Vizio m550nv "2 seconds to black" issue

[Aceofspades16]

Hey everyone. As I stated in the welcome thread , I been a long time lurker. I joined today to finally ask a question of my own.
I searched everywhere and cannot find anyone with my current issue
On my tv, the led backlights suddenly went out. Still have sound and using a flashlight - still have picture.
The research I have done without any schematics for my set, was reading every possible scenario others have posted for this particular model tv. However no one had my exact issue.
So that leads me to believe my power board was to blame.
I tried another board and it's the same exact issue
The tv powers on , the backlights turn on , the vizio logo appears , then the back lights shut off.
I have sound and video.
Would anyone be able to direct me a little bit in where to look next?
Thanks!

[Andrew F. Ali]

Re: Vizio m550nv "2 seconds to black" issue

You have a back-lights problem. On the set/s of strings 1 or more could have gone open or even shorted. Measure the Back-lights supply voltage at start up then when they switch off measure and report the voltage you get.

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

Thank you so much for the reply.
I'll be straight forward when I admit that I am struggling to identify what exact leads to test and what not.
I know it's required to post pictures so I will do that as soon as I get home

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue



This is the power board. The original.

[CapLeaker]

Re: Vizio m550nv "2 seconds to black" issue

Need a hi resolution, straight shot pic, so we can read stuff off the board.
On the top left there are some connectors that go from the PSU to the main board. Put your DMM into DC mode, turn your TV on. Put the negative lead to chassis GND or on any GND pin on the secondary side of the PSU. Measure the DC V on each of the pins. NOte down the pin name with the voltages measured and post them here.

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

Ah my bad I will post my results along with a better picture
I will probably have to wait until tomorrow due to work.
Thanks

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

Ok. I broke down the main board into 4 pictures. Tried to fill my whole viewfinder with the board then close ups of the board.
Also a snap of the "tcon"? Board and main board

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

With the board positioned on the tv the upper right hand side has a few connections

CN 203 reads:
18v top 2 pins

CN 202 reads:
PWM - 2.8v
BL_ON - 3.3v
POWER - 3.1
Each 12v pin was 11.8v
Each 5v pin was 5v


CN 201 reads:
5v on top 2 pins


Top left of board for the LEDs

LCN202
110v
empty
11.6v
14.0v
13.0v
11.0v
empty
12.4v
12.3v
13.3v
11.1v
empty
110v

LCN201 ** one lead was quite high
110v
Empty
13.6v
13.5v
12.2v
12.0v
12.6v
22.9v**
13.6v
13.1v
Empty
110v



****unplugging clip CN202 and plugging back in will cycle my backlights , for about 3 seconds befor they shut off

[CapLeaker]

Re: Vizio m550nv "2 seconds to black" issue

you got a bad led in the backlights. I guess you have to take the panel apart.

[budm]

Re: Vizio m550nv "2 seconds to black" issue

Per Voltages chart, the LED Voltage with load is 138V:
https://www.badcaps.net/forum/attach...8&d=1478291692
TV OFF, leave the Black probe on chassis, red probe on the VLED pin and record the DCV reading, keep the probes connected still then turn on the TV to see if it jump higher than 110Vdc.
The '22.9v**' looks bad.

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

you got a bad led in the backlights. I guess you have to take the panel apart.

The frowny-face concerns me. Is removing those lights going to absolutely suck?

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

Per Voltages chart, the LED Voltage with load is 138V:
https://www.badcaps.net/forum/attach...8&d=1478291692
TV OFF, leave the Black probe on chassis, red probe on the VLED pin and record the DCV reading, keep the probes connected still then turn on the TV to see if it jump higher than 110Vdc.
The '22.9v**' looks bad.

Good call. I'm looking forward to testing this again.
Ive forgotten just how heavy this 55" tv is and lugging it around the house quite the task.

Everyone - thank you for walking me though this

[CapLeaker]

Re: Vizio m550nv "2 seconds to black" issue

The frowny-face concerns me. Is removing those lights going to absolutely suck?

Lesser the actual LED repair that I would be concerned about. Be very careful with the removal and the reinstall of the panel. As larger they get, as harder it is not to break them. There a quite a few threads on people did just that. Take your time and if you need get another set of careful hands. Remember the order of the diffusers to. There are YouTube vids on this.

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

Bars came today. Disassembled literally the entire tv. Powered it on. Works. Thanks everyone
I really hope I never have to do this again

[TiffanyF82]

Re: Vizio m550nv "2 seconds to black" issue

How did you change the backlight bar? Just spent $90 on a new board and this still is doing this to me. I found the part (Part #: 0980-0700-0410R) online for like $9. Is like to do research on how to replace this while I'm waiting for the part to come in the mail. Please help.

[dskall]

Re: Vizio m550nv "2 seconds to black" issue

How did you change the backlight bar? Just spent $90 on a new board and this still is doing this to me. I found the part (Part #: 0980-0700-0410R) online for like $9. Is like to do research on how to replace this while I'm waiting for the part to come in the mail. Please help.

You can start here. https://www.youtube.com/watch?v=Bf5T2wwtydY

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

Hello

Well I'm not sure if that part is correct or not but I do have the actual led bars (I bought 2 sets ). The other set I have listed in eBay if you need them
Anyways
I just removed the bezel and all the surrounding tabs. Best to work on a flat space with plenty of room

Once you have it all stripped down you will need to start removing layer after layer of panels.
I used printer paper to slide between to help separate. I also only touched the paper so no finger prints would ever be on those panels.
Remove them and place them aside.
The LCD is extremely fragile. Do NOT bend this AT ALL. Get somone to help move to ensure it doesn't bend at all! Very important.

Now you have access to the upper and lower light strips

[TiffanyF82]

Re: Vizio m550nv "2 seconds to black" issue

I did find a set of backlights on The VizParts website for like $9. Not sure of the shipping. But I'll gladly take them off your hands for you if you could give me a similar price. Thanks a bunch for the instructions!

http://vizpartsdirect.com/setSearch....rt=19&Submit=p

[Aceofspades16]

Re: Vizio m550nv "2 seconds to black" issue

Hey if that's the correct part for $9 - it's a great deal

If not - I'll sell you mine for what I paid (you can see my eBay history) he wanted $30 plus shipping ($13.84). Not looking for a profit - just trying to help out another member