M550sv

[infringer]

I have an M550SV by Vizio.
The unit powers on works but the picture and auidio if a video is playing both cut out but the Vizio light stays lit up. It is not reproduced by a specific thing leading me to believe it may not be the "firmware issue"
It will also go off if browsing in the menu long enough so it is not just playing video.

I was sold a kit to "repair" this problem U3 and U9 were both replaced 1117 voltage regulators I thought this was a full repair kit but I got stiffed out of 25bux for this kit.

They included fuses but I did not replace them seeing as how it would work than shut off.

Can F1 and F2 have intermittent failure is it worth replacing the fuses in this case I'd rather save them for spares if this is really not possible so need to know this if so I will replace?

Would this likely be a power related issue with something on the power board itself or is it more likely to be a mainboard related issue?

Anyone have a service repair manual for the M550SV/M470SV/M420SV from what I can tell the main boards are interchangeable?

Anyone aware of other TV models that use this panel so that I could swap out parts from another TV model and make it a LG instead of a vizio for instance?

The screen is in great condition I don't want to throw it away but I also don't want to spend too much on it either because at a point I can purchase a new TV I also replaced one swollen cap on the main board a 16v 200uf cap.

Really would love to get this one going if possible been messing about for hours trying to figure it all out any help is going to be most excellent!

TV INFORMATION BELOW:

The Model Uses an LG Screen 55" LC550EUH

The Main Board is 0171-2272-3715
http://assets.shopjimmy.com/media/ca...0150-top_4.jpg

The Power Supply Board is the large White One 0500-0612-0140 (PLDK-A002A)
http://assets.shopjimmy.com/media/ca...2-0140-top.jpg

OK with this information out of the way.

[CapLeaker]

Re: M550sv

Sounds like BGA on the main board to me.

[infringer]

Re: M550sv

You think? I know its common with certain gaming systems and certain laptop chip sets but the TV BGA socket has yet to cause me any problems I assumed the same with other main boards and had no luck trying to rework them the same issue cropped up every time the first one I did turned into a dud because I followed the temp curve chart for a PS3 which is incorrect.
After I looked at the specs it was more similar to a laptop for a reflow. Reballing is an art though hope you ain't busy for a while if you do it via hot air lol anyhow interesting you mention that though as I have tried and failed at that so many times maybe this is the time. I should just give up and save up money to buy a new TV one of these days so I don't have to constantly fix hand me downs I suppose kinda hard to justify when you don't get a raise for 6 years though and people think money grows on trees :P

Anyhow still working at it I have a hunch for whatever reason something on the power board is crapping out it seems a bit noisy when it kicks out even though the status indicator stays lit almost if possibly an area is dropping power maybe a bad SCK even? IDK

Wish I had a schematic of everything would make life a lot easier...

[CapLeaker]

Re: M550sv

Here is how that thing works:

STBY voltage is always on, regardless of the state of the TV. You press the power button, the main board returns PSon (all PSU rails on) and BLon (backlicght on) to the PSU. The PSU turns itself fully on, the TV boots, screen comes on etc.

For the TV to cut out there are following possibilities: Either a BGA problem (yes, TV have them too), a PSU problem (cold solder joint), or the wiring between the PSU and the main board.

How to go about this? First measure what happens to PSon and BLon on the PSU, when the TV turns itself off. Better actually to write down the pin name and the voltage you measured with the TV on and then again after it turned itself off. The idea is to figure out if you lose PSon from the main board, or you lose voltages coming from the PSU and post it here.

You didn't post any pictures, so you have to look if there are cold or cracked solder joints on the transformer pins, fets and diodes on the PSU itself.

[infringer]

Re: M550sv

Confirmed it is the power board I managed to get someone to let me use there power board for the night out of their same model TV!

Now there are a couple of oddities his was an after market and there is one capacitor 2200uf that has been replaced with a 1000uf cap and it looks like all of the smaller caps were replaced some of them beefed up voltage wise which don't hurt nothing but what has got me going is this cap they swapped out with less uf's I thought this was a no no in the cap world then again maybe the guy that repaired this TV the first time put the wrong value cap on the power board errrr I so wish I had a schematic with a parts listing anyhow. As far as cracked joints I seen one joint on the transformer that just goes through the board that is not soldered but it isn't on a trace either so I am assuming it does not get connected.

Still analyzing but I shall take some measurements and post back. Would be great to get this thing diagnosed while I got a day with a power board I'm going to mark all the caps that are different for sure and make some notes for starters.

I should just take some good quality pics To make life easy as well bbiab thanks for slumming it with me on my TV issue god old budm helped me with an old RCA I had it just crapped out again and this one as well so I am down two TV's I only really need the computer but its nice to have one in the other rooms as well at times so I don't have to drag friends PC's into here when they nag me to try and fix them.

You know might actually make some headway tonight we will see.

[CapLeaker]

Re: M550sv

Make some high quality, straight shot pictures of the front and back of the PSU. Also note down the pin names and voltages of the bad PSU connected to the main.

At least you found the problem board.

[infringer]

Re: M550sv

On working board I notice a few differences.

12V pins are NOT bridged like non working board

LD ON OFF & BL ON OFF ARE bridged on WORKING BOARD

There was 2 Caps with different values than non working board I have them marked on board.

Non working board is board with X

Measurements are up next but something to take a look at at current a very curious deal for me having access to another board is interesting never thought in a million years I'd get this lucky.

Time to run some measurements though while the night is still a bit younger.

[infringer]

Re: M550sv

PIN ON OFF
18V 18.1 18.2
18V 18.1 18.2
PWM 3.2 0
LDON 3.2 0
BLON 3.1 0
PWRON 3.0 0
12V 11.9 0
12V 11.9 0
12V 11.9 0
5V 5.2 0
5V 5.2 0
5V 5.2 0


I will note 12V is a somewhat slow drain to zero it sits at about 1v then goes to .7v then 0.

What is the PWM signal for what generates it the power button or the video board or something on the power board?

That would be the measurements. It does actually shut completely off now after a short bit of waiting. Very strange.

[infringer]

Re: M550sv

Better pics of the back etc....

[infringer]

Re: M550sv

No thoughts on the random shutoff hrmmm yes it is hard to tell what is causing it because it is so random oh well hopefully I got enough info have to take the board back the last old RCA I finally figured out was a bad trace not visible by the naked eye or magnifying glass pretty crazy took forever to find it out budm stuck with me for a while then I finally came across a schematic which pointed me to an area where I replaced a smd zd lucky for me I had one on an old junk power supply from a TV. Then that was not it so finally after poking around while on I figured out voltage wasn't carrying over a certain area so I soldered a jumper wire in and viola picture lol now she is dead again what a bum of a TV lasted about a year and crapped out again.

But need to probably turn it in for tonight I'll have to go from there based off of these measurements.

Thanks for your help thus far!

-infringer

[infringer]

Re: M550sv

Ahhh what a blunder I forgot something critical when doing voltage testing...

I will have to test when I can get some help maybe this weekend or something.

Sorry about this the measurements were incorrect due to no signal activating the shutdown long before the error happened I was sitting here thinking to myself hrmm I wonder why Cap Leaker dropped out of the discussion all together... So I am sitting here just pondering a variety of situations reread everything I typed thinking hrmm maybe I said something that was offensive in some way etc ... It is hard to know how someone takes what you type online I could not find anything out of the ordinary.

I kept thinking hrmmm well what could it be and the simple answer is my measurements are not taken at the correct time thus the requirement of too much hand holding likely put the kabosh on the deal I mean at least I know it is the power board but still have a ways to go from there.

Anyways I will get correct readings and post back.

Was there anything else you wanted to know are the pictures and the explanation good enough ?

[CapLeaker]

Re: M550sv

"I wonder why Cap Leaker dropped out of the discussion all together... "

CapLeaker didn't drop out. I am just very busy with work, some days more than others. Depending on that I spend more or less time here. Also sometimes the thread falls back too far and I don't notice it.

"I kept thinking hrmmm well what could it be and the simple answer is my measurements are not taken at the correct time thus the requirement of too much hand holding likely put the kabosh on the deal I mean at least I know it is the power board but still have a ways to go from there."

See... you got the right idea. What you are looking for is to measure the voltage rails continuously until the problem arises. You can easily do that with a DMM set to measure DC and activate the min/max setting.

Also check the DC voltage on the 2x 450V main filter capacitors and do the same trick there.

Btw, your pictures are good in size, but not sharp.

[infringer]

Re: M550sv

Oh yes totally understand thx for the reply Work is a killer been doing it for the last 20 years actually I feel yah a good week of crawling around on concrete diagnosing electronics on arcade games the joints often ache and back neck and shoulder pain seem to be rather common as well due to the odd positions you must been in for extended periods of time and constantly up and down off the floor. People think man what a great job hehe and it does keep you in somewhat of a decent shape but its also hard on the boday as well then when you need to work OT 50 60 hour weeks your body screams I want vacation lol! Part of it is I should sleep more than 5 hours a night but you try and sqeeze as much as you can into a day while you are younger I think.

[CapLeaker]

Re: M550sv

That is true, plus the eyesight isn't quite like it used to be anymore either.

[infringer]

Re: M550sv

odd thing replaced my main board and power board still having power off troubles would be most excellent to figure out what is the cause of this issue. My old board I could get it to stay running for longer periods of time sometimes hours using a VGA to HDMI adapter running on RGB input. But eventually it still shut off.

Still no luck going to replace the timing control board and see if anything gives at this point I am having a whale of a time figuring this one out and doing so in my spare time which is very sparse lots of projects going on solar/wind farm developed a power strip with control over each outlet wrote some dimming software to work with my dimming LED bulbs so they play nice... Hrmmm fixed a few computers, ipod nano, still need to refurb a computer and come up with two different designs of power strip and update firmware to allow for better control and status tracking. Hopefully I keep working overtime so I can get some more lute to expand my solar farm with some solar world panels 245w mono two of these would be excellent. Also fixed up about 8 routers with tomato and DDWRT have about 8 more to go or so. Have a used computer refurb job that I just completed and a rebuild of an old core2duo DELL with upgraded ram OS and hard drive to SSD need to migrate data ton of stuff going on all while working over time and visiting family pretty much every week since Turkey Day lots of traveling have also replaced lighting fixture and about 6 outlets 1 switch have a 4 switch plate that is old and needs replacement as well. And very limited time that is why the late response and the response at wee hours of the morning as well. Naturally the other half wants some attention as well so you must squeeze some time in for that too it has been a marathon really to be rather honest. Thank you for continued chat seems pretty crazy but I've resorted to board swapping to save on time wound up costing me a bit more and no satisfaction should have just purchased a new 4k tv at this point all the money thrown down but I hate perfectly good stuff going to the trash heap.

[infringer]

Re: M550sv

Replaced with a complete kit wires boards and everything included much to my surprise the thing worked for about 2 weeks.

Sold my other tv to recoup some of the costs associated with repairs BAD IDEA!

Last night the TV shut off randomly again could not get it to stay on.

Today it is working fine but I imagine it likely will not last for a reasonable amount of time.

I believe this TV is likely a lemon I don't fully understand the cause weather it is the metal cover on the back causing static issues or something a bit more beyond the scope. Really bothers me that I spent a few hundred in repair it should work without issue really at this point.

I am thinking of possibly discontinuing the purchase of Vizio but really every other tv I owned Vizio has lasted me since the date of purchase still running. But, ever since sony took over Vizio and their direction it seems the quality is good in general but the electronics are not as well thought out which is impossible to tell because they are all laid out excellent on the board better than most other TV brands the power board for this thing looks like a work of art. But somehow somewhere there is a major design flaw in this unit that if fixed would make this thing run for years. Insufficient power possibly somewhere or PCB manufacturing issues not enough copper or something like an issue with static discharge due to not enough space between the board and some metallic object or maybe it is a BGA fault IDK...

I have thought of using KAPTON tape to coat every possible static discharge point or even grounding the cover to my tv stand to see if it helps.

I have tried for hours to recreate the problem today with zero luck.

[infringer]

Re: M550sv

After a bit of investigation I believe the issue people in my shoes are having is faulty backlighting somewhere between the cable to the individual LEDs. I would also like to point out that the buffer board in my m420sv just took a crap there is a main board and a power supply in this unit no separate tcon and both boards are confirmed working lvds cables are good so screen artifacts and freezing looks like timing control issue so much has to be buffer board on bottom screen was inspected well and is healthy so only thing left is the buffer board on the 42 inch. I don't believe tabbing is the issue either as pressure don't seem to make a difference. Anyway check out your LEDs with a bench top psu figure out which ones are faulty and replace them on the m550sv faulty LEDs can allow the panel to run in this TV then at a point it will black out and not shut off until you remove power to the unit you can recreate the same symptoms by simply unplugging one of the backlight cables and powering the set on hope this helps some folks with things to look for in difficult lcd sets!