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ranergeo
Senior Member
Last Activity: 01-19-2023, 06:51 PM
Joined: 10-18-2012
Location: Clifton Park, NY
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    I'll add one last video in the hopes that someone has seen this before, just in case I come across it again!

    [url]https://www.amazon.com/photos/share/cqbEVPBj7OSmAb2cYmBpSgCPnNp6RipA1B0kRAkCTij[/url]

    This was nothing more than the "no source" screen, which helped rule out source problems Re: Samsung PN51F8500 - Power cycle,...ross it again!
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Heya Moreno, I think you're referring to the common problem with the 64" version, where the three 10uF caps on the Y-sus would dry out, go low (on their readings), and shut the set down. I did check the caps on the Y, and didn't find anything out of the ordinary with my ESR meter or my Fluke (although I did "in circuit" testing, so I was basically testing an entire circuit at a time :-/ )

    There is absolutely the possibility that either the x or y I received were just as bad as the ones...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Moreno, that was my thought on the panel as well, 'specially since I just did a Sammy D550 series with 13.5Khrs on it with a bad X-main and no picture issues otherwise! Interesting enough, the F8500 hides the hours pretty well, but it was the logic/main that reported the time... in minutes (it was like 980Kmin)... which worked out to about 16.5 Khrs. (I did later find a sub-sub menu that reported hours and cycles, but it was with the new Main board, which had significantly less hours recorded)

    There...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Yup, but tried it again for the heck of it (-5/+8 on Vs) and (+/-5 on Vsc). No change in overall picture quality or sparkles.

    I know I could change out the SMPS just to rule almost everything out, but since it is putting out the proper voltages, I don't see the point of it. I just hate the thought of parting out a tv that should still be working fine :-/

    I wish I could find a detailed schematic of the boards so I could test them a bit better...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    One last question I wasn't able to search out...

    If I'm getting green/white sparkles on a black screen, I'd usually be looking at YFR and YRR adjustments, and although I could potentially test them (at test points on the Y-sus), I don't see any pots to adjust them at? What should I look for if I'm having what appears to be sparkles on black?
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Yeah, I did swap out both X and Y (w/ buffers) to no effect, so I put my original ones back in.

    I have a 3 hour cartoon video running right now, and it's still going strong after 2 hours. The previous best was 20 minutes, so at least I'm feeling confident I found the power cycle problem.

    I'd be waving the white flag if I was seeing lines across the panel, but it's supposedly Samsung's "best" panel. Although I'm pretty sure there's a couple dead pixels, the symptoms don't easily...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Well... new logic/main arrived and so I popped it in and...

    (drum roll please)

    No change, apart from the fact that it now doesn't (seem to) power cycle anymore. I'm still testing it, but it has gone longer than previous times.

    While I was waiting for the new board to arrive, I did go into the service menu and test anything it would self-test (which was quite a lot, I must say!), and also found the panel on time... in minutes... which converted to 16.5Khrs! I guess this...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    That makes two of us! After all I've been able to find and research, its just confounding me why in some scenes (usually static) everything looks great, but in others, at certain times (darks and lots of motion), just won't fill in quickly (but eventually does).

    It reminds me of my students at 8:00 a.m... they'll get working, but it's usually in their own good time lol!

    So, just a general question to confirm what I think I've learned... (Samsung terminology used) Y-Main sends...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Thanks freakaftr8! I had tried it before, and did so again for the heck of it, and still no real change :-/

    Well, if the logic doesn't work and I can't pinpoint it any other way, at least I know I'll have a bunch of good boards to harvest out of it (and since the screen didn't crack, the y-main is still good, too!)
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    So, I plugged my BD player into the other HDMI ports and it worked fine, so I guess it was something in the way my PC was being decoded. Strange, since I just got done fixing a D550 Samsung, and used that to test w/ no issues.

    I've ordered the logic board, so we'll see what happens. I have trouble thinking a plasma panel rated for 100K hrs has already pooped out, 'specially when I can get images to come up with no pixel mal-discharge at all (aside from the burn-in band on the top).

    Just...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Update: So, I put my old x & y boards back in, confirmed it was working the same, and tried heating the logic with no success. I figured I was doing it wrong.

    So I decided to hook my pc in through the HDMI to see if the board was taking inputs, and guess what... it's only working on HDMI 1, but only video (no sound), and it doesn't recognize the line on 2-4. I'm not sure if this confirms the logic board, but I'll double check with my BD player in a bit to see if I can confirm this. Any thoughts appreciated!...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Whelp, that was a kick in the nuts...

    Update: Received the new x and y boards (w/ buffers), and there was absolutely no change from what I had. Double checked the voltages, but it almost seemed a bit worse than before (but close enough, I'm figuring it's still the same).

    I figure the only next step is to return these boards and get the logic. Unfortunately, this one isn't returnable, so I'll be parting out the tv if this doesn't work, as I'm out of ideas and ways to test at my level....
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Thanks guys!

    I was wanting to point at the logic, but had no clue on how to test it aside from getting a known good one (which isn't a cheap option).

    So, just to understand better, heating the logic/main will help it to work better? I thought heat would help it fail faster? The first bmp on the second post has a thermal image of the main while operating. There are some hot chips on there!

    Just wanted to clarify before I test it out.

    Also, I ordered a y and...
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    Last edited by ranergeo; 03-12-2018, 10:26 AM. Reason: Added the thermal pics of the logic board

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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Thanks for the manual sections, that's great to finally have!

    The second video is from the service menu, as I scroll between different test patterns that make the "slow to light" symptom easy to see (when I switched between black to color areas, many colored pixels would stay black, and slowly fill in with the color. I would go back and forth between them and it would do that consistently.)

    The color pics from my second post are from the test pattern off the logic board. Although...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Thanks Moreno! That's why I grabbed it when I saw it!

    I did check Vsc (on the Y sus) and the Ve (on the x-main, which I'm figuring you're speaking of when talking of the z-board), and the Vsc was only off .5vdc, and there was no Ve spec, although I measured it at something around 90vdc.

    There is white sparkling on a black screen, and sometimes there are blue green relics on very dark scenes, but I wasn't able to capture them with my camera well enough to post.

    To get the...
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Has anyone at least experienced slow pixel fill in, or know of a previous post that may have dealt with such an issue? I'm grasping at straws and would prefer not to simply throw boards at it
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  • Re: Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    The first set of pictures above will show the basic layout of the tv... along with a couple pics of the trouble spots. The first set of colored pics below is from me taking pics at the upper left corner as the tv went through the logic board test patterns. I don't think it ever power cycled during this test, but since it goes straight to the colors without a startup screen, it was hard to tell since I wasn't always looking at it...

    Here's a link to the first video I took. It's just something off amazon...
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    Last edited by ranergeo; 03-10-2018, 03:24 PM.

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  • Samsung PN51F8500 - Power cycle, pixel maldischarge... HELP!

    Alright, this is going to be lengthy to a degree, as I'm pretty stumped since I haven't been able to find a solution after sifting through the forums for the last 2 weeks for what's happening. Here's the backstory.,,

    Picked this up a couple of weeks ago on CL with a "burn in" band on the top, supposedly from the dad watching a bit too much MSNBC (you'll see it in some of the ghosting). As I was loading it into the car, he threw in a, "Oh, and it liked to turn off about every 2 hours..." After getting it home, I plugged it in and it powered on, although there...
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  • Re: Samsung plasma PN51D550 "red mist" pixels

    So I decided to simply go ahead and try tweaking the yrr and yfr by getting a factory test pattern up that showed some red misting on the white and green pixelization on the black.

    Going by Tom66's recommendation, started with yrr and made small increments either way (after marking the pot first). I noticed no discernible change in picture quality, but found the pot to already be in the full clockwise position. I'm not sure if that's low or high voltage without looking at a scope, but it's something I noticed....
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  • Re: Samsung plasma PN51D550 "red mist" pixels

    Thanks! That helps explain it much better! I'll grab a scope from work on Monday, since we use them to test car electronics periodically. Sorry, "trace" is used by one of our manufacturers to refer to the lines the scope can produce over a channel, and I originally thought I would need to trace BOTH yrr and yfr individually. However, the post you sent shows a single form with both patterns. I'll try to clean up my terminology in the future

    Thanks again for the help, I'll post back once I...
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