TCL 65S517 No Backlight, Picture and Sound OK

[rebelkustoms]

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

See attached

[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

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

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

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

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

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

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?

[nomoresonys]

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

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

[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.

[budm]

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

Can you take resistance reading of each pin of the IC with ref to Ground for me?

[vinceroger69]

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

i would certainly change that smd capacitor (certainly discolored etc) you should be able too remove and measure one of the other ones so you can get a replacement

[rebelkustoms]

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

So I kinda ran out of things to test on this thing so I was visually combing over the board. Paying attention to the area around the OZ 16 pin IC. I was testing these 330 resistors and they are testing around 7.8 Ohms which from what I understand is pretty off.
Then I saw this surface mount cap next to them right near the IC and it looks like it is leaking black. It took FOREVER to get a good pic but I think you can spot it here. Let me know what you think. There looks to be some corrosion nearby too.

[rebelkustoms]

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

What's going on with C412, C431 and C432? They look ill, what's on the top of them? If that's leakage then they are shot.

Those are all fine. Must be a bad pic. Just for fun I desoldered and checked them all with my ESR and they are all 3 good.

[nomoresonys]

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

What's going on with C412, C431 and C432? They look ill, what's on the top of them? If that's leakage then they are shot.

[rebelkustoms]

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

Hey Budm,
I think Diah above is trying to explain how to "turn on" the PSU with the motherboard disconnected but he is having a hard time getting it across in english. are there other pins I can jump to PWR_ON and BL_ON to get the PSU to turn on, or is their a guide or video that can help me.

[Diah]

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

When the Main Board is Unplugged from PSU I get 0v or 2mv at Main Board power on pin and 0v or 2mv at BL-ON pin.

With Main Board CONNECTED I get 2.3v at power on pin and 3.2 at BL-ON pin.

that's correct how it should be... BUT running PSU as Standalone ( Main boards unplugged ) you will have on sockets which it goes to MB only about 3.3V at pins stand by. this stand by pins if we jumper it to Power On and to BL-ON. thr PSU will run stand alone with out MB.. at this points you can measure Voltage on BL sockets in case the BL didn't come ON

BTW. was essential from those who are diving with diagram and high level diagram tracing to explain OP with thei mother language how to run PSU stand alone.

[rebelkustoms]

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

if this V. reading you listed after you turn on the PSU as standalone. ( mean the connected pins STB--> power On, STB--->BL-ON ) then you have much issue at LED BL or burned socket / connection at BL

When the Main Board is Unplugged from PSU I get 0v or 2mv at Main Board power on pin and 0v or 2mv at BL-ON pin.

With Main Board CONNECTED I get 2.3v at power on pin and 3.2 at BL-ON pin.

[rebelkustoms]

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

Check Ebay and use 40-L141W4-PWC1CG as the part number.

That one looks very similar and is only 1 number off but piece by piece it has a few differing components on it which make me wonder if it will work.

[Spitz]

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

I suspect there must be something FATAL in these Power Supplys. This was a costco model set manufactured in feb 2019 and there are 0 replacements PS's for sale out there. All out of stock.

Check Ebay and use 40-L141W4-PWC1CG as the part number.