Samsung Plasma Panel tweaks for better blacks. - Page 14 - AVS Forum
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post #391 of 395 Old 10-17-2014, 09:55 AM
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Originally Posted by zoyd View Post
Here are the results of voltage tweaks on a 60F8500. Adjustments are available for Vs, Va, Vscan and Ve but only Vs and Vscan were found to have any effect on black levels.

Turning Vs down from the preset value of 209 to 190 volts reduced the black level for higher APL scenes and reducing Vscan from the preset value of -200 to -190 volts reduced the low APL scene blacks. The net reduction was 15%-20%

Other findings:
  • Reducing Vs also reduces peak white (about 10% in this case).
  • 24Hz playback with CS on has the best black level performance.
This is really cool Zoyd. Thanks for posting...it must have taken quite a while to run through all those measurements!

So I guess my F5300 APL measurements that I shared on the other thread did incorporate the benefit of MLL at higher APL from dropping Vs to the lowest possible value. It's also interesting to note that CS ON with 24Hz playback provides the best black level. I wonder why that is. Your findings might also explain the discrepancy in black levels measured by different folks on this set as some are measuring almost 2X the black level I get on a black screen and that could very likely be attributed to the difference between CS ON v/s OFF.

One thing you might want to check if you retained your Vscan tweak -> Try pulling up an all black screen. Then quickly pull up a white window. You should see the individual pixels firing up to turn white. This usually happens quite rapidly, but when I was experimenting with my F5300, I found that dropping Vscan led to longer turn-on times for some of the pixels. As a result, in certain intro scenes in movies or when using my HTPC, I could actually see artifacts with missing black pixels that are still waiting to turn on. That's why I set Vscan back to the recommended value. In my case, I am measuring ~ 0.007 cd/m2 black level so I don't really think I can benefit too much more with Vscan, but maybe I could drop down to ~0.0015 ftL from 0.0026 at the moment.
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post #392 of 395 Old 10-17-2014, 10:19 AM - Thread Starter
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Originally Posted by orion2001 View Post
This is really cool Zoyd. Thanks for posting...it must have taken quite a while to run through all those measurements!

It's also interesting to note that CS ON with 24Hz playback provides the best black level. I wonder why that is. Your findings might also explain the discrepancy in black levels measured by different folks on this set as some are measuring almost 2X the black level I get on a black screen and that could very likely be attributed to the difference between CS ON v/s OFF.
I'm guessing that the reset pulse width is a bit shorter to accomodate 96Hz refresh, too bad Yrr is not available.

Quote:
One thing you might want to check if you retained your Vscan tweak -> Try pulling up an all black screen. Then quickly pull up a white window. You should see the individual pixels firing up to turn white. This usually happens quite rapidly, but when I was experimenting with my F5300, I found that dropping Vscan led to longer turn-on times for some of the pixels. As a result, in certain intro scenes in movies or when using my HTPC, I could actually see artifacts with missing black pixels that are still waiting to turn on. That's why I set Vscan back to the recommended value. In my case, I am measuring ~ 0.007 cd/m2 black level so I don't really think I can benefit too much more with Vscan, but maybe I could drop down to ~0.0015 ftL from 0.0026 at the moment.
I've seen the delayed turn-on effect with my D-series but only from a cold start, once the panel warmed up the artifacts were not present. I'll see how it goes with this one and dial it back if there are any problems.

edit: I've also only got 20 hours on the panel so things may need to settle a bit first.

Some other things of note in the service menu - there are entries for enabling support for ND adjustment and save/restore CAL values. This sounds to me like external calibration settings control which would be nice. I'll have to poke around and see if it leads anywhere.

The PVR function can be enabled (to record off the DTV receiver) in the extended service menu as well as adjusting movie mode WB.

Last edited by zoyd; 10-17-2014 at 10:32 AM.
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post #393 of 395 Old 10-20-2014, 05:40 PM
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Are there any voltage adjustments that I can make to a PN43F4500? I looked on the board on the right side and there are only two places to make adjustments.
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post #394 of 395 Old 10-23-2014, 03:05 AM - Thread Starter
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What were they labelled? Your power supply board has the Vs resistor which you can adjust and your X/Y sustain board has a Yr5000 adjustable resistor. You'd have to test what effect that adjustment has, if it's a ramp adjustment like Yrr that would be good.
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post #395 of 395 Old 10-23-2014, 03:23 PM
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Good infRmation
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