LG 60PX950 ~ Vertical Pixelation Issue

[kca]

Hello all ~

I recently picked up a 60" LG plasma that is having issues with the picture. I have just begun to investigate it, and will post images soon. It appears to have a somewhat unique issue with green pixelation in the form of vertical bars wherein the pixels are rather transient. Many of these pixels, though not most, show on and then off as they attempt to form a picture. As a start, I've included an image of what it looks like when I pop in a DVD as that image is more stable than when I attempt to simply hook it up to our DIRECTV satellite signal.

I am hoping that someone out there has had the same issue and can help by quickly identifying the component that would cause such a relatively unique signature issue with the picture. Thanks in advance for your replies and assistance.

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Not sure why my image keeps getting posted upside down (see link above), but you get the idea. I attached the file image in both the right-side-up format and when that didn't work, I flipped it over and reposted. But, got the same upside-down results. I'll try to correct it, but in the meantime for those who are assisting, please envision it flipped back up into the upright position. Thanks.

In the meantime, here is a PDF file of the same image:


-- kca

[Hamie]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Looks like a sus fault.

Need to check vsc, -vy and Zbias.

[Andrew F. Ali]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Looks like a sus fault.

Need to check vsc, -vy and Zbias.

+100...Hamie is the expert on this...follow his advice...

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Thanks Hamie and Andrew F. ~

Here's more info:

Tested the Vs and Va this morning. Readings are 202 and 59 respectively, whereas the specs read 203 and 60 on the sticker. All 5v wires are reading 5.12. So, the PSU seems to be in working order.

Vs is running directly to the Zsus board with no Va present. Both the Vs and the Va are running to the Ysus. Perhaps this is standard in the 2010 year plasmas, but it's a bit different configuration than the 2006-2008?Hitachi's I've mostly been working on.

Plugged it in this morning purposefully first with no signal preeent (meaning, I hooked no satellite signal through the HDMI ports nor any DVD player, computer, etc ...). The result was that there was a series of vertical bars that flashed on and off in sequence from left to right and back again. They were all of the scattered green pixelation nature, and varied in size from 12" wide to about 3" wide as they made their way across the screen and back. So, it was like a moving test pattern of sorts, wherein the tv was attempting to read or display an image one section at a time, but failing to do so. I'll try to capture a video of that.

Going to try to post photos now from my phone, to give you more to go on.

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Three images of the Zsus board and one of the PSU.

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Hmmm ..... not sure why the images I'm posting of late are still ending up upside-down, but let's ignore that for the moment.

Hamie ~ Do you think the problem is completely isolated to the Zsus board? That would be nice, as they're only about $20 on Ebay.

I see no bulging caps on the Zsus board (nor on any other board, for that matter), but I know they can still be defective.

Can you walk me though what you mean by vsc, -vy and Zbias? I am assuming vsc is the reading of 202 I'm getting from the PSU directly into the Zsus. Is that correct? I'm not sure what -vy means. And if the ZBias is referring to the knob labeled as VZB near the middle of the Zsus board, I have yet to move that in either direction left or right.

Thanks in advance for the help, Hamie and everyone, I really appreciate it.

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Here's a short video I just shot of the green "banding" I described up above. It gets cut off in the middle b/c my phone ran out of memory, but it gives you the idea. Not sure if it shows up clearly enough, but on the tv screen itself you can faintly see the LG logo and the words No Signal as the green (and white too) pixelation makes its way across the screen and back.There are also some blue pixels and a very few red ones involved.

So, between the evidence of the LG logo brand and the outline of the word "MULAN" from the DVD I was using earlier (please see my first couple of posts), the image is attempting to come through but is being inhibited or prohibited by some fault or another. The "No Signal" message under the LG logo makes sense in the current scenario, because I purposefully have no source signal hooked up right now as I investigate.

[freakaftr8]

Re: LG 60PX950 ~ Vertical Pixelation Issue

How does the solder look on a ERC coils on the Y main board? Can you take a picture of the back side of the Y Main and Z main boards? (Y and Z sustain boards)

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Had to post the video on YouTube. Here is the link:


https://youtu.be/t4NEP_6GMeY

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Hi ~

I can take pics of the back of those sustain boards in a little while. In the meantime, I do have some pics of the front of the Ysus and the other boards involved. See the images below.


I'm a bit hesitant to take the Ysus and Zsus boards off at the moment, until I hear back from Hamie. Wondering .... How likely are those solder points, particularly on the coils you mentioned, would cause this type of green, pixelated "banding" onscreen?

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Other boards:

[Hamie]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Look on the z-sus

I can see a resistor marked VZB.
This is Zbias, measure ACROSS the resistor, post your voltage.

You should have similar points on the ysus for vsc and Vy.

Again there should be test points, measure across them.

Ie: Don't use the frame or screws for ground.

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Hello Hamie ~

I found this post where you had helped someone before (see pic), and took your advice just now to get the readings across the resistors in question. Here are the results:

Zbias = 104 (reading on my sticker is 105)

VSC = 17.4 (reading on my sticker is 150)

and

-VY = 179.7, which I assume is really -179.7 (reading on my sticker is -180)


So, it looks like of the three the VSC is the only problematic one. Unless I measured it wrong, but I did the same to that resistor as I did to the other two.

Have you seen this before, where a reading on the VSC is approximately 1/10 of what it really should be (i.e., 17 / 150)? And, do you think that is a singular source of the picture issue or is there more at hand?

[Hamie]

Re: LG 60PX950 ~ Vertical Pixelation Issue

OK so you either have a problem with the ysus or buffers.

Unplug the buffers so they nolonger are connected to the ysus.

Then retest vsc and see if the buffers are pulling down it down.

If not your problem is the y-sustain.
It might be easy enough to repair by hand if you can't find a replacement.

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Okay. Just disconnected both buffers and the VSC reading is now only 1.5 as opposed to 17.4.

Interestingly, the picture on the screen appeared to be doing the same thing with the green, vertical, pixelated banding even when the buffers were disconnected.

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Also, there was a pitched sound coming from both the Zsus and Ysus before I disconnected the buffers. Probably nothing to worry about, but more audible than I think is normal.

However, when I had the buffers disconnected just now, this same sound grew quite a bit louder and was a combined high tone / buzzing that I'm sure is not present when the set is in full working order.


~ kca

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Were you looking for the appx. 150 reading on the VSC, Hamie, when the buffers were disconnected? It seems odd that it would drop to 1.5 from 17.4 as opposed to climbing to 150.

Can you tell me what all of this means?

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

Images of the Voltage Sticker on this LG 60PX950 UA

(see pics below)

Hamie ~ Does the 150 number in this sequence represent the desired VSC voltage?

[kca]

Re: LG 60PX950 ~ Vertical Pixelation Issue

One more set of images below off of the upper-left hand corner of the YSUS that might be helpful. The two resistors are where I took the readings, and the close up of the VSC control knob sits just below the resistors and slightly off to the right.

Might the VSC control knob need be adjusted? Won't mess with it until I hear back.