Samsung PN58C680 black blobs

[freakaftr8]

this ones throwing me for a loop. The guy picked it up from said all the screen became a little dark in areas And it had a lot of pixelation so I had to go check it out. Ended up picking it up and I brought it home what happens is that it has a lot of black areas in a lot of pixelation kind of Like a bad zsus. all voltages check with its Spec including Vscan. oddly the panel has a label for ve but I cannot find ve on the Z sustain board. so far there watching this TV and I noticed that after a little bit of time the picture starts to clear up the black blotches start to disappear however they don't completely go away. On a full white screen with lettering I see a lot of horizontal purple banding and flickering. Now I have done some research on the internet and noticed that these c-series and b-series 58 inch plasmas from 2010 are known for having bad panels? Well I went ahead and cranked up VS from its original 210 to maximum that the power supply can output about 218. Pictures almost perfect a little black dIthering and some green and red mal discharge . I was able to take care of by turning vscan from its original - 200 -203. so all is well now except for the fact that I'm a little concerned about the higher vs. Voltage but as soon as I went into the menu and started playing around with the picture modes of course it was set in dynamic if I go to movie mode the screen completely starts losing its picture almost as if I unplugged the z sustain. but if its in standard or dynamic the picture seems decent it's still not perfect but a lot better. Now if I put it in 3d its all messed up a lot of green dithering lot of green mal discharge sparkles and some green vertical lines all through the screen. So does this sound like a panel ? Losing it is possibly? I noticed Y & Z sustain boards are relatively cheap for this TV however I have not pulled the boards to find out if there's any bad components but since they're working I would only assume that they're doing their job including especially since all voltages seem to be present and accounted for. I have not heard of Samsung's having bad panels like this have you?

[freakaftr8]

Re: Samsung PN58C680 black blobs

Here are pics. all of these were taken before voltage adjustments.

[tom66]

Re: Samsung PN58C680 black blobs

Looks like an X-main (Z-sus) failure; a lot of panels will work nearly good enough with a missing Ve-bias period, which I think is what you are seeing.

Note, some Samsung panels use Vb instead of Ve. Same voltage.

[freakaftr8]

Re: Samsung PN58C680 black blobs

ok VB I found that on the board that's running at 90 or - 90 but the sticker on the panel says ve. does that sound about right?

[Shinju]

Re: Samsung PN58C680 black blobs

I second what tom66 said, when you ran the test patterns did you see the same ink looking blobs?

When I started on my 60pv450 I was seeing this almost exact same thing and I replaced the xmain and all was restored.

[tom66]

Re: Samsung PN58C680 black blobs

@freak if you've got a scope going spare you can check X-main output and see if it's bad or if the panel is bad (I think 99% x-main here... I can't really see a panel do this if bad.)

[freakaftr8]

Re: Samsung PN58C680 black blobs

okay I'm going to get my scope back from my father in law he's had a long enough lol. Yeah ill scope out the x-main and see if I can find a problem there but maybe before I do that I'll just go ahead and order. it's only $20. I feel a little uncomfortable running the vs 8v higher than normal and vscan about 4 volts over

[freakaftr8]

Re: Samsung PN58C680 black blobs

oddly this TV has 6500 hours on it and in service date on the menu says Feb 2013 even though it's a 2010 model.

[Shinju]

Re: Samsung PN58C680 black blobs

firmware update I am sure.

[freakaftr8]

Re: Samsung PN58C680 black blobs

Good call

[freakaftr8]

Re: Samsung PN58C680 black blobs

I've been searching the internet and finding a lot of threads about these newer Samsung panels going bad in samsung replacing them because of this purple banding issue on a white screen. It seems to me that the purple Bandung people are getting away with adjusting the vs voltage up but now however the screen appear to be getting to the point where they cannot adjust it up anymore. If you had to push vs voltage higher. it looks like an even factory authorised repair centers were going out in changing these voltages to clear the purple banding issue. I mean obviously on a white screen you're pulling maximum voltage and maximum wattage through the power supply. is there a possibility that the plasma panels are losing their charge?

[tom66]

Re: Samsung PN58C680 black blobs

No...

What's happening is as the panel ages, the driver board is failing to compensate for panel changes. Increasing the Vs hides this (and should fix it, as the panels "settle in" to a point.) Samsung set the Vs low to start with to save energy.

The reason you get pink tints on bright images is because the electrode resistance drops the sustain voltage on each cell below the threshold for the blue cells to discharge fully.

Plasma panels don't need regassing and they should last much longer than 6,500 hours... Only if they actually are really worn out (like 50,000+ hours) do they start giving real issues.

[freakaftr8]

Re: Samsung PN58C680 black blobs

okay that makes sense so basically with my VS voltage maxed out the potentiometer will not turn any more I'm at 218 volts so the power supply is under compensated for the task at hand?

[freakaftr8]

Re: Samsung PN58C680 black blobs

kind of like that pioneer that I had a while ago remember that one? They had somewhere around the lines of 73,000 hours on itand it had a black blob in the center of the screen that never cleared up as soon as I cranked the vs voltage way up the screen. Watchable again

[/B]

No...

What's happening is as the panel ages, the driver board is failing to compensate for panel changes. Increasing the Vs hides this (and should fix it, as the panels "settle in" to a point.) Samsung set the Vs low to start with to save energy.

The reason you get pink tints on bright images is because the electrode resistance drops the sustain voltage on each cell below the threshold for the blue cells to discharge fully.

Plasma panels don't need regassing and they should last much longer than 6,500 hours... Only if they actually are really worn out (like 50,000+ hours) do they start giving real issues.

[tom66]

Re: Samsung PN58C680 black blobs

okay that makes sense so basically with my VS voltage maxed out the potentiometer will not turn any more I'm at 218 volts so the power supply is under compensated for the task at hand?

Yes but I don't think this is the same issue as the Pioneer - way too few hours.

[freakaftr8]

Re: Samsung PN58C680 black blobs

Also if you look at these Y and Z boards unfortunately I didn't take any pictures right now I'm at work.

They are set up in such a way that they can be mashed into a flat chassis meaning there are no heatsinks standing out everything is horizontally placed like today's TVs are superflat. However the wall mount pegs stick out the standard amount and so does the power supply. It looks like this was around the era where they were converting to the super flat chassis so the boards were already set up this way.

[Shinju]

Re: Samsung PN58C680 black blobs

The LG I just fixed had severe pinks in the whites when the Xmain was going out. After I replaced the board it was fine, whites look white ect.

Heh, I don't know about you two but now that I have been doing more plasma then LCD but I swear every little pixel noise I see I think OMG somethings wrong! Especially on the big screen plasma because of being up to close.

I have to admit its been a lot of fun playing with Plasma over LED/LCD!

Heh sorry to thread jack!

[freakaftr8]

Re: Samsung PN58C680 black blobs

very true I still think of work done more plasmas then led/LCD myself as well but every once in awhile one of these will throw you a curve ball so you gotta keep up on your game haha

[tom66]

Re: Samsung PN58C680 black blobs

You want thin plasmas? See Panasonic's TC-P54Z1...
http://rapidtvparts.com/image/cache/...-1200x1200.jpg
http://www.zdnet.com/i/story/61/18/0...file-angle.jpg

I think the boards are remnant of the Samsung PN58B860 which was also an ultra slim chassis.

[freakaftr8]

Re: Samsung PN58C680 black blobs

Holy flatness batman!! Think my dads PN64D8000 is a flatty like that one. I don't think he ever turns out off. Still running strong