Vizio VW42LHDTV10A horizontal lines on the left side

[tibimakai]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

I have issues positioning the TV for easier access to the PCB/tab.
My eyes are getting old and I need magnifying lamp/lupe/good light to be able to see what is going on on the PCB.
I'm thinking of grinding off that kapton layer(not sure what is that material) on the tab.
I guess I will have to measure those pads and look for 19-20V first of all. Then remove the top layer from the tab somehow. How about using a screw and nut? The screw would most likely touch that copper, and just wrap the wire under the screw head. From the other side I would screw on a nut.
I also don't understand, why we have to use that thin wire? There is no room to solder thicker wire?
Yes, I agree it would be nice to understand what's going on in these panels.

[budm]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

May be you can use sharp X-acto knife to score X mark on the pad and than you can lift up KAPTON to get to the copper pad. You can use any wire gauge as long as you can fit it ino the frame of the LCD panel when you put it back together.

[tibimakai]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

in my opinion it's hard to get the exact depth of the cut with an X-acto knife without going through the copper too. how about using a sand paper, maybe a Dremel with a drum style sanding wheel.
I keep trying to move the tab, but it's way to hard to get a position where everything looks good. To me the rubber pad fix it looks almost impossible to do, at least on my TV. It seems that I have to push it from both sides to have a clean screen, not just down wards.
This resistor fix is my only hope.

[budm]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

I used the X-acto knife to fix my broken digital camera torn flex KAPTON cable (copper traces laminated between the KAPTON, I scraped it with the knife to expose the copper traces enough to solder wire wrap #28 gauge wire jumper. The trick is to take your time doing it.

[tibimakai]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

Thanks, I will give it a try. The question is which pad I need to clean?

[tibimakai]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

Ya, I messed up the top side tab. Cut through the tab and cut some lines too. If I touch the problematic tab, does not change the picture anymore.
The biggest voltage I'm measuring is 15.6V. I don't see any V_on or V_off on that board.
I guess I will keep this TV until I find another one with a different issue and I will swap the panel then.

[tibimakai]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

Anybody understands what is going on here with the resistor and wire?
What are we trying to do here? The side tab(s) is missing a voltage?
Only one tab or all of them?
If I supply the right voltage to one of the tabs the others will be getting it too?
It matters to which tab I solder that wire?

[tibimakai]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

It tooks 3 tabs before i got a good lasting connecting between 1 of the tabs and the wire running to the resistor

Could you please explain to me about those three tabs a bit more?
You mean that you tried soldering on the second tab and then on the third one you finally succeeded?
We are talking about the side tabs here?
My problem is that the tabs and the LCD panel pcb looks totally different then on the Sony ones.

[budm]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

I like to know too, since there are ICs (little rectangular bump) on those side tabs for driving the Gate of the TFT's. The first person that figure that out must have known how the panel is wired up. Each one of those need power to operate.

[cashkennedy]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

Sorry I have been away (working 12 hour shifts at my day job)

First: The guy who came up with this method probably did know the layout of the tab from some experience in the factory / or designing these panels.

Second: The 32 / 40 inch ones are from a totaly different factory, that is very clear now from seing your closeup pictures.

Third: Every panel maker has different proprietary designs for the little crystals in each pixel, which changes the drive currents (these get better every year anyways). Also the currents are often changed between models even from the same factory to satisfy refresh rate specs... So you might have a Von that is considerable different then 19/20v , and yours might be 16v that you found. It appears they name the voltages completly different in the samsung factory vs wherever the 32/ 40 are made (probably a chungwa factory)

Basically it appears the side tabs on every model have a few circular pads for testing the important conections that go to every pixel. Those appear to be things like Von, Voff, and ground. They were so small on mine that i made holes in 3 of them before i could get a good connection
Tab 1> I cut the ground wire (didnt seem to matter), and then couldnt get anything to stick to the tab. Tab 2) pictured it more carefully so didnt cut the ground, but while soldering the solder finally stuck to the backs of the pads (the green side), much easier and bridge Voff (i guess?) to Von, and then even without the resistor the tv wouldnt display anything, so i cleaned all the solder off and move to tab 3, finally got something to stay soldered.
By the way if you ever connect the 19v(Von) to ground (since ground is so close in the tab), picture goes to crap for a second, then it turns the TCON off, and you have to restart the TV to reset the TCON.

With your 46" tv were not even 100% sure that its the Von that is not getting properly through the top tab. So first id recommend getting through the Kapton with a needle and testing what voltages you see at all the pads. In my case i wasnt getting any voltage on the the pad that the video told me to run the resistor to.

BTW: I have a feeling the image BUDM linked is rotated so to speak (some tvs have tcons on the sides / botoms anyways...), but if Source implys the individual data that is in varied pulses to indicate what pixel , then i think that goes top down vertically throught he screen, while if gate is the common voltages that go to each pin and decrease by a set amount every row, then they would be what travels through side tabs? (as well as gets to the side tabs initially through the very far edge of the top of the screen (uses about 10 connections on each side vs the total of like 2000 conections on the top of the screen). Actually after looking at the pic again, The pic is correct lol, its just what i described...

[budm]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

The Source means Source pin of the Mosfet (TFT), the Gate drive is for each Gate of the Mosfet (TFT). Sources and Gates are scanned to turn each TFT ON/OFF. Just think of them as X/Y grid, and the T-CON tell which X/Y location to turn it ON/OFF. The block diagram is from SONY training manual. All LCD panel will have X/Y drivers.

[cashkennedy]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

I didnt think about it in a transistor manner.

From that manual it sounds like the source is varied though and the gate is a constant voltage for the whole row. As in to adjust the contrast the source voltage is varried. (instead of using a adjustable transistor that varying the gate changes the output).

The transistors output though is only 1 charge of the 2 charges necessary to arrange the liquid crystals. So there must be another voltage applied to the color filter / glass. (Perhaps thats what Von is?) Then again i think there is voltage always applied to both sides, that way the pixels stay in whatever state they were left in, and the transistor just gives enough voltage to push it either way.

[budm]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

1 pixel contains 3 sub-pixels, Red, Blue, and Green. So 1 pixel will have three TFT per pixel, when all R, G, B are ON then you get White.

[cashkennedy]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

Oh i very much understnad that all 3 colors are seperate pixels per say. But you dont create 32bit color by only adjust red on / off, blue on/ off , green on /off. Cause that would only create 8 colors.

You have to do 16% blue, 37% red, 40% green (for brown for example) , and thus each tft / pixel has to be able to vary its transmitance based on source voltage (or gate, but as i said gate is held constant, and source is what comes in at varying voltages).

[budm]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

"So there must be another voltage applied to the color filter / glass" that is the point, you vary the Source, there is no voltage for the color filters.

[tom66]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

Yes a 1080p panel is essentially 5760x1080 pixels, nothing special about each pixel. Maybe they are different sizes for some colours to balance panel colour.

[cashkennedy]

Re: Vizio VW42LHDTV10A horizontal lines on the left side

I think usually all 3 colors are the same size pixel, but the filter might have varying transmitance levels for each color, and everything can be adjusted in the firmware / service menu anyway.

Anyway returning to the topic... Its hard to say what the voltage will be on yalls sets, but considering that it appears the voltage gets to 1 side of the screen fine, and just isnt connected on the other side, if you use pins to peirce the tabs on 1 side you should be able compare the readings to the working side. Once you find a difference (that your sure is not just cause you cant make good contact with the pad on the other side) you could then search for that voltage at the top, or run a wire from the tab on the other side (but honestly its probably better to run the wire from the top since its so impossibly hard to solder to the tabs)