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TCL 55S405 TJAA 4k TV Question (Replacing the T-CON board)

B_Styles27

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Hello All,

I'm looking to replace the T-Con board of my TCL 55S405 TJAA 4k TV, however for the life of me I'm unable to locate that particular board within the back enclosure of the TV. Per the manufacture, a replacement T-Con board for this specific model can be purchased directly from their parts supplier - which can be found using the link below.

https://encompass.com/item/12426862/TCL/4T-TCN550-CS27/
55s405 tcon.PNG


As you can see in the image below of a similar model 55" TCL TV, the T-Con board should be located between the TV's power supply and main board, and connects to the main board via the L-shaped black ribbon cable that runs along the center of the TV.

TCON.png


When looking within the back enclosure of my TV, I cannot seem to find any such component\board that matches the size\layout of the T-Con board shown in the images above. As you can see below, the black ribbon cable within my TV instead connects to a thin board that runs horizontally along the bottom of the TV - which to my eyes does not resemble the replacement board recommended to me by the manufacturer for this particular model TV (I provided them with my TV's serial number when inquiring about the part). I'm not sure if the TCL 55S405 TJAA model has a different hardware configuration when compared to other 55" TCL TV's of the same series, as it is to my understanding the 55S405 has a TMAA model (55S405 TMAA), and possibly a few others following the 55S405 naming convention. I am more than willing to install the replacement T-Con board myself, however I just want to make sure I'm looking at the right part before making the purchase. If I am simply overlooking the TV's T-Con board, please don't hesitate to call me out. Otherwise, and guidance\insight in helping me locate the T-Con board in question will be greatly appreciated.

TCL 55S405TJAA.jpg

closeup.png


Thanks in advance!
 
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Clearly it's not the board they linked for you.
Check the part in your system for a part number as that strip along the base appears to be it.
 
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Clearly it's not the board they linked for you.
Check the part in your system for a part number as that strip along the base appears to be it.
It appears that it's either a different model or they redesigned the board in your model.

Good luck.
 

B_Styles27

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Clearly it's not the board they linked for you.
Check the part in your system for a part number as that strip along the base appears to be it.

Thanks for the suggestion. After not finding the T-Con board in my system, I also began to consider it may be the strip you mentioned that runs along the base of the TV. I noticed in other 55" TLC TV's (such as the one posted in the first screenshot) the T- Con board generally connects to the base strip(s) via the two ribbon cables located at the bottom of the board - one for the horizontal strip on the left side and one for the right, which are both hidden behind a metal covering. Because of that speculation, I ended up removing both metal coverings from my TV to get a closer look at the strips (see below), but couldn't confirm if the one on the left is actually the T-Con board. I called the parts supplier and provided them with the character string shown on the left strip (below the barcode), but they weren't able to identify the part and again explained the part I need is the T-Con board found via the link I posted initially. I explained to them I'm not seeing a component\board within the TV that matches their replacement boards, but they insisted it is the only board of that nature for this particular model TV (based off the serial number).

20200909_122848 (002).jpg

20200909_123125 (002).jpg


While speaking with the parts supplier, I also inquired about a diagram for the 55S405, and they explained they do not have them on hand (???) and pointed me towards the internet. I was able to find a site that has service manuals\circuit diagrams for TCL TV's, but none of them appear to be for the 55S405. I also looked for the model number of the chassis within the back enclosure of the TV, but wasn't able to find any numbers that match the models listed on the service manuals website (link below).

https://www.smarttvmanuals.net/tcl/

I also found others on the internet that are experiencing the same issue (see link below) with their TCL 55S405 as I am with mine; which is a black screen with a faint image of the onscreen display when the TV is powered on, and majority of the solutions I've seen for said issue point towards replacing the T-Con board. What I find extremely odd is that all other owners I've seen with this model TV have an easily identifiable T-Con board mounted smack in the middle of the TV (between the power supply and main board), which truly leaves me baffled.

https://www.badcaps.net/forum/showthread.php?p=927835

Additionally, I did some light Googling to determine if the TJAA model possibly has a combo board that serves as both a T-Con and main board, but couldn't find anything useful in my searches. Perhaps as @Fangio1951 suggested, there was a redesign of this particular model 55S405 that differs from the majority?? If that is the case, perhaps someone just forgot to leave a memo before these things went into production???

I know I have ventured pretty far down the rabbit hole chasing this rogue part - but I just thought it would be nice to salvage this TV (as opposed to throwing it away) since it's less than 2 years old, and would only cost me a couple bucks and a few minutes of my time to perform what seemed to be a fairly simple repair...but boy, have I been wrong thus far.
 
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Sounds more like the backlight has failed if you have a black screen and the image can be barely seen.
 

B_Styles27

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Sounds more like the backlight has failed if you have a black screen and the image can be barely seen.

I was really hoping that wasn't the case, which is why I wanted to at least rule out the T-Con as the culprit. I'll look out for that the next time I open up the TV. Thanks!
 

Cdthompso1

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Did you find the right part for your 55S405? I have the exact layout inside mine, however my model is identified as TKAA, not TJAA. Black screen with sound leads to the conclusion the the t con board should be replaced but no Google searches can find it. Your post here has given me hope. (FWIW, my model was purchased at Target in winter 2018.)

TCL online support provided 4T-TCN550-CS18
 
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