e701i-a3 no picture but backlights

[Alexbry1981]

Re: e701i-a3 no picture but backlights

So by reading this thread it seems like this may be my issue. I'm new to all this...so here's my current situation...no image, do have backlights, installed a new tcon board, tv worked for about 10 secs and then screen went dark again. What are the chances the new tcon board isnt fried?

[budwich]

Re: e701i-a3 no picture but backlights

none... :-) :-(

[CactusCat]

Re: e701i-a3 no picture but backlights

Just a quick update. I used this thread to fix my free 70" Vizio in Sept 2017 and now coming on almost 2 yrs later, it's still going strong. It sees a LOT of use and I am not worried that it might fail. Freak and Bud are definitely a couple of studs and once again, I wish to show them my thanks and appreciation. So while there are no guarantees of how long these things will last, it looks like this particular fix is solid. YMMV

[frica]

Re: e701i-a3 no picture but backlights

+1

[NautilusComputer]

Re: e701i-a3 no picture but backlights

Hey all, I just picked up a Vizio E70i-A3E for free that was "sound but no picture." Backlight works, but I'm sure the T-con is shot so I can't test left or right side drivers to see which ones to peel off.

First question - is the ribbon cable to disconnect the one that goes into CN15?

Second question - does anyone have spare MOSFETs they would mail 2 or 3 of to PA (18603)? I'd rather send one of you folks a couple bucks than give it to a random ebay seller.

Thanks for all the info - I almost bought a replacement main board but came across some of this info as I 'over-researched'!

[nomoresonys]

Re: e701i-a3 no picture but backlights

Too EARLY to say it's a bad panel, need to do some basic testing first.

[nomoresonys]

Re: e701i-a3 no picture but backlights

With tv unplugged from power, unplug cable from poweboard to mainboard, plug tv back into power, see if backlights come on and stay on.

[jetadm123]

Re: e701i-a3 no picture but backlights

Second question - does anyone have spare MOSFETs they would mail 2 or 3 of to PA (18603)? I'd rather send one of you folks a couple bucks than give it to a random ebay seller.

Thanks for all the info - I almost bought a replacement main board but came across some of this info as I 'over-researched'!

Did you actually test the mosfet to see if it's shorted?

[NautilusComputer]

Re: e701i-a3 no picture but backlights

With tv unplugged from power, unplug cable from poweboard to mainboard, plug tv back into power, see if backlights come on and stay on.

I disconnected the twisted-color cable from power board to main board at the power board, then plugged into AC - no backlight at all.

Too EARLY to say it's a bad panel, need to do some basic testing first.

I figured I'd start from bad panel that way if someone had spares they'd be willing to send, I could get them on the way while I do the rest of the testing.

Did you actually test the mosfet to see if it's shorted?

I was too busy to get into the t-con, I just guessed that it must have been the failure point. Pulled the board just now; according to freakaftr8:

You need to set your voltmeter to ohms mode and black probe the center pin red probe the right bottom pin and 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.

I'm getting 4.8 ohms to one pin, and 567 ohms to the other. So then the T-con is okay...?

Thusly, if not the T-con, I guess I need a new something else?

Also, this one was........'nicotine enhanced.' I'm still scrubbing down the back panel to get rid of the smell. Screen is clean as a whistle already.

[budwich]

Re: e701i-a3 no picture but backlights

based on your "clip" of the post, I am not seeing "infinite" in your measurements... that would appear indicate that the device is not good.

[NautilusComputer]

Re: e701i-a3 no picture but backlights

based on your "clip" of the post, I am not seeing "infinite" in your measurements... that would appear indicate that the device is not good.

I found one and have it on the way for $9.

I think from the looks of this driver that I *do* have a bad panel and likely a blown FET on the T-con. This is the so-called 'right' side; the driver at the bottom of the screen closest to the 'Vizio' logo:

https://i.imgur.com/32O4au8.png


Compared to the other drivers on that same side, it's the only one with brown 'staining' towards the white lettering on the cable.

[nomoresonys]

Re: e701i-a3 no picture but backlights

.

[nomoresonys]

Re: e701i-a3 no picture but backlights

Is it hotter than the others or just cold like it's no longer working at all? but usually if they're all black looking compared to the others, there's your problem, looking like it might need "the fix" (tab removal) VERY important that you get the correct side and ONLY remove one side, operation can not be reversed.

[budwich]

Re: e701i-a3 no picture but backlights

I think at this point, nautiluscomputer can't get the set to turn on so I don't think he would be able to feel if the chip in question is hotter than others.... but you are right about proceeding with care. first, getting or fixing the tcon. then disconnecting the corner cable on the side that has the bad chip. this should save the tcon AND get him a picture. He can go from there.

[nomoresonys]

Re: e701i-a3 no picture but backlights

Right, long thread, hard to keep track of who had power and who didn't.

[NautilusComputer]

Re: e701i-a3 no picture but backlights

I think at this point, nautiluscomputer can't get the set to turn on so I don't think he would be able to feel if the chip in question is hotter than others.... but you are right about proceeding with care. first, getting or fixing the tcon. then disconnecting the corner cable on the side that has the bad chip. this should save the tcon AND get him a picture. He can go from there.

I can power up, and I do have backlight. I do not have a remote and I have no idea what input the TV is on. It was advertised as 'sound but no picture' when I got it.

[NautilusComputer]

Re: e701i-a3 no picture but backlights

I have a working TV! It appears that there may be one bad LED in the backlight, though.

The T-con I used was part RUNTK5489TPZA, thanks to Charleyd's post (https://www.badcaps.net/forum/showpo...&postcount=797)

I paid $9 for mine on ebay. Started up TV with RIGHT side (Vizio logo side) drivers disconnected, and got good left picture.

Proceeded to remove right side drivers, and it came right up!

It is difficult to see on the test pattern, but much more visible on the other image - is that a blown LED in the backlight causing the dark half-circle on the bottom right side?

[diif]

Re: e701i-a3 no picture but backlights

It is difficult to see on the test pattern, but much more visible on the other image - is that a blown LED in the backlight causing the dark half-circle on the bottom right side?

Yes, I think so.

[cliff_hootarski]

Re: e701i-a3 no picture but backlights

Just "fixed" one of these (VIZIO E70i-A3). I took the front bezel off to more easily access the right side(as looking at the front of the TV) metal enclosure of the TV. I removed the 5 tabs by gently peeling the tabs towards the front of the TV. TV powered up and seems to be working. Oddly enough, the suspect transistor on the Tcon board was never shorted, before or after the procedure.

Original symptoms of the TV when powered on were no picture, backlights on and sound was not tested. Original owner said sound did work.

[nomoresonys]

Re: e701i-a3 no picture but backlights

@ cliff_hootarski, did you try removing one ribbon cable at a time from tcon to panel to diagnose? wondered what your process was.