Samsung PN64H5000 flickering magenta problem

[meeotch]

My 6 year-old Samsung PN64H5000 plasma t.v. has developed a flickering problem recently. It primarily manifests as a magenta color that flickers on and off. It's most visible in areas that are blurred / low contrast / subtle gradients. But it's also visible as a very slight brightness flicker in other scenes, even when the magenta cast isn't present. It happens most in bright scenes, but not always. It's also intermittent - it will sometimes go away for several minutes.

I'm sure it's not the cable, the video source, the files being played, or the HDMI input, having switched out each of these with no improvement. I've also tested changing every picture setting, turning on/off all the various processing features, resetting to defaults, etc. Lowering the brightness / "cell light" level reduces it, as does bringing up the t.v.'s menu display, but neither eliminates it. Interestingly, it continues even when the video source is paused.

It's difficult to capture with a phone camera, but this below is my best attempt. You can see the magenta cast in the brighter areas. Also typical is magenta flicker in the "fringing" around objects, where the focus shifts from sharp to blurry. Additionally, when the effect is present, I'm able to see burn-in from the on screen video playback controls more strongly.

Also, for a year or so previously, the t.v. exhibited periodic rapid flicker between image and total black when a scene switches from dark to light. Turning it off and on again would clear the flicker, and I could re-watch those scenes with no problem. But that symptom seems to have lessened / disappeared after this new magenta flicker started.

I did find threads about samsung "pink banding" elsewhere, but the models mentioned, and the logic.bin files supplied, do not match my model. (Also, the magenta I see is not typically in a band, but in arbitrarily shaped areas.)

I found a thread with an image that closely matches my symptom. However, my firmware is 1006.0, which is the most recent listed on the samsung site, so I can't apply the suggested fix: https://www.avsforum.com/threads/sam...dging.1971929/

I'm trying to determine whether this is a sign the t.v. is just failing (after only 6 years?), or if it's something that's likely to be repairable.

[dick_barton]

It may be worth inspecting your circuit boards for any poor joints that have aged / cracked over the years especially around any coils or heatsinked components.

Also check the voltages as given on the label at the rear of the plasma panel match the voltages read at the test points.

[William1967]

Because the screen is dated, you can get such image errors. The software in the logic board can no longer sufficiently compensate for the image. Sometimes it helps to change the VS voltage a bit but the wear on the screen remains, the problem can only become less visible.

[meeotch]

Thanks for the reply. I did a quick google for test point locations, but didn't come up with anything for my model. Is there a source you could point me to for such info?

[dick_barton]

Post some good quality photo's of your circuit boards and the white label.

[crt man]

Originally Posted by William1967

Because the screen is dated, you can get such image errors. The software in the logic board can no longer sufficiently compensate for the image. Sometimes it helps to change the VS voltage a bit but the wear on the screen remains, the problem can only become less visible.

Sorry to highjack thread, but do you turn VS voltage up or down.
I have a Samsung Ps51d8000 with the same problem but with a
blueish spodge in th center plus alot of screen burn
Thanks
Alan.

[Th3_uN1Qu3]

Turn VS up by 2 volts, turn the contrast up as high as it will go without clipping the highlights which is usually going to be between 93 to 97, turn -Vy and Vscan down a bit and adjust Set_up and Set_dn on the No Signal screen for deepest black until you get a small amount of sparklies uniform across this screen. The No Signal screen is "blacker than black" levels and you will not get this level under normal program content, and even if you do, the only thing that needs to be done is turning the brightness up by 1 click in the regular picture menu.

[meeotch]

Minor update: while watching t.v. last night, it powered off/on/off a few times in succession, then refused to turn back on. I tried the unplug / hold power button gag, but now when I plug it in, it clicks five times and still refuses to power on.

Managed to wrangle it onto the couch and pull the back off, and didn't seen anything obviously burned, nor bulging caps. Will post photos tomorrow.

[meeotch]

Here are the board images. The power board appears to be a bn44-00690B, and is the source of the clicking noise when first plugged in.

I'll post a separate thread about the new won't-power-on problem, but if anyone's still watching this thread and spots something, feel free to post here.