e701i-a3 no picture but backlights

[freakaftr8]

I'm just going to go ahead and get this going with a new thread.

As you all know the Vizio model referenced above as a major failure point. There are other members on this forum including myself they have had failures of the Vizio 70 inch model. It represents itself with it was working fine and then the picture went out but the back light stays on. On at least two occasions including myself replacing the t-con board which is the affected problem just blows the board again. There are repair kits for this t-con which includes a DC converter also EEPROM and a few small SMD transistors. First of all it seems the only transistor that gets taken out is the coxa that is directly connected to the small square SMD style IC to the right of the board. This IC is known as the gamma processor.

To my finding the reason that it keeps blowing this one transistor which is usually the only problem on the tcon board is because of a failed horizontal driver tab on the right side of the LCD panel. It appears that usually only one of these tab drivers fail. With this particular set up the main board does not have the ability to shut down the TV in protection mode like some other manufacturers do. The tcon board and the panel are both made by sharp. The problem lies within the driver IC built into the tab on the panel.

If you have this problem and you order a new t-con board, do not and I repeat do not power up the TV with the new board before you try this first. On the right side of the screen, if you're looking at the back side of the TV then look at the bottom left, you will find a small white ribbon cable that connects the side boards of the panel to the bottom boards of the panel. You want to disconnect the white ribbon cable connecting to the right side board you should see the ribbon cable connector on the bottom of the screen on the side. Just disconnect that small white cable. Now you should be safe to power on the TV with the new board. If what has happened to your TV is correct, you will see the screen presented itself with a nice solid bright picture on the left hand side on the right hand side it will be dark, and possibly a little blurry. However you will see as small section spanning horizontally that looks completely normal. And what I mean by normal is that it's just as bright on the right hand side in this small section as it is on the left. Wherever this lies on the screen is in the same area where you have the failed driver.

Now then I don't endorse this as a permanent fix but if you have given up all odds and you're about to throw this TV out in the trash because you cannot make it work anymore many have tried everything, what I did to Repair mine was carefully peel on the right hand side driver tabs directly clean off the panel. Remember this is only done on the side that is causing the failure. A few have had success with this and some have not. I however had excellent success with it so far.

The reason that the t-con board is shorting out is because this is causing a direct overload to an already subpar t-con board.

This was just my fix and remember if you do manage to pull the tab drivers off the panel this is a permanent thing that cannot be reversed.

I will add pictures in a little bit

[budm]

Re: e701i-a3 no picture but backlights

Can we see some pictures so I can understand what you mean regarding to the cables? Thanks.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Ok here's some pictures ranging from the beginning to the end result. The only picture I do not have is disconnecting the flat white ribbon cable from the side boards that connect to the bottom boards of the panel. But if you have the back off and you're looking at the side of the screen at the bottom sandwiched between the metal frame you will see where the white ribbon cable connects to the bottom of the side drivers.

The first picture shows you what the screen look like after I disconnected the flat white ribbon cable.

The second picture shows you pulling away the frame to access the side tab driver boards.

The third picture is showing those driver boards with the tabs pulled off the panel.

The 4th picture shows you a close up of one of the tabs pulled from the panel but the board still connected to the panel.

The fifth picture shows you the screenshot of what you're seeing after you remove those defective tab drivers.

The sixth picture shows you another screenshot of just the fifth driver download from the panel.

The seventh picture shows you the original problem.

The 8th picture shows you the defective transistor. The last picture is the end result.

[tjmethod]

Re: e701i-a3 no picture but backlights

Hello I've got the same backlights but no picture issue on my E701i-A3. Just to confirm, this is the same exact state of your set before your first picture illustration? Then removing one cable + turning on the set brings up what is in picture 1?
I firmly believe I have the same issue and want to better fully understand the process of detecting and repairing the panel. But firtsly, does the the t-con have to be new or this transister to be replaced before powering on with one ribbon cable disconnected?
Thanks for your help,
TJ

[tom66]

Re: e701i-a3 no picture but backlights

If the transistor is not yet bad, you may be able to power it up with the ribbon removed as Freak stated. If that is good then try the surgery on the panel, removing the ribbons. Please note - this is a last resort. It is not a reversible operation. If you do something wrong, the TV is not fixable past that point.

[budwich]

Re: e701i-a3 no picture but backlights

Hello I've got the same backlights but no picture issue on my E701i-A3. Just to confirm, this is the same exact state of your set before your first picture illustration? Then removing one cable + turning on the set brings up what is in picture 1?
I firmly believe I have the same issue and want to better fully understand the process of detecting and repairing the panel. But firtsly, does the the t-con have to be new or this transister to be replaced before powering on with one ribbon cable disconnected?
Thanks for your help,
TJ

The "test" that freakaftr mentioned DOES NOT rely on the tcon card or transitor being fixed / working and will not harm the existing state of ALL cards. With the corner ribbon cable removed (nothing to do with those associated with the tcon card), this is a test to see if the tv responses with a "startup" sequence and possible picture. IF that happens with the existing cards (ie. tcon card, power board, main board) then things are "OK" and you need to make a decision about "surgery" on the TV. IF nothing happens, then you have issues, probably with either power board (which you check as mentioned to output 12v) or the tcon board / transistor which you can then test and / or replace BUT then as mentioned DO NOT put the fixed board back in UNLESS you remove the corner cable to check the set for "operation" (ie. picture / startup or NOT). From there, its then a decision on removing the edge boards associated with that corner ribbon cable and PERMANENT leaving the TV in that "compromised" but working state.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Yes this is all correct I found that the problem relies on the right side of the screen essentially peel back the side trim bezel of the TV on the side where the Vizio logo is on that side. You can have the TV standing upright and ever so slightly pull the trim bezel back to expose the sideboard. On the bottom of the side board on the right side of the screen there is a flat ribbon cable connector. Disconnect that ribbon cable. With a new or repaired t-con board you can now try to power the TV up with both cables connected to the Tcon board. If the TV presents a picture of course it will not look proper please take a photo of that picture and post it so I can see what it looks like. We'll go from there.

Technically you can can disconnect this ribbon cable without even removing anything you can see it from the back of the TV.

[tjmethod]

Re: e701i-a3 no picture but backlights

Ok thanks guys when I got this set I learned it's history of being left on hours on end and all night long etc. I bought and fixed a 60 for a relative that just needed a main board. The 60's main board is the same as the 70, I've checked it in the 60 and it works fine after buying a supposedly new t-con that of course didn't change anything. My next thought was the LED inverter or driver on the power board. I was told that the 60's power board can be used to test- if the output voltages are the same 12, 12, 12 and of course the connectors. First I will follow your instructions and disconnect each ribbon t-con separately and power on with either one off, if a messed picture comes up then I will have confirmation its the panel and surgery is eminent.
Thanks again!

[freakaftr8]

Re: e701i-a3 no picture but backlights

Make sure you disconnect this first. This is a picture of the sideboard connected to the panel on the right side of the screen. Make sure you disconnect the flat white ribbon cable that connects the bottom board to the sideboard before you attempt to power up the TV. This flat ribbon cable is only about three quarters of an inch wide. It is located on the bottom of the right side of the panel. & I would like to note that when I say right side that is looking at the TV front if you're behind the TV it is the left side on the lower side of the tv. Near the vizio emblem..

[budwich]

Re: e701i-a3 no picture but backlights

Ok thanks guys when I got this set I learned it's history of being left on hours on end and all night long etc. I bought and fixed a 60 for a relative that just needed a main board. The 60's main board is the same as the 70, I've checked it in the 60 and it works fine after buying a supposedly new t-con that of course didn't change anything. My next thought was the LED inverter or driver on the power board. I was told that the 60's power board can be used to test- if the output voltages are the same 12, 12, 12 and of course the connectors. First I will follow your instructions and disconnect each ribbon t-con separately and power on with either one off, if a messed picture comes up then I will have confirmation its the panel and surgery is eminent.
Thanks again!

I don't think you understand!!!! you don't need to touch the tcon board! The posted herein are referring to the ribbon cables on each bottom corner side of the panel.

[tjmethod]

Re: e701i-a3 no picture but backlights

With power disconnectwd I disconnected the bottom right white ribbon cable coming up from the panel connecting to the t-con board then powered it on and got all backlights. I shut it down then repeated the test process and got the same thing- no 'V' or any input indication in the upper righthand corner- only backlights. Mind you ths is a supposedly new t-con that I replaced thinking it would fix the problem. I don't know if I did the test correctly or if I did should I move on to the power board?

[tjmethod]

Re: e701i-a3 no picture but backlights

Repeated with the left cable and then the the right

[budwich]

Re: e701i-a3 no picture but backlights

With power disconnectwd I disconnected the bottom right white ribbon cable coming up from the panel connecting to the t-con board then powered it on and got all backlights. I shut it down then repeated the test process and got the same thing- no 'V' or any input indication in the upper righthand corner- only backlights. Mind you ths is a supposedly new t-con that I replaced thinking it would fix the problem. I don't know if I did the test correctly or if I did should I move on to the power board?

You are not disconnecting the proper cables. Re-read the posts / help suggestions, including my most recent one.

[tjmethod]

Re: e701i-a3 no picture but backlights

Hey bud thanks I was exhausted after a 12 hr day last night when I tried this. So anyway, getting this right I took off the black metal side frames covering the side boards back of the both sides and disconnected the small 3/4" ribbon cable from the back of the right side since this seems to be the side that people are having the problem with. I then plugged in the tv- no change in the picture just backlights, no 'V' just backlights. I then repeated the steps on the back of the left side after plugging the back of the right in. After powering on, it took a second or 2 then the LEDs came on and after a few seconds dimmed down a bit and I recall the back of the right side disconmected was just as if it was connected- the backlight come right on vibrantly. The t-con is the supposed new one I put in- before thinking that was the problem and would fix the issue. Unless I missed something I think I tested this correctly? I did read before you stated the the test doesn't rely on the t-con or transistor being replaced. Does this sou d like it could be the LED inverter on the power board?
Do you anyone know where to find this coxa transistor or an upgraged transistor replacement?, I may as well buy 2-3 since I now have 2 t-cons
Thanks again

[budwich]

Re: e701i-a3 no picture but backlights

"right" side is the side looking from the front of the TV... hopefully, you are referring to the "right side"... :-)

Further, the rest of the "test" was probably not clearly stated but you potentially need the set to display something. I do believe that the set dims "automagically" when it detects nothing on the inputs. The easiest way that I found to keep it "lit" was to press the "menu" key on the remote forcing the set to display the menu. You should then see the "dimming" revert to "full brightness" and with luck see the menu on the display... in some form. My fingers are crossed for you.

[freakaftr8]

Re: e701i-a3 no picture but backlights

, ok what you have disconnected in your pictures looks proper. However you need to test your t-con board to make sure that its not failed from the get go. A lot of eBay sellers are selling bunk non functioning tcon boards. You'll notice in my illustrations one picture shows which transistor to check mark with the red box. You need to set your voltmeter to ohms mode and black probe the center pin right probe the right bottom pin in the left bottom pin make sure that neither side is shorted. One side should show roughly 500 ohms and the other side should show almost infinite. If your getting anything other than that your tcon board is toast

[tjmethod]

Re: e701i-a3 no picture but backlights

I will definately redo the test when I get home. The thing that convinced me of no progress was no 'V' when powered on- but I guess first things first- checking the t-con- I did buy the damn thing on ebay- the fastnfree shipping realed me in… hell I ordered it on a Saturday afternoon and I had the thing Monday, I don't even know how thats possible. I should only buy from Encompass- has anyone tried their green series yet?. Shopjimmy put a bad taste in my mouth- I bought a powerboard for the 60 from them and it arrived with the fuze snipped put and when I put a good fuze in it- it still did work- but they took care of it.
Anyone got a line on getting these transistors without ordering from China?

[freakaftr8]

Re: e701i-a3 no picture but backlights

Use a sot-23 mosfet labeled QF as equivalent. You can get them in the us. N channel 2 amp 45v.

[tjmethod]

Re: e701i-a3 no picture but backlights

Hi thanks for your instructions freak I retested each ribbon cables to no avail- blacklights but no ‘V' or menu. I then proceeded to test the t-con board. Looking at the back of the set, the t-con is mounted upside down. I put the black probe on the left middle COXA leg which barely had enough room for the probe to fit between the COXA and the module directly to the left in fact I accidentally ripped most of the black cover off that module trying to hold the probe directly on the leg. I put the red probe on the right lower leg. The first picture is a clear shot of the meter display since the pics of the readings weren't all that clear. The 2nd is RX-1, the 3rd is RX-10 and the 4th is RX-100, I did put the red probe on the top leg of the transistor which pinned the needle all the way to the right that I didn't get a picture of. While holding the probe down on the legs, they slid off the legs a few times and I then must have used to much pressure holding probes down and right after I got the reading on righthand top leg, I ended up pushing the COXA off it's solder spots all while the set was on. Now I was fit to be tied. I then used a soldering iron with a tip as sharp as a pencil tip and a fixed magnifying glass then was able to melt the legs back on their solder spots. After plugging it back in- no readings and I wasn't surprised. I plugged in the original t-con board and tested it with the set on also with no readings. The 5th picture is of the t-con board after the molestation. I don't know if the original t-con was bad since I got readings from it unless something else was bad on the board. I might have messed up something else on another board. Anyway, if you have any advice on where to go from here after getting a new t-con of course
Thanks again-

[tjmethod]

Re: e701i-a3 no picture but backlights

Correction I didn't test the original t-con before testing the new one- only after