Vizio M70-C3 diagnosis

[objext]

Hi all, I have an M70-C3 Vizio that won't power on. I do get power/standby LED and optical output operation. I don't seem to have backlighting or display image, or sound.

I have negligible voltage (0.001-0.003V) at T CON_ON and both 12V T CON pins.

I have 12V on both +12VS pins.

I have 33.xxV on 24V1 pins.

TV was working before a thunderstorm, but I'm not 100% sure that's why it quit. I tried to record how the standby LED functions in the attached list. What should I look at? Power supply caps appear okay. Thanks!

[nomoresonys]

Re: Vizio M70-C3 diagnosis

Picture isn't clear enough to read the legend beside the connectors.

[objext]

Re: Vizio M70-C3 diagnosis

Picture isn't clear enough to read the legend beside the connectors.

How about these

[nomoresonys]

Re: Vizio M70-C3 diagnosis

How is the tcon fuse? see if there's continuity.

[nomoresonys]

Re: Vizio M70-C3 diagnosis

Maybe try a firmware update thru usb.

[nomoresonys]

Re: Vizio M70-C3 diagnosis

Guess they want you to put your serial # in, then just follow as directed, sometimes a storm will mess up the firmware, other times a storm will go thru and fry some thing/s, site there: https://support.vizio.com/s/firmware...language=en_US

[objext]

Re: Vizio M70-C3 diagnosis

How is the tcon fuse? see if there's continuity.

Tcon fuse checks out ok

[objext]

Re: Vizio M70-C3 diagnosis

Guess they want you to put your serial # in, then just follow as directed, sometimes a storm will mess up the firmware, other times a storm will go thru and fry some thing/s, site there: https://support.vizio.com/s/firmware...language=en_US

Hate to sound helpless, but their page doesn't work. After I enter the s/n (LFTRSYAR3002382), it takes me to a page that says

Most Recent Firmware Version: 1.5.16
Please click here for more information regarding this firmware.

...but when you click for more information it takes you to an invalid page.

[nomoresonys]

Re: Vizio M70-C3 diagnosis

Yep, I get the same, wonder if they took it off their site, maybe try contacting them and see if they can send it to you or point you to where it is, might have to get a supervisor if they say they don't have it or they start to be difficult.

[objext]

Re: Vizio M70-C3 diagnosis

Yep, I get the same, wonder if they took it of their site, maybe try contacting them and see if they can send it to you or point you to where it is, might have to get a supervisor if they say they don't have it or they start to be difficult.

Updating the firmware doesn't require anything to be seen on-screen?

[nomoresonys]

Re: Vizio M70-C3 diagnosis

I don't think it does for this model.

[objext]

Re: Vizio M70-C3 diagnosis

Also nothing on this tcon connector. I do get PS-ON signal, etc. Power supply seems to be working (?). Have tried pressing on main board heatsink, but no change.

[nomoresonys]

Re: Vizio M70-C3 diagnosis

Can you post a picture of the whole back, as to see how everything is connected and a good clear one of the mainboard, also give it a good smell test, see if you can detect any faint burnt smells or see any small burnt traces etc.

[objext]

Re: Vizio M70-C3 diagnosis

Can you post a picture of the whole back, as to see how everything is connected and a good clear one of the mainboard, also give it a good smell test, see if you can detect any faint burnt smells or see any small burnt traces etc.

No smell of burning

[nomoresonys]

Re: Vizio M70-C3 diagnosis

Unhook cable from powerboard to mainboard, check voltage at each pin of CN201, report readings, if anyone has any ideas on what to test or whatever, lets hear it, appears to be a tough one.

[objext]

Re: Vizio M70-C3 diagnosis

0
4
0
0.43
0
0
0
12.7
12.7
0
0
0
0
0
0

This doesn't surprise me because it can't be powered on without the main board.

[howardc64]

Re: Vizio M70-C3 diagnosis

Probably the classical ~2015 Vizio BGA solder failure. While this main board has a better heatsink with a heat transfer pipe to the rear chassis, the symptoms sound quite classic to these common Vizio BGA solder ball failures. Although other Vizios with the BGA failure often exhibit blinking standby LED lights thats not present here.

Here is the pic of M70-C3 main with heat sink removed (copied from ebay)



Here is a post with likely same Vizio BGAs with heat sink removed (memory layout orientation slightly different but probably the same BGAs). OP in this thread did the typical heat reflow and got the TV to boot with display in post #11.

https://www.badcaps.net/forum/showpo...72&postcount=3

Here is badcap search result for "m43. Probably all with this typical Vizio BGA solder failure problem. Lots of ~2015 era Vizios used these BGAs and have solder failure problems. Likely from using older (cheaper) hotter chip fab while pushing it with more smart TV functions (makes it hotter) Combined with the problematic lead-free BGA solder balls results in balls cracking over time and failing. AMD/nVidia GPUs first encountered this in the late 2000s.

https://www.badcaps.net/forum/search...rchid=33613311

You can try to heat the heatsink with hairdryer for awhile and see if TV boots.
I believe the only long lasting fix is using a proper BGA reflow station : Remove chip, reball (typically leaded balls), resolder. Short cuts like heat gun, hot air station, oven bake will not last very long

[objext]

Re: Vizio M70-C3 diagnosis

I did try hot air but without removing the heatsink. Will the studs pop out without pulling the board? Otherwise, sounds like a main board issue, yeah?

[nomoresonys]

Re: Vizio M70-C3 diagnosis

Was trying to verify the powerboard, but I thing Howardc64 is on the money, probably need a new chip or reworked with leaded balls.

[nomoresonys]

Re: Vizio M70-C3 diagnosis

You can send it to Nick's, he will fix it without robbing you: https://www.youtube.com/watch?v=G1Rh6Snf94g