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High frequency strobe effect, then blank screen.

by constantoss / November 20, 2011 12:49 AM PST

This began about 3 weeks ago on my LN46C750 TV. It's about 11 months old (whew). The screen image began a smooth, high frequency flicker effect, like an old style movie. It began with scene cuts, like to a commercial, and persisted until the tV was cycled off/on. It got more and more frequent, and then all the time, regardless of the source of input, and regardless of settings. Then, the right side of the screen darkened, and finally the whole thing went black. There was no sound effect, and sound remained normal to date. Also, no effect on Cable box upgrade or on modifying the cables. This appears to be entirely within the TV. Other posts suggest it may be due to the video power board. I'm expecting service on it this tuesday, and hope it's an easy fix. If it's that capacitor thing, I'd be surprised as there is no clicking thing going on, and the image had degraded in steps, not all or none. More data to follow.

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All Answers

Best Answer chosen by constantoss

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High frequency strobe effect, then blank screen.
by Samsung_HD_Tech Samsung staff / November 21, 2011 3:08 AM PST

constantoss -

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HDTECH
by tampascene / November 21, 2011 3:26 AM PST

HD Tech -

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HDTECH
by Samsung_HD_Tech Samsung staff / November 21, 2011 7:59 AM PST
In reply to: HDTECH

tampascene -

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Follow up to my own post
by constantoss / November 22, 2011 6:25 AM PST

First, to Tampa scene: buzz off my post! Next, follow up to service call. The guy was a seasoned veteran. He opened the back, and took me on a tour of the 3 boards: The low voltage input/logic board, connected with a ribbon cable to two other boards: the high voltage board, which took the logic boards input and powered it up to control the picture (this is likely the problem child), and another board, which was shielded by a perforated metal cover, which I think drives the speakers. Not a problem there. So, back to the high voltage board. He started by simple tapping it with a tool, to see if there were simple loose connections. Surprisingly, that helped a bit. Took the TV from a blank screen to a flickering one, but that only lasted a few moments, then blank again. He checked voltage output, and found several connection to the screen were very low, or ZERO. Next he removed the board, and visually inspected it for bad solders, tried fixing some know areas of problems. No benefit. Finally, decided to switch it out with new one. Based on my forum research, that's what I would have done. The board prices out about 85 bucks, but this is under warrantee, so I'll wait for the replacement and see. For those with the clicking problem, with the leaky capacitors, that was NOT the problem here. All capacitors appeared OK. So, I'll check in again when the new video/power board arrives.

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video problem solved!
by constantoss / December 3, 2011 3:53 AM PST

Well. Let's see.... OK, first, I lost all video regardless of source. Next, repair guy shows up, and removes the power board, and says he'll have a new one sent. This is the board that had all the capacitor problems, though mine were fine. As it turns out, I received 2 replacement boards: the power board: BN44-00341B, and another one, the shielded one at the bottom, between the two speakers. This is a pure logic board, and i think it runs the video somehow. only ICs and SMDs and the like. No hi voltage stuff. Anyway, I replaced that board first, and got my picture back! However, no sooner had I cheered, that the video started the high frequency flicker again, though no other video abnormalities occurred. So, I then changed out the power board, and VOILA! All better! So, apparently, I had 2, yes 2 defective boards! Now what? Get extended warrantee? I hate those, they're a scam! But, I really have no way to identify where the defect is if something goes wrong! Hmmmm, Catch-22! So, now my question is what happens to the warrantee now that there has been a repair? Well, hopefully I won't have to post here again, because if I do, it's because something else broke!!! Happy Holidays All.

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video problem solved!
by Samsung_HD_Tech Samsung staff / December 5, 2011 1:08 AM PST
In reply to: video problem solved!

constantoss -

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