Vizio E70-C3 issue

[NOSValves]

Hi new to this forum. Also not very well versed in modern electronic circuits but well versed vintage vacuum tube electronics I'm owner/operator of www.nosvalves.com I appreciate any insight you folks my have on this TV problem.

Anyway I've owned this TV for 6, 7 or 8 years? It started losing back light LED strips until the picture was getting dark over about 40% of the screen. I checked online and found a full set of led strips for $82 shipped so thought why not give it a whirl. Watched a couple YouTube how to videos. Ended up not being to hard but it was tedious.. the bad part is once done I fired it up all the led lit so I put it back together hung it on the wall hooked all the sources.. it again was obvious the led strips all lit up but it never boots to the "V" Vizio logo. It seems the LCD is inoperable now. I took it back down checked and triple checked all the connections.
So I went to checking all the voltages on cable sockets of the power supply board. See 3 photos for results. 24Vs are 2+ volts high, 12V are slightly up. Tcon volts not present. Some voltage present that are not specified on the board.
Any clue what might be the problem?

Thanks for any help!
Craig

[nomoresonys]

Re: Vizio E70-C3 issue

can you post some good focused pictures? one of the whole back with all the boards in it and one of each board?

[NOSValves]

Re: Vizio E70-C3 issue

Sure! Thanks

[nomoresonys]

Re: Vizio E70-C3 issue

not sure maybe check the fuse on tcon, neg probe on chassis ground, pos. probe on each end.

[Diah]

Re: Vizio E70-C3 issue

sorry to write bad news.. you probably damaged the panel (screen ) when you take it apart... hopefully not.. but you can disconnect one ribbon cable between the T-CON and the panel at time and turn on see if you will have half screen displayed,

another possibility could happen... you damaged the ribbon cable as they are old enough and dried out easily to bracken the contact pins ( take them out and inspect them carefully with good light source and loop )

[nomoresonys]

Re: Vizio E70-C3 issue

being a vizio e, i wouldnt be surprised if the panel was bad, try unhook one side of the tcon ribbon to panel, turn on tv, see what if anything on display, then do the other side, ALWAYS do plug and unplug of cables with tv unplugged from power, to avoid any problems.

[nomoresonys]

Re: Vizio E70-C3 issue

if i recall, i read where they think when the tv is left to run with some leds not working, it may be damaging the panel, see what the test bears out, might be a candidate for the tape cut-off method.

[dskall]

Re: Vizio E70-C3 issue

Your vizio light changes when you power on? Your 3.4v on nc. is puzzling.

[NOSValves]

Re: Vizio E70-C3 issue

Your vizio light changes when you power on? Your 3.4v on nc. is puzzling.

I thought that was strange too. I also wonder about the tcon 12V being 0V and the tcon-ON being 0V....if that board is not turning on how could the display work?
Another thing I found is one low voltage electrolytic cap has zero volts and both the 450V caps in the lower left of the power supply board have zero volts. It does not seem logical that a bad panel would cause these things?

[NOSValves]

Re: Vizio E70-C3 issue

Your vizio light changes when you power on? Your 3.4v on nc. is puzzling.

Oh and yes the power light works as normal....it also does another strange thing that might give a clue. When you fire it up the led are lighting brite then after like 30 seconds they dim to about half of original. If I hit the V button which would bring up the various built in streaming services they go brite again and stay that way.

[NOSValves]

Re: Vizio E70-C3 issue

not sure maybe check the fuse on tcon, neg probe on chassis ground, pos. probe on each end.

What does this fuse look like?

[dskall]

Re: Vizio E70-C3 issue

I thought that was strange too. I also wonder about the tcon 12V being 0V and the tcon-ON being 0V....if that board is not turning on how could the display work?
Another thing I found is one low voltage electrolytic cap has zero volts and both the 450V caps in the lower left of the power supply board have zero volts. It does not seem logical that a bad panel would cause these things?

Your tcon-on should have about 3.4v on it to turn on tcon 12v to power t-con board. No wires where changed? Is that nc pin on power board indeed have no traces coming off of it?

[lotas]

Re: Vizio E70-C3 issue

Fuse 5A

[dskall]

Re: Vizio E70-C3 issue

I
Another thing I found is one low voltage electrolytic cap has zero volts and both the 450V caps in the lower left of the power supply board have zero volts. It does not seem logical that a bad panel would cause these things?

If you are referring to the long caps on hot side of board you have to reference your ground on neg. side of those caps. They should be around 390vdc.

[nomoresonys]

Re: Vizio E70-C3 issue

It's hard doing remote troubleshooting, but if you jump around without doing tests, it just makes it that much harder. did you do any of the tests? without feedback how can we help you?

[NOSValves]

Re: Vizio E70-C3 issue

It's hard doing remote troubleshooting, but if you jump around without doing tests, it just makes it that much harder. did you do any of the tests? without feedback how can we help you?

Sorry I'm not home right now so I can't test anything. I previously already unhooked both ribbon cables between tcon and the LCD it didn't change any of the suspect voltages. I'll do any tests mentioned above tomorrow. I'll be surprised if it is the LCD my wife and I were really careful moving it. If it is damaged it will be the address board to LCD that are a little rough getting loose to tape them out of the way to the front. But I guess from what I've read they can be real delicate.

Craig

[nomoresonys]

Re: Vizio E70-C3 issue

the panel doesn't have to crack to be damaged, what was on the display is what we needed to know as you were doing that test, it can be confusing but these nice people here can help.

[NOSValves]

Re: Vizio E70-C3 issue

the panel doesn't have to crack to be damaged, what was on the display is what we needed to know as you were doing that test, it can be confusing but these nice people here can help.

What was on the display? Absolutely nothing....I'm not home so I can not do anymore test just yet! I think these people are great. I don't see what the fuss is about. I'm not an idiot I know it doesn't have to be cracked to be electrically damaged.

Relax I plan to do every test I'm able to do. It's rough when your 12 miles away....

[NOSValves]

Re: Vizio E70-C3 issue

Fuse 5A

Thanks! I knew it would be near the 32V 5A stenciled on the board but had no clue which device would be the culprit. I do that test tomorrow.

[NOSValves]

Re: Vizio E70-C3 issue

If you are referring to the long caps on hot side of board you have to reference your ground on neg. side of those caps. They should be around 390vdc.

Okay I was using a common chassis ground. I redo that tomorrow also.