EEVblog #781 - Samsung LCD TV Part 2

Dave & David2 have another go at repairing the dumpster dive 46" Samsung LCD TV.
This time a further teardown checking out the LCD panel TAB connections, and then reflowing the T-CON Timing Control board.
You know how it ends. If you don't like the lack of a happy ending, don't watch.

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[artvandelayimports]

Hello Dave, I've been watching your channel for about 2 years and you are the reason I'm somewhat interested in electronics. I've got no idea what you say actually means but I feel like I'm learning

[koffibanan]

I love these attempt to repair videos. Like a good detective story it keeps you wondering. I hope you'll continue your investigations and figure this thing out!!

[arcadeuk]

All the vertical lines, line up exactly with the OSD text, so its looking like it is possibly an issue driving the framebuffer RAM's, I've seen the same style of issue on a much lower tech LED sign display, caused by a decoder with leaky outputs not fully turning off  after drawing a pixel, so you ended up with faint trails on the next lines

[renatoscutube]

Dave, from my experience with my TV, it is indeed the T-con board. You realized that the lines are exactly where the letters of the menu are, as if the menu "caused" the problem. If you put a digital image to it, the lines will probably disappear after some minutes and the image will be totally clear until you bring up the menu again or if you try to watch anything analog and the image will probably get even worse then. I'm telling you this, because that was exactly the symptoms of my set. Replacing the T-con solved completely the problem here.

According to what I read, the chip the causes the problem is a small squared one with the code AS15-G (at least in my set)

[mikeselectricstuff]

The fade-in and shadowing says "floating input somewhere" to me

[michaelhawthorne]

Love this fault finding problem, yes get the Scope out.
This has been fascinating Dave.
What a result if you narrow the fault, even if you can't repair it, great experience.

The fault does't appear straight away, suggesting a heat fault, maybe it is with the tecon board after all.
If the heat fault is in that board, you may need another ASIC.

[lurchmike]

The problem is the LCD panel, this is a very common problem for Samsung TVs. If you disconnect one ribbon cable from the Tconn to the panel the problem might go away (only half the picture will show) and you will know the side that is causing the problem. You can also try some freeze spray on the COFs to see how it reacts.

[blinkybill]

Loving these repair/diagnostics videos, as a tight ass dumpster diver these videos only fuel my passion to fix what others would gladly just bin.

Thanks Dave(s)

[babamx]

From my experience with the same problem on LG 42" LCD TV (exactly the same manifestations), hotbar connections were the problem. That sticky conductive transparent tape (forgot the name) that bonds flatflex conductors from LCD glass to that upper board was not conducting any more. With blowing hot air from hot air gun, and more importantly putting rubber bars that mechanically pressed the connections, TV was again having good picture. That worked for about the year and then started going bad again. Problem with my TV were old CFL lamps that were getting pretty hot (glowing with more red color), and whole tv screen got hot and those contacts to the flatflex were ruined. After that 1 year of extra life, and 6 years form TV,   i just bought new one...

[GadgetAddict]

Have they tried actually feeding a signal in over HDMI or VGA?

[mikeselectricstuff]

Surely it's 1920xRGB=5760 columns?

[dreamfox]

hook up a video signal to it and watch it clear up after the menu text dissappear.

[electronicsNmore]

It would be great if you had a service manual showing testing points. A real time saver.

[frankreiserm.s.]

I used to heat the boards to the oold CRT TVs on the gas stove. Once I heard cracking, I would drop the boare, component side down, and all of the components would fall out. That is how I would quickly collect boxes of components for fee. Great video.
Frank

[brutester]

I would bet on memory problem with some of the cells. I would:
2. run memcheck on PCU board
3. swap/change memory modules on video board

[themaconeau]

Reflow all the boards, hack all the things, drink all the beer :)

[locouk]

The TV manufacturers won't like it if you find a bypass for their "Built in obsolescence" lol..
A very interesting project though. 👍🏼

[FutabaGP]

EEVblog Dave, this whole stuff can be because of low gate open voltage, there is a dc-dc converter on tcon board somewhere which drives gates, check voltages

[montinhoman]

The lines appearing only where the characters are looks like a RAM addressing issue to me, like a floating / stuck address line. Since it fades, it's probably floating, so you get an average over time of white and black (text and background) on the whole column. That also explains why the lines have colors close to the text color and the striped pattern (the regular spacing of thin black lines in the red columns)

[ArcadeMachine]

If you look, the lines only appear where the text is, I'm guessing T-con for sure.