TCL 43S435 NO BACKLIGHT ISSUE, LEDS TEST OK

[thetonywarren]

I have a TCL 43S435 with no backlights. I contacted ShopJimmy and they said power supply. I got replacement power supply, but still doesnt work. I have confirmed that there is an image with flashlight test. I have also verified that the led strips work when I probe them with LED tester. Any ideas would be helpful. I am also geting a double blink on the status led when trying to turn it on......Nothing on the power supply looks suspect, and caps look ok. Where should I start to test......Thanks!

[EazyBone]

Just because they light up doesn't mean there isn't a bad one. How many volts does it light up as? If a second power board didn't fix it I'd be looking at the lights. Sometimes one will light up dim with the led tester and then when under load from being plugged in it won't work. I'm gonna say this is what's happening here.

But it's generally one of the other.

Sometimes a diode goes bad and shorts out and can be the cause. I don't see them near your lights but can check this one also just to see.

[thetonywarren]

When I tested the output to the LED strip, they were around 114V, that's for the ones installed in the set. I also checked the brand new set that I purchased as replacement, if needed. They were also around 114V.......I'll check the diode....

[thetonywarren]

All diodes highlighted in red boxes checked out ok. I also tested the new led strip and it looks to be 114-115v when tested. Existing shows 114-115 as well.

[lotas]

The connector itself provides power for the backlight when turned on with the backlight connected and when the backlight is turned off.

[thetonywarren]

Yes, understood, this is what happens when I plug that connector in and try to power on the set. See video link below.

https://youtube.com/shorts/dtmpVzL3umw

[lotas]

You can upload the video here, because we have problems with YouTube.

[thetonywarren]

Try this video.

Thanks!

[lotas]

Try this video.

Thanks!

Yes, I asked about the voltage on the backlight connector, what it is with the backlight off and with the backlight connected, does it appear at all.

[thetonywarren]

With the LEDs disconnected, there is about 44vdc. When you press power, it spikes to about 70vdc, but then immediately drops back down to approx 44vdc. This happens the same when the LEDs are connected as well.

[lotas]

Then try simply soldering two wires to the new backlight, disconnecting the old one and check how the power supply behaves at the backlight output.

[KYBOSH]

Is this a model where the LCDs light up with the mainboard is disconnected from the power supply (like samsungs)?

[lotas]

Is this a model where the LCDs light up with the mainboard is disconnected from the power supply (like samsungs)?

No, I doubt it. The backlight itself or its wires to the TV case may short-circuit, and the backlight driver protection may be triggered.

[EazyBone]

KYBOSH I believe you can disconnect the ribbon to the t-con and the lights will come on. This is how I test Hisense.
But you need to hit the power button to turn the lights on which is usually attached to the back panel.

And lotas that's a awesome idea to solder those.

[nomoresonys]

Maybe look up the datasheet of that 16 leg IC, fortunately you have the same tv to compare it with.