e701i-a3 no picture but backlights

[brando70]

Re: e701i-a3 no picture but backlights

one reason for doing the "corner cable disconnect" while having all other cables connected is that you get a "full display". IF you are wise and input a known test pattern (smpte color bars or equivalent), you can then readily analyse the screen to look at what is happening... if anything. This may confirm your findings or possibly point to other issues which need further investigation.

Interesting.. why does the corner matter over the output of the Tconn board itself? Also in my pic would that be disconnecting it at 2R or 3R? does it matter which corner connector is disconnected between 2 and 3? I assume even if you disconnect corner board there's still risk of frying the Tconn board when connected to all outputs if something is wrong with the drivers? Is there a way the risk to the Tconn can be minimized? Pic for reference of connector points:

[budwich]

Re: e701i-a3 no picture but backlights

the risk is the same depending on what the state of a given troubled driver might be. Anyways, further disconnecting a cable at 2 or 3 is basically the same assuming that there isn't an issue with the cable itself (possibility). Still further, the more you test with as much circuitry in play, the better you will understand what or where the problem lies. There are some that have found an issue with the way the corner cable is connected (not properly seated) and as a result, checking / reconnecting them resulted in a "solved problem"... NOTE this is just an example, not a "its the answer". Checking cabling EVERYWHERE is part of the analysis.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Disconnecting 2r or 3r is going to kill voltage to the driving horizontal tabs. So if there is a short in that tab on to that side of the panel the t-con no longer has to drive that short thus relieving the t-con of the short completely. The way that this panel is set up the voltage driving circuitry goes through the bottom board completely ignoring the bottom drivers and gets carried along to that 2r corner cable. So in turn the bottom vertical gate driver boards just act like a carrying circuit where the board carries the voltage from the t-con directly over. When you disconnect that corner table you're relieving the short that is causing the issue. The panel doesn't care about driving dead drivers it's just going to load the panel down running drivers with no voltage going to them however when there is a short in one of those driver chips you're going to see it on the panel with the voltage killed to that circuit.

The reason that you can pull one side off the panel is due to the fact that each side acts like a half duty cycle and with one side that's bad removed the last remaining side has to act as a full duty cycle . It puts a little more stress on those drivers I'm sure however that is the LCD panels last remaining hope to operate . Of course if you do not have either side you will have a picture like what you seen earlier with just vertical strips going up and down the screen due to the fact that the screen has no way of producing a horizontal driving picture . It is kind of like the old days and CRT technology if you lose your horizontal oscillator you no longer have a picture except for a white stripe going down the screen . This is why if both sides are bad, the panel is essentially useless. I hope that makes it easier to understand.

[brando70]

Re: e701i-a3 no picture but backlights

Disconnecting 2r or 3r is going to kill voltage to the driving horizontal tabs. So if there is a short in that tab on to that side of the panel the t-con no longer has to drive that short thus relieving the t-con of the short completely. The way that this panel is set up the voltage driving circuitry goes through the bottom board completely ignoring the bottom drivers and gets carried along to that 2r corner cable. So in turn the bottom vertical gate driver boards just act like a carrying circuit where the board carries the voltage from the t-con directly over. When you disconnect that corner table you're relieving the short that is causing the issue. The panel doesn't care about driving dead drivers it's just going to load the panel down running drivers with no voltage going to them however when there is a short in one of those driver chips you're going to see it on the panel with the voltage killed to that circuit.

The reason that you can pull one side off the panel is due to the fact that each side acts like a half duty cycle and with one side that's bad removed the last remaining side has to act as a full duty cycle . It puts a little more stress on those drivers I'm sure however that is the LCD panels last remaining hope to operate . Of course if you do not have either side you will have a picture like what you seen earlier with just vertical strips going up and down the screen due to the fact that the screen has no way of producing a horizontal driving picture . It is kind of like the old days and CRT technology if you lose your horizontal oscillator you no longer have a picture except for a white stripe going down the screen . This is why if both sides are bad, the panel is essentially useless. I hope that makes it easier to understand.

Interesting... So the question comes to mind why not just disconnect the ribbon right at the outlet of the tconn board (yellow line)? Or is there something extra happening by letting power run all the way down the blue line till it gets to 2r?Can I still damage the tconn by doing this?

And disconnecting connector 2r should at least let me keep all 4 connections at the tconn plugged in without worry of frying the board I assume?

Think I'm getting there.. just gotta try it I guess.

[brando70]

Re: e701i-a3 no picture but backlights

Ok, baby steps.. so I plugged in the left cable from the output on the tconn board, and I disconnected the connector at 2R and I have what you see here:



I didn't try the reverse because that's what killed my tconn before (just want to be 100% sure it's the right side before I pull em off still).

Then I pulled off both 2R and 2L and I get this (just leaving vertical driver boards connected) and connected both outputs from tconn and I get this:



This is the screen it's supposed to be:




Is this on the right track or are my vertical drivers f#@cked? Just don't have the balls to try the right side to not blow another tconn..

[budwich]

Re: e701i-a3 no picture but backlights

balls and maybe wisdom... :-) remember the point about using a KNOWN test pattern. Its pretty hard for anyone to accurate evaluate what you have "snap shot" without knowing what the still is actually supposed to look like... one is its busy and two its a "stopped moving frame".

[Vinish]

Re: e701i-a3 no picture but backlights

On my Vizio e701i-a3, I successfully replaced the transistor and removed the tabs on the right side of the TV (as viewed from the front). This was about 3-4 months ago. The TV worked fine after that. Yesterday, the TV stopped working again and now only shows what is seen in the picture below when it is connected to a TV cable channel or even when just being turned on. Any help diagnosing this problem would be greatly appreciated.

G'day,

Vinish

[budwich]

Re: e701i-a3 no picture but backlights

It appears that you lost a driver on the opposite side which means its done... :-( Double check your cables to make sure things are seated correctly just in case.

[Vinish]

Re: e701i-a3 no picture but backlights

budwich, Thanks for the quick response. I will look at the cables as you suggest. Any cables in particular? The tv has been mounted on the wall since the previous tab removal repair and has not been so much as nudged since that time. While it is possible a cable has lost connection, it seems more likely that the unit is toast.

Please pardon my lack of knowledge of the technical terms. Is a "driver" something that I can replace or is the "driver" the remaining tabs along the vertical left side of the TV which obviously can't be removed since I have already removed the right side tabs.

By the way, the sound works on the TV if that is any clue (probably not).

G'day,

Vinish

[freakaftr8]

Re: e701i-a3 no picture but backlights

[QUOTE=Vinish;741303]On my Vizio e701i-a3, I successfully replaced the transistor and removed the tabs on the right side of the TV (as viewed from the front). This was about 3-4 months ago. The TV worked fine after that. Yesterday, the TV stopped working again and now only shows what is seen in the picture below when it is connected to a TV cable channel or even when just being turned on. Any help diagnosing this problem would be greatly appreciated.

That unfortunately looks like the other side gave up... I've seen it one other time now same results.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Ok, baby steps.. so I plugged in the left cable from the output on the tconn board, and I disconnected the connector at 2R and I have what you see here:



I didn't try the reverse because that's what killed my tconn before (just want to be 100% sure it's the right side before I pull em off still).

Then I pulled off both 2R and 2L and I get this (just leaving vertical driver boards connected) and connected both outputs from tconn and I get this:



This is the screen it's supposed to be:




Is this on the right track or are my vertical drivers f#@cked? Just don't have the balls to try the right side to not blow another tconn..

Yes it would appear your right side is toast. The top picture shows your left side works. Leave those alone.

[johnboy1313]

Re: e701i-a3 no picture but backlights

My repair lasted about sixteen months. Looks like the other side has failed now.

[budwich]

Re: e701i-a3 no picture but backlights

:-(
looks like the vizio "panel" isn't as tough as some of the others.... my friend's sharp is still going... looking at 19 months. guess its to be expected as the design is compromised.

[TheRic]

Re: e701i-a3 no picture but backlights

Got a Vizio 70" from Sams Club Special Black Friday deal several years ago. It finally went out on me a couple of weeks ago. Been reading this forum on the fix since.

Ordered a new T-con board, disconnected the right side ribbon cable, fired it up, blew the T-con board. So I ordered some MOSFET (specs from this forum), soldered one in, disconnected the two bottom cables from the T-con board, checked my voltages, most of them were within range (more on that later). Plugged in the right side cable (as you look at the front of the TV), hooked backup up the ribbon cable on the side also. Left side cable from t-con still is disconnected. Fired up the TV, the picture on the right is there but red. The left side is solid white. No lines going across, or down. SO is my whole left side bad or is there something else going on?

The voltages I got where:
Drain 15.7v
Gate 0.84v
Source 0.0v
Big Cap 15.52v
4R7 1.2v
100 12.19v
3r3 3.3v

Both cards were getting about the same numbers. At first I thought the gate was supposed to be higher, so I tried a different MOSFET (ordered several just in case), kept getting basically the same results. Must admit I fried one of the cards as I was taking the last reading before writing this (must have crossed something). Now it smokes if power is connected but before power button is pushed.

Any help would be greatly appreciated. Will be happy to answer any questions / give more details on request.

Thanks in advance for your help.

[budwich]

Re: e701i-a3 no picture but backlights

you are likely close (ie. determining which side takes out your tcon / fet). There are small ribbon cables at each corner of the panel... connecting the bottom edge boards to the side edge boards. Disconnect the corner cable for the side you think is bad (left side if I understand your description / test). Leave the tcon cables all connected. IF you have an issue with the side tab drivers on the left, disconnecting the corner cable on the left will prevent the drivers from blowing the tcon and you should see a complete picture. Post the picture of the result with a display of some test pattern. This will help in determining if you have any issues and go from there.

[TheRic]

Re: e701i-a3 no picture but backlights

Got the cable disconnected (for others it is right behind the control panel on the side). Picture is fine on the right side, but the left is darker and redder. It seems to be the worst at the middle and gets a little better as it gets near the left edge for some colors like green. Red washes out most of the left side.

There are no lines that I can see.

[budwich]

Re: e701i-a3 no picture but backlights

there is certainly a lot of "lefts" and "rights" being thrown around. :-)
As I suggested, get a hold of some test patterns for setting up your tv(found on dvd's or equivalent... things like smpte color bars, etc)... feed them in. Looking at a "still" of a "moving picture" may not highlight issues.

Anyways, as you can see... IF I understand what cable you have unplugged (maybe post that picture as the description that you provided leaves me confused... "control panel on the side"?????), it appears you have potentially found the "right area"... maybe.

[TheRic]

Re: e701i-a3 no picture but backlights

Here are some Test Patterns: SMPTE, Indian Head, Solid Red, Solid Green, Solid Blue. The waves in the solid colors, are not on the TV. The Yellow /white in the
Solid colors I think are from the Flash or light glare, since they are not on the TV.

When the Video goes from Red to Green to Blue it takes a little over 1 sec for the color to fill in on the left edge. See RedGreen and GreenBlue image.

The Control Panel (power, volume, channel) on the lower left side behind that is the white ribbon cable I removed from it's connector. The blue end is laying in front of the connector. That white ribbon cable goes under the TV and connects to board on the bottom.

[budwich]

Re: e701i-a3 no picture but backlights

good stuff. hmmm.... certainly doesn't appear to be a "normal tab driver" issue... although depending on where and how the driver is compromised, it can have lots of different impacts (based on others that have been posted). You might want to look at the tab drivers / ribbons along that side to see if any are looking "not so good".
I am somewhat "leery" that you have a side issue. Some on other sets have had problems with the seating of the corner cables. Once properly seated, there "problems" disappeared. I guess the question is... do you more replacement FET's that you could replace if you connect the cables all back up with the risk of taking out the FET again?

I guess the picture with the red / green smear is probably an indication of a tab problem. Question: the disconnected corner cable... is it disconnected at the bottom board or at the side board? IF its at the side, meaning its still connected to the bottom... maybe its an issue... ensure that it is disconnected at the both boards.

[TheRic]

Re: e701i-a3 no picture but backlights

I have more FET's, bought several, knew better. Could try re-seating the cable. But the $100,000 question is how many times do you blow a FET after re-seating before you are 100% sure it's not that.

I disconnected the ribbon cable from the side board only, the ribbon cable is still connected to the bottom board. It was easier to disconnect the cable on the side than on the bottom. Question / clarification: You want the other end of the cable disconnected NOT a cable going to the bottom board?

I'll check out the side boards and tabs looking for things that don't look correct.

Any other boards to disconnect / Anything else to try?

Side Question / Note: We don't move the TV around, it sits on it's TV stand. I question the cable just all of a sudden acts up from being improperly seated?! But will admit I have seen many strange things while repairing things over the decades. More than once have taken something apart that didn't work, put it back together without doing anything, it works fine after that.