TCL 55S401 Backlights, no image, responds to buttons

[DXseekerMO]

So this TCL 55S401 I got today has backlights, no image on screen but responds with audible clicks when I press the buttons. I tried another t-con but no change in status.

When I detach the FFCs one at a time from the T-CON to the Source Driver Boards I expect that side of the screen would be white, but when I do this both sides remain black (or blue with the backlights) with either FFC detached.

The t-con has 12v going to it and the processor is very warm to the touch in short order, but the processor on the Main Board seems cool/ambient temperature.

I've never seen a full black screen when the FFC's are detached individually. Does this suggest the main board has a problem, or does anyone think the screen is likely the culprit?

This TV is hardly worth putting much time and money in so I'm hoping for the short answer...if anyone has any ideas?

Thanks everyone!

[budwich]

Re: TCL 55S401 Backlights, no image, responds to buttons

you are going to have "fun" trying to isolate the problem with these sets. They are "roku based". It appears that the main processor "talks" to the tcon which does checks on the panel. IF anything is out of sorts in that "comms", the set does not produce any thing on the screen. There have been a couple of posts that were unsuccessful in getting any where at "high level troubleshooting" of them because of lack of detailed circuit information. Basic checks done on voltages at the tcon and edgeboards provide some potential to determine if there is obvious failure but that's about it. In the thread that I am aware of, the OP tried both tcons and main boards and had some "ups and downs" with the set some times showing a display and then not happening thereafter for whatever reason. The set ended up at the recycle (cards probably removed).

[DXseekerMO]

Re: TCL 55S401 Backlights, no image, responds to buttons

you are going to have "fun" trying to isolate the problem with these sets. They are "roku based". It appears that the main processor "talks" to the tcon which does checks on the panel. IF anything is out of sorts in that "comms", the set does not produce any thing on the screen. There have been a couple of posts that were unsuccessful in getting any where at "high level troubleshooting" of them because of lack of detailed circuit information. Basic checks done on voltages at the tcon and edgeboards provide some potential to determine if there is obvious failure but that's about it. In the thread that I am aware of, the OP tried both tcons and main boards and had some "ups and downs" with the set some times showing a display and then not happening thereafter for whatever reason. The set ended up at the recycle (cards probably removed).

Thanks for the reply Budwich, I did see that thread and know it didn't turn out well. Too bad these TVs are turds!

[DXseekerMO]

Re: TCL 55S401 Backlights, no image, responds to buttons

So for now this TV is going in the "repairable" tv rack....with the hope I'll get the same model in for parts someday.

[BradW]

Re: TCL 55S401 Backlights, no image, responds to buttons

Well, 2-years later and it looks like TCL TV's still have this issue. I have TCL 43S525 with exact same symptoms. (Manufactured June 2020)
Backlight Ok, seems to boot up and audible dings when pressing buttons. But no picture.
Just starting troubleshooting so nothing to add yet.