavior of the stick and what happens on the screen.

From the USB perspective - the USB stick light doesn't show "activity." when you plug it in - again, it just stays illuminated -- "idle." The TV screen doesn't show anything indicating that an update is in progress or that it detected a USB stick was inserted with an update file. I had to manually go into the settings and find the software update menu.

From there, i selected the offline update option, THEN it read the USB stick (the light on the USB stick flashes accordingly). The screen then gave me the 12 digit code. (See Pic1).

I entered this code on the tvupdate.roku.com website. It gave me a 6 digit response code that i entered on the TV. (Pic 2, Pic3). Then it updated.(PIC4) When it got to 100%, it had a "update successful" message followed by indicating that it will reboot.

Well... after the reboot, i was back to the same non-functioning screen state. The TV was still "ON" (i can hear the clicking sounds when i increase/decrease the volume).

I think I'm done with this TV. Thank you for the help and suggestions and for being persistent through the last two weeks. I really appreciate it.

[budwich]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

:-(... I don't think the set like you... :-) I don't believe the main card has fully started up IF the usb port does not cause any light to happen on the a plugged in stick. Check for 5v at the usb plug.

[ngth82]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

I haven't been able to get this TV to turn on correctly again. It may be the end of the line

Budwich - negative, this TV has not been connected to my wireless network (BUT it does have a wired Ethernet port on the main board. I can try hooking that up and looking at my DHCP tables to see if this thing pulled an IP address. I can put a packet sniffer on the network too and see if it "phone's home" to TCL

[budwich]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

One other question: has either card ever been attached to a valid network?

[ngth82]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

Hey CapLeaker / I tried heating up the board before and cooling them down - no difference as far as I can tell. I tried it again this evening. No dice.

For heat, I used a hair dryer and went back and forth on the slender panel PCBs.
For cooling - my only option is to move it to the garage (or boards go in the fridge). I don’t have cans of compressed air (only a compressor in the garage.. way more economical) Cooling didn’t do anything.


As previously mentioned, the tv appears to work “more” when it’s cold / hasn’t been turned on in a while. But no such luck today.

[budwich]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

ngth82, I think you missed something maybe... I thought you said that when you plugged in the usb, nothing happened at the usb. IF the usb is "light capable", then the light will flash IF any attempt is made by the system to access the drive. IT can't do that to "validate" the file and show you a code IF the drive is never accessed.

As far as "blind" is concerned, navigation of screens can be done if you find the sequence or see a layout of the screen on the internet. The sequence appears to be:
"Using the remote control, press the Home button, then select Settings > System > System update > I can’t connect." So that is half the puzzle, just need some "captured menu maps" or even a youtube "helper".

[CapLeaker]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

I see you guys aren’t giving up yet! So I do have a suggestion:
Did you try freezing or heating any components on the little skinny board with the tab bonds?

[ngth82]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

Hi Budwich -

No, I did not try the firmware load sequence (e.g. manually going through the menus on the TV) since i'm "blind" without the display working. Per the instructions, it won't actually update until you get the 12 digit "check code" and the 6-digit "response" code

Per the manual, the 12 digit code appears to be an "interlock" of sorts. Page 122 of the manual (LINK):

• Step 4: When the download finishes, take the USB flash drive to the TV and plug it into the USB port. When you do, the TV validates the files on the flash drive and displays a 12-digit code.
  
• Step 5: Write down the code and the web address, and take this information back to your Internet-connected computer.
  
• Step 6: On the 12-digit code page, enter the code your TV displayed, and then click Next (This is what i call the "check code")
  
• Step 7: On the 6-digit code page, write down the 6-digit code that appears, and then take it back to your TV. (this is what i call the "response code")

"12- and 6-digit codes The USB update process uses a pair of codes to validate that you are authorized to install an update, and to ensure you are not attempting to install an old, unsupported version of the system software."

• Step 8: Using the TV remote control, select Next to move to the next screen, and then use the on-screen keyboard to enter the 6-digit code. When finished, select OK. The system update begins. Do not remove the USB flash drive until the TV restarts.

Holy moly, thats one way to keep people from messing up the update.. TCL/Roku's version of checks and balances. The firmware update experiment will have to wait until the display decides to work again. No luck at the moment.

[budwich]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

ahhh.... they appear to have a very interesting "protocol" to prevent loading of software either by choice or accidentally. I suspect the code causes a "launch exchange" between the roku (got the spelling right) module and the roku server system which maintains "compatibilities" among other things. So unlike other sets, it does even attempt to access and read the usb at the lowest level to see what's on it. Having said that, you did try the "firmware loading sequence" with your remote... right?

[ngth82]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

good on you... I couldn't determine the 4 digit number plus letter to get that far.

Not sure what you mean about the web site want a 12 digit number... have you tried plugging in the usb?

Further, a while back I suggested you "finger some of the smd devices on the edge board during your testing ... especially in and around caps to see if they change anything... have tried any of that? your response at the time was you "fingered that tab" with no improvement. Another set / thread had a person cause imaging to show up with an "accidental touch" of some of the SMD's... hence the suggestion.

Hey budwich -
Please see the screenshot from the Roku site. Not sure what they want from this. I tried plugging in the USB with the update.roku file the root directory.

When i plug in the USB, there is no behavioral difference for the status LED - nothing happens (the LED remains off).

Regarding touching the caps / using my fingers as extra capacitance - I've tried that and the result didn't do anything different. Thanks for the follow up.

[budwich]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

good on you... I couldn't determine the 4 digit number plus letter to get that far.

Not sure what you mean about the web site want a 12 digit number... have you tried plugging in the usb?

Further, a while back I suggested you "finger some of the smd devices on the edge board during your testing ... especially in and around caps to see if they change anything... have tried any of that? your response at the time was you "fingered that tab" with no improvement. Another set / thread had a person cause imaging to show up with an "accidental touch" of some of the SMD's... hence the suggestion.

[ngth82]

Re: TCL 55S405TBBA - backlights on, no video; T-con and main board replaced.

As far as firmware updates go: i don't see it directly on the TCL website.

The tvupdate.roku.com site, however, offers what appears to be an update for their FW package... go to: https://tvupdate.roku.com/index?p=ve...CL&model=7105X

Step 1 - Brand - TCL; then type in model number 7105X. A dialog box confirms if the TV model is a 55S405... i chose "Confirm"

Step 2 - I downloaded the latest software. (an update.roku file)

Step 3 - This is where i get stuck. The website wants me to type in the 12-digit code that appears on the TV screen when i plug in the USB drive.

The labels on the main board don't offer help here as far as FW/SW versions go.

The screen doesn't want to cooperate so far today... i'll try continuing with the update the next time it displays video.