e701i-a3 no picture but backlights

[bleed4me]

Re: e701i-a3 no picture but backlights

I was afraid you were going to say that...lets say I do connect the tab and power it up how much time do I have before I have to rebuild the tcon?

[freakaftr8]

Re: e701i-a3 no picture but backlights

Roughly 4 seconds.

Should be enough time to at least get the V to show up on the screen
If you see anything except for that any liens any red lines. Sparkles noises smells anything unplug it right away

I was afraid you were going to say that...lets say I do connect the tab and power it up how much time do I have before I have to rebuild the tcon?

[bleed4me]

Re: e701i-a3 no picture but backlights

Risky business I tell ya, man I would really hate to blow a good tcon board but here goes nothing. Lets say all that was wrong with it was the tcon my question would be why would it go in the first place knowing these issues? Man this is nerve wracking!!!!

[bleed4me]

Re: e701i-a3 no picture but backlights

Well that was a complete bust. After 4 seconds and still no V I hurried up and unplugged it. Unplugged the lower cable again and powered it on to see if I had any kind of picture and there was nothing. Back to square one.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Dammit I'm sorry man. It blew the COXA transistor I bet. Well at the least can you get an exchange or a refund? At least it's for sure the panel now needs to be butchered. The right side needs to come off.

I was hoping your panel was ok because it doesn't exhibit the same symptoms others including myself see. I was hoping that possibilityyou wouldn't have to do an unnecessary panel mod if not needed.

[bleed4me]

Re: e701i-a3 no picture but backlights

No worries man, all this comes with the territory. I got lucky and got a working one on ebay unfortunately I have passed the 14 day return policy. You say transistor like the one at the beginning of your post? You mentioned earlier how to test it black probe on middle then test the other two legs...getting a reading of 001 and 459...

[freakaftr8]

Re: e701i-a3 no picture but backlights

The replacement you need is a RTR020N05 2a 45v n channel SOT-23 style mosfet. This mosfet will be replacing the COXA. It's much more robust than the original and can take abuse.

Yes. That 001 reading means it's shorted

I think tjmethod still has some if you cant locate online.

[bleed4me]

Re: e701i-a3 no picture but backlights

Just so that we are on the same page this is what needs to be replaced? You sent me a link bout a month back and I have some. Should be interesting, I can solder caps day and night but this, this is out of my comfort zone. Should be fun. Also I noticed there are like 2 more of these in the area of the one that needs replaced. Are they the same and do they need to be tested?

[bleed4me]

Re: e701i-a3 no picture but backlights

Just an update... It took me awhile and to be honest I am still in shock but the new mosfet has successfully been put on the tcon board. I am not a fan of this particular task but it was a good experience for me to learn so I am glad it happened. It is now in the tv and the lower right tab has been removed and now when I power on the tv I am back to where I was, picture on left and black on the right. We now know that horizontal lines dont have to be present for this issue AND this tcon will fry in 4 seconds, yes I counted out loud. So for future reference lets not do this again cause I am sure not a fan. It is safe to say those right tabs need to come out and possibly burned in a blaze of fire! Just want to say thank you freakaftr8 for all your help in this, it is much appreciated. I will continue onto phase 2 tomorrow, I have had enough TV drama for one night.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Good to hear you're board as backup and functioning. So now we know that yes there is an inherent short on the right hand side


Ok. Now watch my video and remove the righthand side driver boards and ribbons from the panel. Good luck and sorry for that. I guess it was better to find out if you had to butcher the panel or not but now you know for sure On the bright side you beefed up your tcon so it can't short easily again

[bleed4me]

Re: e701i-a3 no picture but backlights

So took the boards and ribbons off and got some interesting results. For the most part if the pictured is colored it is flawless, but if there is blacks in the picture it shows vertical red lines in it. Get the same thing if I power on the tv with no signal and the entire screen is black with thin red vertical lines all across. Only when I give the tv a picture will it go flawless.

[tom66]

Re: e701i-a3 no picture but backlights

So took the boards and ribbons off and got some interesting results. For the most part if the pictured is colored it is flawless, but if there is blacks in the picture it shows vertical red lines in it. Get the same thing if I power on the tv with no signal and the entire screen is black with thin red vertical lines all across. Only when I give the tv a picture will it go flawless.

I've seen this kind of fault when the LVDS cable on a t-con wasn't seated properly. The poor connection causes an impedance mismatch signal reflection (it's a transmission line) and this causes data corruption. Check all cables are seated properly.

[bleed4me]

Re: e701i-a3 no picture but backlights

Ok so I was wrong they are blue vertical lines from top to bottom all the way across and it also appears that whites have a slight haze around them. I will check the cables right after dinner, thanks tom66 for the suggestion.

[freakaftr8]

Re: e701i-a3 no picture but backlights

U yes is sounds like lvds cable to me also. But they are all the way across?

[bleed4me]

Re: e701i-a3 no picture but backlights

Well she is alive! Add this one to the list of successful fixes Freakaftr8 and thank Tom66 those LVDS cables must be super sensitive. I will ask this though for the most part it looks fantastic but sometimes I have little white specs that are present on some scenes then disappear on other scenes. What would cause that?

[freakaftr8]

Re: e701i-a3 no picture but backlights

Those white specks are an inherent design flaw in the polarizer sheet behind the LCD panel. Mine has the same problems and a lot of others I have seen do this also including the demo units that are still at Target and Walmart. It seems to happen more with more frequent use. I believe it is heat related. Those. You'll just have to live with unfortunately..

If you look at the consumer report on this model you will see a lot of people having that problem

[bleed4me]

Re: e701i-a3 no picture but backlights

Sounds good, just wanted to make sure there was nothing I could do before buttoning it up. I appreciate all the help you gave me, pretty sure theres nothing about this tv you dont know.

[freakaftr8]

Re: e701i-a3 no picture but backlights

You got it. Were here to help anytime. Congrats on the repair

[Jim1590]

Re: e701i-a3 no picture but backlights

Ohh, ohh! My turn!

Got the vizio 70 inch on craiglist for $100. Guy already got a replacement t-con and main board. Said he opened the back and got scared, decided to sell instead. He powered it up for me and only got a backlight.

I opened it up and the t-con was disconected at all 4 ribons. Pulled the t-con and grabbed his replacement. 000 and 000 readings on the mosfet for both boards. So he either replaced the board and shorted, or the new one is bad.

Anyone have a link to buy the ones referenced above?

While waiting on that, will I see anything if I plug the shorted board back in? Maybe enough to figure out which side is bad? (if any, but having that mosfet shorted leads me to thinking I will be pulling some drivers) Or will the shorted t-con give me the same no picture as if it is not plugged in.

Heck, if nothing else, I can repair both boards (hopefully, my soldering skills are lousy) and have a backup so I can test both sides if I need to.

Thanks

[Sandman262]

Re: e701i-a3 no picture but backlights

Guys, am one of those lucky ones that bought this Vizio Black Friday deal in 2013 and the TV went bad after 2 years, blue screen audio OK. Vizio offering no help.

So I am turning to the masters of badcaps to hopefully help me fix it.
Bought a new T-Con board off ebay (mistake?) and hooked up, disconnected to small driver cable on the lower right side. Powered on. Only blue screen, but had no input connected? Checked COXA at get some reading on one leg and 0 on the other.

Any help appreciated.