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Old 04-12-2021, 03:00 PM   #1
thelug
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Default TCL 65S4 Backlight Troubleshooting

Good afternoon, I have a TCL Roku TV 65S4 with a service number of 65S4TDAA. I searched and didnít find any posts about this TV.
Device was working properly no issues. One day screen randomly went black. I noticed ghosting symptoms of the back light being out. I power cycled and was doing some troubleshooting and it turned back on and was fine for 6+ months. It went out again last week and wonít turn back on like it did the first time. Sound and picture as expected, just no back light. I have tried the reset and power drain steps. If I fully drain the power when unplugged, when it is powered back up it will power the backlight and the TCL logo shows and appears to work then immediately (less than 2 seconds) the lights turn back off. I got a known working power supply board from another TV and tried swapping it and the symptoms are still the same. Since the sound and picture still work, I donít believe it is a TCONN board, but since the lights turn on after a power cycle, I am hesitant to think it is the back lights themselves, but I am a computer guy not a TV guy. I am comfortable with boards and ribbon cables etc, I have replaced TCONN and power boards before successful, but this is my first possible bad backlight and wanted to know the best troubleshooting steps since the light turn on for a moment then off. Any help would be greatly appreciated.
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Old 04-12-2021, 06:13 PM   #2
neilc6
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Default Re: TCL 65S4 Backlight Troubleshooting

Backlight issues are almost always caused by bad backlights. Protection circuitry is kicking in to shut them down because an error is detected. https://techhometravel.com/lg-ln-ser...ed-backlights/
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Old 04-12-2021, 07:17 PM   #3
thelug
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Default Re: TCL 65S4 Backlight Troubleshooting

Quote:
Originally Posted by neilc6 View Post
Backlight issues are almost always caused by bad backlights. Protection circuitry is kicking in to shut them down because an error is detected. https://techhometravel.com/lg-ln-ser...ed-backlights/
Thanks for the info... So that is LG specific and also mentions the Samsung and a few others. Is it similar for the TCL? Can I find a repair / disassembly guide for my TCL version? I see mixed info on if itís worth replacing on bigger TVs.
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Old 04-12-2021, 08:00 PM   #4
neilc6
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Default Re: TCL 65S4 Backlight Troubleshooting

Very difficult to disassemble a 65 inch panel without damaging it. Suction cups may help. All tvs are very similar. Differences will be if screws are used versus clips and if double sided tape is used. You may find a video for TCL models if you search.
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Old 05-04-2022, 12:18 PM   #5
JohnyRuffneck
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Default Re: TCL 65S4 Backlight Troubleshooting

Hello there,
I'm dealing with the same situation myself , I'm wondering if you had luck with it.
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Old 05-04-2022, 10:43 PM   #6
Storyteller12
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Default Re: TCL 65S4 Backlight Troubleshooting

I just replaced the backlights in this model. It’s definitely the backlights causing your issue.
The screen is difficult to get out since they used double sided tape. Have to be careful not to break the screen removing it.

Other than that it’s straight forward backlight repair.
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