Vizio M70-C3 ... Help with Diagnosis

[sixspence]

Thanks for any help here!
I'm trying to narrow down which board may be the culprit for my non-functioning TV.
The symptoms:
I was watching (actually playing Elden Ring on) my VizioM70-C3 when half the screen went snowy (sort of a digital snow). I shut down and restarted and the screen was blank.
The indicator LED light in the bottom corner turns on and the audio fiber optic light in the back lights up but no screen.
I tried the "flashlight test" but am not seeing any images on the dark screen.
The internet is telling me that the caps go bad frequently on the M70-C3 power board, so I unmounted the TV from the wall and removed the back. The caps look fine - not bulging - although I know that can be deceiving. I don't want to pull them out to test because I might send the board to a repair service and they don't want to work on boards that some unqualified DiYer like me screwed up.
I have an Atlas ESR reader, but the results from that seem dodgy - although I may be interpreting or performing the in-circuit readings wrong.

So.. any ideas on if the power board is the issue or if one of the other boards is to blame?
Any other simple tests a simpleton can perform to help find the problem?

[nomoresonys]

Re: Vizio M70-C3 ... Help with Diagnosis

how to clean cables, he talks about the panel at the end but further tests can be made to determine if that is the issue, doesn't seem like a bad panel tho: https://www.youtube.com/watch?v=aOCLpJub2l0

[sixspence]

Re: Vizio M70-C3 ... Help with Diagnosis

Thanks... I'll give that a try and report back.
Only thing that gives me pause is that the screen in the video is at least showing half the screen lit up. My screen is just completely dark. The half screen digital snow I got was only up for a minute and then the whole screen was dark after I shut down and restarted the TV.

[nomoresonys]

Re: Vizio M70-C3 ... Help with Diagnosis

see if you have about 12 volts on each side of the fuse on the tcon board, black probe on chassis ground.

[Nick's Tvs]

Re: Vizio M70-C3 ... Help with Diagnosis

You said this

"The screen in the video is at least showing half the screen lit up. My screen is just completely dark. The half-screen digital snow I got was only up for a minute and then the whole screen was dark after I shut down and restarted the TV."

That is 100% mainboard. Half screen showing digital snow = mainboard 10 times out of 10.

You might be able to get away with reflowing the BGA chips on the board, I recommend you do both even though technically only one needs to be because the other one is probably not far behind. But there is a chance you may have to do a replacement.

[sixspence]

Re: Vizio M70-C3 ... Help with Diagnosis

Hypothetically.... If I found a mainboard (1P-0149J00-6012) on ebay, but it was pulled from a different tv model, is it still usable?

Edit:... So, not so hypothitically.... I found a board on ebay pulled from a VIZIO D58U-D3. Is there a reason it would not work?

[nomoresonys]

Re: Vizio M70-C3 ... Help with Diagnosis

Does the board you want to buy have the serial number available? it's a way to check for compatibility.

[sixspence]

Re: Vizio M70-C3 ... Help with Diagnosis

Different serial numbers...
That would have been too easy.

[sixspence]

Re: Vizio M70-C3 ... Help with Diagnosis

Does anyone know if this place is legit? https://smarttvparts.com
They have a M70-C# main board for sale, but their website is a bit dodgy.

[nomoresonys]

Re: Vizio M70-C3 ... Help with Diagnosis

private message sent.

[Storyteller12]

Re: Vizio M70-C3 ... Help with Diagnosis

Nicks TVs is right. It’s the main board. And for the used one you may have found. Most likely it’s just been reflowed anyway. Might as well donut yourself or send yours out for repair.

[sixspence]

Re: Vizio M70-C3 ... Help with Diagnosis

Follow up.... You guys were right.
It was the Main Board. I ordered a used board online, popped it in an BINGO!
Thanks for the help from everyone here! I learned a lot along the way.

[nomoresonys]

Re: Vizio M70-C3 ... Help with Diagnosis

Glad you could save that one, nice big screen. time.

[TroutCaptain]

Re: Vizio M70-C3 ... Help with Diagnosis

see if you have about 12 volts on each side of the fuse on the tcon board, black probe on chassis ground.

I couldn't find a fuse on the t-con board. Where is is this actually? I originally fixed mine with the heating up the mainboard and worked for a little bit and then broke again. I ordered a replacement mainboard and it did not fix the issue. Now looking into the t con board and this fuse assuming the mainboard I ordered was good. Thanks

[nomoresonys]

Re: Vizio M70-C3 ... Help with Diagnosis

If after heating and it worked fine, then I'll bet they sent you a bad mainboard or it was damaged during shipping.

[TroutCaptain]

Re: Vizio M70-C3 ... Help with Diagnosis

Sorry I think what I said was misleading. My original mainboard was an issue and I did the heat trick and it worked for a little while and broke again. I attempted to do the same trick again and didn't work. So I then ordered a replacement mainboard and it did not fix my issue. So now I am looking into the t con board for problems assuming that likely the mainboard I received is good. This fuse mentioned on the t con board interested me but cannot find it. I am getting no t con on voltage on pin 15. PS-ON works as expected when powering TV on. Getting proper voltage on PIN 8 and 9 for +12V.

[R_J]

Re: Vizio M70-C3 ... Help with Diagnosis

If your tv worked with the original main board (when it was heated) I suspect the problem is with the replacement board which likely has the same issue only worse (bad bga connections on the main ic)
T-con fuse is F101 (8amp72v) located next to PT plug.
T-Con ON signal comes from the main board

[TroutCaptain]

Re: Vizio M70-C3 ... Help with Diagnosis

Found the fuse and I get what your saying. First need to get t con on voltage coming from the mainboard to even make checking the fuse relevant. You are probably right about the replacement board being bad as well. Was just hoping this wouldn't be the case. Maybe I'll go back to my old board and try heating it up a few more times. Thanks for the help.

[Nick's Tvs]

Re: Vizio M70-C3 ... Help with Diagnosis

Yeah agreed you probably got a bad mainboard.
I would say don't heat your mainboard, actually, reflow it so you don't have to keep heating it every week to get it working.
Lots of info on that in the forum and on youtube.
If you don't want to or don't have the tools, then send it out for servicing. Better to do it right once than only half-fixed several times.

[TroutCaptain]

Re: Vizio M70-C3 ... Help with Diagnosis

Well I received another replacement mainboard and same problem. The only difference between my original board and now the two replacement boards is the optical light stays red on the replacement boards. I guess it could be that both replacement mainboards sent are bad. I am going to reflow my original board. However I did notice that under the heat sink the chips have some plastic cover over them. Does this need to be removed somehow before I reflow. They sure seem attached quite well and blocking the heat. I didn't see this mentioned anywhere. Picture attached for reference. Thanks!