40" Samsung lnt4061f Vertical lines no backlight

[budm]

Re: 40" Samsung lnt4061f Vertical lines no backlight

I expect BOTH transistors will show about 10 Ohms on two pins reading, if you look at the diagram you will see 10 Ohms resistor between Source pin and Gate pin. How about the fuse?

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

FS801? The one also next to the AC input? Checked it, seems to be good

EDIT: oh F1801 just found it, i checked its continuity and it seems good.

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

I measured the voltage across the Fuse F1801 and got a reading of 0.42V and tracing to this component here, that outputed 0.42V but the input had a reading that was oscillating between 0 - 10V dc.

I noticed that the board seemed very dirty, I'm guessing it must of sustained water damage and least this board anyway. Because also some of metal components seem to have rust on them as least thats what it looks like to me.

[budm]

Re: 40" Samsung lnt4061f Vertical lines no backlight

That 0.42v across the fuse is OK since fuse is not 0 Ohm, the fuse is fed with about 390Vdc, you have to use the Negative leg of the large DC filter cap in theprimary side as a reference ground point when you work in the primary side of the circuits. The voltage on either ends of the fuse should be around 390Vdc with ref to primary ground.
The board looks rusted out you may have to clean it out real good with alcohal, some of the component leads may be eaten away, need good inspection on all the traces and leads. How much is the new board? Did you check around yet?

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

You're right i measured across the fuse again and got 392Vdc on both ends.

I checked around and lowest Ive found was on ebay on 60$. Kinda pricey for me and I already spent a good amount on the tv =(

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Well I'm completely lost. I've been checking the components near the transformer and those mosfets and I can't seem to find anything odd or wrong.

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Is there a way to check if a transformer is good or bad?

[budm]

Re: 40" Samsung lnt4061f Vertical lines no backlight

You need Ringer tester to find shorted turn, just Google it. Otherwise you can use Ohm meter to see if the windings are open or not. Which transformer did you pull out. Did you down load the diagram of the board and look at it yet. On page 3, top left, do you have that 12V feeding that transformer driving circuits

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

I pulled out T1802 (the one you were just talking about), I think I just created a new problem... When I pulled out the transformer, I forgot to put it back in the board and I plugged everything back on together and tried to power on the TV, but I noticed it wouldn't power on. So then I soldered the transformer back on and now everytime I plug in the power cable all I get is the standby LED light slowly blinking on and off and pressing the button has no response. Did something fry when I turned on the TV without the transformer?

[tom66]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Well, do your tests methodically: Do you still have standby power?

It's inadvisable to remove components from a power supply and then run it, though I doubt you did damage.

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Checking the power on/off connector pin I still have 5.26V showing, actually it would drop back down to 0.04V for a second and rise by up to 5.26V continuously. (As oppose to 0.04V on standby and 2.79V when turned on from post #8, I received prior the new problem ). And the standby pin measures constant 5.26V. I measured the large cap and still a reading of 162.2V

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Nevermind, I found the problem the power on/off had a broken trace, must of been when it scraped against the panel when I took it off and on the panel.

I'm getting a measurement of 11.83V on the two pins of the transformer.

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Alright so the backlight problem has been solved. Now with the backlight on I see a new problem...

When the TV turns on to the cable input, it starts flickering a bit until it lights up steady however on the left side of the TV has some werid distortion. When I put it into hdmi input there are some lines that appear in that area.. I thought it was a bad panel issue.

Videos of what I'm talking about:
http://www.youtube.com/watch?v=Bn2UDBnE6o8&feature=plcp


The left side of the screen also seems darker and has a bit of color distortion. Its quite noticable that one side is darker when on the cable input where the white noise is pictured.

http://www.youtube.com/watch?v=7QoXoONUjp8


The OSD input doesn't seem to be affected at least I don't think. The OSD menu is hard to tell cuz it was a bit transparent already. I tried messing with the tab bonds to see any effects but there was no change. Around that area on the left is the only area where the picture seems to "ghost"

Video of the input label:
http://www.youtube.com/watch?v=uqkZ5...ature=youtu.be

I simulated the problem I had in the beginning of this thread where it only showed vertical lines all over the screen by removing the component on the tcon below again (photo below, an inductor?) I had to strip away the bottom to reveal the leads so i could solder it back on the tcon board.

If it did have a bad panel wouldn't the vertical lines be more distorted in some way along the left side of the tv? So I'm thinking it might just be tcon at fault? (photos below, pattern changes when i turn the tv off and back on) The Tcon had been damaged already when I got the TV so its possible that there is futher damages.


QUESTION AT HAND:
Is the panel bad itself or is it just the tcon board that is at fault?

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

If I unhook only the left ribbon cable from the tcon board the entire left half of the screen turns white. If I unhook only the right ribbon cable from the tcon board while the left is still on, The entire right side of the screen turns white but the left side also turns white with a few random lines overtop it. It seems like its struggling to maintain the left side of the screen by itself.

If both ribbon cables are unhooked, I get a perfect white screen. Is it the tcon or panel? I don't know at all...

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Any opinions?

[budm]

Re: 40" Samsung lnt4061f Vertical lines no backlight

If I were you, I would try new T-CON board, if it does not fix the problem then you know it has worst problem, the panel, sometime it is worth spending $20~40 to find out.
Or you can post good pictures of the T-CON board then we can try testing some voltages on the regulator IC's and switching power supply output and look for shorted out MLCC (Multi-Layer-Ceramic-Capacitor).
Check the DC voltage of the T-CON fuse also, it should be either 5 or 12V, depends on the panel..

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

Well, heres a photo of the tcon board, where should I start?

Tcon fuse I get around 12.81V

[budm]

Re: 40" Samsung lnt4061f Vertical lines no backlight

If look at the board real close, you will see a lot of test points with Voltage labeling on them, see what I have circle, check those voltage and write down each reading with name of the test points also.

[tieny]

Re: 40" Samsung lnt4061f Vertical lines no backlight

VDD: 3.28V
VCOMG3: 5.55V
VCOMG2R: 6.07V
VST2: 5.76V
VON_P: 22.9V
VCC_3.3: 3.26V
VREF_M: 1.3V
VREF_T: 1.42V
VDDQ: 2.58V
LVDS_33: 3.26V
VCC_1.8: 1.86V
VCC_2.5: 2.6V

Fuse F1: 12.79V

[budm]

Re: 40" Samsung lnt4061f Vertical lines no backlight

The regulated DC reading are within the range for the 1.8, 2.5 (may be a little high, 2.6 is above 2 %), 3.3V voltages. I am not sure other reading though. I am not sure what else I can suggest. One test point I cannot see is the VLOW on the board, it is usually -10V or more. May be more T-CON expert can chime in.