Originally Posted by rob80b
My biggest concern is that I’m seeing folks jump right in without fully understanding the technical consequence of each adjustment, each panel has been measured by LG for their optimum voltage and the VS (highest voltage) and VA (lowest voltage) is marked individually on each set.
The Set_up is clearly indicated in the service manual as the main adjustment for the APL
I've not read the manual but it actually says this?
From my understanding of PDP driving the following makes more sense:
VA = Voltage Address = bottom electrode of cell (vertical)
VS = Voltage Scan = top two electrode(s) of cell (Horizontal)
Set_Up = Reset/Initialization ramp up waveform
Set_Down = Reset/Initialization ramp down waveform
The Set_Up should produce a strong discharge that essentially overcharges all cells and then the Set_Down produces a discharge that removes the charge to a value that is well below the discharge start voltage. At this point all cells are "reset" or "initialized" and ready for addressing.
Messing with Set_up/down messes with both the wall charge and priming electon generation which both affect pixel control.
and will probably vary from panel to panel in conjunction with the minimum voltage required for pixel (panel) discharge, while the other pots affect timing etc; most are realizing that one voltage adjustment has consequences on an other in order to achieve the deepest black without introducing pixel misfires or other artefacts.
For proper panel illumination, I would believe that if there is a bit of tolerance to achieve a deeper black outside the factory configuration, then it would only be a matter of proportionately increasing the wave-forum size and timing, within certain limitations of course, and could be easily dialed in with proper equipment, an oscilloscope and voltage meter to be specific as I mentioned earlier on when starting this thread.
As it stands now the majority are doing it on the fly with hit and miss results.
Another concern when I first picked up on this was the effect on the gray-scale, color and the gamma which I believe is LG's strong point but from tweaking my PG25 it looks as if only the MLL was affected which is good thing. I'll be practicing on the PG25 a bit more before dialing in my PX950 and most likely to use a scope in aiding the process.
Like I tried to state in the other thread, when you adjust the "Reset" waveform (ie - Set_Up/Down) you have probably put the panel into a condition where under very specific circumstances (APL, temp, pixel on time, age..etc) some pixels will lose all control and either fire or not fire when asked to. In other words, your panel will work perfectly fine (with the lower black level) until a specific condition is met (even for a moment) and then you may see misfires.
This is due to many factors such as dishcarge delay, discharge probability and wall charge bleed that are all directly addressed via the "reset" waveform.