TCL 65S517 No Backlight, Picture and Sound OK

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I tested them all. Here is an attached picture. the pin with the PINK DOT leads straight to the Surface mount cap that I pictured earlier that I desoldered so it seems to have a weird reading. It took the solder pad with it so....shit. But let me know what you think and where you are headed with this.

I am not above buying another power board but I am not seeing my series for sale. There is a model that looks identical but not sure if it will work. Yhanks for the help as always.

[nomoresonys]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Not bad for a 65: https://www.ebay.com/itm/TCL-65S517-...wAAOSwwMZfRP3W

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I tested them all. Here is an attached picture. the pin with the PINK DOT leads straight to the Surface mount cap that I pictured earlier that I desoldered so it seems to have a weird reading. It took the solder pad with it so....shit. But let me know what you think and where you are headed with this.

I am not above buying another power board but I am not seeing my series for sale. There is a model that looks identical but not sure if it will work. Yhanks for the help as always.

Pin 8 (Status) shows as 0.2 Ohms?
if it is that is not right based on the diagram.
https://www.badcaps.net/forum/attach...9&d=1602826861
Can you see what are connected to pin 8?

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Pin 8 (Status) shows as 0.2 Ohms?
if it is that is not right based on the diagram.
https://www.badcaps.net/forum/attach...9&d=1602826861
Can you see what are connected to pin 8?

That is correct. I tested again and it only show .2 ohm. I included a good pic of that are on the board. It looks like it may lead through the capacitor to the right C612. It also looks like the trace supplies those 2 resistors R6060 and R643 and maybe leads through Z49.

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

That is correct. I tested again and it only show .2 ohm. I included a good pic of that are on the board. It looks like it may lead through the capacitor to the right C612. It also looks like the trace supplies those 2 resistors R6060 and R643 and maybe leads through Z49.

It looks like pin 8 is tied to ground, so that resistance is correct.

Can you leave your Voltmeter (Set meter to 200VDC scale) probes Red on Cathode of D615, Black on Anode of D618 then turn on the TV while watching the meter to see if there is any activity.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

It looks like pin 8 is tied to ground, so that resistance is correct.

Can you leave your Voltmeter (Set meter to 200VDC scale) probes Red on Cathode of D615, Black on Anode of D618 then turn on the TV while watching the meter to see if there is any activity.

Measured the voltage between the diodes. About 5 seconds after i turn it on voltage jumps to about 10vdc then back down to nothing within a second.

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Measured the voltage between the diodes. About 5 seconds after i turn it on voltage jumps to about 10vdc then back down to nothing within a second.

Hmm, that means the power supply is not completely dead since it does puts out something but not high enough to drive the LED strings.'
Please do the same test without the LED connector in place.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Hmm, that means the power supply is not completely dead since it does puts out something but not high enough to drive the LED strings.'
Please do the same test without the LED connector in place.

I have a min/max button on my dmm. When I turn it on without the connector it reads anywhere from 222vdc to 235vdc.

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I have a min/max button on my dmm. When I turn it on without the connector it reads anywhere from 222vdc to 235vdc.

OK, It is putting out the high Voltage as expected.

In your post #1:
I checked the red and white and black and brown cable pins coming from the bottom left PS board (guessing by where they are running these are the LED supply lines) I have 0v on all of those while powered on.

Repeat the test of your post #1 on the LED connector LED connector in place and not in place, make sure to keep the meter probes (Black on chassis, Red on each pin of the LED connector at a time) in place before turning on the TV, do the test on each pin of the LED connector.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

See attached

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

OK, so the Voltage on the LED connectors are not all 0V after all which throw us off on troubleshooting based on the reading in post #1.
The one on LED1+ when connected looks really bad.
Do you have LED tester? At this point we need to test the LED strings.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I have not gotten one yet. Idk what voltage these particular ones take but can I rig something up to test. Man this tv is thin and Huge. im thinking 50% chance it is going to get broke trying to get these out.

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I have not gotten one yet. Idk what voltage these particular ones take but can I rig something up to test. Man this tv is thin and Huge. im thinking 50% chance it is going to get broke trying to get these out.

It is worth it to spend about $25 on the LED tester, if you crack the screen it will be the end of it, taking the panel apart is the last thing you want to do unless you really have to.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Yea it may be time to invest in one. Do you have a suggestion on a decent make/model. I have tested and fixed strips before but in a little 20 something inch. Used a 12v battery pack or something to test back then.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Yea as advertised I accidentally broke this screen pulling it from the bezel. Just knicked a corner and it split. Oh well. I salvaged some parts from the power supply and I got a Vizio coming my way. Did check and there is definitely one if not each one of the LED strips has a short in it, just in case someone reads this for future reference.

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Too bad, it is big panel so it can get damaged easily.
Shorted LED's is probably why the reading on LED+ was very low when connected. I am glad I had you test the Voltage on the LED pins each time you turn on the TV otherwise we would have not caught that the power supply is actually putting out Voltages.

[onyx59]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Hello .
I have a simular power supply on a Thomson tv (tcl) and same size(65inch).
How to shunt protection on OZ9976AGN ?
No (clean)datasheet on this ic.
Sorry for bad english.

[brucetv]

Re: TCL 65S517 No Backlight, Picture and Sound OK

You can get these power supplies from Encompass. $30.95 plus shipping. TCL is one of the biggest piece of crap Tv's and I strongly discourage everyone to not buy one on my website. We stopped doing backlight repairs on them because the panels are too thin and fragile and don't lay down into the bezel deep enough so when you go to put the outer bezel on it presses down on the panel and usually breaks in the corners. Here is the url
https://encompass.com/item/12514469/...71W44-PW210AA/

[MichaelPitts]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I have the same model as rebelkustoms and it's doing the same thing. When I reset the set, the backlight will flicker for a split second, two times, every time. So it's not dead. I bought a 'Jeston' LED tester and have read each of the 4 strips. They all read the same. The readings start at 164, then after a few seconds the reading increases to between 169 and 171. Every strip reads exactly the same so, I'm reluctant to disassemble the screen because these readings indicate to me that the LEDs are likely okay.

The BL_EN pin gets a constant 3.26v while the set is on. So it's not the main board turning them off. I suspect the OZ9976 chip or surrounding circuitry. I'm just not very skilled at diagnosing these tiny components. I'm nervous about shorting pins when reading the legs of the chip.

But I do plan to go through many of the tests budm called out, then will post results.

Any other advice before I possibly destroy this set trying to fix it? :-)

[nomoresonys]

Re: TCL 65S517 No Backlight, Picture and Sound OK

does seem like backlight issue, I think they should start up then settle a little lower, looks like yours is doing the opposite.