Vizio M60-C3 black screen

[paqman]

So our beloved M60-C3 up and died the other day. I was not there, my wife mentioned that it came on, displayed the logo, then showed the right half of the screen white and fuzzy, with the left half of the screen ok. However when I got around to looking at it, the screen would not come on at all. The indicator LED will come on, then dim a bit. After a while, the LED might blink a bunch of times. I can't get it to be consistent to do that.

So I've got the back off and am checking voltages. The capacitors on the power supply board visually check out. No bulges or anything. They all show 12v on the positive lead as well.

On the power supply board, with the TV off, for the connector to the main board (CN201) everything is zero volts except for pins 8 and 9, showing 12v, and pin 2 (AC-DET) reads 3.9v. When powered on, pin 3 (PS-ON) gets 5v, and pin 4 (12V AU) gets 12v. Pins 8 and 9 remain at 12v. On the connector for the LDVZ board (CN301), pins 3 through 8 all ready 26v, and pin 13 (VSNS) reads 2.4v. The LED driver board itself, pins 3-8 are showing the 26v as well.

The one thing that is strange to me is on the top left connector (CN202). Pins 1-4 (12V T CON) were always showing 0v, even when powered on. Even if I unplugged the cable from the power supply board. Except for one time. At one time during my testing, I could see that the screen had come on, displaying the half white fuzziness from before. During this time, I was reading 12vs on pins 1-4 on that CN202 connector. I can't tell if this means the TCON board is going bad, or if this is still a main board issue, which I was suspecting up until this point.

Most of the symptoms that I could see seemed to point to a main board issue. But when I noticed that anomaly on the TCON connector, now I'm not so sure. Any ideas or other things I can check? I'm just going off a few threads here to see what others have tested, so I'm not sure if there's something else I can check.

Thanks in advance!

[nomoresonys]

Clear focused pictures of each board and one of the whole back as to see how everything is connected.

[paqman]

Clear focused pictures of each board and one of the whole back as to see how everything is connected.

Sorry, my bad. I edited the original post and added some pics. Thanks!

[nomoresonys]

Videos save SOO much typing, Maybe try this simple procedure first: https://www.youtube.com/watch?v=aOCLpJub2l0

[paqman]

Videos save SOO much typing, Maybe try this simple procedure first: https://www.youtube.com/watch?v=aOCLpJub2l0

I will definitely try this thanks!

Although I will say I misspoke in my original post. Because the TCON connector on the power supply board (CN202) also shows no voltage when the connector is disconnected, I think that would indicate a problem on the power supply board, not the TCON board.

Regardless, your suggestion is easy and I will definitely try it.

[nomoresonys]

Theres so many different designs it's hard to keep up, in a lot of tvs, you will have just standby voltage and ac_det if there, then when you hit the power on button the mainboard wakes up and sends the signal to turn on the rest of the voltages at the powerboard, and of course theres the tvs with the always on powerboards, no idea why they need so many different designs.

[nomoresonys]

You can test the powerboard as stand alone, I'm not sure how it's done on this model.

[paqman]

Theres so many different designs it's hard to keep up, in a lot of tvs, you will have just standby voltage and ac_det if there, then when you hit the power on button the mainboard wakes up and sends the signal to turn on the rest of the voltages at the powerboard, and of course theres the tvs with the always on powerboards, no idea why they need so many different designs.

Sorry I maybe still didn't explain well enough. Both times I was testing those connections, the TV was powered on, not on standby. And most of the time I don't see 12v on them like I should. The only time I did see the 12v on the power board connections to the TCON (CN202), it so happened that was the time when I noticed the TV screen actually had an image on it. (half white fuzzy, the other half normal.)

So what I'm saying is that it seems like that something on the PS board that sends power to that CN202 TCON connector seems to be faulty.

Which is annoying because even when it worked, we had half a fuzzy screen, which may indicate a bad main board ad well. (however I still need to clean the contacts on the TCON ribbons like you suggested.

[Diah]

so much writing and stories.. which will never explain the fault
let start frpm Zero Point
you have on the PSU 3 sockets output..
1- to Mainbiards
2- to LED driver boards
3- to TCON 12V-

disconnect all of three sockets.. plug it in wall and chech on CN101 you will have at least only one line had voltage... write down here and tell which pin regards to the print chart of the socket.

[paqman]

so much writing and stories.. which will never explain the fault
let start frpm Zero Point
you have on the PSU 3 sockets output..
1- to Mainbiards
2- to LED driver boards
3- to TCON 12V-

disconnect all of three sockets.. plug it in wall and chech on CN101 you will have at least only one line had voltage... write down here and tell which pin regards to the print chart of the socket.

I'm assuming you mean CN201, which is the connector going to the main board. I don't have a CN101.

Anyway, I did as you said, I disconnected all three sockets, and plugged in the TV. I see voltage on three pins, as expected:

CN201 (to main board)
Pin 2 - 3.9v
Pin 8 - 12v
Pin 9 - 12v

And I see no power to any pins on either CN301 (to LED controller) or CN202 (to TCON)

[Diah]

I'm assuming you mean CN201, which is the connector going to the main board. I don't have a CN101.

Anyway, I did as you said, I disconnected all three sockets, and plugged in the TV. I see voltage on three pins, as expected:

CN201 (to main board)
Pin 2 - 3.9v
Pin 8 - 12v
Pin 9 - 12v

And I see no power to any pins on either CN301 (to LED controller) or CN202 (to TCON)

okay, so Pin 2 AC_DET have low voltage which we can use it as standby
keep the socket which go zo mainboards disconnected... other 2 sockets to LED driver and T_CON plugg them bacl in place....
disconnect the socket between the mainboards and LED driver boards and 2 LVDS cable between MB and T-CON

- connect direct or via 1KR in case you have one under hand ... pin 2 ----- 1KR ----- to pin 3 & pin 15 plug in and check if you got 12V on T-CON fuse F101 close to the socket on T-CON.. and see ig the screen show you any sign of picture ... in case no LED BL on .. use light to explorer the screen.

[paqman]

okay, so Pin 2 AC_DET have low voltage which we can use it as standby
keep the socket which go zo mainboards disconnected... other 2 sockets to LED driver and T_CON plugg them bacl in place....
disconnect the socket between the mainboards and LED driver boards and 2 LVDS cable between MB and T-CON

- connect direct or via 1KR in case you have one under hand ... pin 2 ----- 1KR ----- to pin 3 & pin 15 plug in and check if you got 12V on T-CON fuse F101 close to the socket on T-CON.. and see ig the screen show you any sign of picture ... in case no LED BL on .. use light to explorer the screen.

OK I think I get what you're wanting here, but a bit confused about how you want the 1k resistor hooked up. You're saying on CN201, I should connect it from pin 2 to pin 3 AND pin 15?

So pin 2 ----- 1KR ----- to pin 3
And
Pin 2 ----- 1KR ----- to pin 15?

[nomoresonys]

Yes that is correct.

[paqman]

Sorry for the weird arrangement of pictures. (on mobile) In the one you can see how I connected the 1K resistors from pin 2 to 3, and from pin 2 to 15.

And then in the other image I pointed out the F101 fuse just to make sure I've got the right one. I plugged it in and I did indeed measure 12v at the F101 fuse.

The other pic shows all boards how they were connected during this test.

I did not get an image on the screen, and I used a flashlight and still could not seen an image.

[Diah]

so the LED BL didnt come on at this test.. an no image at all on screen.... so we need now to configure the last test in other way..

all sockets / LVDS should back in place as original also the one which connect to mainboards.
we will slide out ( take it out from circuit ) the wire of pin 15 " TCON_ON) from the sockets isolate it so no short will be to chassis..
we connect pin 3 PS_ON via 1KR to pin 15 on boards only
power up the TV .. yours BL should now come on... check the image on screen if there are issue at panel or T-CON we will see it.
in case no image you need to do the test again at time you disconnect half screen ribbon once from the T-CON

[paqman]

we will slide out ( take it out from circuit ) the wire of pin 15 " TCON_ON) from the sockets isolate it so no short will be to chassis..

Is there a trick to pulling this wire out of the socket? I don't want to damage the connector.

Edit: I got it. Was able to pry the little tab in the back up enough to get it out.

[paqman]

so the LED BL didnt come on at this test.. an no image at all on screen.... so we need now to configure the last test in other way..

all sockets / LVDS should back in place as original also the one which connect to mainboards.
we will slide out ( take it out from circuit ) the wire of pin 15 " TCON_ON) from the sockets isolate it so no short will be to chassis..
we connect pin 3 PS_ON via 1KR to pin 15 on boards only
power up the TV .. yours BL should now come on... check the image on screen if there are issue at panel or T-CON we will see it.
in case no image you need to do the test again at time you disconnect half screen ribbon once from the T-CON

OK I reconnected everything, removed pin 15 from the CN201, connect 1KR from pin 3 to pin 15, and powered the TV on, and still the BL does not come on. I do see 12v at pins 1-4 on CN202, which is strange to me. But I'm probably getting ahead of things there.

I also tried removing one of the two screen ribbons from the TCON at a time. Never got any BL.

[Diah]

nothings strange.. CN202 should read correct 12V pins on 1-4. because we added 1KR from Power_on to T-CON_ON which trick the PSU to generate this t_con 12V.

but no LED BL. are the subject we need more deep investigated at it,

A- during the last test...please list all voltage you have on CN201 sockets during the test and listed the no and name of the pins..( if all correct as i suspected ) then :-

1- at yours last test did you noticed the Mainboards working..... by check USB 5V. or hear sound when you fed it with external signal... or if the Audio Optic port lit red and remain on ?
2- did you measure if there any voltage on the LED driver socket sockets at PSU side and how much ?
3- did you take out the PSU out from the TV and inspect the down side if there any soldering crack or unusual sign ?

[paqman]

nothings strange.. CN202 should read correct 12V pins on 1-4. because we added 1KR from Power_on to T-CON_ON which trick the PSU to generate this t_con 12V.

but no LED BL. are the subject we need more deep investigated at it,

A- during the last test...please list all voltage you have on CN201 sockets during the test and listed the no and name of the pins..( if all correct as i suspected ) then :-

1- at yours last test did you noticed the Mainboards working..... by check USB 5V. or hear sound when you fed it with external signal... or if the Audio Optic port lit red and remain on ?
2- did you measure if there any voltage on the LED driver socket sockets at PSU side and how much ?
3- did you take out the PSU out from the TV and inspect the down side if there any soldering crack or unusual sign ?

OK so I didn't pay attention to some of that stuff on the last test, so I did it again. Interesting note, the screen cam on this time! But intermittently. It didn't stay on the whole time. And when I unplugged and tried again, it came on again. But again it is not consistent. And most of the time it won't come on. When it does, the right side of the screen is white fuzzy, the left shows normal image, so I am able to use the remote and change inputs and change volume, etc.

As for the test, here are the voltages I measured:

CN201 (PS to main board)
1 (NC) 0v
2 (AC-DET) 3.8v
3 (PS-ON) 5v
4 (12v-AV) 12v
5-7 (GND) 0v
8-9 (+12VS) 12v
10-13 (NC) 0v
14 (12V TCON) 12v
15 (TCON ON) 5v (connected to pin 3)

CN202 (PS to LED driver)
1-2 (GND) 0v
3-8 (X00020) 26v
9-12 (GND) 0v
13 (VSNS) 2.3v
14 (GND) 0v

USB is working. Optic port is lit red, but I haven't been able to test audio really. I did put something in comp and changed input to it, but didn't get anything. Not sure of the best way to test this.

I haven't taken the PS board off to check for anything unusual. I will try to do that tonight. But I will say that last night when checking some voltages, I accidentally touched two connectors at the same time on a big bar labeled HS10 that caused a spark/short. So I am not sure if I did further damage there!

[paqman]

Took the PS board off, the back looks good to me. No real solder cracks, burn marks, or other issues that I could see.