Samsung UE48J6200K - No image but sound

[Francesc V.]

Fixed. It's working for the last week. I used some tape and I've covered a few lines from the left ribbon. Image appears interlaced and blurred for about 1 minute but then, like magic, clear image appears and it lasts until TV is switched off. Let's call it a partial fix :-)

[Davi.p]

Unhook the panel strip boards, flip them and see accurately the point where the leftmost and rightmost glued flats attaches to the pcb, you have to see if there is a small portion of the flexy pcb where traces are uncovered by the green paint.. there could being the problem..

[Francesc V.]

TV situation has improved quite a lot as long as I've removed the horizontal plastic that provides with a silver line at the bottom of the TV. I realized when I was moving TV from horizontal position to vertical position that maybe this was the piece that was touching/bending the back ribbons.
TV now is not fixed but image last now for hours. (at least for the last 2 days) Once image is gone, I simply switch off and on the TV and the counter resets :-)

To be honest, I see in good condition the 12 ribbons that come from the panel.......but it must be something there. A soft connection is somewhere.

Current TV situation is not that bad.........and I am afraid to get things worse I am touching this part of the TV.


Regards,
Francesc.

[Francesc V.]

Thank you guys for the feedback. Let's see how it ends.

I am uploading the t-Con picture with some voltages taken on it. I see all of them "ok" and stable.

[Diah]

My guess you pick the wrong cards, with the same defects, i wanna make you a test, sorry i have no time to try it myself, no time to dedicate to tv these days, i wanna you to reinforce the 1,1v and 3,3v lines by soldering a 330/470uF 6,3/10v low esr electrolytic cap across condensers CM03, CD26, respecting the polarity, then turn on tv with everything connected..

very good PIZZA recipe, how about salt and pepper please tell how much in uf or pf? rhx

[Davi.p]

My guess you pick the wrong cards, with the same defects, i wanna make you do a test, sorry i have no time to try it myself, no time to dedicate to tv these days, i wanna you to reinforce the 1,1v and 3,3v lines by soldering a 330/470uF 6,3/10v low esr electrolytic cap across condensers CM03, CD26, respecting the polarity, then turn on tv with everything connected..

PS: the test is to see if normal image lasts longer or forever..

[Francesc V.]

Hi:

These days I bought both mainboard and TCON..........but changing both cards didn't solve the problem. It might be that any of these cards have same problem as originals, but also it might be that panel is faulty :-))

As long as TV works ok for some minutes until loosing some voltages I was wondering whether somehow we could force the DC-DC enable pin or something like that to "bypass" the problem.
I am attaching the reference.........I haven't been able to find anything with this numeration.

Regards,
Francesc.

[Davi.p]

BN94-xxxxx must match

[Francesc V.]

If I would need to buy a new main board.....
Is it enough to buy exactly the same model number? or here also mainboard eeprom needs to be programmed/swapped? (I am seeing 2 mainboards with exactly same numeration, however one comes from same model, other seems to come from a 55' panel.)

[Davi.p]

Are you meaning the 6 small marks? Yes are those, every line is composed by one pair, with final 100ohms resistor between, if you capture AC voltage across those lines, about 1,5v, then signal is present, get a pair of single hole mammuth screw clamps, and put a needle on to them and them on to tester probes..

[Francesc V.]

this tells that the missing image could be due to bad main board (processor balls), then you have to check lvds lines before and after the image disappears, it is so if lvds signal disappears,, but the screen stand alone test tells bad screen with tcon, it can even be both damaged

Ok. Makes sense...........I've attached a picture just to be sure that you're refering to the pair of lines that are coming from the MAIN.

Regards,
Francesc.

[Davi.p]

P.S: Silly question of the day.........what if I have the feeling that everything might be screwing up when requesting for OSD activity? For instance,when pressing volume that requires pictures popup on the screen and these kind of staff, or Smart TV menu capabilities.........when nobody touches or request something from the TV........it seems to last working for long times.

this tells that the missing image could be due to bad main board (processor balls), then you have to check lvds lines before and after the image disappears, it is so if lvds signal disappears,, but the screen stand alone test tells bad screen with tcon, it can even be both damaged

[Francesc V.]

When you installed the jumper on RM15, did you have voltages at t-con approximately: VGH - (+27v), VGL - (-8v), VDD - (+3.3v), VDA - (+15v), VCOM - (+8v)?

Maybe not looking at the right place, but I am not able to find these "basic" testing points in the T-CON you're referring to.
Also, panel strips PCBs doesn't have any markings or labels.

Do you see them in any of the pictures I've been attaching? (VGH, VGL..........).

Regards,
Francesc.


P.S: Silly question of the day.........what if I have the feeling that everything might be screwing up when requesting for OSD activity? For instance,when pressing volume that requires pictures popup on the screen and these kind of staff, or Smart TV menu capabilities.........when nobody touches or request something from the TV........it seems to last working for long times.

[Diah]

I will continue with the test suggested by Diah.......because maybe, and just maybe it's not the T-CON neither the panel. Saying this because during testing, the image freeze (a frame)

thought you did trick the t-con by RM15. which it trick also the MB to transfer raw data.. now the RAM on MB stick full so the frame will freeze... find the chance as it is on now to log in service menu and make hard reset to clear RAM / T-CON action

[Diah]

T-CON are slave as well the Panel.... all what you are seeking after VGH/ VGL/VDD(VDA/VCOM will not present if there no GPU signal... that's all search after the source to make all of these present. as OP he did.

[lotas]

When you installed the jumper on RM15, did you have voltages at t-con approximately: VGH - (+27v), VGL - (-8v), VDD - (+3.3v), VDA - (+15v), VCOM - (+8v)?

[Davi.p]

First things i want to say, right to be clear, the led 3 is for the presence of panel supply voltages, when led 2 is for tcon circuitry supply present, the first to be executive is the pmic, then it is energized the main chip, and last the panel, since some time the panel has flaws or it is right the tcon unable to drive it well (and this is the main point , se next) it happens that panel feed it is released, this is my point now, my recent findings tells that with no visual oxidation or shorted components on strip boards, the main goal for the protection circuitry is to unload the tcon supply part, that could suffer, and not to protect the panel, and my bet is that you have bad bga balls on the couple of ic on board, more than this, im wondering witch chip is the one under radiator, seems a memory, lcd tcon uses no big flash or ram, sounds strange.. has it FRC function in the same chip? High integration is typical of developing bga problems..


you have not clarified about led3 on the tests..

another point, by cheating the tcon feedback circuit, and disconnecting one side, you are unloading a certain amount the tcon, so led 2 and vcore stays on, but connecting both sides dcdc stages suffers and vcore is shut down

[Francesc V.]

To me is not clear the post 19, the status of led 3, if present an image.. etc..

Yes, by unblocking the TCON I have been able to see picture and point the issue on left side of the panel (theoretically).


Right now, TV is working for an hour and I have done "anything" .

- Removing ribbons and clean them with isopropyl alcohol.
- Removing the jumper RM15.
- Playing with tape on the left panel ribbon with no success. Image was crap in all tests, but at least there was image :-)

Tired of no success with tape, I've removed the tape and installed back the ribbon.


Clear picture and sound for quite a long time...........it will not last very long, I know.

I will continue with the test suggested by Diah.......because maybe, and just maybe it's not the T-CON neither the panel. Saying this because during testing, the image freeze (a frame) was kept in the background in the meantime the realtime picture was playing (not sure if you understand what I mean).


Regards,
Francesc.

[Davi.p]

To me is not clear the post 19, the status of led 3, if present an image.. etc..

[Diah]

Ok..........I had time to test your suggestions.

Second test I performed "finally" was to disconnect Tcon from Mainboard and inject 12V. In parallel, TV was switched on to have backlight. The result has been a nice blank screen. Not sure if you where expecting a whole white screen there.

Regards,
Francesc.

remove yours by pass RM15 and do it again as you explained
Note you can do it also in half screen a time