Vizio M3D550SL

[tjmethod]

I've taken on fixing a Vizio M3D550SL for my dad that has backlights but no picture. Thinking the main board is the issue since the t-con is part of that board, I was lucky to find a one on ebay since it isn't manufactured anymore or available anywhere. It was supposedly from a smashed screen set guaranteed but after swapping it out, still backlights only. I read about similar problem being the backlight inverter but all seem to check out on the volt meter. I dont know if the backlight inverters are good how or how or if it would change the multimeter readings. There's no physical damage to the panel. I am now confused as to where to pinpoint the problem. Once I got the main board (well packaged), I saw a video where the guy replaced a regulater. This board only has 2 and the voltages are virtually the same as the original boards regulaters but that doesnt mean this very well could be the t-con section on this board having the same problem. I'm leaning towards this since the flashlight test shows nothing and could be a board with the same problem Any suggestions from the far more experienced would be great?
Thanks, TJ

[budm]

Re: Vizio M3D550SL

The question is, do you see the screen glow or see the lights on the back side of the LCD panel in the dark room or not?

[tjmethod]

Re: Vizio M3D550SL



Hey there bud I have not shut out the lights but when turning it on and the "vizio" bezel light turns from amber to the white, the LEDs light up on the front of the screen and appear to look toally normal. In the back of the panel every hole is lit up from the LEDs. I am guessing there is a difference between what looks like normal LED lights when turning on as oppsed to a glow lime you are mentioning? That will be the first thing I heck when I get home

[budm]

Re: Vizio M3D550SL

As long as you have backlights then the problem for not having pictures on the screen will be the main board or the panel. You can also try having one ribbon cable to the panel connected one at a time to see what happen.
Pictures of the whole back side of the TV showing all the boards?

[tjmethod]

Re: Vizio M3D550SL

Will do as soon as I get in- thanks

[tjmethod]

Re: Vizio M3D550SL


https://s15.postimg.org/6vo1mytl7/20160928_215243.jpg
https://s18.postimg.org/waxlgofmh/20160928_215347.jpg
https://s15.postimg.org/et8uvf3x7/20160928_220432.jpg
https://s22.postimg.org/wtsrc5wf5/20160928_220459.jpg
https://s12.postimg.org/uz1ursmql/20160928_220725.jpg
https://s12.postimg.org/qwsf7ecul/20160928_220741.jpg

Here are the pictures with the lights out and with the cable behind from behind the right side disconnected to the panel then with just the cable behind the left side disconnected. The screen appeared to be normal backlights with the lights out before disconnecting anything. When disconnecting the cable behind the left right side showed the screen split in half with vertical lines on the left and a white screen on the right. Once plugged back in and turning on I noticed that the a definate line between the 2 sides so I disconnected it again, cleaned it with alcohol and made sure it was seated perfect and it seem to look like normal backlights at that point but still a separation line and as if there was a vertical 'grain' that I hadn't noticed before. Appearance of the screen with only the cable behind the left side didn't change anything.

[budm]

Re: Vizio M3D550SL

It is one of those LCD panel that has the tab bonding on the bottom edge of the LCD panel which usually get damaged by the cleaning fluid that the customer spray on the screen directly instead of damping the cloth.
That is what I suspected to what had happened to the screen.

[tjmethod]

Re: Vizio M3D550SL

Do you think there is any remedy or do you think the screen is smoked? Do you think carefully cleaning the boards and socmets with alcohol might work?
Thanks again

[budm]

Re: Vizio M3D550SL

You need to remove the LCD metal frame to get to the tab bonding boards and do the visual inspection to see if there is any corrosion damages to the bonding.

[tjmethod]

Re: Vizio M3D550SL

Ok so corrosion would be the culprit but with any luck it would be buildup of some type of cleaner. I'll be checking that when Iget in tonite.

[budm]

Re: Vizio M3D550SL

What happen is that the corrosion will eat away the fine traces, and parts.

[tjmethod]

Re: Vizio M3D550SL



Well you pinpointed right to the source of fhe problem... there were 3 drivers on each board and the it was only one, the middle one on the right side board. I guess the panel is junk?
Thanks for all your help

[tjmethod]

Re: Vizio M3D550SL

Even though I cleaned it thoroughly woth alcohol, that only made it look like it wasn't corroded.