Samsung LH50QETELGCXGO

[mmaven806]

Hi everyone,
This is a display versus television, but same panel and board structure as UN(E)XXTU8000 and QNXXQ60TA's.
First the background, I have several of these with lot more at work that died the same death and from the same cause.
All of them are missing the havdd and avdd voltages.
1.8v, 1.9v, 3.3v, are ok. Backlighting, smps board, sound, processor all seem ok.
I started a schematic, converted to pdf so everyone could see it. I started this past weekend so it is just a beginning, I'm working on the fb_trdy_x traces as I type.
I think this will really help everyone that has the combo main / t-con board using Silicon Mitus' VPMS2SM ic.
Please ignore the footprints and model data if the pdf included it...I haven't gotten that far yet.
Ok, so I have A13V through Q211 no problem. I believe the VIN_12 feeds the 1.8v, 1.9v, and 3.3v.
I have VIN_12 at Q400...source, but no HVIN_12V at the drain. Gate wrings good to U400-6. Not sure if R4143 should be 33 ohm's it is the same on all my boards.
Does anyone know what enables 'GD'? Maybe 'EN2' for HAVDD and AVDD, and 'EN1' for 1.8v, 1.9v, and 3.3v.
I have no HAVDD or AVDD with or without flex ribbon connected.
I did order the service manual, but received it missing pages, chapters, and the pinouts don't match up.
Looks like it was photoshopped from different manuals.
Any help would be appreciated. Maybe a moderator could make a sticky from the pdf...when we get closer to done.

[cmagavilano]

Re: Samsung LH50QETELGCXGO

me a servido tu diagrama revisare la main para verificar

[cmagavilano]

Re: Samsung LH50QETELGCXGO

encontré esto espero que te sirva

[cmagavilano]

Re: Samsung LH50QETELGCXGO

esto mas es del fabricante

[mmaven806]

Re: Samsung LH50QETELGCXGO

Thank you so much, the SM4109 is similar to the one on my main board. I got 4 of mine fixed. Firmware was corrupted. 14 more to go! I ended up copying the firmware from the 2 remaining good display's.

[KYBOSH]

Re: Samsung LH50QETELGCXGO

Thank you so much, the SM4109 is similar to the one on my main board. I got 4 of mine fixed. Firmware was corrupted. 14 more to go! I ended up copying the firmware from the 2 remaining good display's.

Very good to hear you are making progress.
I will have to follow your lead and look for the firmware on my TV set which is having the exact same symptoms as yours is/was.
You are very fortunate to have a working set to pull the firmware from.
It sees like there are a lot of dumps floating around for obscure brands I have never heard of. But that just shows that the people passionate about the firmware dumps are in different regions than I am in.

[mmaven806]

Re: Samsung LH50QETELGCXGO

Here is the latest schematic, hope it will help someone.

[charafmak77]

Re: Samsung LH50QETELGCXGO

Thank you

[Davi.p]

Re: Samsung LH50QETELGCXGO

You don't have avdd havdd because tcon disables it and it does it because there is a short on the panel's boards or on the cof/cog.. you surely haven't also voff, vgh.. search for fb-trdy-3 and connect to fb-trdy-1 then disconnect panel, turn on and measure all voltages, you will have..

[MAXMIL]

Re: Samsung LH50QETELGCXGO

Hello mmaven806, Do you have this schematic (Samsung_BN41-02790.pdf )complete?
Thanks,

[Andreas_de]

Thanks for the schematic. I have to Samsung TVs here which are from 2021 and they seem to be in bootloop. I disconnected the left panel and then there was an initial sound. I started measuring around the vpms2sm chip. 12.8V input to vpms2sm is okay. 1.8V, 1.9V and 3.3V is also okay bug VGH voltage is 0v. Measuring was done with disconnected panels.
I ordered 2 x vpms2sm chip. I think some new chips will solve the issue.

Is there anybody who had the same issue and has exchanged the vpms2sm dc/dc ic?

Thanks.

[lotas]

VGH voltage is 0v.

These voltages will not appear when the panel is turned off, T-CON does not see the panel and blocks the output voltages to the panel (VGH, VHL,...), in order for them to appear, you need to deceive the feedback between them (panel - t-con), you need On the motherboard, install a jumper between the feedback points FB_TRDY_1 and FB_TRDY_3.

[lotas]

I ordered 2 x vpms2sm chip. I think some new chips will solve the issue.
.

99% your chips are fine, the problem is in the panel or panel buffer strips.

[Andreas_de]

So, you think there is a short on the small bords or an issue with one of the cof?

[Andreas_de]

There is a "short" (2ohm) on test point TEST_EN1, TEST_MODE1. It's the same on the left and right panel. All caps on the small bords are okay.

Seems the panel is itself is the problem. So it's impossible to repair.

Thanks for further help if there are any ideas.

[lotas]

Place a jumper and check the supply voltages without the panel and each half of the panel.

[Andreas_de]

Installing the bridge was a good advice. Thanks a lot! VGH Voltages and all other voltages were available now. It seems the panel is the problem. That brings me to the next question: Is there a posibility to fix this panel issue or is it "game over" now? The panel itself has no mechanical damage.

Left to right:
1. Measurements of mainbord voltages with bridge
2. Installing the mainboard with bridge into tv to test.
3. disconected one panel for testing
4. Result with panel error. Was testing the panel just some seconds to take a picture.